This manual contains all the required information to install, operate and maintain the Liquidew EExd. Prior
to installation and use of this instrument, this entire manual should be read and understood. Installation
and operation of this product should be carried out by suitably competent personnel only. The operation
of this product must be in accordance with the terms of this manual and associated safety certifi cates.
Incorrect installation and use of this product for other than its intended purpose will render all warranties
void.
This product is intended for use in a Hazardous Area and is awarded an ATEX, IECEx and CSA Certifi cate.
The relevant certifi cates should be fully examined prior to installation or use of this product.
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 and where particular attention to
personal and personnel safety must be observed.
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 input power supply voltage limits are 90 to 260 V AC,
47/63 Hz.
Pressure Safety
DO NOT permit pressures greater than the safe working pressure to be applied directly to the instrument.
Refer to the Technical Specifi cations in Appendix A.
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 only be maintained either by the manufacturer or an accredited service agent. Refer
to www.michell.com for details of Michell Instruments’ worldwide offi ces contact information.
Calibration (factory validation)
Prior to shipment, the analyzer undergoes stringent factory calibration to internationally traceable
standards, NPL (UK) and NIST (USA). Due to the inherent stability of the instrument, only periodic
calibration is required under normal operating conditions.
Michell Instruments recommends that calibration of the sensor should be maintained on a 12 monthly
basis to ensure optimum operation. Michell Instruments offers a calibration exchange program, where
a refurbished and re-certifi ed sensor is supplied as an operational replacement and the original item
returned to Michell to complete the exchange.
NOTE: This interval may need to be reduced if the operation of the sensor is within potentially
aggressive or corrosive sample media (such as sour natural gas). The calibration interval
may therefore need to be shortened to 6 months (or lower in extreme cases) in order to
maintain satisfactory analyzer performance.
Safety Conformity
This product meets the essential protection requirements of the relevant EU directives.
Michell Instrumentsvii
Page 8
Abbreviations
!
DANGER
Electric
Shock Risk
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
°C degrees Celsius
°F degrees Fahrenheit
dp dew point
EU European Union
GPM gallons per minute
Hz Hertz
IEC International Electrotechnical Commission
kg kilogram
l/min liters per minute
ml/min milliliters per minute
l/min normal liters per minute
lb pound
mA milliampere
max maximum
min minute(s)
mV millivolt(s)
N/C normally closed
N/O normally open
No number
ppm
parts per million (by weight)
W
psig pound(s) per square inch (gauge)
RH relative humidity
RTU Remote Terminal Unit
temp temperature
V Volts
" Inch
Liquidew EExd User’s Manual
Warnings
The following general warnings listed below are applicable to this instrument. They are
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.
Where this symbol appears in the following
sections it is used to indicate areas of
potential risk of electric shock.
viii97097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
1 INTRODUCTION
1.1 General
The Liquidew EExd is designed for continuous, automatic measurement of the moisture
content in hydrocarbon solutes, utilizing the Michell Ceramic Moisture Sensor. It is the
result of more than 30 years' experience in the supply of analyzers to the worldwide oil,
gas and petrochemical industry.
The analyzer comprises either a single or a dual channel moisture measurement sensor
cell, control electronics and a display interface housed in an Exd enclosure. The analyzer
is ATEX Directive, IECEx or cCSAus compliant for use in a Zone 1 or 2 Hazardous Area
and Class I, Div 1 Hazardous Location. See marking label located on right hand side of
analyzer to identify approvals. An accompanying sample handling panel, designed to be
positioned close to the process sample point to prepare the sample prior to entry into
the Liquidew EExd, can also be supplied.
The instrument offers several user-selectable display options based on a calibrated
dew-point measurement range of -100 to +20°C (-148 to +68°F), traceable to the
humidity metrology standards of NPL (UK) and NIST (USA). The instrument provides
indication in moisture in liquids (ppm
INTRODUCTION
).
W
The requirements for operation are a 90 to 260 V AC, 47/63 Hz power supply of 180W
and fi eld communications Modbus RTU and/or 4-20 mA. Refer to the System Wiring
Diagram in Appendix B.3.
1.2 Liquid Sample Path
The Liquidew EExd analyzer system must be supplied with a liquid sample at a pressure
up to 50 barg (725 psig), via a sample handling panel providing fi ltration & fl ow control.
Suffi cient differential pressure will be required (typically greater than 0.5 barg (7.2
psig)) between the process sample source and return points. This should enable a
fl ow between 0.1 and 0.3 l/min (0.03 and 0.08 GPM) through the Liquidew EExd and its
associated sampling system. Sample entry and exit ports direct the liquid through fl ame
arrestors which, along with the Exd enclosure, provide the explosion proof protection.
The measurement system components are housed within a cast aluminum Exd rated
enclosure. The enclosure has a screw cover incorporating a sealed window. It is
chromate primed, polyester coated in black, and provides environmental protection to
IP66/NEMA 4. An enclosure breather is fi tted in the form of an additional fl ame arrestor.
It is important that no pipe connection is made to this breather and that no restriction
is allowed to occur.
For accuracy and long term reliability, the temperature of the sample entering the
Liquidew EExd should be less than +40°C (+104°F) and higher than +10°C (+50°F).
The sample and operating temperature must not exceed the T ambient rating of +60°C
(+140°F).
All sample wetted metallic parts are manufactured in AISI 316L stainless steel with
Viton soft parts that comply with the NACE standard MR-01-75 (latest edition). Tube
fi ttings are twin ferrule compression type. All electrical and liquid connections are made
through the base of the enclosure. Refer to the Mounting Drawing in Appendix A.1.
Flow components for Channels 1 & 2 comprise the following:
Flow Meter: Provides indication of low, OK or high fl ow that is present
throughout the sample measurement stream.
Measurement Cell: The point of measurement that incorporates the Michell Ceramic
Moisture Sensor.
Michell Instruments1
Page 10
INTRODUCTION
1.3 Operating Overview
The system continually measures moisture and temperature in an uninterrupted liquid
sample fl ow rate. Moisture content is determined in part per million by weight (ppm
through Henry’s Law, from the measured dew-point temperature and liquid temperature.
It uses an extensive list of saturation concentration data pre-programmed for a variety
of petrochemical liquids, with provision for easy entry of ‘custom’ characteristics data
by the user.
Moisture and temperature for each channel are logged at a user-defi ned interval. The
logs are available through the user interface or via the serial communications. Two
4–20 mA outputs for each channel are available to remotely read the humidity and
temperature in real time.
1.4 User Display and Interface
The Liquidew EExd User Display and Interface Unit is presented via the circular window
of the enclosure. Operation is achieved by a unique system, which allows full control
through the glass of the enclosure cover. The cover is fully detachable for greater
access into the enclosure during the installation and initial set-up of the instrument.
During normal operation of the instrument the cover must remain fully secured.
Liquidew EExd User’s Manual
W
)
1.5 Advanced Sensor Technology
Liquidew EExd utilizes the Michell Ceramic Moisture Sensor, an advanced impedance
sensor technology, with integrated temperature measurement. This sensor is used in
more than 1,000 natural gas and petrochemical installations worldwide.
Semiconductor thick- and thin-fi lm technologies combine in metallized ceramics,
producing an exceedingly durable sensor with the physical resilience to provide longterm reliable service in liquid phase measurements.
The Ceramic Sensor responds to the partial pressure of water vapor in the fl uid being
measured, which is directly related to the dew-point temperature. Every Liquidew EExd
sensor is calibrated against fundamental dew-point measurement systems in Michell’s
laboratory, which is internationally accredited and directly traceable to both NPL(UK)
and NIST(USA) metrology standards.
1.6 Measurement Units
The hygrometric unit can be set by the user to °C/°F dew point or moisture content in
.
ppm
W
The advanced fi rmware of the Liquidew EExd provides moisture measurements in ppm
through the application of Henry’s Law. It uses pre-programmed saturation concentration
(Cs) values for the following common pure hydrocarbon liquid applications:
W
Hexane, Propane, Isopropylbenzene, Benzene, Butane, Isobutane, Propylene,
Cyclohexane, 1-Butene and Octene. See Appendix B for instrument display names.
297097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
Four user-programmable tables enable the Liquidew EExd to be applied to virtually any
immiscible solute. For simple mixtures of hydrocarbons, a proportional combination
of the Cs values for two or three individual substances can be applied, although with
increased measurement uncertainty. For applications with complex mixture fl uids,
customers can enter their own Cs values (in ppm
(+32 to +122°F)) from their own library sources or from actual laboratory titration
analysis of the fl uid concerned.
1.7 Elimination of Temperature Effects
To ensure continuous optimum analysis conditions the Liquidew EExd Main Unit is
temperature controlled (internally) at a stable level. The control temperature level is
selected to suit the climate at the point of installation, being set to the normal maximum
temperature. Such steady state control within the analyzer greatly reduces the effects of
diurnal (day-night) swings in temperature. These temperature changes could otherwise
induce transitional adsorption and desorption effects of the fl owing sample and result
in erroneous measurements.
In addition, the Liquidew EExd features an advanced temperature compensation
algorithm that automatically maintains best possible measurement accuracy in the
event of heater failure or if the prevailing climate exceeds the set temperature level.
INTRODUCTION
for temperatures from 0 to +50°C
W
1.8 Calibration
Maintenance of calibration is essential to the lifetime performance of all analyzers. To
ensure that all customers worldwide can maintain the performance of their Liquidew
EExd, the unique Michell Calibration Exchange Service offers freshly calibrated
replacement Ceramic Sensors certifi ed traceable to NPL and NIST. The calibration
characterization data for each Liquidew EExd Sensor is programmed into on-board
non-volatile memory. Fitting the Calibration Exchange Sensor refreshes the calibration,
returning the measurement performance to day-one. This takes only a few minutes of
downtime while the interchange is made. No programming or data input is required by
the user to complete this.
The calibration exchange is available globally, typically taking less than two weeks, with
comparable cost of a traditional ‘return to manufacturer’ re-calibration service.
The recommended calibration maintenance interval is 12 months.
Michell Instruments3
Page 12
INTRODUCTION
1.9 Liquidew EExd Sampling System
(Optional – see separate manual if you have purchased this item)
Liquidew EExd User’s Manual
Figure 1
Good sample conditioning and handling is particularly important in the fi eld of moisture
measurement. As the moisture sensor has to be exposed directly to the process liquid
stream in order to detect the dissolved moisture present, key sampling issues such as the
avoidance of particulate contamination are imperative to successful operation. Michell's
30 years of expertise in on-line process moisture analyzers are used to optimize the
design of the Liquidew EExd Sampling Systems. Contact Michell Instruments for further
details: www.michell.com.
Liquidew EExd Sampling System
497097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
!
2 INSTALLATION
2.1 Electrical Safety
During the installation of this product ensure that all
applicable national and local electrical safety regulations
Always ensure that power is switched off prior to accessing
the product for any purpose other than normal operation or
INSTALLATION
WARNING:
are observed.
WARNING:
Isolate the power prior to installation.
WARNING:
prior to disconnecting any cables.
2.1.1 Equipment Ratings and Installation Details
The mandatory statements contained within refer to the Ex certifi ed Liquidew EExd
Analyzer only (not including the sampling system).
This equipment must be supplied with a voltage between the range of 90 to 260 V AC,
47/63 Hz. Maximum power rating is 180W.
The power is connected via PL1 on the mains connector PCB.
Figure 2
All input and output connectors are 2-part PCB mounted type, rated at 300 V 10 A.
The detachable, screw terminal half of each connector is designed to accept 0.5 to
2.5mm2 [24 -12 AWG] stranded or solid conductors.
