Appendix A Technical Specications .............................................................................. 16
Appendix B Quality, Recycling & Warranty Information ................................................... 18
Appendix C Decontamination Declaration ......................................................................20
iv 97065 Issue 16.3, October 2019
Easidew Portable User’s Manual
Safety
The manufacturer has designed this equipment to be safe when operated using the procedures
detailed in this manual. The user must not use this equipment for any other purpose than that
stated. Do not apply values greater than the maximum value stated.
This manual contains operating and safety instructions, which must be followed to ensure the safe
operation and to maintain the equipment in a safe condition. The safety instructions are either
warnings or cautions issued to protect the user and the equipment from injury or damage. Use
qualied personnel and good engineering practice for all procedures in this manual.
Electrical Safety
The instrument is designed to be completely safe when used with options and accessories supplied by
the manufacturer for use with the instrument. The instrument is powered by an internally mounted
rechargeable battery. The input power supply voltage limits for the battery charger supplied with the
instrument are 90 to 264 V AC, 47/63 Hz.
NOTE: No battery charger unit other than that supplied with the instrument should be
used.
NOTE: Do not allow the battery to fully discharge.
Pressure Safety
DO NOT permit pressures greater than the safe working pressure to be applied to the instrument.
The specied safe working pressure is 20 barg (290 psig). Refer to the Technical Specications 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 be maintained either by the manufacturer or an accredited service agent. Refer
to www.michell.com for details of Michell Instruments’ worldwide oces contact information.
Calibration
The recommended calibration interval for the Easidew Portable is one year, unless otherwise
specied by Michell Instruments Ltd. The instrument should be returned to the manufacturer, Michell
Instruments, or one of their accredited service agents for re-calibration (go to www.michell.com for
contact information).
Safety Conformity
This product meets the essential protection requirements of the relevant EU directives. Further
details of applied standards may be found in the product specication.
Michell Instruments v
Abbreviations
!
The following abbreviations are used in this manual:
AC alternating current
atm pressure unit (atmosphere)
barg pressure unit (=100 kP or 0.987 atm) gauge
°C degrees Celsius
°F degrees Fahrenheit
dp dew point
ft feet
kg kilogram
lb pound
Easidew Portable User’s Manual
mA milliampere
m meter
mm millimeter
MPa megapascal
Nl/min normal liters per minute
psig pound(s) per square inch (gauge)
scfh standard cubic feet per hour
μm micrometer
Ω ohm
V Volts
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.
vi 97065 Issue 16.3, October 2019
Easidew Portable User’s Manual
1 INTRODUCTION
The Easidew Portable comprises an Easidew sensor tted into a sample block with
an integrated lter cartridge, and Legris push ttings on the gas inlet and outlet. The
measured dew point from the sensor is shown on the clear red LED display on the front
panel of the instrument.
The Easidew Portable can be supplied with either °C or °F dew-point measurement
units.
A 4-20 mA analog output is provided for connection to a chart recorder, data-logger or
computer system, so dew-point trends can be analyzed over time.
The electronics are housed in a rugged Peli case, providing NEMA 6 protection when the
lid is closed. The case is supplied with a lifetime guarantee.
INTRODUCTION
The Easidew Portable is powered by a rechargeable NiMH battery pack, giving between
12 and 16 hours of measurement time from a full charge. The instrument is delivered
complete with a universal battery charger stored in the lid. It takes 16 hours to fully
charge the battery pack, during which time the instrument can be switched on or
o. The charger is suitable to connect power to the instrument indenitely, but it is
recommended to allow the battery pack to go through a full charge-discharge cycle at
least once per month.
All Michell Ceramic Moisture Sensors are subject to a 13-point calibration, where their
performance is characterized against a fundamental reference hygrometer. This process,
and subsequent quality testing, ensures that all sensors behave optimally before they
are used in the eld. Each Easidew Portable is supplied with a calibration certicate
traceable to national standards (NIST) from Michell Instruments accredited laboratory.
Michell Instruments 1
INSTALLATION
2 INSTALLATION
On delivery, please check that all the following standard components are present in the
packing box:
• Easidew Portable
• 2m of 6mm O/D PTFE tube
• Battery charger
• Mains lead
• 3 pole ¼” jack plug (inside lid) - for analog output connections
• Certicate of calibration
Before using the Easidew for the rst time it is recommended that the battery pack is
charged for a minimum of 12 hours.
Easidew Portable User’s Manual
2 97065 Issue 16.3, October 2019
Easidew Portable User’s Manual
3 OPERATION
Maximum operating pressure is 20 barg (290 psig).
It is important that the gas ttings are correctly tightened, and
!
