Dew Point Meters for Compressed Air and Industrial Gases
Seacom supplies portable dew point meters, fixed transmitters and probes for compressed air, air dryers, industrial gases and low-humidity processes. The range supports both occasional spot checks and continuous measurement, with instruments for dry rooms, pressurised pipelines and industrial drying.
Choosing a dew point meter for compressed air starts with the expected dew-point range, operating pressure and measurement purpose. A portable instrument suits checks at multiple locations, while a fixed transmitter provides continuous readings for monitoring and control. Use the application table below to identify suitable products, then confirm the probe, installation accessories and output requirements.
Vaisala DMP probes can operate as standalone Modbus RTU devices or connect to an Indigo transmitter when a display, analogue output, relay, Ethernet connection or local configuration interface is required.
Vaisala Indigo80 for portable measurement, probe configuration and field diagnostics.
Discontinued Vaisala Dew Point Instruments
Some established Vaisala dew point models have been discontinued. The best replacement depends on the original probe version, process connection, pressure, output and measured gas. Use the following table as a guide rather than a direct drop-in guarantee.
Do not assume a direct replacement for its combined SF6 measurement functions.
Information Needed for Dew Point Transmitter Selection
For a suitable recommendation, provide as much of the following information as possible:
Expected minimum and maximum dew point
Process gas or measured environment
Operating temperature and pressure
Pipe size, process connection and available insertion depth
Direct installation or sampling-system preference
Required output, such as 4–20 mA, Modbus RTU, relay or Ethernet
Portable spot checking or permanent online monitoring
Portable Dew Point Meter or Fixed Transmitter?
Portable and permanently installed instruments serve different purposes. Choose according to how often readings are needed, how many locations must be checked and whether the measurement needs to trigger an alarm or control action.
Measurement requirement
Suitable approach
What to consider
Checking several dryers or compressed-air outlets
Portable dew point meter
Probe range, pressure rating, sampling accessories, stabilisation time and data logging
Continuous dryer-outlet monitoring
Fixed dew point transmitter
Measurement range, controller interface, alarm provision and service access
Investigating intermittent moisture problems
Measurement with recorded trends
Logging duration, sampling interval and the ability to relate readings to operating conditions
Checking an installed transmitter
Suitable calibrated reference instrument
Comparable pressure, a representative sample and sufficient time for both readings to stabilise
Using a Portable Dew Point Meter for Compressed Air
A portable dew point meter is useful for maintenance checks, commissioning and investigating differences between measurement points. For a complete portable system, select the handheld indicator, compatible dew-point probe and sampling accessories together.
Refer to the Indigo80 with DMP80 link in the application table above for portable measurement options. Confirm the required dew-point range, process pressure and gas compatibility before choosing the probe.
For permanent measurement connected to a PLC, display or monitoring system, explore the dew point transmitter range.
Pressure Dew Point and Atmospheric Dew Point
Pressure dew point describes the dew point at the compressed-air system's operating pressure. Atmospheric dew point describes the reading after the gas is reduced to atmospheric pressure. They are not interchangeable: changing the measurement pressure changes the dew point.
Before comparing a reading with a dryer specification or another instrument, confirm the pressure at which each value was measured or reported.
Getting Reliable Dew Point Measurements in Compressed Air
Choose a representative point: Measure where the result answers the application question, such as dryer-outlet performance or conditions at a critical point of use.
Control sampling pressure: Avoid unintended pressure drops when measuring pressure dew point.
Maintain suitable sample flow: Follow the probe and sampling-cell instructions.
Prevent sample contamination: Check connections for leakage and avoid condensation in the sampling line.
Allow stabilisation: Wait for the probe and sampling arrangement to reach a stable reading before recording the result.
Frequently Asked Questions
Can a portable meter replace continuous dew point monitoring?
A portable meter provides readings during a check or logging session. It does not provide ongoing protection when disconnected. Where an unnoticed dryer problem could affect production, consider permanent measurement with an appropriate alarm system.
Can I compare readings taken at different pressures?
Not directly. Confirm the measurement pressure and reporting basis first. If conversion is needed, use a suitable calculation with the required pressure information.
What information should I provide when requesting a dew point meter?
Provide the gas, expected dew-point range, operating pressure and temperature, measurement location, and whether you need portable checks or continuous monitoring. Include any logging, output and calibration requirements.
Dew Point Measurement Application Guide
Choosing a dew point meter or transmitter for a dryer? Read our guide to dew point measurement in compressed air for measurement pressure, fixed and portable instruments, and sampling considerations.
The best dew point instrument depends on whether the measurement is portable or permanent, the type of dryer or process, operating pressure and the required dew-point range. Use the table below as a starting point, then confirm the actual gas, pressure, temperature, process connection and required output.
Discuss Your Compressed Air Application with Seacom
Seacom Process Instruments Sdn Bhd can help you select a Vaisala dew point transmitter or portable measurement system for your compressed air application. Send us your dryer type, operating pressure, target dew point and preferred output so we can review a suitable instrument configuration and sampling arrangement.