Power Connection Connector
Michell Instruments5
Page 14
INSTALLATION
Any power connection cable should be 3 core over sleeved, with minimum 0.5mm
insulation and rated at 300 V. Cables should have Live (L), Neutral (N) and Earth
[Ground] (E) conductors. Ensure suitably rated power supply cables and glands are
used to ensure that electrical safety is maintained. Connect each of the Live (L), Neutral
(N) and Earth [Ground] (E) conductors to the similarly marked terminals (L, N, E) on the
Power In connector shown in
power consumption requirement.
Any power supply terminals and voltages must be suitably separated from the other I/O
requirements of this product.
Before applying power, perform a continuity test to ensure that the power supply cable
and product are effectively connected to the protective Earth.
The Protective Earth terminal is mounted internally and the Earth wire connected to it
should never be disconnected. The product enclosure is supplied with an external earth
stud at the lower right hand side. At installation, connect this earth stud to plant earth
by a minimum 4mm2 earthing bonding. M6 stud and 2 off M6 nuts and washers, all
nickel plated.
Figure 3
Liquidew EExd User’s Manual
. Ensure the power supply can deliver suffi cient
Figure 3
Fuse: A replacement fuse can be obtained by contacting Michell Instruments' technical
support. Fuse rating = 5 x 20mm 2.5 A anti-surge to IEC 60127-2.
This product is designed to be safe at least under the following conditions: between a
temperature range of -40 to +60°C (-40 to +148°F), in maximum 80% relative humidity
for temperatures up to +31°C (+88°F) decreasing linearly to 50% RH at +50°C
(+122°F). Supply voltages of ±10% and transient over voltages up to Overvoltage
Category II. Pollution Degree 2. Altitudes up to 2000m. Outdoor mounting is permitted
using suitably rated glands equivalent to NEMA 4 / IP66. See Appendix A, Technical
Specifi cation, for full operating parameters.
Do not remove or exchange any of the cables or electrical components supplied with
this product. Doing so will invalidate all warranties.
There are no additional or special electrical safety requirements other than those
referred to in this manual.
Earthing Stud And Nut Washer Assembly
697097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
Location and mounting arrangements - refer to the relevant sections of this manual for
the location and mounting details.
Installation of this equipment must include the provision of a suitable and locally
positioned power isolation switch or circuit breaker. Indication of the purpose of the
switch or circuit breaker is strongly recommended. An over-current protection device
should be rated to a maximum of 10 A.
This equipment and all power isolation devices must be installed in a location and
position that allows safe and easy access to their operation and is able to rigidly support
the equipment.
Do not install this equipment in a location that would expose it to impact or high levels
of vibration.
Operation of this equipment, other than in a manner specifi ed by the manufacturer, may
impair the safety protections provided.
The safe installation of this equipment and any system incorporating this equipment is
the responsibility of the installer. Ensure local regulations and requirements are referred
to prior to any installation commencing.
INSTALLATION
Michell Instruments7
Page 16
INSTALLATION
!
2.2 Hazardous Area Safety
Refer to Appendix H for the Hazardous Area Certifi cation of this product.
This product is fi tted with a marking label that contains Hazardous Area information
pertinent to the suitable location and installation.
During all installation and operation activities, local regulations and permitted working
routines must be observed. Installation should only be performed by competent personnel
and in accordance with the latest version of IEC/EN60079-14 or local equivalent.
Repair and servicing of this equipment must only be carried out by the manufacturer.
An Installation and Maintenance Information Sheet is supplied separately to the manual.
This product is certifi ed safe for use in a Zone 1 and Zone 2
area only. This product must not be installed or used within
Liquidew EExd User’s Manual
WARNING:
a Zone 0 area.
WARNING:
This product must not be operated within an explosive
atmosphere greater than 1.1 bara.
WARNING:
This product must not be operated with enriched oxygen gas
samples (more than 21% oxygen content).
WARNING:
This product must not be operated outside of the
temperature range of -40 to +60°C (-40 to +140°F).
WARNING:
The enclosure of this product provides Exd protection, partly
through the threads used for mounting the lid, stopping
plugs and cable gland. At all times effort should be made to
ensure these threads are suitably protected from damage
and that only appropriately rated mating parts are applied
to them, in accordance with the certifying requirements.
897097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
!
!
!
2.3 Pressure Safety
This product is used in conjunction with pressurized gases.
Observe pressurized gas handling precautions.
Pressurized gas should only handled by suitably trained
INSTALLATION
WARNING:
WARNING:
Pressurized gas is dangerous.
personnel.
This product requires pressurized gas to be connected to it. Observe pressurized gas
handling regulations. Only suitably trained personnel should carry out tasks that include
the use of pressurized gas mediums.
2.4 Lifting and Handling
Personnel must observe suitable lifting and handling
This product is not designed as portable or transportable equipment. It should be rigidly
fi xed in position as per the full installation instructions.
The weight of the analyzer is in excess of 18kg (40lbs). Therefore, appropriate lifting and
handling techniques should be used during the installation process. Before commencing
any lifting or handling ensure that its intended location is suitable and appropriately
prepared. Make sure that mounting point design considerations have employed locally
approved safety factors.
WARNING:
This instrument is in excess of 18kg (40lbs).
precautions.
When handling and installing this product (particularly after removal from its packaging)
ensure that it is not dropped, impacted or subjected to high levels of vibration or
environmental conditions that may impair its operation.
Michell Instruments9
Page 18
INSTALLATION
2.5 Analyzer System
Refer to the Installation & Maintenance Information sheet (supplied separately) and the
System Drawings in Appendix A.
The instrument is housed in an aluminum EExd enclosure suitable for wall or panel
mounting. Four mounting points are available with M12 clearance holes on fi xing centres
of X = 270mm x Y = 318mm.
Height: 355mm (13.9”) 500mm (19.68”) including installation clearance
Width: 310mm (12.20”) 500mm (19.68”) including installation clearance
Depth: 245mm (9.64”)
The enclosure provides environmental ingress protection IP66 and should be mounted
vertically in a location free of any appreciable vibration. It should be placed in a shaded
position to prevent heating effects through sun radiation.
NOTE: Ensure that the process sample gas supply line is well fl ushed
through to clear any debris present, prior to connection to the instrument.
A sample handling system must prepare the liquid in terms of fi ltration and
temperature reduction (if greater than +40°C (+104°F) before entering into
the measurement system.
In accordance with the Certifi cation requirements, the Liquidew EExd must have, as a
minimum, those components described in the Sample System Flow Diagram shown in
The following points should be considered when installing the sample liquid supply line:
PTFE tape is recommended for pipe connections. Solvent based pipe thread sealant
should not be used, as condensable components or contaminates can be leached during
the curing period.
It is recommended that Viton is used for all O-rings.
Filtration is critically important to avoid particulate contamination. For process fl uids
with high levels of particulates present, two-stage fi ltration may be required.
For elevated temperature processes, the sample fl ow temperature should be moderated,
preferably to less than +40°C (+104°F) (max. +60°C (+140°F)), prior to entering the
Liquidew EExd Main Unit.
There should be suffi cient differential pressure between sample source and return points
to enable a fl ow of between 0.1 and 0.3 l/min (0.03 and 0.08 GPM) through the analyzer.
The internal volume of the impulse tubing between the process line and any sampling
system should be as low as possible (sample lines should be kept as short as possible)
to minimize response lag time to changing process conditions.
Liquidew EExd User’s Manual
Piping should be lagged and/or trace heated if ambient temperatures could cause the
sample liquid to fall below its saturation temperature.
It should be standard procedure to isolate the measurement system during shutdowns
or when plant problems are being experienced. The supply lines must be fully purged
before restarting.
2.5.2 Power Connections
A single-phase AC power connection is required.
The power supply can accommodate voltages from 90 to 260 V AC, 47/63 Hz. The unit
requires a maximum of 180W to function correctly.
The connection is made via a two-part connector mounted at the base of the unit. See
Appendix A.
Cable entry into the measurement system is made through the bottom of the enclosure.
• For ATEX/IECEx compliant versions of the product, 3 off ISO M20 tapped
holes are provided.
• For cCSAus compliant version of the product, 3 off ½” NPT entries are
provided.
NOTE: EExd Stopping Glands MUST be used for ATEX/IECEx installations.
Refer to the separate installation & maintenance information sheet supplied.
The terminals are marked:
L = Live
N = Neutral
E = Earth
1297097 Issue 13.1, July 2018
Page 21
Liquidew EExd User’s Manual
AL3AL2AL1AL4COMMSChannel 1Channel 2
PL16
NC C NO NC C NO
7891011
h
12
NC C NO NC C NO
123456
INSTALLATION
Optional
{
mA1+
mA1-
mA2+
B A GND
13 14 15
PL20PL15PL14PL19
16 17 18 1920 21 22 23
mA2-
LEN
mA3+
mA3-
mA4+
mA4-
Enclosure wall
Figure 6
2.5.3 Analog and Digital Communications
Two active 4-20 mA outputs and a Modbus RS485 digital interface (see Appendix F for
details) are provided with the Liquidew EExd. mA1 and mA3 output the moisture or
dew-point values. mA2 and mA4 output the sample temperature values of Channels 1
& 2 respectively.
NOTE: The maximum output resistance for the 4-20 mA outputs is 500Ω.
See Section 3.7 on the setting of the 4-20 mA outputs via the user interface and
Appendix F on setting the outputs via the Modbus interface.
Refer to
Figure 7
for cable wiring.
Hook-up Wiring Diagram
h
h
Gland
Cable screen
2.5.4 Process Alarms and Analyzer Status Alarms
Each channel has an associated process and fault alarm, as shown below:
AL1: Channel 1 process alarm
AL2: Channel 1 analyzer status alarm
AL3: Channel 2 process alarm (Optional)
AL4: Channel 2 analyzer status alarm (Optional)
The process alarm contacts can be set as either Normally Closed (
Open (
The process alarm contacts change from
N/O).
N/C to N/O when the moisture value becomes
N/C) or Normally
greater than the alarm set point.
The fault alarm contacts change from
N/C to N/O when an error associated with the
channel occurs or when there is a supply failure.
Michell Instruments13
Page 22
INSTALLATION
!
Liquidew EExd User’s Manual
2.6 Liquidew EExd Start-up Purge Procedure
This is a mandatory procedure stipulated in the ATEX/IECEx
certifi cation of the product. The procedure must be fully
carried out prior to the Liquidew EExd having any power or
signal connections applied. It must also be fully carried out
after the Liquidew EExd and associated sample handling
equipment has been installed and leak checked. Always refer
to Appendix H.4 - Special Conditions of Safe Use.
This procedure must be carried out at any time following
service or maintenance periods that cause any of the
Liquidew EExd or associated sample handling equipment
pipe work to be disconnected.
It is not necessary to carry out this procedure if power or
signal connections only have been disconnected.
1. Before start-up ensure that all power and signal connections to the
Liquidew EExd are fully isolated.
2. Ensure that all Inlet & Outlet liquid connections to the Liquidew EExd are
made correctly and are leak tight checked.
3. Fully open the sample Inlet & Outlet isolation valves.
4. Allow the sample to purge the system for the period of time indicated in
the table below:
TOTAL PURGE TIME
must be a minimum of 1 minute at 1 l/min (0.26 GPM)
Assumes total system pipe length is 3m (9.8') and internal pipe bore is the
recommended 4mm (0.16") internal bore.
For every additional 1m (3.3’) of pipe work, continue the sample purge for
an additional 15 seconds at 1 l/min (0.26 GPM).
