In PLAN52, the top vent is kept open in the centrifugal pump seal flushing scheme – then what is the purpose of installing a pressure gauge?
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In PLAN52, the top vent is kept open in the centrifugal pump seal flushing scheme – then what is the purpose of installing a pressure gauge? If there’s pressure, isn’t it released right away?
Above is our Plan 52 diagram; I wonder if yours looks the same? Under normal conditions, the valve at port N1 is closed, and the buffer tank should be pressure-free, which indicates that the mechanical seal is functioning properly with no leaks. When there is a leak in the mechanical seal, the pressure in the buffer tank rises; when this pressure reaches the set value of the pressure switch, an alarm is triggered, signaling that there is a leak in the mechanical seal that needs to be addressed. During processing, after stopping the pump, open valve N1 to release the pressure in the buffer tank to the flare or the atmosphere. If the seal selected is too permeable to water, minor leaks in the seal will occur frequently, the pressure in the buffer tank will trigger alarms often, repairs will be needed regularly, and maintenance staff will be extremely troubled by this ； To reduce the workload, they will open the N1 port partially or fully, which significantly reduces the frequency of alarms. As a result, it becomes difficult to detect major leaks in the mechanical seal, or detection is delayed, posing a safety risk. I invite all experts to participate in the discussion.
Those checking for leaks found that a sudden rise in pressure indicated a leak
Bro, that vent valve at the top should be kept open, right?
If the pressure rises, why is that vent usually open? If there’s pressure, just release it, right?
The 52 sealing flare line is equipped with an orifice plate to allow a small amount of fluid to be discharged through the flare. If there is a significant leakage in the seal, it does not meet the operating conditions for the orifice plate, and the pressure gauge can provide an intuitive indication of this.
The common operating condition for scheme 52 is volatile olefin-based media. The reason for using the pressure-free version of scheme 52 is to allow any minor leaks of such media to be discharged through a buffer tank and burned in the flare system. In the event of a large leak, the orifice plate will prevent further flow, causing the pressure inside the tank to rise; this leads to a high-pressure alarm, indicating a failure in the internal sealing；