Portable Instruments
MDM50
Portable Hygrometer
A compact and easy to use portable hygrometer with fast response, integrated sampling system
and traceability to National Standards.
Highlights
• Rapid spot-check measurements to –50°Cdp
• T95 to –35°C dew point in <10 minutes
• Simple operation
• Integral sampling system
• Industrial case
• ±2°Cdp accuracy
• 9-point traceable calibration
• 16 hours of operation between charges
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Applications
• Compressed air dryers
• Medical gases
• Plastic molding dryers
• Instrument air
• Ozone generators
Portable Instruments
MDM50
Hygrometer
Affordable, Simple Dew-Point
Measurement
The MDM50 Hygrometer has been designed to make spot
checks of the dew point in air and gases as simple and fast
as possible. This completely self-contained instrument weighs
just 4kg and is delivered ready to use. Simply connect your
sample gas to the Quick Connect (or optional Swagelok
fi ttings, turn on the instrument and it will automatically begin
to measure the dew point of the applied sample.
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Intelligent and Interchangeable Sensor
Technology
The MDM50 uses Michell’s advanced polymer moisture
sensing technology. The sensor is coupled with the latest
microprocessor-based measurement circuitry to produce a fully
calibrated and interchangeable sensor transmitter module. All
calibration data is stored in fl ash memory, so on-site sensor
exchange for calibration or service can be performed quickly,
even by untrained personnel.
Fully Integrated Sampling System
The MDM50 is unique among portable hygrometers. Michell
Instruments has built into the standard design, a complete
sampling system that easily allows you to measure the dew
point of any air or gas line, at up to 2 Mpa (20 barg) pressure.
The two interchangeable inlet/outlet fi ttings allow you to
choose between dew point measured at atmospheric, or at
line pressure, by simply swapping the position of the fi ttings.
An integrated fi lter housing uses standard fi lter cartridges and
provides 99.5% protection against particles down to 0.3m.
Optionally, Swagelok
operation of the unit at up to 30 Mpa (300 barg).
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tube couplings can be specifi ed to allow
Designed For Use In The Field
A fi eld instrument must be easy to carry and use. As its name
suggests, the MDM50 has been designed to be perfectly
transportable. It is small with an ergonomic carrying handle
and weighs only 4kg. The case of the hygrometer provides
NEMA 6 protection and the outer case is covered by a lifetime
guarantee, so can be returned to the factory for repair or
replacement, free of charge.
Long Battery Life
The MDM50 uses a rechargeable NiMH battery pack and is
delivered complete with a universal battery charger that fi ts
neatly into the instrument lid. It will operate for up to sixteen
hours on a full charge.
Reproducibility and Calibration Integrity
The MDM50 polymer moisture sensors are subject to a 9-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 fi eld.
Traceable Calibration
Each MDM50 is supplied with a calibration certifi cate traceable
to national standards (NPL & NIST) from Michell Instruments’
accredited laboratory.
Measurement Under Your Control
The hygrometer features an extremely clear and bright 0.5”
red LED display making it easy to determine the dew point of
your process even in dim conditions or direct sunlight. Michell
also provides a 4–20 mA analog output for connection to a
chart recorder, data-logger or computer system, so dew-point
trends can be analyzed over time.
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Technology:
Polymer Sensor
A capacitive humidity sensor works like a plate
capacitor. The lower electrode is deposited on a ceramic
substrate. A thin polymer hygroscopic layer acts as the
dielectric, and on top of this is the upper plate, which
acts as the second electrode but which also allows
water vapour to pass through it, into the polymer.
Upper electrode
Thin film polymer
Portable Instruments
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The dielectric strength of the polymer is proportional to
the water vapour content. In turn the dielectric strength
affects the capacitance, which is measured and processed
to give a relative humidity measurement. By combining
this fi gure with a measurement of temperature, a dew
point or absolute humidity value can be calculated.
Advantages of Polymer
• Very fast response
• Long-term stability
• Resistant to most chemicals
• Not permanently damaged by liquids
• Insensitive to contamination by particulates
Lower electrodes
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Glass substrate
Michell polymer sensor tile
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Portable Instruments
Technical Specifi cations
Performance
Measurement technology Polymer Capacitive
Measurement range –50 to +20°Cdp
Accuracy ±2°Cdp
Run time 12 to 16 hours
Charge time 16 hours for maximum charge
Flow rate 1 to 5 Nl/min
Electrical Input/Output
Output 4–20 mA current maximum load
Power supply Rechargeable NiMH battery pack,
Operating Conditions
Operating temperature –20 to +50°C
Storage temperature –40 to +75°C
Operating pressure
Low pressure version
High pressure version
Mechanical Specifi cations
Display Flush mounted 3.5 digit red LED
Case Yellow propylene with charger, sample tubing
Weight 4kg total weight
Enclosure rating
Case closed NEMA Type 6
Sample connections Optional: Legris pneumatic fi ttings
Sample block Stainless steel, fully self-contained
Filter cartridge Removes 99.5% of particles 0.3m
Sample tubing
Low pressure version
High pressure version
resistance 400
charger included
Up to 2 MPa (20 barg / 290 psig)
Up to 30 MPa (300 barg / 4350 psig)
and output connector stored in the lid
6mm Swagelok
1/4” Swagelok
sample system with fi xed orifi ce ports
for fl ow control/pressure or atmospheric
measurement and built-in fi ltration using a
standard drop-in cartridge
supplied with cartridge installed.
Spare cartridges are available
(part no: SSF-PF-10PK)
2m of 6mm O/D PTFE supplied
Metering valve and port adaptor
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tube fi ttings
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tube fi ttings
Dimensions
Michell Instruments Ltd, Rotronic Instruments Corp. 135 Engineers Road, Suite 150, Hauppauge NY 11788
Tel: 631 427 3898, Email: us.info@michell.com, Web: www.michell.com/us
Michell Instruments adopts a continuous development programme which sometimes necessitates specifi cation changes without notice.
Issue no: MDM50_ 97477_V1.2_US_0219
© 2019 Michell Instruments
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