5. After the appropriate purge duration, close the sample Inlet & Outlet
isolation valves.
6. Ensure the window is replaced and fully secured before applying the
power.
1497097 Issue 13.1, July 2018
Page 23
Liquidew EExd User’s Manual
MINIMUM REQUIREMENTS FOR START UP PURGING
INSTALLATION
INLET
NEEDLE VALVE
SAMPLE
INLET
INLET
NEEDLE VALVE
SAMPLE
INLET
Figure 7
2.7 Sample Flows
The fl ow meter provides the user with an indication of the sample fl ow status via a
message displayed on the STATUS Page. The three states available are
HIGHfl ow.
X
CHANNEL 1
X
SAMPLE INSAMPLE OUT
LIQUIDEW EExd
X
SAMPLE INSAMPLE OUT
CHANNEL 2
X
Minimum Requirements for Start-up Purging
X
FLOW CONTROL
NEEDLE VALVE
X
FLOW CONTROL
NEEDLE VALVE
X
X
NON-RETURN
VALVE
SAMPLE
OUTLET
LOW, OK and
LOW Flow rate of <0.1 l/min (<0.03 GPM)
OK Flow rate of between 0.1 and 0.3 l/min (0.03 and 0.08 GPM)
HIGH Flow rate of >0.3 l/min (>0.08 GPM)
OK is the recommended setting during normal operation.
Michell Instruments15
Page 24
OPERATION
3 OPERATION
3.1 System Operation
At switch-on, the instrument will display the MAIN Page. It will synchronise itself to the
on-board real time clock, in order to begin logging data at the next minute that is a
multiple of 5, i.e. 5, 10, 15 etc. The MAIN Page will show the moisture and temperature
readings of either 1 or 2 sensors and a countdown to the time when it will take the next
data log.
Figure 9
below shows the MAIN Page for both 1 and 2 sensor confi gurations.
Liquidew EExd User’s Manual
DEWPOINT
Figure 8
3.2 User Interface
3.9
0
Cdp
TEMPERATURE
0
Cdp
0
C
0
Cdp
0
C
0
C
25.4
TIME TO NEXT DATA LOG: 7m 45s
DEWPOINT CH1
4.6
25.5
DEWPOINT CH2
-3.9
24.5
TIME TO NEXT DATA LOG: 6m 45s
MAIN Page in Single Channel (top) and Dual Channel Modes
3.2.1 Interface Controls
Figure 10
illustrates the user interface. It has a vacuum fl uorescent display and four
touch sensitive pads that facilitate user interaction through the glass of the enclosure.
Liquidew EExd
Process Moisture Analyzer
DEWPOINT
3.9
TEMPERATURE
25.4
TIME TO NEXT DATA LOG: 7m 45s
j
Up/Down
Arrow
Buttons
0
Cdp
0
C
SELECT
j
SELECT
Button
Figure 9
j
j
MENU
MAIN
jj
MENU/
MAIN
Button
User Interface
VFD Display
Blue LEDs
1697097 Issue 13.1, July 2018
Page 25
Liquidew EExd User’s Manual
3.2.2 ‘Up/Down Arrow’ Buttons
OPERATION
Up () and Down () buttons are used to change pages, scroll through lists and
The
adjust values.
3.2.3 ‘SELECT’ Button
Figure 10
Figure 11
Up/Down Arrow Buttons
SELECT
‘SELECT’ Button
SELECT button is used to select or de-select a highlighted item in a menu list.
The
3.2.4 ‘MENU/MAIN’ Button
The MENU/MAIN button is used to toggle between the MAIN Page and the MAIN MENU
Page, or return to the MAIN Page from any location within the menu structure.
Figure 12
MENU
MAIN
‘MENU/MAIN’ Button
Michell Instruments17
Page 26
OPERATION
3.3 Menu Structure
Liquidew EExd User’s Manual
Figure 14
Status Page
j
NO
below shows a map of the menu structure.
KEY
Main Menu
jj
SELECT
j
Error ?
YES
j
Error Report
Page
SELECT
j
SELECT
Choices
Menu Pages
Other Pages
STATUS
View
Logged
Data
SELECT
LOGGING
j
View
Statistics
SELECT
j
Page
1
Page
2
MENU
SELECT
System
Error Codes
View
Faults
SELECT
j
Logged
Start-Up
Banner
j
Main Page
MENU
MAIN
j
VIEW/ADJ
VARIABLES
SELECT
j
Password
Page
NO
j
SELECT
j
Password
Correct?
YES
SENSOR
INFO
Press MENU/MAIN button to
get back to Main Page from
CONTACT
INFO
SELECT
SELECT
j
Sensor 1Sensor 2
SELECT
j
Sensor 1
Info
SELECT
j
Sensor 2
Info
OPTIONAL
MENU
MAIN
any location
MENU
MAIN
Contact/About
j
j
Page
1
j
j
j
Logged Pages
Page
2
Page
3
Variables Pages
j
j
Use Up/Down arrow buttons
to scroll through
menu items and pages
Figure 13
Menu Structure
1897097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
3.4 MAIN MENU Page
This page is accessed by pressing the MAIN/MENU button from the MAIN Page. The
instrument’s status, variables, logged data and system information are available through
this page. Use the
press the
SELECT buttonto access.
Up () and Down () buttons to highlight the page of interest and
STATUS
LOGGING MENU
VIEW/ADJ VARIABLES
SENSOR INFO
CONTACT INFO
OPERATION
MENU
3.5 STATUS Page
This page shows the status of the process alarm and fl ow for one or both channels
depending upon the confi guration. When the measured moisture or dew-point value
rises above the alarm set-point, the alarm condition will be displayed as
are shown as
meter.
Figure 14
LOW, HIGH or OK. See Section 2.7 for more information on the fl ow
MAIN MENU Page
ON. Flow rates
STATUS PAGE
CHN1 ALARM OFF
CHN1 FLOW LOW
TIME TO NEXT DATA LOG: 2m 11s
Figure 15
STATUS Page
Press the MAIN/MENU button to return to the MAIN Page.
Michell Instruments19
Page 28
OPERATION
3.6 LOGGING MENU Page
This page allows the viewing of data or statistical information on the logged data. Press
SELECT button to see the following options:
the
View Logged Data
View Statistics
View System Faults
Liquidew EExd User’s Manual
Press the
pages. If there is no data available then
access will be given to the other two options.
3.6.1 VIEW LOGGED DATA Page
This page allows access to the previous measurement results made by the instrument.
A rolling total of a maximum of 150 samples can be logged, which represents a
measurement history of 150 x (measurement time) in minutes. Sample 1 represents
the most recent measurement taken. After 150 measurements have been logged, the
oldest measurement will be deleted and replaced as each new measurement is logged.
Caution: Changing the moisture value, e.g. from dew point to moisture, will
reset all the logged data and start a new fi le.
Access to each measurement sample is via the
may be used to scroll through each page of information. If faster scrolling is required
(to quickly move to another sample) press the
will increase by 10. When the sample number selected is greater than that acquired, or
is greater than 150, Sample 1 will be selected and displayed.
Up () and Down () buttons and the SELECT button to enter these options
Sample NumberTime of Sample
jjj
No Data Available will be displayed and no
Up () and Down () buttons, which
SELECT button and the sample number
Date (day/month)
LOGGED DATA
NO. 1 11:40 03/09
MOIST -3.6 oCdp
TEMP 25.0
Figure 16
Each page of logged data contains:
• Sample number 1 to 150, 1 being the most recent
• Date of sample dd/mm
• Time of sample 24 hr format, hh:mm
• Values Moisture content/dew point and
• Units of measurement °C / °F or ppm
LOGGED DATA Page
temperature for 1 or 2 channels
o
C
W
Press the MAIN/MENU button to return to the MAIN Page.
2097097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
3.6.2 VIEW STATISTICS
These pages display the maximum, minimum and average values for each measured
parameter for up to 150 previous measurement samples.
MENU Page re-sets the logging statistics.
STATISTICS PAGE 1/2
MOIST MAX -3.6 oCdp
at 11:40 on 03/09
MOIST MIN -3.6
at 11:40 on 03/09
OPERATION
RESET LOG on the MAIN
o
Cdp
MOIST AVR -3.6
Figure 17
Use the Up () and Down () buttons to scroll through the statistics.
Press the
3.6.3 VIEW SYSTEM FAULTS Page
This page displays a record of the last six system faults that have occurred and have
subsequently been corrected. This assists in the diagnosis of any past anomaly in
measured values. Any present system faults will be displayed in the bottom message
line of the MAIN Page.
MAIN/MENU button to return to the MAIN Page.
LOGGED ERROR CODES
CODE TIME & DATE
0008 11:10 02/08/12
o
STATISTICS Page
Cdp
Figure 18
Refer to Section 4.4 for descriptions of the error messages and codes.
Press the
MAIN/MENU button to return to the MAIN Page.
SYSTEM FAULTS Page
Michell Instruments21
Page 30
OPERATION
3.7 VIEW/ADJ VARIABLES Page
For more information on each variable refer to Appendix B.
3.7.1 Password
To safeguard against unauthorized adjustment of set-up parameters and variables, an
entry lock is provided.
The user must fi rst input the access code to enter the VIEW/ADJUST VARIABLES Pages.
The password is 7316.
ENTER PASSWORD
USE ARROW KEYS AND
SELECT KEY
Liquidew EExd User’s Manual
0 0 0 0
Use the Up () and Down () buttons to change the highlighted digit and press the
SELECT button to enter and move to the next digit. Inputting 4 correct digits will result
in access to the Variables Pages as detailed in the following sections.
3.7.2 VARIABLES Pages
Three pages (four pages in the dual channel confi guration) are used to display the
system variables. They can be adjusted by using the Up (), Down () and SELECT
buttons.
Use the
To select a variable for adjustment, scroll to the desired variable and press the
button
the Up () and Down () buttons to change the value. NOTE: Numerical values
can be changed at a faster rate by extending the duration of the
Up () and Down () buttons to scroll through the list and from page to page.
. A small box will appear beside the value to indicate that it can be adjusted. Use
Down () button press.
Figure 19
PASSWORD Page
VARIABLES PAGE 1/3
UNITS
apply
alarm
OP1 MIN
OP1 MAX
OP2 MIN
Dew Point
n/a
0
-100
20
0
o
C
o
C
o
C
o
C
SELECT
Up () and
Variables Page in single channel confi guration with Dew Point selected
2297097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
VARIABLES PAGE 1/3
UNITS
apply
alarm
OP1 MIN
OP1 MAX
OP2 MIN
Variables Page in single channel confi guration with Moisture & Solute Cumene selected
Moisture
cumeme
0 PPM(W)
-100
20
0
PPM(W)
PPM(W)
o
C
OPERATION
Figure 20
3.7.3 Single Channel Confi guration Variables Pages
For more information on each variable refer to Appendix B.
Variables Page 1
VariableBrief Description
UNITS
apply
alarm
OP1min
OP1max
OP2min
Variables Page 2
Measurement, either moisture content or dew point
When calculating moisture content, this variable is used to select the
sample solute type or user-defi ned solute
Moisture content or dew-point value that trips the process alarm
Moisture content or dew-point value that gives 4 mA on mA1 output
Moisture content or dew-point value that gives 20 mA on mA1 output
Temperature value that gives 4 mA on mA2 output
VARIABLES Pages (Examples)
VariableBrief Description
OP2max
°C/°F
INT TEMP
TIME
DATE
ADDR
Variables Page 3
VariableBrief Description
LOG INT’VAL
RESET LOG
SET DEFAULT
Temperature value that gives 20 mA on mA2 output
Temperature units selection
Set-point temperature of the internal heater
System time
System date
Sets the instrument address for serial communications
Time interval between data logs
Clears the logged data
Sets the system defaults
Michell Instruments23
Page 32
OPERATION
3.7.4 Dual Channel Confi guration Variables Pages
For more information on each variable see Appendix B.