3.1 General Operation
To operate the Easidew Portable, follow these instructions:
any tubing is secure in the push ttings before use.
Failure to do so will aect the instrument's pressure rating.
OPERATION
1. Ensure that all gas ttings are fully tightened before use.
2. Gas under test should be restricted to ow rates between 1 and 5 Nl/min
(2 and 10.6 scfh) and pressures from atmospheric to 2 MPa (20 barg (290
psig)).
3. Connect the sample gas supply line to the instrument Gas In port.
4. Connect the sample gas vent line to the instrument Gas Out port.
5. Switch the instrument on. The display will begin to change as the sensor
responds to the applied dew point.
6. Allow the gas to ow until the display shows a stable reading. Typically
this would be around 15 to 30 minutes for spot checks at dew points of
-40°C (-40°F) and above.
7. Switch the unit o and disconnect the sample lines.
NOTE: Filters are essential for potentially dirty/contaminated gases – the
tted lter should be checked before and after use and replaced regularly - as
required.
Michell Instruments 3
OPERATION
Easidew Portable User’s Manual
3.2 Atmospheric or Line Pressure Measurements
The Easidew Portable is supplied with two labelled, interchangeable, gas inlet/outlet
ttings.
NumberDescription
14mm free ow tting
20.4mm restricted tting
Figure 1
2
Gas Out
LINE PRESSURE
1
Gas Out
ATMOSPHERIC
1
Filter Fitted
2
Filter Fitted
Interchangeable Gas Inlet/Outlet Fittings
Gas In
Gas In
In order to perform measurements at line pressure, the restricted tting should be on
the gas outlet port.
To perform measurements at atmospheric pressure, the restricted tting should be on
the gas inlet port.
The Gas In port is ALWAYS on the right hand side.
!
497065 Issue 16.3, October 2019
Easidew Portable User’s Manual
3.3 Measuring Dew Points Below -40°C (-40°F)
Due to the signicantly lower levels of moisture present at dew points of this level, the
response times of the sensor will be signicantly increased. The table below oers an
approximate guide to the times taken for the instrument to stabilize at a given dew
point (from a starting point of 10°Cdp (50°Fdp) ambient):
OPERATION
Target Dew Point
°C°F
-30-2215
-40-4030
-50-5860
-60-76180
The Easidew sensor tted to the Easidew Portable is designed and calibrated to measure
dew points as low as -100°C (-148°F). However, due to the large internal volume of
the sample block, the hygroscopic nature of the built-in lter, and the potential of the
gas ttings to trap moisture at very low dew points, we recommend that the Easidew
Portable is not used to measure dew points below -60°C (-76°F). Suitable alternative
solutions in our range would be the Easidew Online, Pura xed installations, MDM300
Portable, or our cooled mirror range of instruments.
T100 Response Time
(mins)
Michell Instruments 5
OPERATION
3.4 User Controls
Easidew Portable User’s Manual
2
1
EASIDEW Portable Hygrometer
PowerFuse
°Cdp
4-20
Gas In
To measure
line
pressure
atmospheric
pressure
Gas Out
at
21
21
Gas Out
34
o
-
mA
O/P
Battery
Charger
Filter Fitted
5
6
Gas In
7
Figure 2
User Controls
Indicates the measured dew point in °C from -100 to +20 (-148 to
+68°F).
Under certain conditions the following error messages may be
1Digital Display
displayed:
ErrL = Sensor under range
ErrH = Sensor over range
Err I = Sensor fault or sensor disconnected
2Power SwitchSwitches the Easidew Portable ON or OFF.
This 1A quick blow fuse provides protection for the display
3Fuse
NiMH Battery
4
Pack
Analog Output
6
Socket
7Gas Fittings
electronics in the event of a fault with the charger or battery pack.
Another protection fuse is located on the display PCB.
Located in the top right hand corner of the instrument, it can be
accessed by removing two screws (5). The battery pack can be
recharged using the supplied charger, via the battery-charging
socket. See Section 5.5 for troubleshooting information.
The battery pack will charge if the instrument is switched ON or
OFF.
The Easidew portable features an analog output socket that
provides a linear 4-20 mA current loop, scaled to -100 to +20°C
(-148 to +68°F)dew point. This allowed the instrument to be
connected to a chart recorder, data logger or PC to enable dewpoint trends to be analyzed over time. For wiring information see
Section 3.5.
The Easidew Portable can be used for measurements at line
pressure (up to 20 barg (290 psig)) or atmospheric pressure.
Legris push ttings are supplied for use with 6mm OD PTFE
tubing. There is a 32mm particulate lter (99.5% removal of 0.1
micron particles) tted as standard under the Gas In port position.
