Omega MDM300 User guide

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MDM300

Advanced Dew-Point Hygrometer

User Manual

97122 Issue 16.2

June 2022

Page 2

Please ll out the form(s) below for each instrument that has been purchased.

Use this information when contacting Michell Instruments for service purposes.

Product Name

Order Code

Serial Number

Invoice Date

Installation Location

Tag Number

Product Name

Order Code

Serial Number

Invoice Date

Installation Location

Tag Number

Product Name

Order Code

Serial Number

Invoice Date

Installation Location

Tag Number

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MDM300

Advanced Dew-Point Hygrometer

For Michell Instruments' contact information please go to

www.michell.com

This document is the property of Michell Instruments Ltd and may not be copied or

otherwise reproduced, communicated in any way to third parties, nor stored in any Data

Processing System without the express written authorization of Michell Instruments Ltd.

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MDM300 User Manual

Contents

Safety ...............................................................................................................................vii

Electrical Safety .........................................................................................................vii

Pressure Safety ...........................................................................................................vii

Toxic Materials ............................................................................................................vii

Repair and Maintenance .............................................................................................. vii

Calibration .................................................................................................................. vii

Safety Conformity .......................................................................................................vii

Abbreviations .................................................................................................................... viii

Warnings .......................................................................................................................... viii

1 INTRODUCTION ................................................................................................1

1.1 Controls and Indicators ....................................................................................... 3

1.2 Function Keys ..................................................................................................... 5

1.2.1 Enter Key ..................................................................................................... 5

1.2.2 Up () and Down () Keys ........................................................................... 5

1.2.3 Right () Key ............................................................................................... 5

1.2.4 Left () / Escape Key .................................................................................... 5

1.3 Instrument Display ............................................................................................. 6

1.3.1 Display Units................................................................................................. 7

1.3.2 Status Display Indications .............................................................................. 8

2 INSTALLATION ..................................................................................................9

2.1 Safety ................................................................................................................ 9

2.2 Unpacking the Instrument ................................................................................... 9

2.3 MDM300 Accessories ........................................................................................ 10

2.4 Operational Requirements ................................................................................. 12

2.4.1 Environmental Requirements – MDM300 Instrument ...................................... 12

2.4.2 Charger Electrical Requirements ................................................................... 12

2.5 Instrument Gas Connections ............................................................................. 12

2.5.1 Gas Inlet /Outlet Fittings ............................................................................. 13

2.6 Connect External Transmitters ........................................................................... 14

2.6.1 Set-Up Pressure Transmitter Parameters ....................................................... 14

2.6.2 Set-Up External Temperature Transmitter Parameters .................................... 15

2.6.3 Set-Up External Dp (Easidew) Transmitter Parameters ................................... 15

2.6.4 Entering User Pressure ................................................................................ 16

2.6.5 Connecting your own Temperature or Pressure Transmitter ............................ 16

2.7 Battery Charging .............................................................................................. 17

3 OPERATION ....................................................................................................19

3.1 Preparation for Operation .................................................................................. 19

3.2 Instrument Start-Up ........................................................................................ 20

3.3 Overall Menu Structure and Operation................................................................ 21

3.3.1 SET-UP Menu .............................................................................................. 21

3.3.2 Chart Page ................................................................................................. 21

3.4 SET-UP Menu Parameters .................................................................................. 23

3.4.1 SETTINGS .................................................................................................. 23

3.4.2 LOGGING ................................................................................................... 24

3.4.3 BLUETOOTH ............................................................................................... 25

3.4.3.1 Bluetooth Pairing Procedure ................................................................... 26

3.4.4 EXTERNAL (Sensor Interface) ..................................................................... 27

3.4.5 CLOCK ....................................................................................................... 28

3.4.6 HMI ........................................................................................................... 29

3.4.7 INFO .......................................................................................................... 30

3.4.8 CHART Page ............................................................................................... 30

3.4.9 LOG FILES Page .......................................................................................... 31

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MDM300 User Manual

3.4.10 LOGS Page ................................................................................................. 31

3.4.11 CALIBRATION ............................................................................................. 32

3.5 Default Parameters ........................................................................................... 33

3.6 Guide to Measurement and Sampling ................................................................. 34

3.6.1 Measuring at Atmospheric or System Pressure .............................................. 35

3.6.2 Measurement Guide .................................................................................... 36

3.6.3 Conditional Sensor Purge ............................................................................. 38

3.7 Battery Management ........................................................................................ 38

3.7.1 Battery Troubleshooting ............................................................................... 38

4 GOOD MEASUREMENT PRACTICE .....................................................................39

4.1 Sampling Hints ................................................................................................. 40

5 APPLICATION SOFTWARE ................................................................................43

6 CALIBRATION ..................................................................................................44

6.1 Traceability ...................................................................................................... 44

6.2 Calibration Method ........................................................................................... 45

6.3 Calibration Correction Method ........................................................................... 46

6.3.1 Easidew Oset Adjustment .......................................................................... 47

6.3.2 Easidew One Point Adjustment ..................................................................... 48

7 SHIPPING .......................................................................................................49

Tables

Table 1 Controls and Indicators ................................................................................4

Table 2 Instrument Display Descriptions ...................................................................6

Table 3 Adaptor Fittings ......................................................................................... 12

Table 4 SETTINGS Parameters ...............................................................................23

Table 5 LOGGING Parameters ................................................................................ 24

Table 6 BLUETOOTH Parameters ............................................................................ 25

Table 7 EXTERNAL Sensor Parameters .................................................................... 27

Table 8 CLOCK Parameters .................................................................................... 28

Table 9 HMI Parameters ........................................................................................ 29

Table 10 MDM300 Default Parameters ......................................................................33

Table 11 MDM300 Measurement Procedures ............................................................. 36

Table 12 Example Of Calibration Run Readings ..........................................................45

Table 13 Status Register Flags ................................................................................. 55

Appendices

Appendix A Technical Specications ..............................................................................51

A.1 Dimensions ................................................................................. 52

Appendix B Datalog Status Display ...............................................................................54

Appendix C FCC Declaration ......................................................................................... 57

Appendix D Quality, Recycling, Compliance & Warranty Information ................................59

Appendix E Return Document & Decontamination Declaration ........................................ 61

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MDM300 User Manual

Figures

Figure 1 MDM300 Advanced Dew-Point Hygrometer ...................................................2

Figure 2 User Connections, Controls and Indicators ....................................................3

Figure 3 Instrument Display .....................................................................................6

Figure 4 Packing Method ..........................................................................................9

Figure 5 Gas Port Adaptors ....................................................................................10

Figure 6 Accessories ..............................................................................................11

Figure 7 Bonded Seal Fitting ..................................................................................13

Figure 8 Gas Coupling Examples for Atmospheric Pressure Measurement ...................13

Figure 9 External Transmitter Connection ................................................................14

Figure 10 Typical External Pressure Display ...............................................................14

Figure 11 Typical External Temperature Display .........................................................15

Figure 12 Typical External Dew-Point Display .............................................................15

Figure 13 P/N MDM-27767 .......................................................................................16

Figure 14 Battery Charger Connection ......................................................................17

Figure 15 Start-Up Sequence ...................................................................................20

Figure 16 Menu Structure ........................................................................................22

Figure 17 SETTINGS Page ........................................................................................23

Figure 18 LOGGING Page .........................................................................................24

Figure 19 BLUETOOTH Page ....................................................................................25

Figure 20 Typical Bluetooth Pairing Sequence ............................................................26

Figure 21 EXTERNAL SET-UP Page ............................................................................27

Figure 22 CLOCK Page .............................................................................................28

Figure 23 HMI Page .................................................................................................29

Figure 24 INFO Page ...............................................................................................30

Figure 25 CHART Page .............................................................................................30

Figure 26 LOG FILES Page .......................................................................................31

Figure 27 LOGS Page ...............................................................................................31

Figure 28 CALIBRATION Page ..................................................................................32

Figure 29 Easi-Fit Sample Kit MDM300 Panel-Mount Sampling System .........34

Figure 30 Large and Small Orice Fitting ...................................................................35

Figure 31 Material Permeability Comparison ..............................................................39

Figure 32 Typical Application Software Screen ...........................................................43

Figure 33 Typical 7-point Calibration Certicate .........................................................44

Figure 34 Calibration Page .......................................................................................46

Figure 35 Calibration Menu Page ..............................................................................46

Figure 36 Easidew Oset Adjustment ......................................................................47

Figure 37 Easidew Single Point Adjustment ...............................................................48

Figure 38 Instrument Packing Details ........................................................................49

Figure 39 Dimensions ..............................................................................................52

Figure 40 Current Datalog File Display ......................................................................54

Figure 41 MDM300 Status Register ...........................................................................54

Figure 42 MDM300 Status Register (Hex 28) .............................................................54

vi 97122 Issue 16.2 June 2022

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MDM300 User Manual

Safety

The manufacturer has designed this equipment to be safe when operated using the procedures detailed in this manual. The user must not use this equipment for any other purpose than that stated. Do not apply values greater than the maximum value stated.

This manual contains operating and safety instructions, which must be followed to ensure the safe operation and to maintain the equipment in a safe condition. The safety instructions are either warnings or cautions issued to protect the user and the equipment from injury or damage. Use competent personnel using good engineering practice for all procedures in this manual.

Electrical Safety

The instrument is designed to be completely safe when used with options and accessories supplied by the manufacturer for use with the instrument. The instrument is powered by an internally mounted rechargeable battery - this battery should never be allowed to fully discharge. The input power supply voltage limits for the battery charger supplied with the instrument are 90...264 V AC, 50/60 Hz.

NOTE: No other battery charger unit, other than that supplied with the instrument should be used.

NOTE: Do not allow the battery to fully discharge.

Pressure Safety

DO NOT permit pressures greater than the safe working pressure to be applied to the instrument. The specied safe working pressure (SWP), for this instrument is 350 barg (5076 psig).

Toxic Materials

The use of hazardous materials in the construction of this instrument has been minimized. During normal operation it is not possible for the user to come into contact with any hazardous substance which might be employed in the construction of the instrument. Care should, however, be exercised during maintenance and the disposal of certain parts.

Repair and Maintenance

The instrument must be maintained either by the manufacturer or an accredited service agent. Refer to www.michell.com for details of Michell Instruments’ worldwide oces contact information.

Calibration

The recommended calibration interval for the MDM300 is 12 months. The instrument should be returned to the manufacturer, Michell Instruments Ltd., or one of their accredited service agents for re-calibration.

Safety Conformity

This product meets the essential protection requirements of the relevant EU and UK directives. Further details of applied standards may be found in Appendix D.