Variables Page 1
VariableBrief Description
Liquidew EExd User’s Manual
CHN1
apply
alarm
CHN2
apply
alarm
Variables Page 2
VariableBrief Description
OP1min
OP1max
OP2min
OP2max
OP3min
OP3max
Moisture content or dew-point value for Channel 1
When calculating moisture content, this variable is used to select the
sample solute type or user-defi ned solute for Channel 1
Moisture content or dew-point value that trips the process alarm for
Channel 1
Moisture content or dew-point value for Channel 2
When calculating moisture content, this variable is used to select the
sample solute type or user-defi ned solute for Channel 2
Moisture content or dew-point value that trips the process alarm for
Channel 2
Moisture content or dew-point value that gives 4 mA on mA1 output
Moisture content or dew-point value that gives 20 mA on mA1 output
Temperature value that gives 4 mA on mA2 output
Temperature value that gives 20 mA on mA2 output
Moisture content or dew-point value that gives 4 mA on mA3 output
Moisture content or dew-point value that gives 20 mA on mA3 output
Variables Page 3
VariableBrief Description
OP4min
OP4max
°C/°F
INT TEMP
TIME
DATE
Variables Page 4
VariableBrief Description
INST ADDR
SET DEFAULT
LOG INT’VAL
RESET LOG
Temperature value that gives 4 mA on mA4 output
Temperature value that gives 20 mA on mA4 output
Temperature units selection
Set-point temperature of the internal heater
System time
System date
Sets the instrument address for serial communications
Sets the system defaults
Time interval between data logs
Clears the logged data
2497097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
3.7.5 User-Defi ned Solutes
When selecting the sample solute type it is also possible to select up to four different
user-defi ned solutes, labelled by default as U1, U2, U3 and U4. These are available by
scrolling through to the end of the list of sample solute types. The table of saturation
constants (or Cs values) of each user-defi ned solute can be edited by the user. From
the Variables page, to edit your solute, scroll down the solute list and choose one of
the user-defi ned solutes. Select the solute and it will show the the Cs value editor page.
Each user-defi ned solute may also be given a customized label which will be appended
to the end of the default labels.
3.7.5.1 Editing the Table of Cs Values
VariableBrief Description
OPERATION
0°C
10°C
20°C
30°C
40°C
50°C
To view the table of Cs values, scroll to the desired user-defined solute using the
Cs Value at temp of 0°C
Cs Value at temp of 10°C
Cs Value at temp of 20°C
Cs Value at temp of 30°C
Cs Value at temp of 40°C
Cs Value at temp of 50°C
Up () and Down () buttons, press the SELECT button and the relevant table will
appear.
To edit any of the values use the
the list. Scroll to the desired temperature and press the
will appear beside the Cs value to indicate that it can be adjusted. Use the
Down () buttons to change the value - these can be changed at a faster rate by
and
extending the duration of the arrow button press. Press the
fi nished and to adjust another value.
Press the
MENU/MAIN button to display the label editing page.
Up () and Down () buttons to scroll up and down
SELECT button. A small box
Up ()
SELECT button again when
3.7.5.2 Editing the Label for the User-defi ned Solute
The custom label can be up to 8 characters in length and consists of any combination
of letters from A-Z, space, hyphen and numbers from 0 to 9.
To enter the page, press the
Cs values. Use the
Up () and Down () buttons to select the character and press the
MENU/MAIN button from the page showing the table of
SELECT button to save and move to the next character position.
To exit back to Variables Page 1, press the
MENU/MAIN button.
Michell Instruments25
Page 34
OPERATION
3.8 SENSOR INFO Page
This page contains the information relating to the water dew-point sensors.
Hours Used Duration that the sensor has been in active use
Liquidew EExd User’s Manual
SENSOR INFO
HOURS USED 00006
NEXT CAL 11/2012
SENSOR S/N FD79-0430
Figure 21
SENSOR INFO Page
Next Cal Next recommended calibration date of sensor
Sensor S/N Serial number of sensor
3.9 CONTACT INFO Page
This page contains contact information for Michell Instruments.
The power to the enclosure must be turned off before any
work is carried out in the measurement system enclosure.
Sample line connections to the measurement system must
be isolated and de-pressurized before any work commences.
Before powering up the instrument the “Start-up purge
procedure” must be carried out. See Section 2.6.
MAINTENANCE
Observe de-energize durations.
To ensure the full requirement of this product's safety
certifi cate is maintained, any loosened or disturbed tubework
or couplings must be subject to a gas pressure test and
appropriate leak check at 1.5x the max operating pressure
before the full product is re-energized.
The design of the Liquidew EExd sensor cell and measurement system is such that
no specifi c routine maintenance is required. If, however, a fault does occur with your
system that is not covered within this manual, please contact Michell Instruments (www.
michell.com) or your local representative.
4.1 Enclosure Cover and User Interface
The enclosure cover is part of the fl ameproof protection for the enclosure and has an
IP66 rating. It should be fi rmly closed to ensure fl ameproof integrity and continued
environmental protection. For prolonged and easy operation ensure that the threads
are always lubricated with a light grease. A grub screw is used as a locking device. This
should be loosened before unscrewing the cover counter-clockwise.
The user interface assembly uses two ¼ turn bayonet style fasteners to secure it. These
are fi nger operated and should be turned clockwise to lock and counter-clockwise to
release. The user interface, once disconnected from the two ¼ turn fasteners, can
be temporarily re-positioned on the instrument by securing the right-hand fastener
in the left-hand mount. This will situate the interface assembly in an overhanging
position outside of the enclosure allowing greater access. If there is insuffi cient space
to accommodate the overhanging user interface assembly on the left-hand side, it may
be rotated 180° (upside down) and placed on the right-hand side.
Michell Instruments27
Page 36
MAINTENANCE
!
DANGER
Electric
Shock Risk
Liquidew EExd
Moisture in Liquid Analyzer
Liquidew EExd User’s Manual
Figure 23
Always keep the bayonet fi ttings lightly lubricated. If required, the user interface can
be fully disconnected from the instrument by disconnecting the ribbon cable connection
to the main processor PCB.
Unscrew the enclosure cover and remove the user interface
assembly before carrying out the procedures below.
Ribbon Cable Connection
4.2 Replacement of the Sensor Assembly
The power to the enclosure must be turned off before any
work is carried out in the measurement system enclosure.
Observe de-energize durations.
1. Isolate the incoming sample line by CLOSING the sample inlet isolation
valve and allow the system to depressurize and drain. Isolate the power
and observe the de-energize duration.
2. Remove the enclosure window and mount the user interface (see Section
4.1).
3. Using a 2.5mm hex key, remove the M3 cap head screw (1 in
securing the moisture sensor assembly to the stay bracket.
4. Restrain the sensor assembly. Using an 14mm wrench, loosen and remove
the 2 off 6mm water dew-point sensor sample pipe connections (2 in
Figure 25)
.
Figure 25)
2897097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
1
MAINTENANCE
2
Figure 24
5. Carefully pull the sensor block assembly out of the enclosure. This will
allow access to the two sensor connections.
6. Disconnect the ribbon cable connectors from the sensor pcb.
7. Fully remove the sensor assembly from the enclosure.
8. Reconnect the sensor connections to the replacement moisture sensor
assembly. Reposition the assembly on the stay bracket and secure with
the M3 cap head screw.
9. Refi t and fully tighten the 6mm moisture sensor sample pipe connections.
10. To ensure the full requirement of this product's safety certifi cate is
maintained, any loosened or disturbed tubework or couplings must be
subject to a gas pressure test and appropriate leak check at 1.5x the max
operating pressure before the full product is re-energized.
Moisture Sensor Assembly Replacement
Michell Instruments29
Page 38
MAINTENANCE
DANGER
Electric
Shock Risk
3)
4)
4.3 Replacement of the Flow Meter
The power to the enclosure must be turned off before any
work is carried out in the measurement system enclosure.
1
Liquidew EExd User’s Manual
Observe de-energize durations
2
Figure 25
1. Isolate the incoming sample line by CLOSING the sample inlet isolation
valve and allow the system to depressurize. NOTE: Always refer to
Appendix H.4 - Special Conditions of Safe Use.
2. Remove the enclosure window and mount the user interface (see Section
4.1).
3. Restrain the fl ow meter assembly (1) and use a 14mm wrench to loosen
and remove the 2 off 6mm sample pipe connections.
4. Unscrew the 2-wire cable connector (2) from the fl ow meter.
5. Carefully withdraw the fl ow meter assembly out of the enclosure.
6. Replacement of the fl ow meter is simply a reversal of the above procedure.
Flow Meter Replacement
7. To ensure the full requirement of this product's safety certifi cate is
maintained, any loosened or disturbed tubework or couplings must be
subject to a gas pressure test and appropriate leak check at 1.5x the max
operating pressure before the full product is re-energized.
3097097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
4.4 Troubleshooting
4.4.1 Error Messages
If a system errors occur, an error message will appear at the bottom line of the MAIN
Page describing the problem. If more than one system error has occurred, the error
messages associated with those faults will continually scroll in turn.
DEWPOINT
MAINTENANCE
3.9
0
Cdp
TEMPERATURE
55.4
TEMPERATURE OUT OF RANGE
Figure 26
Error MessageDescription and Possible Causes
DEWPOINT UNDER RANGE
DEWPOINT OVER RANGE
TEMPERATURE OUT OF
RANGE
LOW FLOW
HIGH FLOW
SATURATION
CAL TABLE ERROR
INTERNAL HEATER FAULT
Dew point <-120°C (<-184°F) or sensor tile failure
Dew point >+30°C (>+86°F) or sensor tile failure
Temperature >+50 or <0°C (>+122 or <32°F)
Flow through sensor measurement cell is <0.1 l/min
(0.03 GPM) or fl ow meter has failed / disconnected
Flow through sensor measurement cell is >2.6 l/min
(0.69 GPM)
Dew point is greater than or equal to temperature
Fault with sensor calibration data
Internal temperature set-point not achievable or fault
with the internal temperature control devices
Error Message Line
0
C
4.4.2 Error Messages Flashing over Displayed Values
A short message will fl ash over the displayed value in the MAIN Page, in certain
conditions, as indicated below:
Flashing Message Over ValueCondition
error
error
under
over
error
Dew-point or
moisture content
Dew-point or
moisture content
Dew-point or
moisture content
Dew-point or
moisture content
Temperature
Moisture saturation condition (dew point
temperature)
Calibration table error (checks sensor
impedance values are increasing in the
correct direction)
Dew point under range <-120°C (<-184°F)
Dew point over range >+30°C (>+86°F)
Sensor temperature fault <-40 or >+70°C
(<-40 or >+158°F)
Michell Instruments31
Page 40
MAINTENANCE
4.4.3 Logged Error Codes
This page displays a record of the last six system error codes that have occurred in
order to assist in the diagnosis of any past anomalies. Error codes are only logged at the
end of every measurement cycle and indicate a change in status of single or multiple
errors. For example, if an error code
TEMPERATURE ERROR. If an error code of 0000 was logged next, this would indicate
that the error had now cleared.
Liquidew EExd User’s Manual
0004 was logged, this would indicate CHANNEL 1
LOGGED ERROR CODES
CODE TIME & DATE
0008 11:10 02/08/12
Figure 27
Logged Error Codes and Error Indication (Modbus Register 35)
Also see Appendix G, Register Confi guration C, for more details
The 4-digit error codes are hexadecimal numbers that are dependent upon the bits set
within the error indication register.
