What to do if the EJA shows an out-of-range condition (above the lower limit)?
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On the 29th day of the 12th lunar month, an EJA differential transmitter in our factory was not functioning properly. The operating pressure was 10 MPa, the range was 10 KPa, and the displayed value changed only slightly (but still within the specified range). Upon inspection, it was found that there was a blockage in the liquid phase; by loosening the vent hole for the liquid phase, liquid started to flow out, but then the flow stopped (probably due to freezing, as the medium was dilute ammonia water). Using steam to clear the liquid phase pipeline resolved the issue quickly, but the differential transmitter continued to malfunction, showing a value that exceeded the lower limit. What could be the cause of this fault? How to repair it? Can it be solved by adjusting the zero scale?
It’s likely that the diaphragm of the negative pressure chamber has suffered permanent deformation after freezing; zeroing out the device will not resolve the underlying issue. It is recommended to send it back to the factory for repair
Try sending it to the calibration laboratory for re-calibration; if that doesn’t work, send it back to the factory.
1. Try turning off the power. 2. Remove the clamps to check the diaphragm box. 3. See if the handheld controller can be used for configuration
It’s still a problem with the positive pressure side; first, use a standard gauge to check whether there is an issue with the transmitter. If there is no problem, then there must be a blockage somewhere in the positive pressure sampling tube
It’s likely that the diaphragm box is damaged, so it has to be scrapped. How long has this transmitter been in use?
One batch of transmitters we are using has failed; the diaphragm box has been damaged due to freezing, and they have been in use for three months； Contact the manufacturer; it is the user’s responsibility to handle this. If a sensor needs to be replaced, the cost will be more than twice the price of a new gauge. It feels terrible.
What brand is it? Is there no heat tracing at all? More than double? Half again?
The diaphragm box has been damaged by freezing; sending it back to the factory for repair is expensive. There are specialists in China who can carry out the repairs at a lower cost
The cost of replacing the sensor is more than twice the price of a new gauge. For example, if the new gauge costs 5,000 yuan, they suggest a reference price of around 7,000 yuan for replacing the diaphragm box. In other words, it requires users to replace their old watches with new ones. That’s just the way it is with imported goods.
It is unlikely that the diaphragm box has been damaged by freezing; it is possible to warm the diaphragm box area slightly (using a little warm water will suffice). This is done either because of suspicions of freezing or of crystallization；
What brand of gauge is it? Share it! This is absolutely terrible!
Instrumentation must have proper anti-freezing measures in place
It’s very likely that the diaphragm box has been damaged by freezing. Transmitters are extremely sensitive to their diaphragm boxes being frozen; if they freeze, they will almost certainly get damaged. Therefore, steam pipelines must be insulated.
Ours is from a big brand, so it doesn’t really make much sense to specify that. Actually, this is also related to the user’s operating environment; it’s just impossible to determine whether the diaphragm box is subjected to a pressure level that reaches the values they claim when a failure occurs. If the pressure is within 20 MPa, damage to the transmitter is a quality issue of the product. “The topic of “Sensor types for pressure and differential pressure transmitters” is meant to allow us to discuss these issues together. abcd5878212@163.com can be used to discuss in detail.
How about switching to a FOXBORO transmitter? It’s affordable and easy to repair!
When we opened our diaphragm box, we saw that the diaphragm in the positive pressure chamber was deformed (bulging outward in two irregular shapes). Today, on a whim, I decided to give it a try and destroyed the deformed diaphragm; there was oil inside, and I saw a tiny pore leading inward. When power is applied again, the zero position is negative, but no out-of-range code appears; zeroing works. Adding water to the positive pressure chamber results in a corresponding response. In conclusion, it can still be used, but the medium must be extremely clean and must not clog the micropores (consider using isolation devices); its display stability may be inferior to before, with large fluctuations, and the zero point may also be unstable. This post was last edited by daifangwu on 2009-2-19 23:09.]