Humidity Measurement

Contact ThermX Southwest at 800-284-3769
for Availability and Engineering Support.

Humidity Measurement
Vaisala's wide variety of relative humidity measurement instruments cover all the applications from
ventilation to process control in demanding explosive areas. Some of these products include:

Vaisala HM70 Hand-held

Vaisala HUMICAP® Hand-Held Humidity and Temperature Meter HM70
The HM70 is a user-friendly meter for demanding spot-checking humidity measurements. The
HM70 is ideal for field checking and calibration of Vaisala's fixed humidity instruments such as the HMP230 Series Transmitters.

Three probes are available:
• HMP75 general-purpose probe
• HMP76 long, stainless steel probe, especially suitable for spot-checking in ducts
• HMP77 with a small sensor head at the end of a 5-meter cable, ideal for difficult-to-reach areas and for
on-site calibration of Vaisala's process transmitters in Environmental Chambers.

The HM70 features a multilingual, menu-based user interface, and a clear graphical LCD display. Three measurement parameters can be displayed and logged into the meter's memory at the same time. An analog output option is also available.

Technical specifications
Measurement range:0...100 %RH

Accuracy against salt solutions
±2 %RH (0...90 %RH)
±3 %RH (90...100 %RH)

Max. accuracy against high quality certified standards
±1 %RH (0...90 %RH)
±2 %RH (90...100 %RH)

Temperature measurement range
HMP75: -20...+60 °C
HMP76: -50...+120 °C
short time: -50...+180 °C
HMP77: -70...+180 °C

Vaisala DM70 Hand-held

Vaisala DRYCAP® Hand-Held Dewpoint Meter DM70
The DM70 can be used in many industrial spot-checking applications as well as a one-point calibration check for fixed dewpoint transmitters such as the DMT242 and DMP248.
Ideal for to sample dry gas flow or compressed air.

Key features
- Vaisala DRYCAP® Sensor with patented autocalibration function
- Low maintenance need due to superior long-term stability
- Sensor withstands condensation
- Fast response, enhanced by Sensor Purge option
- Easy-to-use user interface
- Data can be logged and transferred to a PC via MI70 Link software
- Compact, small and light
- For measurements in very hot and dirty processes, the DSS70A sampling system is available as an accessory
- For connection to pressurized processes, a variety of sampling cells are available
- Also a two-pressure sampling cell for measurements in both process and ambient pressure available

Technical specifications
Dewpoint measurement range
A-probe: -40...+60 °C (-40...+140 °F)
B-probe: -60...+20 °C (-76...+68 °F)
C-probe (for SF6 gas):
-50...+20 °C (-58...+68 °F)

Accuracy: ± 2 °C (3.6 °F)

Operating temperature: -10...+60 °C (+14...+140 °F), process temperature up to
+200 °C (+328 °F) using DSS70A Sampling System

Pressure: 0...20 bar (0...290 psig)

Vaisala MM70 Hand-held

Vaisala HUMICAP® Hand-Held Moisture and Temperature Meter for Oil MM70
The MM70 is ideal for the preventive maintenance of oil-filled systems. It measures moisture in terms
of the water activity and temperature. Water activity directly indicates whether there is a risk of free
water formation. The MM70 features the Vaisala HUMICAP® Sensor with excellent pressure,
temperature and chemical tolerance.

Key features:
• In-line process checking through ball valve, no need to drain the oil.
• Measurement is independent of oil type, age and temperature.
• Compatible with Vaisala's fixed oil moisture instruments.
• Graphical display, data logging and transfer to PC
• Robust industrial-style construction.

Technical specifications

Water activity measurement range: 0...1 aw

Typical accuracy: ± 0.02

Temperature measurement range: -40...+100 °C (-40...+212 °F)

Vaisala HMI41 Hand-held

The hand-held HMI41 indicator is versatile and easy to use. With a choice of five different probes it
gives you flexibility to work in a variety of applications. The indicator also provides a calibration option:
by using a suitable probe and connection cable, most Vaisala's humidity transmitters can be easily calibrated at one point.

All five probes incorporate the Vaisala HUMICAP® Sensor, known for its high accuracy, reliability and long-term stability.

* Vaisala HMP41 relative humidity and temperature probe fix-mounted on the HMI41 indicator
* Vaisala HMP42 for structural humidity measurements from very small spaces (probe diameter 4 mm)
* Vaisala HMP44 for construction moisture measurements (read more...)
* Vaisala HMP45 with a cable for measurements in ducts and chambers
* Vaisala HMP46 for measurements in high temperatures and places hard to reach

Vaisala HMP228

Vaisala HUMICAP® Moisture and Temperature Transmitter for Oil HMP228
The HMP228 is a fast, reliable and accurate on-line detection system for water in oil.

