Problem of medium leakage at the shaft seal of a centrifugal pump? ? ?
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Equipment: Centrifugal pump (heat transfer water) Status: Standby Problem: Leakage at the shaft seal (in the form of a stream); the leakage stops once the pump is rotated or started up. I’d like to know what the cause is. Please help me figure this out, thank you
It’s likely that it wasn’t installed properly; the spring hasn’t returned to its original position, and the sealing surfaces of the stationary and rotating rings aren’t in proper contact
If repairing it again, it is recommended to increase the compression slightly, and sand the shaft sleeve with water-sandpaper!
There is no leakage after turning the shaft; it’s likely a problem with the sealing surface. The rotating and stationary rings need to be taken out and ground. It is also possible that the specific pressure on the sealed end face is low
It is possible that there is a problem with the sealing surface; it is recommended to disassemble it for inspection, and measure the compression amount of the spring when reinstalling it.
Poor follow-up of the static ring causes this fault. Reason 1: The designed compression amount of the static ring O-ring is too large, or expansion occurs due to the action of the medium during use. Reason 2: Sticking occurs in the axial movement of the spring, which is part of the compensation mechanism
The problems we encounter usually stem from 1) the static ring O-ring deforming over time, which can be resolved by replacing it; or 2) dirt between the spring of the dynamic ring and its shaft sleeve, causing the spring to stick
It is also possible that the medium crystallizes on the sealing surface
To resolve the issue completely, 1) open the seal chamber and clean out any solid debris, 2) check whether the elastic elements of the seal are aged, rusted, or inflexible, 3) check if the O-rings are worn out or no longer functional, 4) check whether the friction surfaces between the stationary and rotating rings are damaged. Try to avoid excessive grinding of the various sealing surfaces. It is quite common for there to be slight leakage when the mechanical seal is stopped, but no leakage once it is in operation; there’s no need to worry about it.
The problem lies in the leakage that occurs due to poor fit between the dynamic and static seals, with the leak coming from the seal ring on the shaft sleeve; the root cause is the loss of effectiveness of the seal ring on the shaft sleeve. Damaged or too thin.