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Abbreviations

The following abbreviations are used in this manual:

AC alternating current atm pressure unit (atmosphere) barg pressure unit (=100 kP or 0.987 atm) gauge bara bar absolute °C degrees Celsius °F degrees Fahrenheit K Kelvin (absolute temperature) COM common DC direct current ft foot (feet) Hz Hertz kg kilogram(s) lb pound Nl/min liters per minute m meter(s) mA milliampere Mb megabytes max maximum min minute(s) mm millimeter(s) MPa megapascal No. number PIN personal identication number ppmV parts per million (by volume) ppmW parts per million (by weight) psig pounds per square inch scfh standard cubic feet per hour SWP safe working pressure sec second(s) V volts

MDM300 User Manual

Warnings

The following general warning listed below is applicable to this instrument. It is repeated in the text in the appropriate locations.

Where this hazard warning symbol appears in the following

sections it is used to indicate areas where potentially

hazardous operations need to be carried out.

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MDM300 User Manual

1 INTRODUCTION

The MDM300 Advanced Dew-Point Hygrometer is a portable instrument designed for on-line measurement of moisture content in non-corrosive gases over an operational range of

-100 to +20 °C (-148...+68 °F).

The instrument is contained within a steel ber-loaded high-impact polyamide 6 case, sealed to IP66 / NEMA4 standard and is powered by an internally mounted Nickel Metal Hydride (NiMH) battery, designed to typically provide 48 hours continuous use between charges. Continuous battery charge status indication is provided. Additional battery status information is provided by a battery indicator icon, in addition to a warning beep and Shutdown Mode.

The MDM300 is tted with an internally mounted ceramic sensor, which is enhanced for a quicker response to dew points as dry as -75 °Cdp (-103 °Fdp).

A 4...20 mA current loop input is provided, which can be programmed to interface with a number of dierent external transmitter inputs.

INTRODUCTION

• Pressure range 0...350 barg (0...5076 psig)

• Temperature range -100...+100 °C (-148...+212 °F)

• Dew-point (Easidew transmitter) range -100...+20 °C (-148...+68 °F)

A graphical display presents the dew-point data in large format characters and simultaneously provides a primary display of real time dew-point readings and a secondary display, in smaller characters, for the external sensor input. If no external input is programmed, gas temperature (measured by the internal sensor) is displayed by default.

A fully programmable, real-time, datalogging facility is provided which has an internal memory capacity of 8Mb, capable of storing up to 10,000 logs per le (typically giving a maximum of 64 log les).

A Bluetooth, wireless, communication system is provided, giving access to a dedicated, PC based, MDM300 Software Application Package which provides the facility for handling the logged data les and uploading and downloading instrument parameters.

A user-friendly operator interface provides easy access to all levels of the instrument’s functionality.

An easy-to-follow calibration routine is built into the instrument’s software.

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INTRODUCTION

Two versions of the instrument are available, an MDM300 (standard) version and an MDM300 (intrinsically safe) version.

This manual covers the MDM300 version only.

For information about the MDM300 I.S. contact your local Michell Instruments’ representative (contact information at www.michell.com).

MDM300 User Manual

Figure 1

MDM300 Advanced Dew-Point Hygrometer

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MDM300 User Manual

1.1 Controls and Indicators

The controls and indicators associated with the MDM300 instrument are located on the front panel of the instrument.

Connections to the MDM300 dew-point hygrometer, comprising the gas ports, battery charger input connector and input connector for the external sensor are all made to the top panel.

INTRODUCTION

Figure 2

operational functions.

shows the layout of these controls and Table 1 describes their respective

Figure 2

User Connections, Controls and Indicators

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INTRODUCTION

Item Panel Description

MDM300 User Manual

1 Front

2 Front

3 Top

4 Top Gas Output port. Refer to Section 2.5.

5 Top Gas Input port. Refer to Section 2.5.

Function keys. Refer to Section 1.2 for the details of these keys.

Instrument display, partitioned to show 3 main panels:

The primary display shows internal sensor parameters.

The secondary display indicates the external sensor parameter.

The status display area shows icons representing battery charge state, initialization in progress, data logging in progress, keyboard lock status and keyboard beep status.

Instrument ON/OFF switch.

NOTE: The instrument does not need be switched ON in order to charge the internal NiMH battery.

Analog input connector for external sensor (pressure, temperature or dew point).

6 Top

7 Top

By default, this signal is displayed in the secondary display area but may be congured to be displayed as the primary display.

Spans for each signal input are separately congurable (refer to Section 2.6).

If no external input is selected, the internal sensor temperature is shown, on the secondary display, by default (refer to Section 3.4.6).

Socket for connection of battery charger (located behind cover).

Table 1 Controls and Indicators

ONLY USE THE CHARGER PROVIDED

Never allow the battery to fully discharge

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MDM300 User Manual

1.2 Function Keys

The function keys, located on the front panel, are used to select operations from the menus and to select and enter parameter variables within those menu levels.

The function key described is shaded darker and the operation of the keys is as follows:

1.2.1 Enter Key

The Enter key is used within the menus to highlight and select options and to accept entered values.

Operation of this key from the Main Display causes the Passcode entry page (for entry to the SET-UP Menu) to be displayed.

1.2.2 Up () and Down () Keys

Within the SET-UP Menu and sub-menus these  and  keys are used to scroll down and highlight options.

INTRODUCTION

Within sub-menu levels requiring the entry of alpha numeric values, these keys are used to change the values. Pressing the key once increases or decreases the selected eld by one step. Pressing and holding the key will cause the selected eld to be continuously increased or decreased until the key is released.

1.2.3 Right () Key

Within sub-menu levels requiring the entry of alpha numeric values, this  key is used to shift the insertion point right in the le name entry eld.

From the Main Display, pressing this  key moves to the Chart Page.

From the Chart Page, pressing this  key moves to the Logging Pages.

1.2.4 Left () / Escape Key

Within sub-menu levels requiring the entry of alpha numeric values, this  key is used to shift the insertion point left in the le name entry eld. As the insertion point is shifted to the left, the entry at the former position is deleted.

Within any menu or sub-menu level, pressing this  key escapes to the previous menu above the current level.

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INTRODUCTION

1.3 Instrument Display

MDM300 User Manual

The graphics display and the associated function keypad ( interface of the equipment. after the instrument’s initialization period has completed.

Table 2 details the elements of the display:

Figure 3

shows all the elements of a typical display page

Dewpoint Internal

°C

6.9

12.7

°C Temp.

Measurement in progress

Figure 3

Item Description

Secondary display

Shows reading from external sensor, if congured; or internal temperature if external sensor is not congured (refer to Section 3.4.6).

Battery charge indicator icon

Flashes when the battery needs charging. A warning beep sounds when the

battery charge level is critical - followed immediately by Shutdown Mode.

NOTE: The icon becomes animated when the charger is connected. Keyboard beep indicator

Indicates that the keyboard beep is switched on.

Keyboard lock indicator

Indicates that the keyboard is locked.

Datalog status indicator

Indicates that logging is enabled and running.

Sensor initializing indicator

Indicates that the initialization process is in progress and that the sensor heating

is on. The presence of this symbol is accompanied by Initializing internal sensor status message.

Primary display

During normal operation, the internal sensor readings are shown in the

primary display. If the external sensor has been congured then this reading can be shown in this display (refer to Section 3.4.6).

8 Status message display area

Displays status and error messages.

Instrument Display

Figure 2),

1234678 5

form the operator

Table 2 Instrument Display Descriptions

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MDM300 User Manual

1.3.1 Display Units

The instrument can display the measured reading in the following units:

Absolute Humidity

INTRODUCTION

• g/m

Moisture Content

• ppm

• ppmW (AIR, USER, SF6, CO2 or N2)

Dew point

• °C

• °F

• K

Relative Humidity (%)

Mixing Ratio

• g/kg (AIR, USER, SF6, CO2 or N2)

To toggle between displayed units, press either the  or  key.

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INTRODUCTION

1.3.2 Status Display Indications

‘Initializing Internal Sensor’

This is displayed immediately after the instrument has been powered up, and indicates that the sensor is being heated up to accelerate equilibrium with the moisture in the sample gas. This has the eect of drying the sensor out, and results in the ‘undershoot’ seen in the rst stage of the measurement process.

‘Measurement in Progress’

This is displayed after the sensor initialization has nished, and indicates that the sensor is running through the following initial measurement procedure:

1. Undershooting the dew-point

2. Making a rst estimate

3. Running a QRA (Quick Response Algorithm), if necessary

MDM300 User Manual

Once the message has disappeared, this indicates that the instrument has nished its accelerated approach to the actual dew point. Depending on the conditions it may continue to respond for a number of minutes more, before settling on (or tracking) the actual measured dew point.

Other Status Display Indications

Internal sensor error

Internal thermistor error

External sensor error

Battery low Battery low -

recharge now

Log nished

Internal sensor not found

Default CONFIG le used

Dew-point reading out of range (> +30 / < -120 °C)

Sensor internal temperature reading out of range (> +100 / < -40 °C) or Thermistor fault

External sensor input out of range (< 4 mA / > 20 mA)

Battery level low - recharge as soon as possible

Battery level critical - recharge immediately

Log le has reached the maximum of 10,000 logs and logging has been stopped

Could not detect internal sensor on power up

Cong. le missing, new le created and default settings used

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MDM300 User Manual

2 INSTALLATION

2.1 Safety

It is essential that the installation of the electrical and

2.2 Unpacking the Instrument

The MDM300 instrument is packed into a standard box and the method of unpacking is shown below:

gas supplies to this instrument be undertaken by qualied

INSTALLATION

personnel.

Figure 4

1. Open the box (1) and unpack carefully.

2. Remove the MDM300 (2) and the accessories box (3).

3. Save all the packing materials for the purpose of returning the instrument for re-calibration or any warranty claims.

4. If the optional carry bag has been ordered it will be located underneath the foam insert, in a cardboard box.

Michell Instruments 9

Packing Method

Page 18

INSTALLATION

2.3 MDM300 Accessories

MDM300 User Manual

The accessories for the MDM300 are shown in standard and item 6 is optional. Please check that all the standard components are present after unpacking. Report any shortages immediately.

1. Calibration certicate

2. Charger unit

3. Country-specic mains lead

4. Gas Input/Output port adaptors

(three provided - two tted to the instrument - see

5. Quick-start card

6. Carrying case (optional)

Three gas port adaptors are provided, two with a large bore orice and one with a small bore orice. Depending upon conguration, this permits the instrument to be run at either system pressure or atmospheric pressure and facilitates the connection of external ow monitoring and control.

Figure 6

Figure 5)

. Items 1...6 are supplied as

NOTE: On delivery the two large orice adaptors are tted into the instrument’s

gas ports (1 and 2) as shown in as a loose spare in the accessory pack (see Section 2.5).