697065 Issue 16.3, October 2019
Easidew Portable User’s Manual
3.5 4–20 mA Output Socket Wiring
The Easidew Portable provides a linear 4-20 mA output scaled from -100 to +20°C.
The socket accepts a 3 pole ¼” jack plug (supplied) and should be wired as shown
below:
OPERATION
+VE
-VE
Figure 3
-VE
Jack Plug Wiring
+VE
Michell Instruments 7
GOOD MEASUREMENT PRACTICE
4 GOOD MEASUREMENT PRACTICE
Ensuring reliable and accurate moisture measurements requires the correct sampling
techniques, and a basic understanding of how water vapor behaves. This section aims
to explain the common mistakes and how to avoid them.
Sampling Materials – Permeation and Diusion
All materials are permeable to water vapor since water molecules are extremely small
compared to the structure of solids, even including the crystalline structure of metals.
The graph above demonstrates this eect by showing the increase in dew point
temperature seen when passing very dry gas through tubing of dierent materials,
where the exterior of the tubing is in the ambient environment.
- 20
- 30
Easidew Portable User’s Manual
- 40
- 50
Dew point (ºC)
- 60
- 70
Figure 4
nickel
stainless steel
12345
Time (hours)
Material Permeability Comparison
nylon
copper
polyethylene
PTFE
What this demonstrates is the dramatic eect that dierent tubing materials have on
the humidity levels of a gas passed through them. Many materials contain moisture
as part of their structure and when these are used as tubing for a dry gas the gas
will absorb some of the moisture. Always avoid using organic materials (e.g. rubber),
materials containing salts and anything which has small pores which can easily trap
moisture (e.g. nylon).
As well as trapping moisture, porous sampling materials will also allow moisture vapor
to ingress into the sample line from outside. This eect is called diusion and occurs
when the partial water vapor pressure exerted on the outside of a sample tube is
higher than on the inside. Remember that water molecules are very small so in this
case the term ‘porous’ applies to materials that would be considered impermeable in
an everyday sense – such as polyethylene or PTFE. Stainless steel and other metals
can be considered as practically impermeable and it is surface nish of pipework that
becomes the dominant factor. Electropolished stainless steel gives the best results over
the shortest time period.
Take into consideration the gas you are measuring, and then choose materials appropriate
to the results you need. The eects of diusion or moisture trapped in materials are
more signicant when measuring very dry gases than when measuring a sample with a
high level of humidity.
897065 Issue 16.3, October 2019
Easidew Portable User’s Manual
Temperature and Pressure eects
As the temperature or pressure of the environment uctuates, water molecules are
adsorbed and desorbed from the internal surfaces of the sample tubing, causing small
uctuations in the measured dew point.
GOOD MEASUREMENT PRACTICE
Adsorption
solid to the surface of a material, creating a lm. The rate of adsorption is increased at
higher pressures and lower temperatures.
Desorption
constant environmental conditions, an adsorbed substance will remain on a surface
almost indenitely. However, as the temperature rises, so does the likelihood of
desorption occurring.
Ensuring the temperature of the sampling components is kept at consistent levels is
important to prevent temperature uctuation (i.e. through diurnal changes) continually
varying the rates of adsorption and desorption. This eect will manifest through a
measured value which increases during the day (as desorption peaks), then decreasing
at night as more moisture is adsorbed into the sampling equipment.
is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved
is the release of a substance from or through the surface of a material. In
If temperatures drop below the sample dew point, water may condense in sample
tubing and aect the accuracy of measurements.
Maintaining the temperature of the sample system tubing above the dew point of the
sample is vital to prevent condensation. Any condensation invalidates the sampling
process as it reduces the water vapor content of the gas being measured. Condensed
liquid can also alter the humidity elsewhere by dripping or running to other locations
where it may re-evaporate.
Although ambient pressure does not change drastically in a single location, the gas
sample pressure does need to be kept constant to avoid inconsistencies introduced
by adsorption or desorption. The integrity of all connections is also an important
consideration, especially when sampling low dew points at an elevated pressure. If
a small leak occurs in a high-pressure line, gas will leak out; however, vortices at the
leak point and a negative vapor pressure dierential will also allow water vapor to
contaminate the ow.
Theoretically ow rate has no direct eect on the measured moisture content, but
in practice it can have unanticipated eects on response speed and accuracy. An
inadequate ow rate may:
Michell Instruments 9
GOOD MEASUREMENT PRACTICE
• Accentuate adsorption and desorption eects on the gas passing through
the sampling system.
