Vaisala DMT132 Dew Point Transmitter for Refrigerant Dryers

Vaisala DMT132 Dew Point Transmitter for Refrigerant Dryers

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
  • Two-wire, loop-powered 4–20 mA output
  • Operating pressure up to 20 bar
  • Resistant to condensation and compressor oil
  • Optional warning LED and loop-powered display

Measure the Dryer Outlet Dew Point Directly

The Vaisala HUMICAP® DMT132 is designed specifically for refrigerant dryers and related OEM compressed-air equipment. Instead of estimating dryer performance from the refrigeration temperature, it measures the actual dew point of the outlet air.

This gives operators and equipment manufacturers a clearer indication of delivered-air quality. The measurement can reveal changing dryer performance, support alarm functions and help avoid unnecessary dryer capacity or maintenance.

Why Dew Point Is Better Than Refrigeration Temperature

The internal refrigeration temperature does not always represent the moisture condition of the compressed air leaving the dryer. Direct outlet dew-point measurement shows whether the dryer is achieving the required air quality under the actual load and operating conditions.

Monitoring methodWhat it indicatesPractical limitation
Refrigeration temperature Cooling-system operating condition Indirect indication that may not equal the delivered compressed-air dew point
DMT132 outlet dew point Actual moisture condition of the compressed air Requires a representative installation point and correct pressure setting

Key DMT132 Specifications

SpecificationDMT132 performance
Measured parameter Dew point or frost point temperature
Calculated parameter Dew point or frost point converted to atmospheric pressure
Measurement range −30 to +50 °C Td/f
Typical refrigerant-dryer accuracy ±1 °C from −3 to +20 °C Td/f
Operating temperature −30 to +50 °C
Operating pressure 0 to 20 bar
Measurement gases Non-corrosive gases
Analog output Scalable two-wire 4–20 mA
Supply voltage 10 to 28 VDC
Process connection ISO G1/2
Electrical connection Four-pin M8 connector
Protection rating IP65 / NEMA 4
Recommended calibration interval Two years in normal refrigerant-dryer applications

Simple OEM and Control-System Integration

The loop-powered 4–20 mA output allows the DMT132 to connect directly to a dryer controller, PLC, indicator or monitoring system. Its low supply requirement and compact housing suit both new OEM equipment and upgrades where panel space and wiring are limited.

  • Optional LED indication for a configured dew-point limit or device error
  • Optional loop-powered local display
  • RS-485 service connection for setup, calibration and diagnostics
  • Fast start-up for equipment integration

Communication note: the DMT132 provides its continuous process signal through the two-wire 4–20 mA output. Its RS-485 connection is intended for service functions and should not be presented as a standalone Modbus process output.

Pressure Compensation

The DMT132 does not measure pressure. The system pressure is entered as a compensation value during configuration. An approximate pressure value is normally sufficient for standard process dew point, but an accurate absolute-pressure setting is important when the transmitter is configured to output dew point converted to atmospheric pressure.

Confirm the normal measurement pressure when ordering. If the dryer operates over a wide or changing pressure range, review whether a fixed compensation value is suitable for the required result.

Direct Installation or Sampling Cell

Installation methodAdvantagesCheck before installation
Direct installation Fast response, simple arrangement and measurement at line pressure Safe isolation, G1/2 connection, available space and representative gas flow
Sampling cell Easier isolation, controlled sample flow and convenient removal for calibration Tubing material, leaks, sample pressure, exhaust arrangement and response time

For sampled measurements, use clean tubing with low moisture permeability and keep the line short. Leaks, wet tubing, dead volumes and ambient-air ingress can cause a slow or incorrect dew-point reading.

Compare DMT143, DMT132 and DMT153

Selection pointDMT143 / DMT143LDMT132DMT153
Current status Current Current Current; successor to DMT152
Best application Small dryers, glove boxes, compressed air and general OEM integration Refrigerant dryers and economical dryer-performance monitoring Very-low-dew-point OEM and industrial applications
Calibrated dew-point range Configuration-dependent; family coverage extends from −70 to +60 °C Td/f −30 to +50 °C Td/f −80 to −20 °C Td/f
Typical accuracy Up to ±2 °C Td/f Up to ±1 °C in the refrigerant-dryer range ±2 °C from −80 to −40 °C Td/f; ±3 °C from −40 to −20 °C Td/f
Sensor technology DRYCAP® HUMICAP® DRYCAP®
Pressure capability Up to 20 bar standard; selected DMT143 configurations up to 50 bar Up to 20 bar Up to 50 bar absolute
Primary output options Analog output and RS-485 Modbus RTU Two-wire 4–20 mA; service RS-485 Analog output or RS-485 with Modbus RTU
Portable and transmitter compatibility Indigo80 handheld indicator HM70 or DM70 handheld for spot-checking Indigo transmitters and Indigo80 handheld indicator
Best choice when You need a small, versatile transmitter for dry industrial gas You need cost-effective verification of a refrigerant dryer You need traceable measurement down to −80 °C Td/f with modern connectivity

Choose by operating range: DMT132 is intended mainly for refrigerant dryers, DMT143/DMT143L provide compact and flexible OEM dew-point measurement, and DMT153 is the current choice for demanding ultra-dry applications down to −80 °C Td/f.

Calibration and Field Checking

The DMT132 is factory calibrated. Vaisala recommends a two-year calibration interval in normal refrigerant-dryer service, or one year when the transmitter is regularly used near the dry end of its range. The appropriate interval should also reflect the site quality system and the importance of the measurement.

A calibrated Vaisala DM70 reference instrument can be used for a field comparison at a stable dew point. Confirm that both instruments are measuring the same gas condition and that the pressure-compensation settings are correct before assessing the difference.

Vaisala DMT132 Supplier in Malaysia

Seacom Process Instruments supplies and supports the Vaisala DMT132 Dew Point Transmitter in Malaysia for refrigerant dryers, compressed-air equipment and OEM dryer manufacturing.

Our team can assist with the measuring range, 4–20 mA scaling, pressure-compensation setting, process connection, sampling cell, warning indication, installation arrangement and calibration planning.

Contact Seacom with the dryer type, expected outlet dew point, operating pressure and temperature, installation point, power supply, control-system input and alarm requirement so we can check whether the DMT132 is the right selection.

Download

  DMT143 Catalogue   (210.05k)

  DMT143L Catalogue   (201.61k)

  DMT132 Order Form   (160.39k)

  DMT132 Catalogue   (372.13k)


Specific References

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