Figure 5

. One small orice adaptor is provided

Small orice

Large orice

2 1

Gas In Gas Out

Figure 5

Gas Port Adaptors

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MDM300 User Manual

INSTALLATION

Figure 6

Accessories

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INSTALLATION

2.4 Operational Requirements

Operational requirements are as follows:

Sample gas ow rate: 0.2...1.2 Nl/min (0.5...2.5 scfh)

Operating pressure: 0...350 barg (0...5075 psig)

2.4.1 Environmental Requirements – MDM300 Instrument

Operating temperature range: -20...+50 °C (-4...+122 °F)

Humidity: 0...100 % rh (non-condensing)

Altitude: Up to 2000 m (6562 ft)

2.4.2 Charger Electrical Requirements

Charger supply voltage: 90...264 V AC, 50/60 Hz

MDM300 User Manual

2.5 Instrument Gas Connections

POSSIBLE INJURY! The tubing, valves and other apparatus

attached to this instrument must be adequate for the

Sample gas connections are made via the Gas In (2) and Gas Out (1) ports located on the rear of the instrument as shown in

The MDM300 is supplied with a large bore orice tting installed into the Gas In and Gas Out ports. These ttings have an 1/8” NPT female thread to allow the user to connect other components of their choice.

Atmospheric pressure or system pressure dew point can be measured depending on the conguration of the adaptor ttings as shown in Table 3.

For gas pressures outside the range 2.5...10 barg, the instrument requires external ow control components, as shown in

Dew point at

Atmospheric Small bore orice Large bore orice

System Large bore orice Small bore orice

Either (using

other ow control

components)

maximum pressure which will be applied, otherwise physical

injury to the operator or bystander is possible.

Gas Inlet port

tting

Large bore orice Large bore orice

Figure 5

Figure 8.

Gas Outlet port

tting

Sample gas

pressure

2.5...10 barg

(36...145 psig)

2.5...10 barg

(36...145 psig)

0...350 barg

(0...5076 psig)

Table 3 Adaptor Fittings

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MDM300 User Manual

2.5.1 Gas Inlet /Outlet Fittings

HIGH PRESSURE! High pressure gases are potentially

hazardous. Energy stored in these gases can be released

Before making a measurement, the gas ttings should be attached to the instrument as shown in Table 3

1. Fit the required orice ttings with supplied bonded seals. Ensure bonded seals are correctly seated in recessed grooves.

suddenly and with extreme force. High pressure systems

should be assembled and operated only by people who have

INSTALLATION

been trained in proper safety practices.

- I.S.

PTFE tape here

Adaptor



1/8” Swagelok

tting



Figure 7



Bonded seal

Bonded Seal Fitting

2. Fit any other adaptors that might be required.

3. If the small bore orice tting is not being utilized then one of the optional application kits could be tted (as shown below).

Figure 8

Gas Coupling Examples for Atmospheric Pressure Measurement

NOTE: The application kit shown above (excluding the orice ttings) is not

supplied as standard, but is part of a range of kits which can be ordered from Michell Instruments, on request.

NOTE: The bonded seals used for the MDM300 are Dowty part number 400228-4490-74 (available from Michell instruments, part number MDM300-DS).

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INSTALLATION

2.6 Connect External Transmitters

Dew point, pressure and temperature sensors and connecting cable can be ordered from Michell Instruments or a local representative. The connector and cable can be ordered separately to allow connection to any 4...20 mA loop powered sensor.

MDM300 User Manual

External transmitters are plug-in devices and

Figure 9

External Transmitter Connection

Figure 9

To remove the transmitter, fully unscrew the locking collar (2) of the connector and withdraw the connector. Close the hinged protective cover (1) when the connector is not in use.

2.6.1 Set-Up Pressure Transmitter Parameters

shows the method of connection.

After adding a pressure transmitter, the following parameters must be dened. Switch on the instrument and initially set the required pressure units from the Settings Menu (refer to Section 3.4.1).

Using the EXTERNAL option from the SET-UP Menu, set up the instrument for an external 4...20 mA pressure transmitter input as follows. Refer to Section 3.4.4.

EXTERNAL TYPE Select PRESS EXTERNAL ZERO Enter Zero point (pressure represented by 4 mA input) EXTERNAL SPAN Enter Span (maximum pressure represented by 20 mA input) USER PRESSURE Auto set to OFF (instrument uses the measured pressure reading)

After completion of the above settings, return to the Main Display and the instrument will now display pressure in the secondary display area and the selected units.

An example is shown below:

Calc dp at pressure External

-36.9

°C

112.7

Psig Press

Figure 10

Typical External Pressure Display

The measured pressure will be used in the calculation of atmospheric equivalent or pressure dew point, moisture content and absolute humidity.

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MDM300 User Manual

2.6.2 Set-Up External Temperature Transmitter Parameters

After adding a temperature transmitter, the following parameters must be dened. Switch on the instrument and initially set the required DP/TEMP units to either °C, °F

or K from the Settings Menu (refer to Section 3.4.1).

Using the EXTERNAL option from the SET-UP Menu, set-up the instrument for an external temperature transmitter input as follows (refer to Section 3.4.4).

EXTERNAL TYPE Select TEMP EXTERNAL ZERO Enter Zero point (temperature represented by 4 mA input) EXTERNAL SPAN Enter Span (maximum temperature represented by 20 mA input)

After completion of the above settings, return to the Main Display and the instrument will now display temperature in the secondary display area and the selected units.

An example is shown below:

INSTALLATION

Dewpoint External

6.9

Figure 11

The measured temperature will be used to calculate Relative Humidity.

2.6.3 Set-Up External Dp (Easidew) Transmitter Parameters

After adding an external dew-point transmitter, the following parameters must be dened. Switch on the instrument and initially set the required DP/TEMP units to either °C, °F or K from the Settings Menu (refer to Section 3.4.1).

Using the EXTERNAL option from the SET-UP Menu, set-up the instrument for an Easidew transmitter input as follows (refer to Section 3.4.4).

Typical External Temperature Display

°C

12.7

°C Temp

EXTERNAL TYPE Select EASIDEW EXTERNAL ZERO -100 °C (DP TEMP represented by 4 mA input - can be reset) EXTERNAL SPAN 20 °C (DP TEMP represented by 20 mA input - can be reset)

After completion of the above settings, return to the Main Display and the instrument will now display pressure in the secondary display area and the selected units.

An example is shown below:

Figure 12

Calc dp at pressure External

-26.9

Typical External Dew-Point Display

°C

-25.7

°C dp

Michell Instruments 15

Page 24

INSTALLATION

GREEN

MDM300 User Manual

2.6.4 Entering User Pressure

The MDM300 can be programmed with a pressure to be used in the calculation of atmospheric equivalent or pressure dew point, moisture content or absolute humidity.

NOTE: Care should be taken to ensure that the entered pressure is correct as

it may have a considerable eect on the measurement.

Using the EXTERNAL option in the SET-UP Menu, set a user pressure as follows.

1. Scroll to USER PRESSURE.

2. Use the  and  keys to select either ATM (for atmospheric pressure) or the required pressure.

NOTE: The pressure units are selected in the Settings Menu.

2.6.5 Connecting your own Temperature or Pressure Transmitter

To connect your own 4...20mA temperature transmitter or pressure transmitter, the connector P/N MDM-27767 is required.

Wiring is shown below in gure 13.

If connecting an external temperature transmitter, refer to 2.6.1 for setup instructions.

For an external pressure transmitter, refer to 2.6.2 for setup instructions.

RED +POWER

GREEN

SIGNAL

(SOURCE)

VIEW ON REAR OF CONNECTOR

OUTER SHEATH

GREEN

RED

Figure 13

GREEN - 4-20Ma (SOURCE)

RED - +POWER

SOLDER BUCKET VIEW

P/N MDM-27767

RED

16 97122 Issue 16.2 June 2022

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MDM300 User Manual

2.7 Battery Charging

The MDM300 is powered from an internally mounted, rechargeable Nickel Metal Hydride (NiMH) battery. Typically, depending upon the instrument settings, the battery will typically provide up to 48 hours of continuous operation when fully charged.

A graphical display of battery charge state is provided and an audible warning is given as the battery approaches full discharge.

INSTALLATION

Figure 14

Connect an AC power supply, 90...264 V AC, 50/60 Hz, to the battery charger unit.

NOTE: The MDM300 instrument does not need to be switched on in order to charge the battery.

Battery Charger Connection

Michell Instruments 17

Page 26

INSTALLATION

The battery charger supplied is a ‘Smart’ charger.

MDM300 User Manual

WARNING: DO NOT use any other charger than that supplied

with this product.

The smart charger goes through three charging stages:

• pre-charge

• fast-charge

• trickle charge

If the battery has been damaged then the charger will not begin the fast-charge stage. Please contact Michell Instruments’ service department for advice.

Once the charger has nished the fast-charge stage it can be safely disconnected. Switch o the AC power supply, remove the charger unit and close the instrument’s charge connector protection cover.

A complete charge cycle will take 2 to 4 hours for a fully discharged battery.

The table below shows the dierent charging stages and durations.

The use of any charger other than that supplied for use will

invalidate the product warranty.

Stage / Charger

Pre-charge Flashes Orange Orange Up to 5 minutes

Rapid-charge Flashes Green (Fast) Red 2...4 hours

Trickle-charge Flashes Green (Slow)

Charging complete

FW 7219 Type

(Older)

Green Green N/A

FW 7219

Cell-con

(Newer)

Green, ashes

Orange

Duration

Indenite - Cell-con

One hour - FW

Cell-con

18 97122 Issue 16.2 June 2022

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MDM300 User Manual

3 OPERATION

extreme force. High pressure systems should be assembled

and operated only by people who have been trained in proper

POSSIBLE INJURY! The tubing, valves and other apparatus

maximum pressure which will be applied, otherwise physical

OPERATION

High pressure gases are potentially hazardous. Energy

stored in these gases can be released suddenly and with

safety practices.

attached to this instrument must be adequate for the

injury to the operator or bystander is possible.

3.1 Preparation for Operation

Before operation it is recommended that the user becomes familiar with Section 1 of this manual in which the equipment controls and indicators, and the elements of the display are described.

Prior to making a measurement, the instrument must have been connected to a sample gas stream, see Section 2.5.

It is recommended that the battery is charged before conducting any tests (refer to Section 3.7).

The instrument will have been set up with a number of factory default parameters. These default parameters are shown in Table 10, together with a reference to the relevant part of this manual which details the method of changing these default values.

Michell Instruments 19

Page 28

OPERATION

3.2 Instrument Start-Up

At switch on, the instrument goes through an initialization process lasting several minutes. During this time the internal sensor is heated to a maximum of +70 °C (+158 °F). The heating process increases the mobility of water molecules and accelerates equilibrium with the passing sample gas.