• Allow pockets of wet gas to remain undisturbed in a complex sampling
system, which will then gradually be released into the sample ow.
• Increase the chance of contamination from back diusion. Ambient air
that is wetter than the sample can ow from the exhaust back into the
system. A longer exhaust tube can help alleviate this problem.
• Slow the response of the sensor to changes in moisture content.
An excessively high ow rate can:
• Introduce back pressure, causing slower response times and unpredictable
changes in dew point
• Result in a reduction in depression capabilities in chilled mirror instruments
by having a cooling eect on the mirror. This is most apparent with gases
that have a high thermal conductivity such as hydrogen and helium.
Easidew Portable User’s Manual
System design for fastest response times
The more complicated the sample system, the more areas there are for trapped moisture
to hide. The key pitfalls to look out for here are the length of the sample tubing and
dead volumes.
The sample point should always be as close as possible to the critical measurement
point to obtain a truly representative measurement. The length of the sample line to the
sensor or instrument should be as short as possible. Interconnection points and valves
trap moisture, so using the simplest sampling arrangement possible will reduce the time
it takes for the sample system to dry out when purged with dry gas.
Over a long tubing run, water will inevitably migrate into any line, and the eects of
adsorption and desorption will become more apparent.
Dead volumes (areas which are not in a direct ow path) in sample lines, hold onto
water molecules which are slowly released into the passing gas. This results in increased
purge and response times, and wetter than expected readings. Hygroscopic materials
in lters, valves (e.g. rubber from pressure regulators) or any other parts of the system
can also trap moisture.
Plan your sampling system to ensure that the sample tap point and the measurement
point are as close as possible to avoid long runs of tubing and dead volumes.
Filtration
All trace moisture measurement instruments and sensors are by their nature sensitive
devices. Many processes contain dust, dirt or liquid droplets. Particulate lters are used
for removing dirt, rust, scale and any other solids that may be in a sample stream.
For protection against liquids, a coalescing or membrane lter should be used. The
membrane provides protection from liquid droplets and can even stop ow to the
analyser completely when a large slug of liquid is encountered, saving the sensor from
potentially irreparable damage.
10 97065 Issue 16.3, October 2019
Easidew Portable User’s Manual
5 MAINTENANCE
Routine maintenance of the Easidew Portable is conned to regular re-calibration of the
internal, removable Easidew sensor and replacement of the lter cartridge.
5.1 Calibration
The calibration of the internal sensor is traceable to national standards. For this reason
it should only be calibrated in an accredited, e.g. UK
Service (UKAS)
laboratory. If these facilities do not exist it is recommended that the sensor is returned
to the manufacturer, Michell Instruments, or an approved agent. A calibration certicate
bearing a seven-point calibration is issued with each sensor.
In most applications, annual re-calibration ensures that the stated accuracy of the
Easidew sensor is maintained.
or US
National Institute of Standards and Technology
MAINTENANCE
United Kingdom Accreditation
(NIST) standards
5.2 Sensor / Battery Replacement
To remove the sensor, or battery pack:
1. Ensure instrument is switched o and that the battery charger, current
output and any sampling components are also disconnected.
2. Remove and retain the 10 cross-head screws from the top plate.
3. Lift the small battery pack cover in the top right corner of the instrument.
A small at bladed screwdriver may be required to gently pry the edges
of the cover if it has become stuck to the waterproof seal underneath.
Removing this cover rst will make it easier to lift the entire top panel out
of the instrument.
4. Lift the top plate of the instrument out of the case. Disconnect the battery
pack before removing the top plate completely to prevent it from straining
on the attached cable. If only replacing the battery pack, do not follow
the next two steps.
5. Undo the screw from the centre of the sensor connecting plug and pull
o the connector.
6. Unscrew the sensor from the block.
Fitting the replacement is simply a reversal of the above procedure. When tting a new
sensor it may be necessary to change the alignment of the GDSN connector (see next
page).
Michell Instruments 11
MAINTENANCE
If the front panel prevents the connector from tting onto the sensor, follow the
instructions below:
• Completely unscrew the cable gland on the GDSN connector to release
the cable tension.
• Remove the locking screw from the back of the connector (retaining the
metal O-ring).
Easidew Portable User’s Manual
• Remove the connector block using a small screwdriver.
• Rotate the connector block and push it back into the connector housing.
Take care not to trap any wires against the hole for the locking screw.
12 97065 Issue 16.3, October 2019
Easidew Portable User’s Manual
• Replace the locking screw and cable gland.
5.3 Filter Cartridge Replacement
Unscrew the gas inlet tting to reveal the lter, which can then simply be removed for
checking or replacement.
