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We had installed several high end snap-action pressure switches from a well known manufacturer over the years. These switches were used on natural gas system, dry, clean and ambient temp is within specification. Generally the sepoint ranges are ~ 7psig lo/22psig hi.
We have been experienced non-responsive diaphragm problem from time to time with these switches. The process pressure is regulated and therefore seldomly activated the high gas pressure switches (may be only once a year). During a normal maintenance check, we discovered that some of these switches do not respond. It appears that the diaphragm/spring built up a memory after few years in service (2 -3 years). Failure rate is ~ 3 out of 8 over the 12 year period.
We then replaced them with solid state microproscessor based switches recommended by the same company. We had 3 failures on the solid state recently. This time it is related to cycling power on/off to the switches or overvoltage, we do not know for sure. Failure rate is 3 units out of 8 during a 5-year period.
We are ready to change all of these electronic switches out.
I am looking at a different manufacturer, someone with history of reliablity and performance. In my opinion a reliable switch should last more than 10 years with normal maintenance.
Please post your comments. I am looking forward to hear from you.
Thank you for your assistance.
We have been experienced non-responsive diaphragm problem from time to time with these switches. The process pressure is regulated and therefore seldomly activated the high gas pressure switches (may be only once a year). During a normal maintenance check, we discovered that some of these switches do not respond. It appears that the diaphragm/spring built up a memory after few years in service (2 -3 years). Failure rate is ~ 3 out of 8 over the 12 year period.
We then replaced them with solid state microproscessor based switches recommended by the same company. We had 3 failures on the solid state recently. This time it is related to cycling power on/off to the switches or overvoltage, we do not know for sure. Failure rate is 3 units out of 8 during a 5-year period.
We are ready to change all of these electronic switches out.
I am looking at a different manufacturer, someone with history of reliablity and performance. In my opinion a reliable switch should last more than 10 years with normal maintenance.
Please post your comments. I am looking forward to hear from you.
Thank you for your assistance.