Gas detector is a very important security equipment in any chemical plant. It can provide information on any small leak in any pipeline, and with early action, we can save any production safety incident in the plant.
In any chemical plant generally we use four types gas detectors:
1、Hydrocarbon Detecto
3、NH3 detector
4、Chlorine detector
Here we discussed about Ammonia detector.
Principle :
Ammonia detector works on electrochemical principle. Electrochemical gas sensor is used to measure partial pressure of gas under atmospheric conditions. The ambient air being monitored diffuses through the film into the liquid electrolyte in the sensor. The electrolyte comprises a measuring electrode, a counter electrode and a reference electrode. An electronic potentiostatic circuit ensures a constant voltage between the measuring electrode and the reference electrode.
Voltage, electrolyte and electrode material are selected to suit the gas being monitored so that it is transformed electrochemically on the measuring electrode and a current flows through the sensor. This current is proportional to the gas concentration. At the same time, oxygen from the ambient air reacts at the counter-electrode electrochemically. The current flowing through the sensor is amplified electronically, digitized and corrected for several parameters (e.g. the ambient temperature). The resulting measured value is given as an analog, 4-20 mA signal.
Configuration of Gas Detector:
Gas detector can be used as a two wire or as three wire device.
Configuration of Gas Detector:
Gas detector can be used as a two wire or as three wire device.
Calibration of Gas Detector:
For calibration we use N2 gas for zero calibration and 90 PPM ammonia cylinder for span gas .
Parts :
Regulator
Calibration gas cylinders ( Zero Gas Cylinder & Span Gas Cylinder )
Calibration adapter
For zero calibration
1、Connect the regulator with N2 cylinder adapter to detector then adjust the flow to 0.5 l/min
2、Press down navigation key for 5 sec its showing -0- Adj.
3、Tap [OK].
4、The display will show the current value blinking.
5、Wait for the value to stabilize.
6、Use [UP] / [DOWN] navigation to adjust the value to 0.
7、Enter [OK] then detector return to main menu.
8、Turn off gas flow and remove the calibration adapter from the sensor or disconnect tubing.