Transmitter testing
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What are the steps for checking a transmitter? How to check on-site.
It depends on what type of transmitter it is. In the case of a differential pressure transmitter, the valves on both sides of the three-valve assembly are usually closed first, and the balance valve is opened to see if it is possible to return to zero. For pressure applications, the valve in front of the gauge can also be closed; after releasing the pressure, check whether it returns to zero. This is the simplest and fastest way to determine whether a transmitter is broken or not!
It depends on what type of transmitter it is. In the case of a differential pressure transmitter, the valves on both sides of the three-valve assembly are usually closed first, and the balance valve is opened to see if it is possible to return to zero. For pressure applications, the valve in front of the gauge can also be closed; after releasing the pressure, check whether it returns to zero. This is the simplest and fastest way to determine whether a transmitter is broken or not!
The correct answer is upstairs. Usually, it’s about checking whether it returns to zero, right? If it is zeroed out, linear instability may occur; if not zeroed out, calibration should be performed first
I don’t know what’s going on – they keep repeating the incorrect procedure twice! For a differential pressure transmitter, the balance valve must be opened first before the valves on both sides can be closed.
Upstairs, there is also a problem with your approach: when shutting down the three-valve assembly, you should first open the balance valve and then close the valves on both sides. This method works for media that are gases or liquids, but it isn’t suitable for steam or situations where an isolation fluid is used. If the balance valve is opened directly, some of the condensate or isolation fluid in the negative-pressure line will be flushed away, resulting in inaccurate measurements. The correct procedure is to first close the valve on the positive-pressure side or the negative-pressure side, then open the balance valve, and finally close the valve on the negative-pressure side or the positive-pressure side.