During this period the sample gas ow purges the system. After this period, the sensor will be dried to below the dew point of the gas to be measured. The heating is then switched o and the display becomes dynamic.

At switch-on, the System Initializing Page is displayed for several minutes during which the page will show a countdown of the remaining initialization time. NOTE:

The initialization stage is skipped if the initial dew point is detected to be within 2 °C of the dew point when the instrument was switched

o.

Figure 14

shows a typical start-up sequence.

MDM300 User Manual

MDM300

System Initializing

Internal

Initializing: 01:32

Initializing internal sensor

Dewpoint External

°C

6.8

Measurement in progress

Dewpoint External

°C

6.9

Figure 15

Start-Up Sequence

70.4

°C Temp.

70.3

°C Temp.

70.1

°C Temp.

During this period, gas will be owing through the sensor and can be externally regulated to meet the instrument’s ow requirements, and the real time sensor temperature is indicated in the secondary display area. The initializing icon (item 6 in

Figure 3)

is displayed in the status area and the keyboard is locked out until the initialization period has expired.

It is possible to terminate the initialization process before the initialization period has timed out by pressing the  and  keys simultaneously. This action aborts the instrument’s response enhancement system and allows the operator to make an immediate measurement if the measured dew point is wetter than -20 °Cdp (-4 °Fdp).

While the initialization process is in progress, the backlight time-out is inhibited and, if any external sensor has been congured and connected to the instrument, display of the external sensor reading is also inhibited.

After the end of the initialization period, the display reverts to Measurement Mode displaying dew point (in the currently selected unit) in the primary display area, and any external sensor reading in the secondary display area. By default, the internal temperature is displayed in the secondary display area if no external sensor is congured.

If an external sensor has been selected but has either not been connected or is giving an over-range indication, a ashing External Sensor Error message (alternating with a

Measurement in progress message) will be displayed.

While the Quick Response Algorithm is in operation a Measurement in progress message is displayed. After this, depending on the sample conditions, the instrument may continue to respond to the nal dew-point for a number of minutes. This is further explained in Section 3.6.

20 97122 Issue 16.2 June 2022

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MDM300 User Manual

3.3 Overall Menu Structure and Operation

3.3.1 SET-UP Menu

All instrument settings are made from the SET-UP Menu which is accessible from the Main Display by pressing the Enter key.

On the rst occasion after switch-on the Passcode Entry page will be displayed. Enter the passcode 7316 as follows:

1. With the rst digit of the passcode highlighted, enter the rst digit (7) using the  and  keys.

2. Press the Enter key to accept this entry and move to the next digit position.

3. Repeat this procedure until all the passcode digits have been entered. On successful entry of the last digit, the SET-UP Menu will be displayed.

NOTE: If the passcode is incorrectly entered, the passcode page remains displayed showing the entries that have been made. To accept any digit as correct

and to move to the next digit position, press the Enter key. Change the incorrect entry, using the  or  keys, and when the correct passcode has been entered, the SET-UP Menu will be displayed.

OPERATION

Within this SET-UP Menu, eight options are available: SET TINGS, LOGGING, BLUETOOTH,

EXTERNAL, CLOCK, HMI, CALIBRATION and INFO. For more detailed information on

these options refer to Section 3.4.

These options are selected by means of the  and  keys. Pressing the Enter key then provides access to a sub-menu which permits the variables associated with that option to be edited, as follows:

1. Press the  and  keys to highlight the required eld.

2. Press the Enter key to select the eld.

3. Press the  and  keys to edit the parameter value associated with that eld.

4. Press the Enter key to enter the new value.

Quit the sub-menu by pressing the  key and return to the SET-UP Menu. From the SET-UP Menu either select another sub-menu with the  key or press the  key to return to the Main Display.

3.3.2 Chart Page

The Chart Page is reached from the Main Display, by pressing the  key. The chart interval is set up under the SETTINGS Menu. For more information on the Chart Page refer to Section 3.4.8.

Pressing the  key when the chart is displayed will show either the Log Files (if Logging is not selected), or the current data Logs Page (if Logging is selected). If Logging is

not selected press the Enter key for a shortcut to the LOGGING Menu.

Where more than one page of data is available, the  and  keys are used to scroll up or down.

Michell Instruments 21

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OPERATION

MDM300 User Manual

Main Display (Primary, Secondary and Status

PASSCODE FOR

SETUP (on start-up

only)

=7316

PASSCODE

SET-UP

SETTINGS

LOGGING

BLUETOOTH

EXTERNAL

CALIBRATION

Scroll menu items

Windows)

Scroll to

Adjust Digit

YES

CLOCK

HMI

INFO

Scroll Unit

to view

To select

item

Chart page

(only if internal sensor

available)

Chart Reset Page

Scroll to

adjust digit

PASSCODE FOR CAL

=4876

PASSCODE

OK?

Scroll

and edit

previous screen

MDM300 CAL CORREC

EASIDEW OFFSET ADJ

EASIDEW 1 POINT ADJ

Files Page

Logs Page

To return to

PRIMARY DP AT

DP/TEMP UNIT

PRESSURE UNIT

GAS TYPE

MOL WEIGHT

CHART INTERVAL

FILE NAME

PARAMETER

LOG INTERVAL

START?

ENABLE

NAME

EXTERNAL TYPE

EXTERNAL ZERO

EXTERNAL SPAN

USER PRESSURE

YEAR

MONTH

DAY

HOUR

MIN

CONTRAST

BRIGHTNESS

KEY TONE

BL TIMEOUT

LANGUAGE

PRIMARY DISP.

To toggle

selection of

item

To select cal point

To adjust

value

CAL CORRECTION TABLE -100 to -60

CAL CORRECTION TABLE - 50 to -10

CAL CORRECTION

TABLE 0 to -20

LOGGING?

YES

menu items

YES

Enter Key

Left Right Keys

Figure 16

LEGEND

Up Down Keys

Menu Structure

INFO PAGE

EASIDEW

YES

FITTED

EASIDEW CAL PAGE

22 97122 Issue 16.2 June 2022

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MDM300 User Manual

3.4 SET-UP Menu Parameters

Follow the instructions in Section 3.3.1 to select the required parameters.

3.4.1 SETTINGS

OPERATION

PRIMARY DP AT ATMOS

DP/TEMP UNIT °C PRESSURE UNIT Psig GAS TYPE AIR MOL WEIGHT N/A CHART INTERVAL 5 Sec

Parameter Description

Indicates if the primary display sensor is at atmospheric or system

PRIMARY DP AT

pressure. Available Input: ATMOS or PRESS (Atmospheric or Pressure)

DP/TEMP UNIT

PRESSURE UNIT

Sets system temperature units. Available Input: °C, K, °F

Sets system pressure units. Available Input: psig, MPa, psia, bara, KPa, barg

Denes the sample gas type. NOTE: The MOL WEIGHT eld automatically reads N/A for

GAS TYPE

all gases other than USER.

For any other type of sample gas, the molecular weight of the gas must be dened in the MOL WEIGHT eld. Available Input: Air, USER, SF6, CO2, N2

MOL WEIGHT

CHART INTERVAL

Sets molecular weight of user-dened sample gas, default value 1. Available Input: Range 1 to 99

Sets chart time interval, default value 5. Available Input: Range 1 to 60 seconds

Figure 17

SETTINGS

SETTINGS Page

Table 4 SETTINGS Parameters

Michell Instruments 23

Page 32

OPERATION

3.4.2 LOGGING

The LOGGING Set-Up Menu can be accessed by pressing the  key three times from the Main Display. It can also be accessed through the SET-UP Menu.

MDM300 User Manual

FILE NAME

PARAMETER LOG INTERVAL START?

Parameter Description

Denes datalog le name. Field width up to eight alphanumeric characters.

NOTE:  key deletes characters

FILE NAME

NOTE: If a le name is not entered, a logging cycle cannot

be started.

Available Input: 0 - 9, A - Z (keying up and down will change the numbers to letters or vice-versa)

Sets parameter to be logged. This need not necessarily be the same

PARAMETER

as that displayed on the Main Display.

NOTE: Only one parameter may be logged at one time

Available Input: DEWP, GM3, GKG, RH, PPMW, PPMV, CALC DP

LOG INTERVAL

Sets log interval in 5 sec increments. Available Input: Range 5 to 600 seconds

Starts the log cycle after logging parameters are set-up.

NOTE: If a le name is not entered, a logging cycle cannot

START ?

be started.

Once logging has started, log le parameter elds are locked out and cannot be changed.

Available Input: STOPPED, STARTED

Figure 18

DEWP 5 STOPPED

Sec

LOGGING

LOGGING Page

Table 5 LOGGING Parameters

NOTE: If a duplicate le name has been entered an error message will be

shown when attempting to start logging.

A maximum of 64 log les can be stored in the instrument memory before

it is necessary to download or remove them. The START ? option will not be available if this limit is exceeded.

Cycling power will stop the logging.

24 97122 Issue 16.2 June 2022

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MDM300 User Manual

The size of any one log le is limited to 60kb. If the unit is left logging, and the le size exceeds 60kb, then the log le will nish automatically. To ensure that the log le you initiate collects all the data from your test, an

appropriate sample time should be chosen. The table below can be used as a rough guide:

Sample time (secs) Logging duration

OPERATION

5 3 hours 10 6 hours 30 18 hours 60 36 hours

100 60 hours 200 120 hours 400 240 hours 600 360 hours

3.4.3 BLUETOOTH

Bluetooth mode is used, in conjunction with a dedicated MDM300 application software package, for the purpose of uploading datalog les to a PC using a wireless connection. Within the PC the dedicated Michell application software package is used to upload the les to the PC’s desktop, from where they can be loaded into other programs, e.g. Microsoft Excel, for further examination and processing.

Parameter Description

ENABLE NO

NAME MDM300

Figure 19

BLUETOOTH Page

BLUETOOTH

Turns the Bluetooth facility on or o.

When Bluetooth is turned ON - a status message *in

ENABLE

Bluetooth mode* will be displayed. No other menu options

can be selected at this time and this page remains until the Bluetooth mode is cancelled by pressing the  key.

