APSP NH3 long life ammonia gas transmitter –

for continuous measurement applications over years

The Angst+Pfister Sensors and Power (APSP) newly developed ammonia gas transmitter with a measurement range from 0 to 500 ppm is targeting applications in which a constant background level of ammonia is present or thought possible. This for instance could be in a chicken farm or in a pig stable, where constant high levels of ammonia are or can be present and where an ammonia gas transmitter is needed to control the air quality for the animals.

The APSP NH3 transmitter has a very long operational lifetime with no drift issues and an easy and low-cost service concept.

Simple to install and maintain, the APSP NH3 transmitter measures the ammonia concentration in a gas sample in a continuous mode and the data are easily accessible. The heart of the transmitter is a long-life electrochemical gas sensor based on an ammonia specific electrolyte that is embedded in a solid polymer (the SPE technology). The transmitter uses a rugged, small pump to extract a small volume of gas that are analyzed by the SPE electrochemical sensor, which basically is counting the gas molecules in the extracted gas volume – a coulometric measurement approach. There is no or little maintenance needed, including no need for tedious calibration cycles. The transmitter is outputting the precise concentration of ammonia up to 3 years, after which the SPE electrochemical sensor simply can be exchanged, and the main part of the transmitter reused.

The APSP NH3 transmitter has a measurement range from 0 to 500 ppm. The signal output is corrected for variations in temperature and humidity and the signal resolution of +/-0.1 ppm is excellent. The transmitter adapts to the concentration level in the application and is therefore very accurate over the full measurement range. The metal body of the transmitter is made in 1.4404 stainless steel, resistant to high concentrations of ammonia and sulfur-based gases. The cable connector is providing strain release for the cable, which means that the transmitter can be adapted directly into the application, using the cable for holding the transmitter in place. Alternatively, the transmitter can be screw mounted into a fitting, if for instance the transmitter is placed in a ventilation tubing system. The flow in front of the sensor should not be too high, which means that the transmitter should be pulled back a bit to avoid too high flows directly in front of the transmitter. The output signal from the transmitter is RS485 (Modbus protocol) serial digital, which can be interfaced easily to any process control device.  

The high accuracy, in combination with the highly stable signal output and fast response to ammonia concentration changes, means that ammonia levels < 1 ppm can be measured, and level changes ~ 0.1 ppm tracked. Thereby, applications within leakage detection for large cooling facilities using ammonia as refrigerant can also be done using the APSP NH3 transmitter. 

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