3297097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
If more than one error has occurred, then the error codes will be added together:
MAINTENANCE
1 Error Code
Error Code
Error Code
2 Error Code
Error Code
Error Code
Note: In hexadecimal:
A = 10
B = 11
C = 12
D = 13
E = 14
F = 15
4.4.4 Analyzer Fault Alarm Relay
The process alarm contacts can be set as either Normally Closed (N/C) or Normally
Open (
N/O).
0104 =
0100 (Channel 2 dew-point sensor over range) plus
0004 (Channel 1 temperature out of range) (0100 + 0004 = 0104)
0C00 =
0800 (Channel 2 high fl ow) plus
0040 (Channel 1 cal table error) (0800 + 0400 = 0C00)
The process alarm contacts change from
greater than the alarm set point.
The fault alarm contacts change from
channel occurs or when there is a supply failure.
N/C to N/O when the moisture value becomes
N/C to N/O when an error associated with the
Michell Instruments33
Page 42
APPENDIX A
Liquidew EExd User’s Manual
Appendix A
Technical Specifi cations
3497097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
Appendix A Technical Specifi cation
Main Unit – Measurement Parameters
Channel Confi gurationSingle and dual channel
Moisture Contentppm
Temperature°C and °F
Water Dew Point°C and °F
Sample Flow Rate
Sensor Technology
Moisture Sensor
Technology
Calibration Range -100 to +20°Cdp ( -148 to +68°Fdp)
Measurement Range-120 to +30°C (-184 to +86°F) (0.001 ppm
Accuracy
Dew point:
Moisture content:
Analysis temperature:
Resolution
Temperature Coeffi cientAlgorithm compensation
Operating PressureMax. 50 barg (725 psig)
Sample Flow
W
Status indication: LOW/OK/HIGH
<0.1 to >0.3 l/min (<0.03 to >0.08 GPM)
Michell Ceramic Moisture Sensor
±1°C between –59.9 & +20°Cdp
(±1.8°F between -75.9 to +68°Fdp)
±2°C between –60 & -100°Cdp
(±3.6°F between -76 to -148°Fdp)
±10% of reading
±20% of reading
Accuracy ±0.2°C
0.1°C between +20 & -80°Cdp (0.2°F between +68 & -112°Fdp)
1°C between -80 & -100°Cdp (2°F between -112 & -148°Fdp)
Up to 1 Nl/min (0.1 to 0.2 Nl/min recommended)
(Up to 0.26 GPM (0.03 to 0.05 GPM recommended))
APPENDIX A
to saturation)
W
HMI
Keypad/InterfaceCapacitive touch-screen through glass
DisplayVacuum fl uorescent
A rolling maximum of 150 data logs is available
Each log records time, date, moisture and temperature values for
Datalogging
Communications and
Output
each channel
5 minutes minimum and 60 minutes maximum logging intervals can
be set by the user
Two non-isolated 4-20 mA per measurement channel
500 maximum load
Range and parameter settable by user
Modbus RTU @ 9600 baud-rate
Alarms: two volt free contacts per channel; one process value and
one instrument status
Also available via Modbus communications
Chromate primer, Polyester P9010 powder coated (black) - meets
BS3900
Michell Instruments35
Page 44
APPENDIX A
Liquidew EExd User’s Manual
General
Sample Connections1/8" NPT(F)
Weight21kg (46lbs)
Operating Supply Voltage90 to 260 V AC, 47/63 Hz, 180 W - Main Unit
Operating Environment
Indoor/Outdoor -20 to +60°C (-4 to +140°F)
Max 95%RH
Hazardous Area Certifi cation
ATEX II 2G Ex d IIB + H2 Gb T5 (-40°C to +44°C)
T4 (-40°C to +60°C)
Certifi cation Codes
Pattern ApprovalsGOST-R, GOST-K
IECEx Ex d IIB + H2 Gb T5 (-40°C to +44°C)
T4 (-40°C to +60°C)
cCSAus Class I, Division 1, Group B, C, D, T4 Tamb -40°C to +60°C
TC TR Ex 1Ex d IIB + H2 T4, T3 Gb (-40°C to +60°C)
3697097 Issue 13.1, July 2018
Page 45
Liquidew EExd User’s Manual
A.1 Mounting Drawing
APPENDIX A
245mm 9.65"
355mm [13.9"]
1/8" NPT Female (ATEX/IECEx/CSA)
Sample out - Channel 1
1/8" NPT Female (ATEX/IECEx/CSA)
290mm [11.41"]
Sample in - Channel 1
Flame Arrestor
Flame Arrestor
270mm 10.63"
4 o M12 (1/2")
Clearance
318mm 12.52"
Enclosure Breather
Flame Arrestor
Do NOT obscure
Sample in - Channel 2 (Optional)
Flame Arrestor
1/8" NPT Female (ATEX/IECEx/CSA)
Sample out - Channel 2 (Optional)
Flame Arrestor
1/8" NPT Female (ATEX/IECEx/CSA)
Cable Entry Glands
3 o M20 (ATEX)
310mm [12.20"]
3 o 1/2" NPT (CSA)
Figure 28
Mounting Drawing
Michell Instruments37
Page 46
APPENDIX A
A.2 Pipework Connections
Liquidew EExd User’s Manual
h
SENSOR
MICHELL MOISTURE
SAMPLING BLOCK
FLOW
METER
h
h
h
FLAME
FLAME
ARRESTOR
ARRESTOR
{
OPTIONAL
CHANNEL 2
FLAME
BREATHER
ARRESTOR
h
FLAME
ARRESTOR
h
SAMPLING BLOCK
FLOW
METER
h
SENSOR
FLAME
MICHELL MOISTURE
ARRESTOR
{
CHANNEL 1
SAMPLE INSAMPLE OUTSAMPLE INSAMPLE OUT
Figure 29
3897097 Issue 13.1, July 2018
Pipework Connections
Page 47
Liquidew EExd User’s Manual
!
A.3 System Wiring Diagram
APPENDIX A
NC C NO NC C NO
123456
Enclosure wall
NC C NO NC C NO
PL16
Optional
AL3AL2AL1AL4COMMSChannel 1Channel 2
mA1+
mA1-
mA2+
7891011
h
B A GND
12
PL20PL15PL14PL19
13 14 15
16 17 18 1920 21 22 23
LEN
mA2-
h
h
mA3+
Gland
mA3-
mA4+
{
mA4-
Figure 30
System Wiring Diagram
EExd Stopping Glands MUST be used for ATEX/IECEx
installations.
Refer to the separate installation & maintenance
information sheet supplied.
Michell Instruments39
Page 48
APPENDIX B
Liquidew EExd User’s Manual
Appendix B
Variable Defi nitions
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Liquidew EExd User’s Manual
Appendix B Variable Defi nitions
From the Variables Page, press the Up () or Down () buttons to highlight the
variable required. Press the SELECT button to enter the range/options area. Change the
variable using the
the new option. Scroll down to the next variable required. To return to the MAIN Page
press the MENU/MAIN button.
Variable:
Adjustable Range/Options: DEW POINT, MOISTURE
Description: The display units for Channels 1 and 2.
Up () or Down () buttons and press the SELECT button to set
CHN1, CHN2
APPENDIX B
i. When
enabled to allow the selection of the sample Solute.
ii. mA1 and mA3 outputs represent the setting of Channels 1
& 2 respectively.
NOTE: Changing the units clears the data logging memory and resets the
analog outputs and alarm settings
Variable:
Adjustable Range/Options: Range of 10 pre-set sample solutes and 4 user-defined
apply
MOISTURE is selected, the apply option below is
sample solutes
Description: The following samples are available for selection when MOISTURE is
Description: Dew point and temperature unit of measurement in °C or °F
Note: Changing temperature units will set the default values and clear
Variable:
Adjustable Range/Options: hh:mm; 00:00 to 23:59
Description: The real-time clock in 24hr format. Minutes and hours may be adjusted.
°C / °F
the logged data
TIME
Pressing either the
decrement the minute fi eld and the corresponding hour fi eld will change
accordingly and automatically.
Up () or Down () button will increment or
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Liquidew EExd User’s Manual
Variable: DATE
Adjustable Range/Options: Day: 01-31, Month: 01-12, Year: 00-99
Description: The date. Format: ddmmyy. To adjust the day, highlight the DATEfi eld,
press
SELECT (a ‘d’ should appear to the right of the year value). Use the
Up () or Down () buttons to adjust. To adjust the month and year,
press
SELECT again (an ‘m’ should appear to the right of the year value).
Use the
changes, the year fi eld will change accordingly and automatically. Press
SELECT to fi nish.
Up () or Down () buttons to adjust the month. As the month
APPENDIX B
Variable:
Adjustable Range/Options: 01 to 31
Description: Unique instrument address for networking. This address is used by the
Variable:
Adjustable Range/Options: NONE
Description: Sets instrument to default confi guration. The default values for all the
Variable:
Adjustable Range/Options:
INST ADDR
Modbus protocol to specify the location of the Liquidew EExd instrument
in the network.
SET DEFAULT
variables and parameters are set. To initiate, select the variable and then
press either the
Up () or Down () button.
LOG INT’VAL
10 to 60 in intervals of 10 minutes
Description: Sets the interval between the logged data readings.
Variable:
Adjustable Range/Options: select, done
Description: Resets the logging statistics so that the variation in measurements can be
RESET LOG
recorded from a user-defi ned start point. When the
is highlighted press the
SELECT button - the option will go from select to
RESET LOG variable
done.
Michell Instruments43
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APPENDIX B
Variable: CS VALUES
Adjustable Range/Options:
Description: The Cs Values available to adjust or view in the user-defi ned Cs table
Liquidew EExd User’s Manual
0 to 5000 PPM(W)
pages.
Variable:
Adjustable Range/Options: A to Z, hyphen, space, 0 to 9
Description: Characters that make up the user-defi ned solute custom label.
The default values are:
User-defined Solute CUSTOM LABEL CHAR
CHN 1 / 2
Apply
Alarm
OP1 Min
OP1 Max
OP2 Min
OP2 Max
OP3 Min
OP3 Max
OP4 Min
OP4 Max
°C / °F
Int Temp
Cs Values
User Solute Labels
Dew point
N/A
0°C
-100°C (-148°F)
+20°C (+68°F)
0°C (+32°F)
+70°C (+158°F)
-100°C (-148°F)
+20°C (+68°F)
0°C (+32°F)
+70°C (+158°F)
Celsius
+20°C (+68°F)
00
U1 U2 U3 and U4
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Liquidew EExd User’s Manual
APPENDIX C
Appendix C
Software
Michell Instruments45
Page 54
APPENDIX C
Appendix C Software
Software is available for the Liquidew EExd to provide full remote control of up to 31
instruments. It provides access to all readable and write-able registers as described in
Appendix E along with charting and data logging facilities.
The Liquidew EExd application software provides the user with advanced acquisition,
logging and charting features for full remote control and monitoring of the Liquidew
EExd.
