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AMT Dewpoint Transmitter

A reliable solution for continuous trace moisture measurement in process gases or compressed air, featuring our ultra-high capacitance aluminium oxide sensing technology for unmatched sensitivity, accuracy and speed of response.

Our AMT Dewpoint Transmitter is a compact 2-wire 4-20 mA loop-powered transmitter that offers continuous online moisture monitoring across various dewpoint ranges from -120 °C to +20 °C (-184 °F to +68 °F) accurate to ±2 °C (±3.6 °F) dewpoint.

Its advanced RISC microprocessor circuitry provides high resolution and sophisticated self-diagnostics. Equipped with a unique AutoCal span correction feature, the AMT Dewpoint Transmitter facilitates field calibrations and span checks, ensuring optimal accuracy between laboratory calibrations. The rugged stainless steel construction provides protection to IP66 / NEMA 4X, with the transmitter’s electrical connections made via a secure industrial connector.

Category:
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Suitable for continuous trace moisture measurements

Key features

  • Ultra-high capacitance aluminium oxide sensing technology for exceptional sensitivity, speed of response, accuracy, repeatability and stability
  • Factory configured for output in various moisture units: °C or °F dewpoint, ppm(V), ppb(V), g/m³ and lb/MMSCF.
  • Rugged stainless steel construction designed to withstand a maximum pressure of 35,000 kPa (350 bar) and harsh environmental conditions.
  • Easy installation and operation with minimal maintenance requirements.
  • Optional sensor holder/sample cell for optimal sampling conditions and easy removal for annual calibration without process interruption.
  • Supplied with a calibration certificate traceable to National and International Humidity Standards, ensuring reliability and compliance.
  • For flexible installation, the hygrometer can be sited up to 1000 metres away from the dewpoint transmitter.
  • Compatible with the DS1200, DS4000 and DS1500 hygrometer displays.

Technical Data

General
Sensor/Transmitter Type2-Wire 4-20 mA Loop Powered Dewpoint Transmitter
DocumentationInstruction manual, calibration certificate
Sensor
Sensing ElementUltra-high capacitance aluminium oxide
Dewpoint RangeOverall range offered between -120 °C to +20 °C (-184 °F to +68 °F) dewpoint.
-120 °C to +20 °C (-184 °F to +68 °F)
-110 °C to -20 °C (-166 °F to -4 °F)
-100 °C to 0 °C (-148 °F to +32 °F)
-100 °C to +20 °C (-148 °F to +68 °F)
-80 °C to -20 °C (-112 °F to -4 °F)
-80 °C to 0 °C (-112 °F to +32 °F)
-65 °C to +20 °C (-85 °F to +68 °F)
Calibration Warranty12 months from date of dispatch
Automatic CalibrationSpan check and correction are performed using two buttons on the transmitter body.
Factory CalibrationSupplied with a calibration certificate traceable to National and International Humidity standards.
Accuracy± 2 °C (±0.36 °F) dewpoint
Temperature CoefficientTemperature compensated for operating range
Resolution0.005 mA
RepeatabilityBetter than ±0.3 °C dewpoint
Operating Temperature-20 °C to +60 °C
Storage Temperature-20 °C to +70 °C
Response TimesWet to dry: -20 °C to -60 °C - less than 120 secs
Dry to wet: -100 °C to -20 °C - less than 20 secs
Sample Flow RateFlow independent, ideally 2 - 5 L/m. Max: 20 L/min
Electrical
Electromagnetic Compatibility (EMC)Complies with BS EN IEC 61326-1
Warm Up Time10 seconds
Fault ConditionsOpen circuit/under range: output drives to 20.5 mA
Short circuit/over range: output drives to 20.75 mA
Maximum Series Resistance(= {40 x (Supply Voltage – 7)} Ω)
IsolationSensing element connected to the 4-20 mA loop but isolated from the transmitter body
Output SignalLinear 4-20 mA with selectable engineering units and fault indication
Operating Voltage7-28 V DC reverse polarity protected
Engineering UnitsC dewpoint, °F dewpoint, ppm(V), ppb(v), g/m3 and lb/MMSCF
Power Supply12-28 Vdc Reverse Polarity Protected
ApprovalsCE, UKCA
Mechanical
Operating PressureFrom 1 kPa (0.01 bara) to Maximum 35,000 kPa (350 bara)
Operating Humidity (External)Maximum 95 %RH Non-Condensing
Cable TerminationsIP66 / NEMA 4X rated, size C, DIN EN 175301 connector at the Transmitter and other end terminated with bootlace ferrules
CableNominal diameter 3.4 mm, 92 ohms/km at +20 °C
Enclosure/Body316 stainless steel
Sensor Protection316 sintered stainless steel filter – 50 micron
Probe Material (Wetted Parts)316 stainless steel
Weatherproof ClassificationIP66 / NEMA 4X when Connector coupled to Transmitter
Mechanical Connection¾” UNF (16tpi) with integral Viton “O” ring seal
Mechanical Warranty12 months in case of defective parts or faulty workmanship
Dimensions in mm (H x W x D)138.5 x 30 (H x W)
Weight158 grams (0.348 lb)

