Maintenance and troubleshooting
AMI
Analyzer Manual
24
Sensor replacement procedure:
The sensor is provided in a special sealed bag.
1. Turn the three-way valve to the OFF position, in order to prevent gas flowing into the sensor
compartment.
2. Unscrew the cell block cap.
3. Carefully remove old cell by pulling the little black handle.
4. Inspect the cell block cavity, and if any sign of moisture clean it out with a Q tip or similar. Make
sure that the contact springs inside the block are intact. Be careful not to snag them with the Q tip.
5. Carefully open the bag using a pair of scissors or a knife. Make sure you don’t cut yourself or stab
the sensor! In the rare event that the sensor has leaked there will be liquid in the bag. If so do not
proceed - you need a new sensor.
6. Verify that the O ring is in place on the face of the sensor (white membrane side) before installing.
7. Holding the sensor by the little black handle, gently slide it into the cavity with the circuit board
extension mating into the little machined slot, located at the top of the cavity. You really cannot
put it in any other way.
8. Carefully replace the cap, making sure that you do not cross thread it, and tighten firmly by hand.
Do not over-tighten.
9. Press the ALARM HOLD OFF button, and adjust the time displayed suitably (typically 30 minutes).
This prevents unintentionally setting off alarms if the gas value is higher than the alarm set points.
10. Turn the analyzer flow valve on the front of the NEMA 4 box to the SPAN position.
11. Set flow rate for 1 SCFH and flow the gas for a minimum of 25 minutes.
12. Perform a calibration by adjust the analyzer span until it reads the span gas value.
13. Press the “SPAN” button until the “SPAN” flag appears on the display.
14. Release the span button and immediately press and hold the UP or DOWN button until the display
reads correctly.
15. Once you release the UP or DOWN button, after a few seconds, the unit will return to normal mode.
16. If you made some kind of mistake, let go for five seconds, and then try again.
17. Once it is back in normal operation, press the UP arrow and note the number displayed on the
display (called the “Calibration factor”). When new this number is about 500, but as the sensor
ages the number will increase. When it gets up to 1000 the sensor will have to be replaced.
18. Rotate the valve back to the Sample position.
19. Readjust the flow rate to 1 SCFH if necessary.