The Vaisala DMT340 Series provided configurable dew-point and temperature measurement for industrial low-humidity applications. The series is discontinued and replaced by Vaisala Indigo500 transmitters with DMP7 or DMP8 smart probes.
Former models: DMT341, DMT342, DMT344, DMT347 and DMT348
Designed for dry rooms, industrial dryers, compressed air and process gases
Legacy display, data logging, analog, relay and communication options
Use DMP7 for compact, wall-mounted or tight-space applications
Use DMP8 for pressurised processes and pipelines
Pair the selected probe with an Indigo500 transmitter
The Vaisala DMT345 and DMT346 provided direct dew-point measurement in hot industrial drying processes. Both models are discontinued and replaced by Vaisala DMP5 or DMP6 smart probes with an Indigo transmitter.
DMT345: former solution for processes up to +180 °C
DMT346: former solution for very hot processes up to +350 °C
DMT345 replacement: DMP5 with a suitable Indigo transmitter
DMT346 replacement: DMP6 with a suitable Indigo transmitter
Direct in-process measurement without a conventional sampling system
Contact Seacom for mechanical and electrical migration review
The Vaisala DMT152 provides accurate dew-point measurement down to −80 °C Td/f for ultra-dry industrial and OEM applications. This model is discontinued and has been replaced by the Vaisala DMT153.
Calibrated dew-point range from −80 to −20 °C Td/f
Accuracy up to ±2 °C Td/f
Operating pressure up to 50 bar
Analog outputs and RS-485 communication
DRYCAP® sensor resistant to condensation and contamination
The Vaisala DMT143 and DMT143L provide compact, dependable dew-point measurement for small industrial dryers, compressed-air systems, glove boxes and OEM equipment.
Dew-point measurement range across the family from −70 to +60 °C Td/f
Accuracy up to ±2 °C Td/f
Vaisala DRYCAP® technology with automatic calibration
Resistant to condensation, compressor oil and particulate contamination
Analog output and RS-485 with Modbus RTU options
Compatible with the Vaisala Indigo80 handheld indicator
The Vaisala DMT132 is a compact and economical dew-point transmitter designed to verify refrigerant-dryer performance by measuring the actual outlet-air dew point.
Dew-point measurement range from −30 to +50 °C Td/f
Accuracy up to ±1 °C in the typical refrigerant-dryer range
The Vaisala DPT146 combines dew-point and process-pressure measurement in one compact transmitter for compressed-air systems. This model is discontinued and should not be selected for new projects.
Dew-point measurement from −70 to +30 °C Td
Absolute-pressure measurement from 1 to 12 bar
Pressure-compensated dew point and ppm calculation
Analog outputs and RS-485 with Modbus RTU
Contact Seacom for existing-unit support and replacement assessment
The Vaisala DM70 was a portable meter for dew-point spot checks, process measurements and data logging. It is discontinued and replaced for general dew-point work by the Vaisala Indigo80 handheld indicator with a DMP80A or DMP80B probe.
Legacy DMP74A, DMP74B and SF₆-specific DMP74C probe options
Direct or sampled measurement in pressurised processes
Portable numerical and graphical display with data logging
Current replacement: Indigo80 with DMP80A or DMP80B
DMP80A for moderate dew points down to −40 °C Td/f
The Vaisala DPT145 provides online dew-point, pressure and temperature measurement for SF6-insulated electrical equipment. The model is being discontinued and should not be specified for new projects.
Measures dew point, pressure and temperature
Calculates SF6 density, normalised pressure and moisture in ppm
RS-485 communication with Modbus RTU
Contact Seacom for availability and replacement assessment
The Vaisala DRYCAP® Dew Point and Temperature Probe DMP8 provides reliable low-humidity measurement in pressurised pipelines with adjustable installation depth.
Dew point measurement range from −70 to +80 °C Td/f
Designed for pressurised processes from 0 to 40 bar absolute
Adjustable insertion depth with ISO R 1/2 or NPT 1/2 process connection
Optional ball-valve kit permits insertion and removal without shutting down the process
Use with Modbus RTU, an Indigo transmitter or the portable Indigo80 handheld indicator
The Vaisala DRYCAP® Dew Point and Temperature Probe DMP5 measures humidity directly in hot industrial processes with a long stainless-steel probe and adjustable installation depth.
Direct in-line measurement at process temperatures up to +180 °C
Dew point measurement range from −40 to +100 °C Td/f
Long probe reaches through insulation and thick process walls
Built-in Modbus RTU or integration with Vaisala Indigo transmitters
Connect to Indigo80 for portable display, diagnostics, configuration and field calibration
The Vaisala Indigo200 Series is the standard transmitter platform for one interchangeable Indigo-compatible smart probe, providing local display and practical automation-system connectivity.
Indigo201 with three analog outputs and two relays
Indigo202 with Modbus RTU and two relays
Colour display with numerical and graphical views
IP65 enclosure for industrial measurement applications
This website uses cookies to ensure you get the best experience on our website