With this application software it is possible to:
• View all main parameters of interest
• Modify parameters
• Record parameters to a virtual chart recorder
• Record parameters to a fi le
Liquidew EExd User’s Manual
• Acquire data from up to 31 process instruments
• Perform remote diagnostics
• Acquire OPC enabled remote access to all parameters and
variables
C.1 System Requirements
For a desktop computer, the following specifi cation applies:
• Microsoft Windows 7, 98SE, ME, 2000 or XP operating system
• Spare RS232 port (normally labelled COM1, COM2 etc)
• Minimum of 64 MB of RAM (128M or higher recommended)
• Minimum of 200 MB of free hard disk space (application
approximately 3.5 MB, spare for log fi les)
• Intel Pentium II class processor, 200 MHz or higher
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APPENDIX D
Appendix D
Calibration Correction
Michell Instruments47
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APPENDIX D
Appendix D Calibration Correction
D.1 Overview
The Liquidew EExd is delivered with a Calibration Certifi cate detailing the deviation at
each measurement point from a known reference value. Data provided on the Calibration
Certifi cate is normally arranged as shown in the following extracts:
Extract from a UKAS Calibration Certifi cate:
Liquidew EExd User’s Manual
Generated
Dew point
°C
-39.89-40.11+0.22±0.26
-20.10-20.31+0.21±0.22
0.390.20+0.19±0.18
Extract from a Standard Calibration Certifi cate:
Dew-point
Temperature
°C
Generated
Dew point
°C
-40.1-40.2
-20.1-20.1
0.20.1
Test Hygrometer
Correction
Required
°C
Instrument
Display
Expanded
Uncertainty
°C
°C
From time to time the Liquidew EExd may be calibrated by an external calibration
agency, and similar data will be provided.
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D.2 Calibration Software
A calibration correction utility has been integrated into the Process Application Software.
This allows authorized users to input calibration information in order to effect a realtime correction of the displayed dew point. This software facilitates the uploading and
downloading of the instrument's calibration via the Modbus RTU interface.
The fi gure below shows the Calibration Correction window; two sets of data may be
entered:
Ref DP Dew-point data for the reference hygrometer
•
(sometimes called the actual dew point or the
standard)
Liquidew DP Measured dew-point value of the Liquidew
•
under test
Data can be entered for 13 calibration points between +20 and -100°Cdp (+68 and
-148°Fdp). However, if no data is available then the
remain equal and be exact for the calibration point as shown in the fi gure below.
APPENDIX D
Ref DP and Liquidew DP should
Cal point Ref Dp Liquidew Dp
Figure 31
Calibration Correction Data
NOTE: The fi gure above shows calibration data for -20 to –40°Cdp only. The
Ref Dp and Liquidew Dp are equal for points where no calibration data is
available.
Michell Instruments49
Page 58
APPENDIX D
!
D.3 Calibration Procedure
be done by a recognized humidity calibration laboratory
accredited by a standards institution such as UKAS or NIST.
1. Press the Get Table button to download the correction table for either
Channel 1 or 2 and check to see if the values are equal and exact. If
not, then the instrument has had its calibration adjusted previously. To
simplify the correction procedure, reset the adjusted values back to their
‘equal & exact’ default values.
2. Connect the Liquidew EExd to a suitable dew-point generator with a
reference hygrometer (preferably chilled-mirror type with traceable
calibration). Purge the Liquidew for a minimum of 5 days with air that is
drier than -100°Cdp (-148°Fdp) before commencing the calibration.
3. Increase the generator set-point in steps of 10°Cdp (18°Fdp), moving
sequentially up the Liquidew’s measurement range from –100 to +20°Cdp
(-148 to +68°Fdp) and record the dew point measured by the reference
and the Liquidew.
Liquidew EExd User’s Manual
Caution: A valid correction of the calibration can only
Any calibration performed by an unrecognized body will
invalidate the calibration of the instrument.
Suitable stabilization periods should be allowed between changing the
generator setting and taking the fi nal sensor count and reference hygrometer
values. Actual stabilization times will depend to a degree on the type of
generator used, the gas fl ow rate and the integrity of the pipe work and
sensor manifold. As a rule of thumb, it is strongly suggested that the following
stabilization times are taken as a minimum requirement:
Dew-point Temperature
°Cdp
-1005 days
-9012 hours
-8010 hours
-708 hours
-604 hours
-502 hours
-401 hour
-301 hour
-201 hour
-101 hour
01 hour
+101 hour
+201 hour
If calibration is not being done to -100°Cdp (-148°Fdp) then the purge times
can be reduced:
Minimum Stabilization Time
Drier than -70°Cdp (-94°Fdp) 5 days
-41 to -69°Cdp (-41.8 to -92°Fdp) 64 hours
+20 to -40°Cdp (+68 to -40°Fdp) 16 hours
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Liquidew EExd User’s Manual
The purge gas should be as dry as possible, ideally 10°Cdp (18°Fdp) drier
than the driest dew point to be calibrated. The recommended stabilization
times listed above should be followed when changing from one dew point
to the next.
4. Enter the dew point values for the reference and the Liquidew that were
recorded in item 1 above and leave the values 'equal and exact' for used
calibration points.
APPENDIX D
5. To modify a data point, double click on the relevant cell and using the
() and
as shown for the –60 calibration point in
value will turn red to indicate its change of status.
6. After the data points have been changed press the
to upload the data into the Liquidew.
Down () buttons adjust the value or enter the value directly,
Figure 32
. After amendment, the
Write new data button
Up
Michell Instruments51
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APPENDIX E
Liquidew EExd User’s Manual
Appendix E
Modbus RTU
Communications
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Appendix E Modbus RTU Communications
E.1 Introduction
Implemented within the Liquidew EExd are Modbus RTU communications that enable
remote access to the instrument's confi guration and data logging facilities. This protocol
offers two-way communication between a PC or PLC known as the master, to one or
more instruments known as slaves. Communication is achieved by the master reading
or writing to registers within the slave. The slave acts upon information contained
within the registers that can be written, and the master obtains measured values and
status information from the register that can be read. Appendix E lists these registers
and Appendix G specifi es the number or data formats that apply to each register.
E.2 Modbus RTU Basics
Modbus RTU operates on a Query-Response Cycle (see the diagram below). The function
code in the query tells the addressed slave device which actions to perform using the
information contained in the data bytes. The error check fi eld provides a method for the
slave to validate the integrity of the message contents.
APPENDIX E
If the slave makes a normal response, the function code in the response is an echo of
the function code in the query. The data bytes will contain data collected by the slave,
such as register values or status information. If an error occurs, the function code is
incremented by 80H. This indicates that the response is an error response, known as
an exception, and the data bytes contain a code to describe the error. The error check
fi eld allows the master to confi rm that the message contents are valid.
MASTER
Device Address
Function Code
E.3 Physical Layer
Data Bytes
CRC
Query Message from Master
Response From Slave
SLAVE
Device Address
Function Code
Data Bytes
CRC
The physical connection from the master to the Liquidew EExd uses 2-wire RS485 plus
a ground connection. Data lines A, B and ground are connected to communication
connectors within the instrument. The serial port protocol is as follows:
A 120R termination resistor is provided on the instrument’s circuit board for systems
that require it. To connect the resistor, place the link provided across JMP2.
E.5 Register Map
The following tables describe the instrument registers with their address location,
Modbus function and the number format.
Liquidew EExd User’s Manual
Address
dec
00000*Instrument Address R/WF
10001Sensor 1 Humidity Value – Hi Word (dp/moisture)RL
20002Sensor 1 Humidity Value – Lo Word (dp/moisture)RL
30003Sensor 1 Ambient Temperature RH
40004Status RD
50005Sensor 2 Humidity Value – Hi Word (dp/moisture)R L
60006Sensor 2 Humidity Value – Lo Word (dp/moisture)RL
70007Time to next log Mins + Secs RI
80008Sensor 2 Ambient Temperature RH
90009Sensor 1 Flow Reading l/minRF
10000ASensor 2 Flow Reading l/minRF
11000BSensor 1 Humidity Setting (dp or moisture)R/WB
12000C*mA1 output maximum value (sensor 1 humidity)R/WK
13000D*mA1 output minimum value (sensor 1 humidity)R/WK
14000E*mA2 output maximum value (sensor 1
15000F*mA2 output minimum value (sensor 1 temp)R/WM
160010*Sensor 2 Humidity Setting (dp or moisture)R/WB
170011*mA3 output maximum value (sensor 2 humidity)R/WF
180012*mA3 output minimum value (sensor 2 humidity)R/WK
190013*Logging IntervalR/WI
200014*mA4 output maximum value (sensor 2 temp)R/WM
210015*mA4 output minimum value (sensor 2 temp)R/WM
220016*Sensor 1 Alarm Set PointR/WK
230017*Sensor 2 Alarm Set PointR/WK
240018*RTC Year (val1) + Month (val2) R/WI
250019*RTC Date (val1) + Hours (val2) R/WI
26001A*RTC Mins (val1) + Secs (val2) R/WI
27001B*Sensor 1 Solute Ref Number R/WH
28001C*Sensor 2 Solute Ref NumberR/WH
29001DUnits/ Command R/WE
30001EWater DP Sensor 1 – Batch NumberRI
31001FWater DP Sensor 1 – Serial NumberRI
320020Water DP Sensor 1 - YearRI
330021Water DP Sensor 1 – Month and dayRI
340022Water DP Sensor 1– Hours Of OperationRF
350023Error IndicatorRC
360024Not Used
Address
hex
Function
Read/
Write
temp)R/WM
Default
Value
Register
Confi g-
uration
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Liquidew EExd User’s Manual