Available Input: ON or OFF Before enabling Bluetooth (above) set up a Bluetooth name (address)

for the instrument. Maximum eight alphanumeric characters. Default

NAME

name set is MDM300. Available Input: 0 - 9, A - Z (keying up and down will change the

numbers to letters or vice-versa)

Table 6 BLUETOOTH Parameters

Michell Instruments 25

Page 34

OPERATION

3.4.3.1 Bluetooth Pairing Procedure

When the instrument is in Bluetooth mode, a pairing procedure needs to be carried out in order for the PC system to recognize the instrument. This procedure only needs to be carried out once for each instrument. A typical pairing procedure is outlined in procedure is as follows:

1. From the PC’s Bluetooth menu, search for devices in range. This yields the instrument named, i.e. MDM300.

2. Double click the instrument icon and enter the instrument’s pairing passcode (7316) for all MDM300 instruments. NOTE: Each digit will

be shown only briey as it is entered and then hidden.

3. When all digits have been entered click Next.

4. With the serial link established, click Configure. NOTE: The name of

the COM port allocated, i.e. COM7, will need to be entered when starting the Michell application software.

MDM300 User Manual

Figure 19.

The

(7)

(3)

(1)

(6)

Figure 20

Typical Bluetooth Pairing Sequence

26 97122 Issue 16.2 June 2022

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MDM300 User Manual

3.4.4 EXTERNAL (Sensor Interface)

For more information refer to Section 2.6.

OPERATION

Figure 21

Parameter Description

EXTERNAL TYPE

EXTERNAL ZERO

EXTERNAL SPAN

Denes the type of connected external transmitter. Available Input: NONE, EASIDEW, TEMP, PRESS

Denes external zero (lower limit). Available Input: Range - Depends on transmitter type

Denes external span (upper limit). Available Input: Range: - Depends on transmitter type

Used to dene system pressure, for use in calculating moisture parameters. This eld is inhibited if an external PRESS sensor is

USER PRESSURE

congured. The external sensor reading then denes the system operating pressure.

Available Input: Range AT M , 0 to 300 barg (or equivalent in other units)

EXTERNAL TYPE NONE

EXTERNAL ZERO N/A EXTERNAL SPAN N/A USER PRESSURE AT M Psig

EXTERNAL SET-UP Page

EXTERNAL

Table 7 EXTERNAL Sensor Parameters

Michell Instruments 27

Page 36

OPERATION

3.4.5 CLOCK

YEAR 11 CLOCK

MONTH 03 DAY 26 HOUR 09 MIN 32

MDM300 User Manual

Parameter Description

YEAR

MONTH

DAY

HOUR

MIN

Current year Available Input: Range: 00 to 99

Current month Available Input: Range: 01 to 12

Current day Available Input: Range: 01 to 31

Current hour Available Input: Range: 00 to 23

Current minute Available Input: Range: 00 to 59

Figure 22

CLOCK Page

Table 8 CLOCK Parameters

28 97122 Issue 16.2 June 2022

Page 37

MDM300 User Manual

3.4.6 HMI

OPERATION

CONTRAST 80 %

BRIGHTNESS 75 % KEY TONE ON BL TIMEOUT 30 Sec LANGUAGE ENG PRIMARY DISP INTERN

Parameter Description

CONTRAST

BRIGHTNESS

KEY TONE

BL TIME-OUT

LANGUAGE

Sets the contrast on the screen. Available Input: Range: 0 to 100 % in 5 % increments

Sets the brightness of the screen. Available Input: Range: 0 to 100 % in 5 % increments

Turns the key tone on or o. Available Input: ON, OFF

Backlight control. Available Input: OFF, 15 to 60 sec in 15 sec increments

Sets the language required. Available Input: ENG, DEU, ESP, FRA, ITA, POR

Sets the display option.

PRIMARY DISP

NOTE: This option is only accessible if an external sensor has

been congured - see below.

Available Input: INTERN, EXTERN

Figure 23

HMI

HMI Page

Table 9 HMI Parameters

If no external input is selected the internal sensor temperature is shown, on the secondary display, by default.

When an external transmitter has been congured, the primary and secondary displays can be interchanged to show the external sensor reading as the main display and the internal sensor reading as the secondary display.

With an Easidew transmitter connected, the ability to display the output of the external device as the main (large character) display can be particularly advantageous for a number of applications such as:

• Remote monitoring

• Calibration checks on an existing installation

• High pressure measurements

Michell Instruments 29

Page 38

OPERATION

3.4.7 INFO

MDM300 Portable Hygrometer

Firmware 36171 Ver 10.10 Sensor serial number B585-006 Sensor next cal due 26/03/09 Sensor hours used

www.michell.com

371 hr

MDM300 User Manual

This page contains system information and no changes can be made.

Information available:

• Firmware number and version

• Sensor serial number

• Date of sensor calibration next due

• Hours that the sensor has been used

3.4.8 CHART Page

At any time while the Main Display is indicating internal sensor parameters, a graphical display of the output can be obtained by pressing the  key from the Main Display.

Figure 24

INFO Page

The chart can be reset at any time by pressing the Enter key. Reset the chart by pressing the  key or return to the chart, without resetting, by pressing the  key.

A typical chart plot is shown below:

t-5

Figure 25

CHART Page

Val 55.6 Min 55.3 Max 68.7

%RH

tMinutes

The X-axis (time) has a default range of 5 minutes and the graph is incremented (drawn) at the interval set up under the SETTINGS Menu (see Section 3.4.1). The Y-axis shows the measured value, with respect to time.

The current, maximum and minimum values of the displayed parameter are shown to the right of the graph and the unit of the selected parameter is displayed below.

30 97122 Issue 16.2 June 2022

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MDM300 User Manual

3.4.9 LOG FILES Page

If the instrument is not logging, pressing the  key, while the chart is displayed, will show the FILES Page. This page provides a list of all the previously saved log les, together with an indication of the available memory capacity (see through the list, use the  and  keys as required.

11/64 les

1.txt 1K 0130 1318

2.txt 1K 0130 1319

3.txt 15K 0305 1352

4.txt 4K 0315 1738

Not logging, press ENTER to setup logging



169K used 8397K Free



OPERATION

Figure 25)

. To scroll

The content of the datalog les cannot be examined but, by enabling the instrument’s Bluetooth mode, (see Section 3.4.3), the MDM300 application software may be used to upload the datalog les to a PC.

In the FILES Page a shortcut to the LOGGING Set-Up Menu is provided by pressing the

Enter key. Refer to Section 3.4.2 for logging set-up details.

3.4.10 LOGS Page

If the instrument is logging, pressing the  key, while the chart is displayed, will show the LOGS Page. The page shows the current log le.

In the LOGS Page a shortcut to the LOGGING Set-Up Menu is provided by pressing the

Enter key. Refer to Section 3.4.2 for logging set-up details.

The  and  keys are both active while the log le is being displayed. To view log points taken earlier in the logging cycle, press the  key. To continuously scroll back, keep the  key pressed down.

Figure 26

LOG FILES Page

Similarly, to move forward in the list press the  key, once for a single step, or press and hold to continuously scroll forward.

106 107 108 109 110

INT

26.8

26.2

25.9

25.8

25.5

EXT

-100.0

-90.0

-80.0

-70.0

-60.0

Figure 27

0028 0028 0028 0028 0028

File CR270309 INT RH EXT. EXT_DP INTVAL 05 Sec D# 090327 T# 123606

LOGS Page

Michell Instruments 31

Page 40

OPERATION

The display shows:

MDM300 User Manual

INT

EXT

Indicates a log number for each set of log points

Value of primary display parameter

Value of secondary display parameter Status column which reports the status of the instrument at each log

point in hexadecimal code. The status codes are explained in Appendix B.

• FILE File name

• INT Primary display parameter being logged

• EXT Secondary display parameter being logged

• INTVAL Logging interval

• D# Current date in YYMMDD format

• T# Current time in HHMMSS format

NOTE: The chart and datalogging are independent functions; therefore the

parameter displayed on the chart may not necessarily reect what is being

logged.

3.4.11 CALIBRATION

Entry to the CALIBRATION Menu is protected by a passcode (4876). The passcode is entered in a similar manner to that described in Section 3.3.1.

This page gives access to the internal sensor’s calibration look-up table and provides the facility to select and change any single point, or number of points. It also allows an oset to be applied to a connected Easidew transmitter.

Section 6 details the use of the calibration routines.

Select calibration

MDM300 Calibration Correction

Easidew Offset Adjustment Easidew One Point Adjustment

Figure 28

CALIBRATION Page

32 97122 Issue 16.2 June 2022

Page 41

MDM300 User Manual

3.5 Default Parameters

OPERATION

Parameter Default Value

SETTINGS

PRIMARY DP AT ATMOS DP/TEMP UNIT °C PRESS UNIT psig GAS TYPE AIR MOL WEIGHT N/A CHART INTERVAL 5 sec

LOGGING

FILE NAME PARAMETER DEWP LOG INTERVAL 5 sec START? STOPPED

BLUETOOTH

ENABLE NO NAME MDM300

EXTERNAL

EXTERNAL TYPE NONE EXTERNAL ZERO N/A EXTERNAL SPAN N/A

CLOCK

Current UK time & date

Associated Section

Reference

Section 3.4.1,

Section 3.4.2,

Section 3.4.3,

Section 3.4.4,

Section 3.4.5,

Figure 16

Figure 17

Figure 18

Figure 20

Figure 21

HMI

CONTRAST 80 % BRIGHTNESS 40 % KEYTONE OFF BL TIME-OUT 15 sec LANGUAGE ENG PRIMARY DISP INTERN

CALIBRATION & INFO

Default values not

applicable

Table 10 MDM300 Default Parameters

Section 3.4.6,

Section 3.4.11 & Section 6

Figure 22

Michell Instruments 33

Page 42

OPERATION

3.6 Guide to Measurement and Sampling

Operating the MDM300 is very straightforward, but sampling conditions can vary greatly from one application to another. To get the best possible response speed, the appropriate procedure should be followed.

HIGH PRESSURE! High pressure gases are potentially

hazardous. Energy stored in these gases can be released

For the most basic measurement it is recommended to have a ow meter (0...1 l/min), and at least one metering valve.

suddenly and with extreme force. High pressure systems

should be assembled and operated only by people who have

been trained in proper safety practices.

POSSIBLE INJURY! The tubing, valves and other apparatus

attached to this instrument must be adequate for the

maximum pressure which will be applied, otherwise physical

injury to the operator or bystander is possible.

MDM300 User Manual

A number of sampling kits are available from Michell Instruments:

• The Easi-t sample kit is a low cost sampling system consisting of 2 metering valves and a ow meter which is suitable for many applications.

• The MDM300 panel-mount sampling system oers a complete package for conditioning of a sample, prior to measurement with an MDM300. It is contained within an optional ight case which allows for easy transport of everything required to make the measurements.

Figure 29

Specialized kits are available for the measurement of atmospheric pressure samples, compressed air, medical gas and SF6. Contact a Michell Instruments’ representative for more information.