Moisture measurements from lubrication oil can significantly cut maintenance costs and prolong
machine lifetime. The HMP228 measures water activity and temperature from oil. In connection with
oil, water activity measurement offers several advantages compared to the traditionally measured
variable, parts per million (ppm). Water activity indicates directly whether there is risk for free water formation. The measurement is independent of the type, aging or temperature of the oil.

Technical specifications

Measurement range: 0...1 aw

Typical accuracy: ± 0.02

Operating temperature: -40...+180 °C (-40...+356 °F)

Vaisala HMT330 Series

Vaisala HUMICAP® Humidity and Temperature Transmitter Series HMT330
The top-of-the-line humidity transmitter for demanding industrial applications. Proven Vaisala HUMICAP® technology provides reliable measurements. The chemical purge function helps to
maintain the accuracy in high concentrations of chemicals. The warmed sensor head (available for HMT337) provides true humidity readings in condensing conditions.

The large display shows measurements both numerically and graphically. 1-year measurement history
is also available. This makes it easy to monitor measurement trends.

The series consists of six models:
• Vaisala HMT331 for wall mounting
• Vaisala HMT333 for ducts and tight spaces
• Vaisala HMT334 for pressurized processes up to 100 bar
• Vaisala HMT335 for high temperatures
• Vaisala HMT337 for high humidities
• Vaisala HMT338 for pressurized pipelines up to 40 bar

Vaisala HMT300TKM Replaces HMP247T

Vaisala HUMICAP® Dewpoint Transmitter HMP247T
The Vaisala HUMICAP® Dewpoint Transmitter HMP247T was developed to monitor the air intake of
gas and liquid-fuelled power turbines. It is ideal for measuring in water vapor injection applications because the sensor has been optimized for high humidity environments by utilizing a patented,
warmed sensing probe. Water vapor is added to the intake of the turbine to increase the mass flow,
which in turn increases compression and electrical power output.

Power turbines also require exact water vapor injection in the chamber to reduce pollutant emissions.
The HUMICAP® sensor technology is ideal because of its reliability in the field. The only suggested scheduled maintenance is annual calibration.

The HMP247T has been replaced by the HMT300TMK Turbine Mounting Kit for Power Turbine Intake Air Measurement

Vaisala HMW61 HMW71 HMT100

Vaisala HUMICAP® Humidity and Temperature Transmitters HMW61/71
The wall-mounted HMW61 and HMW71 transmitters are designed for dusty and humid air conditioning applications where accurate and stable measurement and control of relative humidity and temperature is required. The transmitters are protected against dust and sprayed water, meeting IP65 requirements. All the materials used have been chosen for excellent corrosion resistance. This makes the transmitters especially suitable for humid and wet environments such as greenhouses, livestock farms, indoor swimming pools, or any other wash-down areas.

The HMW61/71 transmitters are available in two models: for humidity measurement only and for
humidity and temperature measurement. The transmitters are available with either current
(loop-powered) or voltage output.

Note that the HMT100 Replaces the HMW61 and HMW71.

Vaisala HMD60 HMD70

Vaisala HUMICAP® Humidity and Temperature Transmitters HMD60/70
The duct-mounted HMD60 and HMD70 humidity and temperature transmitters are designed for use in
air conditioning applications where accurate and stable measurement of humidity and temperature is required. The transmitters are easy to calibrate on-site without disturbing the measurement.

The transmitters incorporate the Vaisala HUMICAP® Sensor, which is known for its accuracy and
long-term stability, negligible hysteresis and resistance to dust and most chemicals. The HMD60/70 transmitters are available in two models: for humidity measurement only and for both humidity and temperature measurement. Both true two-wire and three-wire models are available.

Vaisala HMW60 HMW70

Vaisala HUMICAP® Humidity and Temperature Transmitters HMW60/70
The wall-mounted HMW60 and HMW70 transmitters are designed for use in air conditioning
applications where accurate and stable measurement of humidity and temperature is required. They are
the ideal choice for demanding energy management applications. The transmitters are easy to calibrate
on-site without disturbing the measurement.

The transmitters incorporate the Vaisala HUMICAP® Sensor, which is known for its accuracy and long-term stability, negligible hysteresis and resistance to dust and most chemicals. The transmitters are available in two models: for humidity measurement only and for both humidity and temperature measurement. Both true two-wire and three-wire models are available.

Contact ThermX Southwest at 800-284-3769
for Availability and Engineering Support.