How to deal with blocked pressure tapping pipes in instruments
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What should be done if the pressure tapping tubes of the differential pressure flow meter in the process pipeline become blocked? Are there any tools for clearing blockages, and are they available for purchase? Or homemade? Could you provide some pictures or something?
What medium is blocked? Mechanical impurities? Crystallization? Gel?
For self-made connectors, after backwashing nitrogen from the drain street to behind the root valve, if there is a blockage in front of the root valve, it can only be removed; if it cannot be removed, the machine must be shut down.
A pneumatic isolation fluid system can be used, which provides excellent protection for instrument pressure leads against freezing, condensation, and blockage. It is necessary to understand your specific conditions (stress, medium, ambient temperature, etc.) and develop a reasonable installation plan in order to achieve the desired effect. Our plant (refinery) uses it on a large scale. This isn’t something that just any manufacturer can resolve for you. Many manufacturers lack experience in this area. For media that are highly prone to clotting and clogging, special measures can be considered.
Methods for determining if the pressure transducer’s pressure lead pipes are blocked In instrument maintenance, blockages in the positive and negative pressure lead pipes occur frequently due to delays in draining the pressure from the transducer, or because of dirty or sticky media. Typically, when the positive pressure lead pipe is blocked, the transducer’s output either decreases, increases, or remains unchanged. Effect of increased flow rate on the output of the transmitter (the transmitter itself performs the square root operation on the output signal). Due to blockage in the pressure pipe, when the actual flow rates are F1 and F2 respectively, P1+ = P2+. When the actual flow rate decreases from F1 to F2, the static pressure in the pipe also decreases accordingly; let this decrease be P0. At the same time, when the actual flow rate drops to F2, the value of P2- increases as well due to the reduced flow velocity of the fluid in the pipe; let this increase be P0’. At this time, the relationship between P2- and P1- is as follows: Under normal circumstances, the blockage of the pressure guiding tube is mainly caused by irregular cleaning of the measuring pressure guiding tube, or by the high viscosity of the measuring medium or the presence of particles in it.
For on-site maintenance, it’s more common to use a pressure pump, right?
Previously, we used pressure pumps; we manually removed the gauges and connected pressure tubes to the pumps. It was possible to reach a pressure of 60 KG manually, but still many pipes couldn’t be pressurized, so they had to be cut away