5.2 Perform a check of the Gas Detector accuracy
The PG11 and PGE11 have been calibrated for life at the Factory and do not require to be
recalibrated. At the Factory great care has been taken to take into account environmental
effects such as gas concentration, the temperature of the gas, ambient pressure and humidity
to make a very precise calibration of the Detectors. Calibrating in field it is very difficult to take
such considerations so it is therefore not possible to calibrate the Detector in field since it
would not improve the accuracy. Below is the procedure to verify the Detector accuracy.
Requirements:
● Gas Sample kit
● Gas cylinder with calibrated test gas
○ Concentration of test gas recommended to 50 ±10 %FS
○ Flow rate shall be between 0.5 and 1.1 liters/min.
● Flexible gas tube between Gas cylinder and Gas Sample kit
● Data logger connected to the 4.20 mA.
Procedure to verify accuracy of the Detector:
1. Power up and allow the Gas Detector to warm for at least 20 minutes.
2. Insert Gas Sample kit as shown in illustration below.
3. Connect the tube from the Gas cylinder to one of the nozzles on the Gas Sample kit.
4. Slide the Gas Sample kit on the outside of the detector sensor section as shown below.
5. Apply the gas from the Gas cylinder with a gas flow between 0.5 - 1.1 liters/min.
6. Allow for gas reading to stabilize for at least one minute.
7. Start the data logger and perform logging for two minutes.
8. Calculate average gas value and standard deviation from the data logger and compare
with the specifications of the detector for Accuracy.
The accuracy of the calibration gas has to be taken into account when calculating the
accuracy for the Gas Detector.
The ambient pressure will affect the calibration gas and has to be taken into account.
The Gas Detector is calibrated for an average ambient having a pressure of 100 kPa
(0.987 atm). The ambient pressure can vary a few percentages depending on the
weather conditions and will influence the pressure of the gas leaving the gas cylinder.
Document 022-80036-OM Revision R03 Page 28 of 48
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