34 97122 Issue 16.2 June 2022

Easi-Fit Sample Kit MDM300 Panel-Mount Sampling System

Page 43

MDM300 User Manual

It is highly recommended that a lter is installed upstream of

3.6.1 Measuring at Atmospheric or System Pressure

Without a metering valve

The large and small orice ttings can be used to restrict ow at pressures up to 10 barg (145 psig).

To measure at atmospheric pressure, t the small orice tting to the inlet of the instrument. Fit a large orice tting to the outlet of the instrument.

To measure at system pressure, t the small orice tting to the outlet of the instrument. Fit a large orice tting to the inlet of the instrument.

the MDM300. Refer to the Sample Conditioning section of the

Sampling Hints found in Section 4.1.

OPERATION

Figure 30

With one metering valve

Ensure that large orice ttings are tted to both the inlet and the outlet of the instrument.

To measure at atmospheric pressure the metering valve used to control the sample ow should be tted to the inlet of the instrument.

To measure at system pressure the metering valve used to control the sample ow should be tted to the outlet of the instrument.

With two metering valves

Ensure that large orice ttings are tted to both the inlet and the outlet of the instrument.

To measure at atmospheric pressure the metering valve on the instrument outlet should be fully open. The metering valve on the inlet should be used to control the sample ow.

Large and Small Orice Fitting

To measure at system pressure the metering valve on the instrument inlet should be fully open. The metering valve on the outlet should be used to control the sample ow.

Michell Instruments 35

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OPERATION

3.6.2 Measurement Guide

1. Follow procedure A and note the result.

2. Turn the instrument o.

3. If you wish to measure at sample pressure then use the Michell Humidity

Calculator (http://www.michell.com/uk/downloads/humidity_calculator. msi) to convert this result back to the equivalent at your sample pressure.

4. Using this converted result, and the table below, nd the appropriate

procedure to measure your sample.

MDM300 User Manual

Measure at

Dew Point

>-40 °C Procedure B Procedure A <-40 °C Procedure C Procedure A

Table 11 MDM300 Measurement Procedures

A Standard Purge (Atmospheric Measurement)

1. Connect the MDM300 to the sample gas stream.

2. Adjust the ow rate, using the inlet ow control valve, to between 0.2

and 1.2 Nl/min (0.5...2.5 scfh). The outlet ow control valve should be fully open.

3. Turn the instrument on - the initialization period begins automatically.

The page will show a countdown of the remaining initialization time. The status display will read ‘Initializing internal sensor’.

Sample Pressure

> 2.5 barg

Measure at

Atmospheric Pressure

4. After Initialization, the instrument will begin Measurement mode. During

the rst few minutes of Measurement mode, the displayed moisture value will drop rapidly below the actual moisture value, before returning to a stable reading. The instrument display will show an initial measured

value, and the status display will show ‘Measurement in progress’.

5. Once ‘Measurement in progress’ has disappeared, the instrument is

close to the nal dew point. Depending on the conditions, it may continue to respond for a number of minutes before tracking the measured dew point.

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MDM300 User Manual

B Standard Purge (Pressure Measurement)

1. Connect the MDM300 to the sample gas stream.

2. Adjust the ow rate, using the outlet ow control valve, to between

0.2 and 1.2 Nl/min (0.5...2.5 scfh). The inlet ow control valve should be fully open.

3. Turn the instrument on - the initialization period begins automatically.

The page will show a countdown of the remaining initialization time. The status display will read ‘Initializing internal sensor’.

4. After Initialization, the instrument will begin Measurement mode. During

5. Once ‘Measurement in progress’ has disappeared, the instrument is

close to the nal dew point. Depending on the conditions, it may continue to respond for a number of minutes before tracking the measured dew point.

OPERATION

C Enhanced Purge

1. Connect the MDM300 to the sample gas stream.

2. Adjust the ow rate, using the inlet ow control valve, to between 0.2

and 1.2 Nl/min (0.5...2.5 scfh). The outlet ow control valve should be fully open.

3. Turn the instrument on - the initialization period begins automatically.

The page will show a countdown of the remaining initialization time. The status display will read ‘Initializing internal sensor’.

4. Once 2-3 minutes of the initialization period have elapsed, close the outlet

ow control valve and fully open the inlet ow control valve. Then adjust the ow rate using the outlet ow control valve to between 0.2 and 1.2 Nl/min (0.5...2.5 scfh).

5. After Initialization, the instrument will begin Measurement mode. During

6. Once ‘Measurement in progress’ has disappeared, the instrument is

close to the nal dew point. Depending on the conditions, it may continue to respond for a number of minutes before tracking the measured dew point.

Michell Instruments 37

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OPERATION

3.6.3 Conditional Sensor Purge

In order to ensure consistently fast measurement response speeds after power O/On, the sensor will not be automatically purged when the measured dew point is deemed to be suciently close to the previously measured dew point.

3.7 Battery Management

The battery will typically provide 48 hours of continuous operation from full charge. When the battery approaches discharge, the instrument will display the warning

message ‘Battery low – recharge now’.

Following this, the instrument will enter a Shutdown Mode, accompanied by an audible beep. This mode will disable the operation of the keypad and display backlight, preventing further usage of the unit. Upon connecting the instrument to the battery charger it will exit Shutdown Mode within 30 seconds.

When Shutdown Mode occurs, connect the instrument to the battery charger as soon as possible to prevent complete discharge. Complete discharge may occur if the unit is not connected to a battery charger within a 48 hour period - see below.

MDM300 User Manual

WARNING: If complete discharge does occur, then

diculties may be encountered when attempting to

If this problem is experienced, refer below for a possible

3.7.1 Battery Troubleshooting

Problem: Instrument battery is at and will not charge.

(NOTE: OLDER FW 7219 MODEL BATTERY CHARGER ONLY)

Cause: If the instrument has been left in a completely discharged state for

several days then it is possible that the charger (FW 7219) will not recharge the battery.

Solution: The instrument will need to be connected to a 6 V (500 mA max) power

supply – via its normal charging port – for a maximum of 15 seconds before switching to the charger (FW 7219), which should now behave normally.

recharge the battery.

solution.

DO NOT leave this 6 V power supply connected to the

NOTE: Michell Instruments will replace the older FW 7219 charger with the new Cell Con model free of charge. The Cell Con will re-charge batteries which have completely discharged.

38 97122 Issue 16.2 June 2022

instrument for any longer than the recommended 15 seconds

or the battery may be damaged.

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MDM300 User Manual

4 GOOD MEASUREMENT PRACTICE

Ensuring reliable and accurate moisture measurements requires the correct sampling techniques, and a basic understanding of how water vapor behaves. This section aims to explain the common mistakes and how to avoid them.

Sampling Materials – Permeation and Diusion

All materials are permeable to water vapor since water molecules are extremely small compared to the structure of solids, even including the crystalline structure of metals. The graph above demonstrates this eect by showing the increase in dew point temperature seen when passing very dry gas through tubing of dierent materials, where the exterior of the tubing is in the ambient environment.

- 20

- 30

GOOD MEASUREMENT PRACTICE

- 40

- 50

Dew point (ºC)

- 60

- 70

Figure 31

nickel

stainless steel

1 2 3 4 5

Time (hours)

Material Permeability Comparison

nylon

copper

polyethylene

PTFE

What this demonstrates is the dramatic eect that dierent tubing materials have on the humidity levels of a gas passed through them. Many materials contain moisture as part of their structure and when these are used as tubing for a dry gas the gas will absorb some of the moisture. Always avoid using organic materials (e.g. rubber), materials containing salts and anything which has small pores which can easily trap moisture (e.g. nylon).

As well as trapping moisture, porous sampling materials will also allow moisture vapor to ingress into the sample line from outside. This eect is called diusion and occurs when the partial water vapor pressure exerted on the outside of a sample tube is higher than on the inside. Remember that water molecules are very small so in this case the term ‘porous’ applies to materials that would be considered impermeable in an everyday sense – such as polyethylene or PTFE. Stainless steel and other metals can be considered as practically impermeable and it is surface nish of pipework that becomes the dominant factor. Electropolished stainless steel gives the best results over the shortest time period.

Take into consideration the gas you are measuring, and then choose materials appropriate to the results you need. The eects of diusion or moisture trapped in materials are more signicant when measuring very dry gases than when measuring a sample with a high level of humidity.

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GOOD MEASUREMENT PRACTICE

Temperature and Pressure eects

As the temperature or pressure of the environment uctuates, water molecules are adsorbed and desorbed from the internal surfaces of the sample tubing, causing small uctuations in the measured dew point.

MDM300 User Manual

Adsorption

solid to the surface of a material, creating a lm. The rate of adsorption is increased at higher pressures and lower temperatures.

Desorption

constant environmental conditions, an adsorbed substance will remain on a surface almost indenitely. However, as the temperature rises, so does the likelihood of desorption occurring.

Ensuring the temperature of the sampling components is kept at consistent levels is important to prevent temperature uctuation (i.e. through diurnal changes) continually varying the rates of adsorption and desorption. This eect will manifest through a measured value which increases during the day (as desorption peaks), then decreasing at night as more moisture is adsorbed into the sampling equipment.

is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved

is the release of a substance from or through the surface of a material. In

If temperatures drop below the sample dew point, water may condense in sample

tubing and aect the accuracy of measurements.

Maintaining the temperature of the sample system tubing above the dew point of the sample is vital to prevent condensation. Any condensation invalidates the sampling process as it reduces the water vapor content of the gas being measured. Condensed liquid can also alter the humidity elsewhere by dripping or running to other locations where it may re-evaporate.

Although ambient pressure does not change drastically in a single location, the gas sample pressure does need to be kept constant to avoid inconsistencies introduced by adsorption or desorption. The integrity of all connections is also an important consideration, especially when sampling low dew points at an elevated pressure. If a small leak occurs in a high-pressure line, gas will leak out; however, vortices at the leak point and a negative vapor pressure dierential will also allow water vapor to contaminate the ow.

Theoretically ow rate has no direct eect on the measured moisture content, but in practice it can have unanticipated eects on response speed and accuracy. An inadequate ow rate may:

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MDM300 User Manual

• Accentuate adsorption and desorption eects on the gas passing through the sampling system.

• Allow pockets of wet gas to remain undisturbed in a complex sampling system, which will then gradually be released into the sample ow.

• Increase the chance of contamination from back diusion. Ambient air that is wetter than the sample can ow from the exhaust back into the system. A longer exhaust tube can help alleviate this problem.

• Slow the response of the sensor to changes in moisture content.

An excessively high ow rate can:

• Introduce back pressure, causing slower response times and unpredictable changes in dew point

• Result in a reduction in depression capabilities in chilled mirror instruments by having a cooling eect on the mirror. This is most apparent with gases that have a high thermal conductivity such as hydrogen and helium.