Downloads

AMT User Manual (PDF)
AMT Datasheet (PDF)

What's in the box

Alpha | AMT Dewpoint Transmitter
AMT Transmitter
Alpha |  AMT Dewpoint Transmitter | Cable and Connector
AMT Cable and Connector
Alpha |  AMT Dewpoint Transmitter Manual
AMT Dewpoint Transmitter Manual
Alpha | AMT Dewpoint Transmitter | General Cal Cert
Calibration Certificate

Applications

AerospaceFor the production of high-specification aeronautical parts, vacuum furnace heat treatment with dry argon is essential, and NADCAP mandates the testing of welding shield gas at the torch head for dryness. Our range of transmitters provides continuous trace moisture measurement, ensuring the feed gas for shielding stays within the required moisture content range, maintaining ideal conditions.
Breathing AirHigh moisture levels in breathing air, as used in diving, firefighting, and defence applications, pose health risks and discomfort. Moisture condensation from high humidity levels in compressed air can lead to blocked airlines or cylinder corrosion, with potentially fatal consequences. Our transmitters allow for the continuous monitoring of trace moisture throughout the pipe network.
Food and BeverageMoisture control is critical in the food and beverage industry to prevent food quality loss. Packaging foods in an atmosphere of dry gases like Nitrogen and carbon dioxide extends shelf life. Our AMT and AMT-Ex transmitters enable continuous trace moisture measurement, reducing waste and carbon footprint.
HDPE ProductionEthylene and propylene, key for manufacturing chemicals and plastics, require precise moisture content monitoring for polymerisation efficiency and catalyst yield. Our range of transmitters ensures process optimisation, product quality, and reduced maintenance costs by providing accurate and consistent trace moisture measurements.
Injection MouldingMoisture adsorbed on plastic pellets can lead to extrusion failures and quality degradation. Our transmitters measure trace moisture in the circulating air to detect possible dryer failures, enhancing process efficiency and reducing costs.
Medical GasesIn medical applications, compressed air and gases must be clean and almost sterile, free from contaminants including water vapour and bacteria. Our AMT and AMT-Ex transmitters offer permanent moisture monitoring in air/gas lines, which is essential for maintaining safe patient care environments.
Natural Gas and LNGThe liquefaction and regasification processes in natural gas supply are crucial for global energy distribution. Moisture presence poses risks of pipeline and valve freezing. Installing the AMT-Ex dewpoint transmitter ensures accurate trace moisture measurement, safeguarding gas quality and system integrity.
PharmaceuticalsIn pharmaceutical manufacturing, accurate moisture determination is crucial for product consistency and quality. Our range of transmitters provides fast, repeatable, and accurate online dewpoint control, essential for the control of blanketing gases.
Power GenerationEnergy production priorities include safety, cleanliness, and efficiency. Our range of online transmitters measures trace moisture, protecting equipment, reducing costs, and improving efficiency in power generation processes.
Welding GasesDifferent welding processes require specific inert gases for atmospheric shielding. Our AMT and AMT-Ex transmitters continuously measure moisture to ensure feed gas used for shielding remains within the specified range, maintaining optimal conditions for welding.

Frequently Asked QuestionsIf you have a question that’s not answered below, please contact us

Which sensing technology is used in the AMT Dewpoint Transmitter?

The AMT features ultra-high capacitance aluminium oxide sensing technology, known for its exceptional sensitivity, quick response, accuracy, repeatability, stability, and longevity.

Related products

Whatever the challenge,
you can rely on Alpha
Moisture Systems

If you require a customised trace moisture measurement solution, book a consultation with our expert technical team and find out how you can increase the efficiency and productivity of your operations.

Dewpoint Calculator for Trace Moisture Measurement

in Gases & Compressed Air