Problems with the eja differential pressure transmitter
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Issue with zeroing the EJA differential pressure transmitter: When trying to zero the EJA differential pressure transmitter in our company’s air lift tower, we closed the ball valves on the positive and negative pressure sides and connected them to the atmosphere. The transmitter’s range was displayed as -14 to 0 kPa; we then changed it to 0 to 14 kPa for zeroing. After that, we switched the range back to its original setting and installed the transmitter, but an error occurred. When we opened the manual valves and set the range to full scale, another error appeared. Switching the range back to 0 to 14 allowed normal operation. I’m confused about how the lower limit of -14 is determined in the original range – shouldn’t it always be 0 to 14? It’s really frustrating
It turns out that -14-0 kPa corresponds to 4-20 MA; now, 0-14 kPa corresponds to 4-20 MA, with no negative shift.
It may be that the transmitter is installed in reverse or there is liquid in the negative pressure conduit; the instrument requires negative migration
What is the pressure inside the tower? Measuring differential pressure? What were the actual measured parameters inside the tower during reinstallation?
Is a differential pressure gauge or a gauge pressure gauge the better choice?
Is the positive and negative pressure reversed? Or the negative pressure pipe is not filled with oil. Otherwise, how could it have a measurement range of -14KPa to 0?
How can I check that the original range of the transmitter is -14 to 0 kPa? Was it seen on the handheld controller or during pressure calibration? In my opinion, this transmitter is intended for measuring the liquid level in the oil-filled negative pressure tube. Its original range was 0–14 kPa; due to the oil filling the negative pressure tube, a negative offset of 14 kPa was applied to the zero point, which is why the range becomes -14 to 0 kPa. This operation may have caused the oil in the negative pressure tube to leak, resulting in insufficient replenishment; forcing the transmitter’s range to be set at -14-0 kPa led to incorrect readings from the transmitter.
The pressure differential gauge of the stripping tower should be zeroed directly when there is no gas flow inside the tower, without any other operations being required. Be sure not to attempt to operate the three-valve assembly to prevent the loss of methanol condensate on the negative pressure side.
Do not attempt to zero it at runtime, as you are not aware of the exact differential pressure, nor do you know the pressure difference between the positive and negative liquid phases. Wait patiently until the vehicle has stopped, and then zero the scale when the tower pressure difference is 0.