GOOD MEASUREMENT PRACTICE

System design for fastest response times

The more complicated the sample system, the more areas there are for trapped moisture to hide. The key pitfalls to look out for here are the length of the sample tubing and dead volumes.

The sample point should always be as close as possible to the critical measurement point to obtain a truly representative measurement. The length of the sample line to the sensor or instrument should be as short as possible. Interconnection points and valves trap moisture, so using the simplest sampling arrangement possible will reduce the time it takes for the sample system to dry out when purged with dry gas.

Over a long tubing run, water will inevitably migrate into any line, and the eects of adsorption and desorption will become more apparent.

Dead volumes (areas which are not in a direct ow path) in sample lines, hold onto water molecules which are slowly released into the passing gas. This results in increased purge and response times, and wetter than expected readings. Hygroscopic materials in lters, valves (e.g. rubber from pressure regulators) or any other parts of the system can also trap moisture.

Plan your sampling system to ensure that the sample tap point and the measurement point are as close as possible to avoid long runs of tubing and dead volumes.

Filtration

All trace moisture measurement instruments and sensors are by their nature sensitive devices. Many processes contain dust, dirt or liquid droplets. Particulate lters are used for removing dirt, rust, scale and any other solids that may be in a sample stream. For protection against liquids, a coalescing or membrane lter should be used. The membrane provides protection from liquid droplets and can even stop ow to the analyser completely when a large slug of liquid is encountered, saving the sensor from potentially irreparable damage.

Michell Instruments 41

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GOOD MEASUREMENT PRACTICE

Flow Rates

Theoretically ow rate has no direct eect on the measured moisture content, but in practice it can have unanticipated eects on response speed and accuracy. The optimal ow rate varies depending on the measurement technology, and can always be found in the instrument or sensor manual.

An inadequate ow rate can:

• Accentuate adsorption and desorption eects on the gas passing through the sampling system.

• Allow pockets of wet gas to remain undisturbed in a complex sampling system, which will then gradually be released into the sample ow.

• Increase the chance of contamination from back diusion: ambient air that is wetter than the sample can ow from the exhaust back into the system. A longer exhaust (sometimes called a pigtail) can also help alleviate this problem.

MDM300 User Manual

• Slow the response of the sensor to changes in moisture content.

An excessively high ow rate can:

• Introduce back pressure, causing slower response times and unpredictable eects on equipment such as humidity generators.

• Result in a reduction in heating capabilities of the sensor tile during the initialization period. This is most apparent with gases that have a high thermal conductivity such as hydrogen and helium.

POSSIBLE INJURY! The tubing, valves and other apparatus

attached to this instrument must be adequate for the

maximum pressure which will be applied, otherwise physical

injury to the operator or bystander is possible.

Before disconnecting the MDM300 from the gas line it

42 97122 Issue 16.2 June 2022

is essential to vent the system to atmospheric pressure,

otherwise severe injury could result.

Page 51

MDM300 User Manual

5 APPLICATION SOFTWARE

The latest version of this application software is available for download from the Michell website – http://www.michell.com/uk/support/sware-downloads.htm. The following

authorization code will be required during the installation process: MDM-300-7392

Once the software has been installed and run, the MDM300 can be linked to the PC by activating the Bluetooth on the MDM300 and then connecting with the application software (see Section 3.4.3 for details).

The application software allows modication of all the instrument parameters from the connected PC. The settings currently stored on the MDM300 can be downloaded to the

PC by clicking the ‘Download from MDM300’ button, and can then be changed and stored by clicking the ‘Upload to MDM300’ button.

The software gives access to all logging les stored on the instrument’s internal memory. These can be downloaded to a specic location by right clicking, and selecting

‘download’.

APPLICATION SOFTWARE

A context sensitive help le provides further details on the use of the application software.

Figure 32

Typical Application Software Screen

Michell Instruments 43

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CALIBRATION

6 CALIBRATION

6.1 Traceability

The calibration of this instrument is traceable to national standards. For this reason the instrument should only be calibrated in an accredited, e.g. UKAS or NIST (U.S.) standards laboratory.

If these facilities do not exist it is recommended that the instrument be returned to the manufacturer, Michell Instruments Ltd., or one of the approved agents.

A calibration certicate bearing a seven point calibration is issued with each instrument.

MDM300 User Manual

Figure 31

shows a typical seven point calibration certicate.

Figure 33

Typical 7-point Calibration Certicate

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MDM300 User Manual

6.2 Calibration Method

The calibration procedure for the instrument is as follows:

1. Switch on the instrument. Wait for the initialization period to complete

and allow sucient time for it to stabilize.

2. Ensure the instrument is set up with sample gas as AIR and operating pressure

as ATMOS.

equipment and calibration adjustments should only be carried

out by qualied personnel. If not correctly carried out, the

CALIBRATION

WARNING:

These procedures require the use of specialized test

instrument’s calibration can be lost.

3. Ensure that the temperature units are set up as °C and the primary display is

reading Dew point.

4. Ensure that all sample tubing and connectors are made from stainless steel and

are of suitable quality.

5. Connect the MDM300 to a dew-point generator and establish a gas ow through

the instrument.

6. Apply a dew point of -100 °C and allow the instrument’s reading to stabilize for

a minimum of 96 hours (including dry down).

7. Record the applied REF dew point and the corresponding MDM300 display reading.

8. Repeat steps 6 and 7 at all the required dew-point values over the operating

range of the instrument, as shown in Table 12, allowing the stabilization times shown before recording consecutive readings.

A set of results similar to that shown below could be generated over the calibration range of the instrument.

DP REF

°C

-100 96 -99.8 -30 1 -30.1

-80 12 -79.7 -20 1 -19.9

-70 8 -70 -10 1 -10

-60 4 -59.8 0 1 0.1

-50 2 -49.8 10 1 10

-40 1 -39.9 20 1 20

Stabilize

Time

(Hours)

MDM300

Rdg °C

DP REF

°C

Stabilize

Time

(Hours)

MDM300 Rdg

°C

Table 12 Example Of Calibration Run Readings

Michell Instruments 45

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CALIBRATION

6.3 Calibration Correction Method

NOTE: Any logging procedure currently in operation must be cancelled before the calibration procedures can be entered.

To enter the CALIBRATION Menu page, highlight CALIBRATION from the SET-UP Menu by using the  or  keys and press the Enter key.

Entry to the CALIBRATION Menu is protected by a passcode (4876).

If the MDM300 has been congured for use with an external Easidew transmitter the following page will be shown, once the passcode has been successfully entered.

Select calibration

MDM300 Calibration Correction

Easidew Offset Adjustment Easidew One Point Adjustment

MDM300 User Manual

Figure 34

Calibration Page

The MDM300 Calibration look-up table is divided into three columns.

The values in the rst column POINT represent the thirteen nominal calibration points, spread at 10 °C intervals over the instruments operating range of -100...+20 °C (-148...+68 °F). These points cannot be edited.

The second column REF represents the value of the reference dew-point standard applied at that particular point.

The third column MDM300 represents the reading that the MDM300 was showing at the corresponding REF level input.

The values in both the REF and MDM300 columns can be edited by means of the  and  keys. The  and  keys provide the means of switching between corresponding table columns.

POINT

-100

-90

-80

-70

-60

REF

-100.0

-90.0

-80.0

-70.0

-60.0

MDM300

-100.0

-90.0

-80.0

-70.0

-60.0

CALIBRATION

Figure 35

Calibration Menu Page

After changes have been made press the Enter key to reach the Exit page. No changes are implemented until the  key is pressed at the Exit page.

To exit without implementing any changes, press the Enter key to reach the Exit page. Press the  key, from the Exit page, to return to the SET-UP Menu.

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MDM300 User Manual

6.3.1 Easidew Oset Adjustment

If an external Easidew transmitter has been congured this calibration option may be used to apply a constant oset over its full range, i.e. the calibration curve of the external Easidew transmitter is shifted either up or down depending upon the polarity of the oset.

The calibration procedure is as follows:

1. Set-up the MDM300 and the external Easidew transmitter to monitor the same sample gas stream.

2. From the CALIBRATION Menu, select Easidew Oset Adjustment and press the Enter key.

3. The oset adjustment screen is now displayed which reports the size of the oset (-1.3 °C) between the readings of the MDM300 and the external transmitter as shown in

Figure 34

CALIBRATION

Select calibration

MDM300 Calibration Correction

Easidew Offset Adjustment

Easidew One Point Adjustment

*Communicating with Easidew*

Press  to calibrate or press  to exit

MDM300 6.6° Easidew 7.3° Offset -1.3°

C dp C dp C dp

4. Press the  key to apply the oset.

5. Conrm the operation by pressing the  key or, to exit without applying the oset, press the  key.

6. The oset value is now saved and the external transmitter reading adjusted to match that of the MDM300.

7. Press the  key to return to the CALIBRATION Menu.

Figure 36

Press  to confirm or press  to exit

MDM300 6.6° Easidew 7.3° Offset -1.3°

Offset value saved press  to exit

MDM300 6.6° Easidew 6.6° Offset 0.0°

Select calibration

MDM300 Calibration Correction

Easidew Offset Adjustment

Easidew One Point Adjustment

C dp C dp C dp

Easidew Oset Adjustment

Michell Instruments 47

Page 56

CALIBRATION

6.3.2 Easidew One Point Adjustment

If an external Easidew transmitter has been congured this calibration option may be used to apply a measured oset to just one specic point on the calibration curve of the external transmitter, without aecting any other parts of the curve. The single point selected is moved either up or down depending upon the polarity of the measured oset.

The following calibration correction procedure is applicable to all single points.

1. Set-up the MDM300 and the external Easidew transmitter to monitor the same sample gas stream and connect to a dew-point generator.

MDM300 User Manual

Select calibration

MDM300 Calibration Correction Easidew Offset Adjustment

Easidew One Point Adjustment

2. Apply a dew-point reference to the MDM300 and external transmitter at the required dew point (-20.6 °C) in this example.

3. From the CALIBRATION Menu, select Easidew One Point Adjustment and press the Enter key.

4. The oset adjustment screen is now displayed which reports the size of the oset (1.1 °Cdp) between the readings of the MDM300 and the external transmitter at the applied dew point as shown in

Figure 35.

5. Press the  key to apply the oset.

6. Conrm the operation by pressing the  key or, to exit without applying the oset, press the  key.

7. The oset value for this point is now saved and the external transmitter reading at this one point adjusted to match that of the MDM300.

