In the Oil and Gas industry, we have an H2S analyzer for measuring the concentration of hydrogen sulfide in natural gas. Recently, the analyzer was showing some errors, and it was not working properly. In this article, I shared the activities and troubleshooting steps carried out to fix the problem.
Problem Description: The H2S Analyzer was displaying a Lamp failure Alarm and not responding. Alarm could be visualized in both the local Display Panel & laptop.
The AMETEK 933 model H2S analyzer contains a cadmium lamp and a copper lamp for its operation.
Alarm Analysis
Connect the laptop and open the analyzer software. Open the Optical Bench Data and Filter 3 data, which are found to be abnormal compared to normal operation data.
Filters no. 1, 3 & 5 are responsible for the Cadmium lamp & filters no. 2 & 6 are for the copper lamp. It has been identified that the alarm appeared due to a failure of the cadmium lamp.
Note: You must have some basic knowledge about the AMETEK 933 H2S analyzer to understand this article.
AMETEK H2S Analyzer
Activity
The cadmium lamp was replaced with a New Cadmium lamp. Lamp alignment & Auto setup done, but an error “ALC out of range “appeared. Adjusted the optical bench parameters, and the Auto setup is done.
After this process, the “ALC out of range alarm” got reset, but after zero calibration, the same alarm appeared again. (Note: During the Auto setup process, Zero gas should be in line up to the sample cell)
As per the reference manual, the error description & suggested corrective Action following activities were also carried out.
Removed the analyzer from housing & adjusted the lamp & completed the lamp replacement procedure, but no improvement was found.
Inspect & cleaned the sample cell with DM water for any contamination, and Auto setup activities were done, but no improvement was found.
Checked all the cables of the Analyzers for tightening & found ok.
Replace the Optical Bench service electronic card; the problem still persisted.
We are not able to understand where to measure 7.0 V DC as per the manual. We observed the Optical bench Data & found that the ALC Lamp pulse (mV) is the value to check. Opened current Optical bench data & found that filter mV was 7815. Then, the following procedure was carried out to resolve the issue:
Open the optical bench setup and compare the parameters with the Optical Bench Data:
ALC Set point in Optical bench setup should equal (difference up to 600 allowable) to PMT Reference (mV) in Optical Bench Data.
ALC lamp Pulse (mV) values in all the filters should be less than 7000mV after the lamp replacement process. (Lamp replace–Auto setup—Manual zero calibration). If more than 7000mV appear in any of the filters, then adjust the PMT Level (mV) in the Optical bench setup and again do Auto setup and Manual Zero calibration (2-3 times this procedure is done). After this adjustment, “ALC out of range alarm” disappeared, but “PMT out of range alarm” appeared.
To resolve “PMT out of range alarm”(This alarm appears because PMT measures value reaches 10,000mV, its maximum value), adjusted respective ALC SetPt (mV) to lower values so that PMT Measure(mV) becomes less than 10,000mV, after Auto setup, Manual zero calibration was done. After the above activities, the PMT out-of-range alarm disappeared.
Observed that all Optical bench data are in the allowable range and no alarm appears in the Alarm window.
H2S analyzer calibration completed & taken in line.