APPENDIX E
Address
dec
370025Internal TemperatureRA
380026Internal Temp Set PointR/WA
390027Water DP Sensor 2 – Batch NumberRI
400028Water DP Sensor 2 – Serial NumberRI
410029Water DP Sensor 2 - YearRI
42002AWater DP Sensor 2 – Month and dayRI
43002BWater DP Sensor 2 – Hours Of OperationRF
44002CNot Used
45002DHumidity max – Hi Word – Sensor 1RL
46002EHumidity max – Lo Word – Sensor 1RL
47002FOccurred @ day (val1) + month (val2)RJ
480030Occurred @ hour (val1) + min (val2)RJ
490031Humidity min – Hi Word – Sensor 1RL
500032Humidity min – Lo Word – Sensor 1RL
510033Occurred @ day (val1) + month (val2)RJ
520034Occurred @ hour (val1) + min (val2)RJ
530035Humidity average Hi Word – Sensor 1RL
540036Humidity average Lo Word – Sensor 1RL
550037Not Used
560038Not Used
570039Instrument TypeRI
58003AFirmware Version NumberRI
59003BNot Used
60003CNot Used
61003DHumidity max – Hi Word – Sensor 2RL
62003EHumidity max – Lo Word – Sensor 2RL
63003FOccurred @ day (val1) + month (val2)RJ
640040Occurred @ hour (val1) + min (val2)RJ
650041Humidity min – Hi Word – Sensor 2RL
660042Humidity min – Lo Word – Sensor 2RL
670043Occurred @ day (val1) + month (val2)RJ
680044Occurred @ hour (val1) + min (val2)RJ
69 0045Humidity average Hi Word – Sensor 2RL
700046Humidity average Lo Word – Sensor 2RL
710047Not Used
720048Not Used
730049Temp max – Sensor 1RH
74004AOccurred @ day (val1) + month (val2)RJ
75004BOccurred @ hour (val1) + min (val2)RJ
76004CTemp min – Sensor 1RH
77004DOccurred @ day (val1) + month (val2)RJ
78004EOccurred @ hour (val1) + min (val2)RJ
79004FTemp average – Sensor 1RH
800050Temp max – Sensor 2RH
810051Occurred @ day (val1) + month (val2)RJ
820052Occurred @ hour (val1) + min (val2)RJ
830052Temp min – Sensor 2RH
Address
hex
Function
Read/
Write
Default
Value
Register
Confi g-
uration
Michell Instruments55
Page 64
APPENDIX E
Liquidew EExd User’s Manual
Address
dec
840053Occurred @ day (val1) + month (val2)RJ
850054Occurred @ hour (val1) + min (val2)RJ
860055Temp average – Sensor 2RH
870056Not Used
880057Not Used
890058Set-up access code - 7316WI
90005ADiagnostics/Set-up Command RegisterWG
91005B*CALZ WDP 0 calibration value – Sensor 2RF
92005C*CALS WDP 2nF calibration value – Sensor 2RF
93005D*CALT WDP thermistor cal value – Sensor 2RF
94005E*Not used
95005F*Not used
960060*Not used
970061*mA1 calibration value high in % (100%=23 mA)R/WA
980062*mA1 calibration value low in % (100%=23 mA)R/WA
990063*mA2 calibration value high in % (100%=23 mA)R/WA
1000064*mA2 calibration value low in % (100%=23 mA)R/WA
1010065Force mA1 to a value in % of (100%=23 mA)WA
1020066Force mA2 to a value in % of (100%=23 mA)WA
1030067*CALZ WDP 0 calibration value – Sensor 1RF
1040068*CALS WDP 2nF calibration value – Sensor 1RF
1050069*CALT WDP thermistor cal value – Sensor 1RF
106006A*WDP Pressure cal LO value – Sensor 2RF
107006B*WDP Pressure cal HI value – Sensor 2RF
108006C*WDP Pressure cal LO value – Sensor 1RF
109006D*WDP Pressure cal HI value – Sensor 1RF
110006E*mA3 calibration value high in % (100%=23 mA)R/WA
111006F*mA3 calibration value low in % (100%=23 mA)R/WA
1120070*mA4 calibration value high in % (100%=23 mA)R/WA
1130071mA4 calibration value low in % (100%=23 mA)R/WA
1140072Force mA3 to a value in % of (100%=23 mA)WA
1150073*Force mA4 to a value in % of (100%=23 mA)WA
1160074*Not used
1170075Not Used
1180076*Sensor 2 pressure f.s.d.R/WF
1190077*Sensor 1 pressure f.s.d.R/WF
1200078Internal Thermistor Calibration ValueR/WA
1210079Supply Voltage as % of 12V (1.00 = 12V)RA
Address
hex
Function
Read/
Write
Default
Value
Register
Confi g-
uration
5697097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
Sensor 1 Calibration Correction
Address
dec
186Sn1 20°Cdp RefR/WH
187Sn1 10°Cdp RefR/WH
188Sn1 0°Cdp RefR/WH
189Sn1 -10°Cdp RefR/WH
190Sn1 -20°Cdp RefR/WH
191Sn1 -30°Cdp RefR/WH
192Sn1 -40°Cdp RefR/WH
193Sn1 -50°Cdp RefR/WH
194Sn1 -60°Cdp RefR/WH
195Sn1 -70°Cdp RefR/WH
196Sn1 -80°Cdp RefR/WH
197Sn1 -90°Cdp RefR/WH
198Sn1 -100°Cdp RefR/WH
199Sn1 20°Cdp CalR/WH
200Sn1 10°Cdp CalR/WH
201Sn1 0°Cdp CalR/WH
202Sn1 -10°Cdp CalR/WH
203Sn1 -20°Cdp CalR/WH
204Sn1 -30°Cdp CalR/WH
205Sn1 -40°Cdp CalR/WH
206Sn1 -50°Cdp CalR/WH
207Sn1 -60°Cdp CalR/WH
208Sn1 -70°Cdp CalR/WH
209Sn1 -80°Cdp CalR/WH
210Sn1 -90°Cdp CalR/WH
211Sn1 -100°Cdp CalR/WH
Address
hex
Function
Read/
Write
APPENDIX E
Default
Value
Register
Confi g-
uration
Michell Instruments57
Page 66
APPENDIX E
Address
dec
213Sn2 10°Cdp RefR/WH
214Sn2 0°Cdp RefR/WH
215Sn2 -10°Cdp RefR/WH
216Sn2 -20°Cdp RefR/WH
217Sn2 -30°Cdp RefR/WH
218Sn2 -40°Cdp RefR/WH
219Sn2 -50°Cdp RefR/WH
220Sn2 -60°Cdp RefR/WH
221Sn2 -70°Cdp RefR/WH
222Sn2 -80°Cdp RefR/WH
223Sn2 -90°Cdp RefR/WH
224Sn2 -100°Cdp RefR/WH
225Sn2 20°Cdp CalR/WH
226Sn2 10°Cdp CalR/WH
227Sn2 0°Cdp CalR/WH
228Sn2 -10°Cdp CalR/WH
229Sn2 -20°Cdp CalR/WH
230Sn2 -30°Cdp CalR/WH
231Sn2 -40°Cdp CalR/WH
232Sn2 -50°Cdp CalR/WH
233Sn2 -60°Cdp CalR/WH
234Sn2 -70°Cdp CalR/WH
235Sn2 -80°Cdp CalR/WH
236Sn2 -90°Cdp CalR/WH
237Sn2 -100°Cdp CalR/WH
Address
hex
Function
Liquidew EExd User’s Manual
Sensor 2 Calibration Correction
Read/
Write
Default
Value
Register
Confi g-
uration
5897097 Issue 13.1, July 2018
Page 67
Liquidew EExd User’s Manual
Address
dec
2570101Time Hours + Mins @ t 0RJ
2580102Humidity 1 Hi Word @ t 0RL
2590103Humidity 1 Lo Word Pressure @ t 0RL
2600104Temperature 1 @ t 0RH
2610105Humidity 2 Hi Word @ t 0RL
2620106Humidity 2 Lo Word Pressure @ t 0RL
2630107Temperature 2 @ t 0RH
2640108Date Day + Month @ t 1RJ
2650109Time Hours + Mins @ t 1RJ
266010AHumidity 1 Hi Word @ t 1RL
267010BHumidity 1 Lo Word Pressure @ t 1RL
268010CTemperature 1 @ t 1RH
269010DHumidity 2 Hi Word @ t 1RL
270010EHumidity 2 Lo Word Pressure @ t 1RL
271010FTemperature 2 @ t 1RH
Address
hex
Function
Data Logging
Read/
Write
APPENDIX E
Default
Value
Register
Confi g-
uration
144905A9Date Day + Month @ 149RJ
145005AATime Hours + Mins @ t 149RJ
145105ABHumidity 1 Hi Word @ t 149RL
145205ACHumidity 1 Lo Word Pressure @ t 149RL
145305ADTemperature 1 @ t 149RH
145405AEHumidity 2 Hi Word @ t 149RL
145505AFHumidity 2 Lo Word Pressure @ t 149RL
145605B0Temperature 2 @ t 149RH
Michell Instruments59
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APPENDIX E
Address
dec
146105B5User Cs Table 1, Cs Value at 10°CR/WF
146205B6User Cs Table 1, Cs Value at 20°CR/WF
146305B7User Cs Table 1, Cs Value at 30°CR/WF
146405B8User Cs Table 1, Cs Value at 40°CR/WF
146505B9User Cs Table 1, Cs Value at 50°CR/WF
146605BAUser Cs Table 2, Cs Value at 0°CR/WF
146705BBUser Cs Table 2, Cs Value at 10°CR/WF
146805BCUser Cs Table 2, Cs Value at 20°CR/WF
146905BDUser Cs Table 2, Cs Value at 30°CR/WF
147005BEUser Cs Table 2, Cs Value at 40°C R/WF
147105BFUser Cs Table 2, Cs Value at 50°CR/WF
147205C0User Cs Table 3, Cs Value at 0°CR/WF
147305C1User Cs Table 3, Cs Value at 10°CR/WF
147405C2User Cs Table 3, Cs Value at 20°CR/WF
147505C3User Cs Table 3, Cs Value at 30°CR/WF
147605C4User Cs Table 3, Cs Value at 40°CR/WF
147705C5User Cs Table 3, Cs Value at 50°CR/WF
147805C6User Cs Table 4, Cs Value at 0°CR/WF
147905C7User Cs Table 4, Cs Value at 10°CR/WF
148005C8User Cs Table 4, Cs Value at 20°CR/WF
148105C9User Cs Table 4, Cs Value at 30°CR/WF
148205CAUser Cs Table 4, Cs Value at 40°CR/WF
148305CBUser Cs Table 4, Cs Value at 50°CR/WF
148405CCUser Solute 1 Label Char 1R/WF
148505CDUser Solute 1 Label Char 2R/WF
148605CEUser Solute 1 Label Char 3R/WF
148705CFUser Solute 1 Label Char 4R/WF
148805D0User Solute 1 Label Char 5R/WF
148905D1User Solute 1 Label Char 6R/WF
149005D2User Solute 1 Label Char 7R/WF
149105D3User Solute 1 Label Char 8R/WF
149205D4User Solute 2 Label Char 1R/WF
149305D5User Solute 2 Label Char 2R/WF
149405D6User Solute 2 Label Char 3R/WF
149505D7User Solute 2 Label Char 4R/WF
149605D8User Solute 2 Label Char 5R/WF
149705D9User Solute 2 Label Char 6R/WF
149805DAUser Solute 2 Label Char 7R/WF
149905DBUser Solute 2 Label Char 8R/WF
150005DCUser Solute 3 Label Char 1R/WF
150105DDUser Solute 3 Label Char 2R/WF
150205DEUser Solute 3 Label Char 3R/WF
150305DFUser Solute 3 Label Char 4R/WF
150405E0User Solute 3 Label Char 5R/WF
Address
hex
Function
Liquidew EExd User’s Manual
User Cs tables
Read/
Write
Default
Value
Register
Confi g-
uration
6097097 Issue 13.1, July 2018
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Liquidew EExd User’s Manual
APPENDIX E
Address
dec
150505E1User Solute 3 Label Char 6R/WF
150605E2User Solute 3 Label Char 7R/WF
150705E3User Solute 3 Label Char 8R/WF
150805E4User Solute 4 Label Char 1R/WF
150905E5User Solute 4 Label Char 2R/WF
151005E6User Solute 4 Label Char 3R/WF
151105E7User Solute 4 Label Char 4R/WF
151205E8User Solute 4 Label Char 5R/WF
151305E9User Solute 4 Label Char 6R/WF
151405EAUser Solute 4 Label Char 7R/WF
151505EBUser Solute 4 Label Char 8R/WF
Address
hex
Function
Read/
Write
Default
Value
Register
Confi g-
uration
NOTE: To download logged data, calculate the start address by the following formula:
(sample number x 8) + 256. Start addresses that do not coincide with the fi rst register
of a sample will generate an exception response. Due to the maximum limit of 125
data registers that can be read in one transmission, as defi ned by the Modbus RTU
standard, only 20 samples can be downloaded at any one time. Therefore, eight reads
are required to download all 150 samples.
Michell Instruments61
Page 70
APPENDIX F
Liquidew EExd User’s Manual
Appendix F
Modbus RTU Details
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Liquidew EExd User’s Manual
Appendix F Modbus RTU Details
F.1 Message Framing
APPENDIX F
STARTADDRESS
3.5t1 byte1 byten x bytes2 bytes3.5t
FUNCTION
CODE
DATACRCEND
Start and End
The message begins and ends with a silent delay of 3.5 character times at the baud
rate of the network.
Address
The fi rst byte transmitted is the address of the instrument, which has a range of 1 to
247 or 01H to F7H. The master addresses an instrument by placing the address in the
address byte and, if matched, a Liquidew EExd will response to the message, otherwise
it will be ignored. See Appendix E on setting the address.