MAINTENANCE
5.4 Checking the Easidew Portable Electronics Calibration
Supply
4-20 mA
PIN 1
PIN 3
Figure 5
To verify the display electronics are within calibration a 4-20mA current source can be
connected in place of the sensor.
At 4 mA the display should show -100.0°Cdp ±0.5°C (-148°Fdp ±0.9°F)
At 20 mA the display should show +20.0°Cdp ±0.5°C ( +68°Fdp ±0.9°F)
If the displayed values are outside of this range, please contact Michell Instruments'
Service Department.
2-Wire Connection - View Showing Rear of Connector Terminal Block
Sensor disconnected
or sensor tile / sensor
thermistor fault.
NOTE: This error is
normally displayed
during the rst few
seconds while the
instrument is starting
up.
Sensor reading underrange.
Check sensor cable is securely
connected inside instrument.
Check instrument electronics with
4-20mA source.
Exchange sensor.
Check instrument electronics with
4-20mA source.
Display shows “ErrH”
Display ickers on
and o.
Sensor current signal
< 4mA
Sensor tile open circuit.
Sensor reading over-
range.
Sensor current signal >
20mA
Sensor tile short circuit.
Battery voltage low.Connect charger.
Exchange sensor.
Sensor may have been exposed
to saturation conditions or liquid
contamination. Check that lter and
sensor guard are clean and dry.
If liquid water has contacted sensor,
or sensor block, then disassemble
and dry thoroughly. After drying, it
is recommend to purge assembled
instrument with very dry (-75°Cdp
(-103°Fdp) / 1ppmV moisture) air for
12 to 24 hours.
Exposure to other contaminants can
cause lasting damage and may require
sensor to be exchanged.
Accuracy±2°Cdp (±3.6°Fdp)
Run time12 - 16 hours
Charge time16 hours for maximum charge
Flow Rate1 to 5 Nl/min (2.1 to 10.5 scfh)
-40 to +20°Cdp (-40 to +68°Fdp)
-100 to -40°Cdp (-148 to -40°Fdp)
Electrical Input/Output
Output
Power SupplyRechargeable NiMH battery pack, charger included
4-20 mA current maximum load
resistance 400 Ω
Operating Conditions
Operating Temperature -20 to +50°C (-4 to +122°F)
Storage Temperature -40 to +75°C (-40 to +167°F)
Operating PressureUp to 2 MPa (20 barg (290 psig))
Mechanical Specications
DisplayFlush mounted 3.5 digit red LED
Case
Weight4kg (8.8lbs) total weight
Enclosure Rating
Case Closed
Sample ConnectionsPush t penumatic ttings for gas inlet/outlet
Sample Block
Filter Cartridge
InterchangeabilitySensor is fully interchangeable with other Easidew products
Sample Tubing2m (6.6ft) of 6mm O/D PTFE supplied
Yellow propylene with charger, sample tubing and output connector
stored in the lid
NEMA Type 6
Stainless steel, fully self-contained sample system using a standard
drop-in cartridge
Removes 99.5% of particles ≥ 0.3 μm supplied with cartridge
installed. Spare cartridges are available (part no: SSF-PF-10PK)
16 97065 Issue 16.3, October 2019
Easidew Portable User’s Manual
APPENDIX B
Appendix B
Quality, Recycling
& Warranty
Information
Michell Instruments 17
APPENDIX B
Easidew Portable User’s Manual
Appendix B 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/compliance
This page contains information on the following directives:
• ATEX Directive
• Calibration Facilities
• Conict Minerals
• FCC Statement
• Manufacturing Quality
• Modern Slavery Statement
• Pressure Equipment Directive
• REACH
• RoHS3
• WEEE2
• Recycling Policy
• Warranty and Returns
18 97065 Issue 16.3, October 2019
Easidew Portable User’s Manual
APPENDIX C
Appendix C
Decontamination Declaration
Michell Instruments 19
APPENDIX C
Easidew Portable User’s Manual
Appendix C Decontamination Declaration
Decontamination Certicate
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
materials. For most applications involving solvents, acidic, basic, ammable or toxic gases a simple purge with dry
gas (dew point <-30°C) over 24 hours should be sufcient to decontaminate the unit prior to return.
Work will not be carried out on any unit that does not have a completed decontamination declaration.
Decontamination Declaration
I declare that the information above is true and complete to the best of my knowledge, and it is safe for Michell
personnel to service or repair the returned instrument.
Name (Print)Position
SignatureDate
F0121, Issue 2, December 2011
20 97065 Issue 16.3, October 2019
Easidew Portable User’s Manual
NOTES:
Michell Instruments 21
http://www.michell.com
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