8. Press the  key to return to the CALIBRATION Menu.

*Communicating with Easidew*

Press  to calibrate or press  to exit

MDM300 -20.6° Easidew -21.7° Offset 1.1°

Press  to confirm or press  to exit

MDM300 -20.6° Easidew -21.7° Offset 1.1°

Offset value saved press  to exit

MDM300 -20.6° Easidew -20.6° Offset 0.0°

Select calibration

MDM300 Calibration Correction Easidew Offset Adjustment

Easidew One Point Adjustment

C dp C dp C dp

Figure 37

Easidew Single Point Adjustment

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MDM300 User Manual

7 SHIPPING

For shipping purposes the instrument should be packed into its original carton which will provide the recommended degree of protection during transit.

To prepare the instrument for shipping, proceed as follows:

1. Switch the instrument o and remove any connections to the Gas In and Gas Out ports and any external sensors connected to it.

2. If tted, remove the instrument from its carrying case.

3. Pack the instrument in its original carton (1) as shown below.

NOTE: It is not necessary to return any accessories unless they require repair/replacement. Any returned accessories can be packed in the box (3).

4. Create a packing list detailing all equipment contained in the box, place it inside the box and seal the box.

SHIPPING

Before disconnecting the MDM300 from the gas line it

is essential to vent the system to atmospheric pressure,

otherwise severe injury could result.

Figure 38

Instrument Packing Details

Michell Instruments 49

Page 58

APPENDIX A

MDM300 User Manual

Appendix A

Technical Specications

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MDM300 User Manual

Appendix A Technical Specications

Performance

Measurement Technology Michell ceramic metal-oxide moisture sensor

±1 °C from -60...+20 °Cdp (-76...+68 °Fdp)

Accuracy

±2 °C from -100...-60 °Cdp (-148...-76 °Fdp) ±0.2 °C (0.3 °F) temperature

APPENDIX A

Calibrated Measurement Range

Uncalibrated Readings From +20...+30 °Cdp (+68...+86 °Fdp)

Measurement Units

Resolution (Display)

Resolution (Measurement) Better than 0.1 °Cdp (0.2 °Fdp)

Typical Response Speed T95 in ≤15 minutes to -60 °Cdp (-76 °Fdp)

Electrical Output/Input

Auxiliary Inputs

Battery Operating Life Up to 48 hours of typical usage between charges

Battery Charger Intelligent charger (supplied)

Operating Conditions

For Spot Checks -70...+20 °Cdp (-95...+68 °Fdp) For Online Analysis -100...-70 °Cdp (-148...-95 °Fdp)

°C, °F, K dew point & gas temperature % rh, ppmV, g/m ppmW & g/kg (for air, N2, CO2, SF6, user-dened mw) aux pressure input: bara/g, psig, MPa, KPa

0.1 for all dew-point derived units and auto ranging where appropriate

4...20 mA external input selectable as either dew point, temperature or pressure

Operating Pressure 35 MPa (350 barg / 5076 psig) max

Operating Environment Outdoors 0...+100 % rh condensing

Operating Temperature -20...+50 °C (-4...+122 °F)

Storage / Transport Temperature -20...+50 °C (-4...+122 °F)

Mechanical Specications

Display Blue LCD graphical display

Enclosure Type Steel ber-loaded high-impact polyamide 6

IP/NEMA Rating IP66/NEMA 4

Gas Connections 1/8” NPT female (other options available)

Flow Across Sensor 0.2...1.2 Nl/min (0.5...2.5 scfh)

Gas Wetted Materials AISI 316L stainless steel

Outline Dimensions 218 x 170 x 90 mm (8.6 x 6.7 x 3.5”) (d x w x h)

Weight 1.35 kg (2.98 lbs)

Data Logging 8 megabytes; Log interval: 5...60 sec. Log les: 64 maximum

Maximum log le size: 60kb

Communications (Wireless) BluetoothTM range up to 5 m (16 ft)

Languages English, French, German, Italian, Portuguese, Spanish

Michell Instruments 51

Page 60

APPENDIX A

A.1 Dimensions

MDM300 User Manual

218mm (8.56”)

170mm (6.69”)

Figure 39

90mm (3.54”)

Dimensions

52 97122 Issue 16.2 June 2022

Page 61

MDM300 User Manual

APPENDIX B

Appendix B

Datalog Status Display

Michell Instruments 53

Page 62

APPENDIX B

Appendix B Datalog Status Display

MDM300 User Manual

When the status of the current log le is displayed, see the current log le display represents the instrument’s status at the time that each log point is recorded.

106 107 108 109 110

This column shows a hexadecimal representation of the instrument’s 16-bit status register shown below in signicant bits 13...16 are for Michell Instruments’ service use and so the rst character in any MDM300 ST display will always read 0.

INT

26.8

26.2

25.9

25.8

25.5

EXT

-100.0

-90.0

-80.0

-70.0

-60.0

Figure 40

Figure 39

0028 0028 0028 0028 0028

Current Datalog File Display

. Bit 1 is the least signicant bit. The four most

File CR270309 INT RH EXT. EXT_DP INTVAL 05 Sec D# 090327 T# 123606

Figure 38

, the ST column in

Status register bit position

16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

N/A N/A N/A N/A

For the example given for each of the log plots shown in output pattern of the status register will be as shown in

16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

N/A N/A N/A N/A

0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 N/A

Figure 41

Status register bit position

0 0 0 0 0 0 1 0 1 0 0 N/A

Figure 42

MDM300 Status Register (Hex 28)

MDM300 Status Register

Figure 38

Figure 40

(Hex 0028), the

Each of the error bits set high (1) represents a specic status or error condition. In this example, bits 4 and 6 are set high indicating that two (status) conditions exist.

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MDM300 User Manual

Table 13 shows the status ags associated with each bit of the status register. If a status ag is set high then the associated condition exists. If it is set low, then that condition does not exist.

APPENDIX B

Status Register bit in Hex

0x0002 = BIT 2

0x0004 = BIT 3

0x0008 = BIT 4

0x0010 = BIT 5

0x0020 = BIT 6

0x0040 = BIT 7

0x0080 = BIT 8

0x0100 = BIT 9

0x0200 = BIT 10

0x0800 = BIT 12

Message Details

Internal sensor error

Internal thermistor error

External sensor error

Battery low Measurement in

progress

Log nished

Internal sensor not found

Default CONFIG le used

Initializing Internal Sensor

Dew-point reading out of range (> +30 / < -120 °C)

Sensor internal temperature reading out of range (> +100 / < -40 °C) or Thermistor fault

External Sensor Input out of range (< 4 mA / > 20 mA)

Battery level low - recharge as soon as possible

Internal dew point not stable

Internal dew point changing <0.2 °Cdp over a 3 minute interval

Log le has reached the maximum of 10,000 logs and logging has been stopped

Could not detect internal sensor on power up

Cong. le missing, new le created and default settings used

Indicates system in purging phase

Table 13 Status Register Flags

For the example given in to left, as bit 4 set External sensor error and bit 6 set Measurement in progress.

Therefore, at the time that these log points were taken, the external sensor was out of range and the internal dew point was not stable.

Figure 38

, from Table 13, Hex 28 translates, reading from right

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APPENDIX C

MDM300 User Manual

Appendix C

FCC Declaration

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MDM300 User Manual

FCC Declaration of Conformity

Appendix C FCC Declaration

APPENDIX C

MDM300 Advanced Dewpoint Hygrometer.

This Device complies with FCC Rules Part 15 Subpart B Unintentional Radiators Class B digital devices. Operation is subject to the following conditions:

1) This device may not cause harmful interference

2) This device must accept any interference received, including interference that may cause

undesired operation.

Note: This product has been tested and found to comply with the limits or Class B digital devices, pursuant to Part 15 of the FCC rules. This product generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not in a particular installation. If this product does cause harmful interference to radio reception, which may be determined by turning the product on & off, the user is encouraged to try to correct the interference by one or more of the following measures:

Reorient or relocate the receiving antenna, Increase the separation between the product and receiver, Connect the equipment into an outlet on a circuit different from that to which the receiver is

connected

Consult the dealer or an experienced radio/TV technician for help.

This product must be operated as per the operating instructions provided. Do not make any alterations or modifications to the product. Any unauthorised alterations or modifications made to this product may require you to stop operating the product.

Canadian Radio Interference Regulations. This Class B digital product complies with Canadian ICES-003, CISPR 22 :1997. Règlement canadien sur les interférences radio. Ce produit numérique de classe B est conforme à la norme NMB-003, CISPR 22: 1997.

Signed for, and on behalf of, Michell Instruments Ltd.

Andrew M.V. Stokes, Technical Director

Issue date: 05/2011

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APPENDIX D

MDM300 User Manual

Appendix D

Quality, Recycling

& Warranty

Information

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MDM300 User Manual

APPENDIX D

Appendix D Quality, Recycling, Compliance & Warranty Information

Michell Instruments is dedicated to complying to all relevant legislation and directives. Full information can be found on our website at:

www.michell.com/compliance

This page contains information on the following directives:

• Anti-Facilitation of Tax Evasion Policy

• ATEX Directive

• Calibration Facilities

• Conict Minerals

• FCC Statement

• Manufacturing Quality

• Modern Slavery Statement

• Pressure Equipment Directive

• REACH

• RoHS3

• WEEE2

• Recycling Policy

• Warranty and Returns

This information is also available in PDF format.

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APPENDIX E

MDM300 User Manual

Appendix E

Return Document &

Decontamination Declaration

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MDM300 User Manual

Appendix E Return Document & Decontamination Declaration

Decontamination Certicate

IMPORTANT NOTE: Please complete this form prior to this instrument, or any components, leaving your site and being returned to us, or, where applicable, prior to any work being carried out by a Michell engineer at your site.

Instrument Serial Number

Warranty Repair? YES NO Original PO #

Company Name Contact Name

Address

Telephone # E-mail address

Reason for Return /Description of Fault:

APPENDIX E

Has this equipment been exposed (internally or externally) to any of the following? Please circle (YES/NO) as applicable and provide details below

Biohazards YES NO

Biological agents YES NO

Hazardous chemicals YES NO

Radioactive substances YES NO

Other hazards YES NO

Please provide details of any hazardous materials used with this equipment as indicated above (use continuation sheet if necessary)

Your method of cleaning/decontamination

Has the equipment been cleaned and decontaminated? YES NOT NECESSARY

Michell Instruments will not accept instruments that have been exposed to toxins, radio-activity or bio-hazardous

materials. For most applications involving solvents, acidic, basic, ammable or toxic gases a simple purge with dry gas (dew point <-30°C) over 24 hours should be sufcient to decontaminate the unit prior to return.

Work will not be carried out on any unit that does not have a completed decontamination declaration.

Decontamination Declaration

I declare that the information above is true and complete to the best of my knowledge, and it is safe for Michell personnel to service or repair the returned instrument.

Name (Print) Position

Signature Date

F0121, Issue 2, December 2011

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