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AMT-Ex Dewpoint Transmitter
A robust solution for continuous moisture measurement in process gases and compressed air, featuring ultra-high capacitance aluminium oxide sensing technology. Certified intrinsically safe to ATEX and IECEx standards for use in hazardous areas.
Our AMT-Ex Dewpoint Transmitter is a compact 3-wire, 4-20 mA, loop-powered transmitter that offers continuous online moisture measurement across various dewpoint ranges from -110 °C to +20 °C — 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-Ex 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.
Whatever the challenge — Alpha Moisture Systems has you covered.
- Highly customised solutions
- Trusted by industry leaders
- Distributors worldwide
- Over 30 years experience
Reliable moisture measurement in hazardous areas
Key features
- Certified intrinsically safe to IECEx and ATEX standards for use in potentially hazardous/explosive atmospheres
- 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
- Withstands a maximum pressure of 35,000 kPa (350 bar), allowing use in extreme 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 and DS4000 hygrometer displays
Technical Data
General | |
| Sensor/Transmitter Type | 3 Wire 4-20 mA Intrinsically Safe Dewpoint Transmitter |
| Documentation | Instruction manual, calibration certificate |
Sensor | |
| Sensing Element | Ultra-High Capacitance – Aluminium Oxide Type |
| Dewpoint Range | Overall 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) |
| Certification | IECEx, ATEX |
| Approvals | CE, UKCA |
| Automatic Calibration | Span check and correction are performed using two buttons on the transmitter body. |
| Factory Calibration | Supplied with a calibration certificate traceable to National and International Humidity standards. |
| Accuracy | ± 2 °C (±0.36 °F) dewpoint |
| Resolution | 0.016 mA |
| Repeatability | Better than ±0.3 °C dewpoint |
| Operating Temperature | -20 °C to +60 °C |
| Storage Temperature | -20 °C to +70 °C |
| Response Times | Dry to wet: -100 °C to -20 °C (-148 °F to -4 °F) - Instantaneous; in less than 5 seconds Wet to dry: 0 °C to -60 °C (14 °F to -76 °F) - less than 120 seconds |
| Sample Flow Rate | Flow independent, ideally 2 - 5 L/m. Max: 20 L/min |
| Temperature Coefficient | Temperature compensated |
| Calibration Warranty | 12 months from date of dispatch |
Electrical | |
| Electromagnetic Compatibility (EMC) | Complies with BS EN IEC 61326-1 |
| Warm Up Time | 10 seconds |
| Fault Conditions | Open circuit/under range: output drives to 20.5 mA Short circuit/over range: output drives to 20.75 mA |
| Isolation | Sensing element connected to the 4-20 mA loop but isolated from the transmitter body |
| Output Signal | Linear 4-20 mA with selectable engineering units and fault indication |
| Operating Voltage | 12-28 V DC reverse polarity protected |
| Maximum Series Resistance | (= {40 x (Supply Voltage – 7)} ohms) |
| Power Supply | 12-28 Vdc Reverse Polarity Protected |
| Engineering Units | C dewpoint, °F dewpoint, ppm(V), ppb(v), g/m³ and lb/MMSCF |
Mechanical | |
| Operating Pressure | From 1 kPa (0.01 bara) to Maximum 35,000 kPa (350 bara) |
| Operating Humidity (External) | Maximum 95% RH Non-Condensing |
| Cable Terminations | IP66 / NEMA 4X rated, size C, DIN EN 175301 connector at the Transmitter and other end terminated with bootlace ferrules |
| Cable | IS (blue) standard cable. Nominal diameter 4.5 mm, 92 ohms/km at +20°C |
| Enclosure/Body | 316 stainless steel |
| Sensor Protection | 316 sintered stainless steel filter – 50 micron |
| Probe Material (Wetted Parts) | 316 stainless steel |
| Weatherproof Classification | IP66 / NEMA 4X when Connector coupled to Transmitter |
| Mechanical Connection | ¾” UNF (16 TPI) with integral Viton “O” ring seal |
| Mechanical Warranty | 12 months in case of defective parts or faulty workmanship |
| Dimensions (mm) | 180 (H) x 30 (W) x 30 (D) (Short sensor guard) |
| Weight | 234g |
Downloads
What's in the box
AMT-Ex
AMT-Ex Cable with Connector
AMT-Ex Dewpoint Transmitter Manual
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
Can I use the AMT-Ex Dewpoint Transmitter for hazardous applications?
Yes, the AMT-Ex is certified intrinsically safe according to IECEx and ATEX standards for use in hazardous areas. Use the specified Signal Isolator in the safe area when operating in potentially explosive atmospheres. It is also suitable for non-hazardous applications, but for such cases, the standard AMT model is recommended. For further details, consult the datasheet.
What dewpoint ranges and units are available for the AMT-Ex Dewpoint Transmitter?
Do I need an isolator with the AMT-Ex Dewpoint Transmitter?
Which display controller is recommended for use with the AMT-Ex dewpoint transmitter?
What is the maximum pressure the AMT-Ex can withstand?
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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