Function Code
The function code tells the Liquidew EExd which operation is to be performed on the
data in the following data bytes. The only valid codes are
06 (Write To Single Register) as these are the only two implemented.
or
An exception can occur if the message contains an unsupported function code, an illegal
data address or an illegal data value. If this occurs, the function code is incremented
by 80H and the data bytes returned are set to a value that describes the error. See
Appendix F.2.
03 (Read Holding Registers)
Data Bytes
The data bytes within the message from the master contain additional information that
the Liquidew EExd must use to perform the action defi ned in the function code, such as
the starting register address and the number of registers to be retrieved.
CRC
The CRC is a 2-byte error check value from the result of a Cyclical Redundancy Check
calculation performed on the message contents. The CRC is appended to the message
as the last fi eld in the message. The low-order byte is appended fi rst, followed by the
high-order byte.
Michell Instruments63
Page 72
APPENDIX F
A
A
F.2 Implemented Functions
03 Read Holding Registers
This function code is used to read the contents of a contiguous block of holding registers,
where the master specifi es the starting address and the number of registers to be read.
Figure 33
that may be raised.
shows the state diagram of how the message is processed with the exceptions
ENTRY
Address in message = Instrument Address
ddress in message = Instrument
Liquidew EExd User’s Manual
Exception Code = 01
Exception Code = 03
Function code supported
0x0000 <= Quantity of Registers <=
0X007d
Exception Code = 02
Exception Code = 04
Starting Address = OK
ND
Starting Address + Number of Registers =
Request Processing
Reading Registers = OK
OK
Sends Exception Response
Figure 32
Sends Response with data
EXIT
Reading Holding Registers State Diagram
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Liquidew EExd User’s Manual
The table below is an example of a message sent by the master, to read the time to
the next log (register 7) and Channel 2 sample temperature (register 8). The message
shows a master addressing a Liquidew EExd with a slave address of 01H and a Modbus
function of 03H that informs the Liquidew EExd that it wishes to read two registers
starting from address 07H. Bytes 3 & 4 hold the starting address and bytes 5 & 6 hold
the number of registers to be read. Bytes 7 & 8 contain the CRC code that is calculated
using bytes 1 to 6 as represented below.
Byte NoMeaningValue
1Slave Address01H
2Modbus function code03H
3Starting Address MSB00H
4Starting Address LSB07H
5No of points MSB00H
6No of points LSB02H
7CRC Lo Byte??H
8CRC Hi Byte??H
APPENDIX F
Read Request Message
In response to the above message, the Liquidew EExd may transmit the following
message:
Byte NoMeaningValue
1Slave Address01H
2Modbus function code03H
3Byte Count04H
4Data MSB05H
5Data LSB26H
6Data MSB00H
7Data LSBFAH
8CRC Lo Byte??H
9CRC Hi Byte??H
Read Response Message
This response repeats the address of the Liquidew EExd and the function code, along
with the byte count, the data and the CRC. In this example, the request asked for the
values from two registers. Therefore, the number of bytes returned is four. The value of
register 7 is contained in bytes 4 & 5 and the value of register 8 in bytes 6 & 7. Register
7 = 5m 26s and register 7 = 00FA = 252 = 25.2°C in this example. Any errors within
the data of Read Request Message will result in an exception being raised.
Michell Instruments65
Page 74
APPENDIX F
06 Write to Single Register
This function code is used to write a 16 bit value into a single register. The master
specifi es the address and the value to be written.
how the message is processed with the exceptions that may be raised.
ENTRY
Exception Code = 01
Liquidew EExd User’s Manual
Address in message = Instrument Address
Function code supported
Figure 34
shows the state diagram of
Exception Code = 03
Exception Code = 02
0x0000 <= Reg i ster Value<= 0xFFFF
Register Address == OK
Request Processing
Write To Single Register = OK
Exception Code = 04
Mirrors Request
Sends Exception ResponseEXIT
Figure 33
Write Single Register State Diagram
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Liquidew EExd User’s Manual
The table below shows the data bytes in a Write To Single Register message. Bytes
1 to 4 contain the address of the Liquidew EExd, Modbus function, starting register
address and the data value to be written. In this example a master sends FC18H to
address 0015H, to a Liquidew EExd with an address of 01H. The CRC is calculated using
the data in bytes 1 to 6.
Byte NoMeaningValue
1Slave Address01H
2MODBUS function code06H
3Starting Address MSB00H
4Starting Address LSB15H
5Data MSBFCH
6Data LSB18H
7CRC Lo Byte??H
8CRC Hi Byte??H
Write Single Register Request and Response
APPENDIX F
The normal response from the Liquidew EExd is to re-transmit the received message.
However, if the data within the message is incorrect then an exception response will be
transmitted.
Michell Instruments67
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APPENDIX F
F.3 Exceptions
A message request from the master will raise an exception response from the slave
(Liquidew EExd) if:
i. the function code is unsupported
ii. the register quantity > 127 (0x007D)
iii. the register address is invalid
iv. the register address + the quantity of register is invalid
v. an error occurred while performing the function
The exception response will contain the function code incremented by 80H and the
exception code.
The table below lists the codes supported, along with an explanation of each code.
Liquidew EExd User’s Manual
CodeNameMeaning
01
02
03
04
Example of an Exception Response that reads a discrete inputs message generating an
illegal function exception.
ILLEGAL FUNCTION
ILLEGAL DATA ADDRESS
ILLEGAL DATA VALUE
SLAVE DEVICE FAILURE
The function code received in the query
is not an allowable action for the slave
The data address received in the query
is not allowable. More specifi cally, the
combination of starting address and
number of registers is invalid for the
slave
A value contained in the query data
fi eld is not an allowable value for the
slave
An unrecoverable error occurred while
the slave was attempting to perform
the requested action
The example above shows the function code (02H) sent in the request has been
incremented by 80H with the exception code 01H included as the data within the
message.
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Liquidew EExd User’s Manual
APPENDIX I
Appendix G
Register Number Formats
Michell Instruments69
Page 78
APPENDIX I
Appendix G Register Number Formats
Register Configuration A
1514131211109876543210
rrrrrrrrrrrrrrrr
Sign bit = 1 for –ve values (signed int)
7FFF = 327.67
8000 = -327.68
The value in bits (15 to 0) + 1 is divided by 100 to give 0.01 resolution for dew-point
and temperature values.
Value
Register Configuration B – Sensor Humidity Setting
0x0000 = Dew point in degrees
0x0001 = Moisture in ppm
W
Register Configuration C – Error Register
1514131211109876543210
rrrrrrrrrrrrrrrr
BitHEXError Condition
00001Channel 1 dew point under range <-120°C (<-184°F)
10002Channel 1 dew point over range >+30°C (>+86°F)
20004Channel 1 temperature out of range >+50 or <0°C (>+122 or <32°F)
30008Channel 1 low fl ow (<0.1 l/min)
40010Channel 1 high fl ow (>0.9 l/min)
50020Channel 1 moisture saturation condition (dew point temperature)
60040Channel 1 calibration table error (checks sensor impedance values are
increasing in the correct direction)
70080Channel 2 dew point under range <-120°C (<-184°F)
80100Channel 2 dew point over range >+30°C (>+86°F)
90200Channel 2 temperature out of range >+50 or <0°C (>+122 or <32°F)
Sign bit = 1 for –ve values (signed int)
7FFF = 32767
8000 = -32768
Register Configuration L - Floating Point Representation
The humidity values for sensors 1 & 2 are represented in IEEE-754 single precision
fl oating point format, in order to cater for the wide range in the value of ppmV. This
format is ‘Big Ended’ which means that the High byte is at a lower address in memory
than the Lo byte, and is represented as such in the register memory map. The IEEE-754
format is shown below.
Bit 31
Sign bit
0 = +
1 = -
Bits 30 to 23
Exponent Field
Has a +127 bias value
Bits 22 to 0
mantissa
Decimal representation of binary
Where 1.0 value < 2.0
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Liquidew EExd User’s Manual
Examples of fl oating point to HEX are shown below.
1) +10.3
sign bit = 0
Exponent = 3, therefore exponent fi eld = 127 + 3 = 130, and bits 30 to 23 = 1000 0010
Mantissa = 1.2875 which in binary representation = 1010 0100 1100 1100 1100 1101
Adjusting the mantissa for the exponent moves the decimal point to the right if positive
and to the left if negative.
As the exponent is = 3 then the mantissa becomes = 1010 0100 1100 1100 1100 1101,
therefore:-
The Liquidew EExd is certifi ed compliant to the ATEX Directive (2014/34/EU) and IECEx
for use within Zone 1 and Zone 2 Hazardous Areas and has been assessed so by Element
Materials Technology Ltd (Notifi ed Body 0891).
The Liquidew EExd is certifi ed compliant to North American Standards (USA and Canada)
for use within Class I, Division 1, Groups B, C and D Hazardous Locations and has been
assessed so by CSA.
This product is attributed with the product certifi cation code:
ATEX & IECEx
II 2G Ex d IIB + H2 T5 Gb (-40°C to +44°C)
T4 Gb (-40°C to +60°C)
North American
Class I, Division 1, Groups B, C & D T5, Tamb -40°C to +44°C
T4, Tamb -40°C to +60°C
These certifi cates can be viewed or downloaded from our website at:
http://www.michell.com
Special attention should be paid to the
for Safe Use
and the
certifi cates shown on our website.
Conditions of Certifi cation
Special Conditions
listed in the
Michell Instruments75
Page 84
APPENDIX H
H.4 Special Conditions of Use
1. Do not open when an explosive gas atmosphere may be present.
2. External cables shall be compatible with a temperature of 93°C (T5) or 109°C (T4).
3. Maximum process pressure shall not exceed 50 barg. Maximum permissible
process pressure is marked on the equipment.
4. Maximum permitted sample fl ow rate into the enclosure shall not exceed
0.3LPH.
5. All process lines shall be purged to ensure the process gas or liquid is above
its upper explosive limit before applying power.
6. Where painted or powder coated, the enclosures could present an electrostatic
hazard. Clean only with a damp or anti-static cloth.
7. The enclosure is to be earthed externally using the earth point provided.
8. Only suitably ATEX / IECEx certifi ed (as appropriate) cable glands and blanking
elements shall be used.
Liquidew EExd User’s Manual
Refer to the relevant sections within this manual for the connection, wiring and cable
glanding requirements.
H.5 Maintenance and Installation
The Liquidew EExd must only be installed by suitably qualifi ed personnel and in
accordance with the instructions provided and the terms of the applicable product
certifi cates.
Maintenance and servicing of the product must only be carried out by suitably trained
personnel or returned to an approved Michell Instruments’ Service Center.
Flame paths are not intended to be repaired.
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Liquidew EExd User’s Manual
APPENDIX I
Appendix I
Quality, Recycling
& Warranty
Information
Michell Instruments77
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APPENDIX I
Liquidew EExd User’s Manual
Appendix I Quality, Recycling & 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/uk/compliance
This page contains information on the following directives:
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.
InstrumentSerial Number
Warranty Repair?YESNOOriginal PO #
Company NameContact Name
Address
Telephone #E-mail address
Reason for Return /Description of Fault:
Has this equipment been exposed (internally or externally) to any of the following?
Please circle (YES/NO) as applicable and provide details below
BiohazardsYESNO
Biological agentsYESNO
Hazardous chemicalsYESNO
Radioactive substancesYESNO
Other hazardsYESNO
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?YESNOT NECESSARY
Michell Instruments will not accept instruments that have been exposed to toxins, radio-activity or bio-hazardous
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
SignatureDate
F0121, Issue 2, December 2011
8097097 Issue 13.1, July 2018
Page 89
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http://www.michell.com
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