Seeking advice on external flushing for mechanical seals
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The several lime slurry pumps I have here (single-stage, single-suction centrifugal pumps) use single-face mechanical seals with external flushing, using filtered water as the flushing medium. The mechanical seal has a short lifespan. I’d like to optimize the flushing process, so I’m seeking answers to a few questions: 1. Is there any difference in whether the flushing water enters through the inlet and exits through the outlet from top to bottom, from bottom to top, or from side to side? 2. Is a control valve needed to be installed at the rinse water outlet? 3. Should the pressure of the flushing water be determined based on the pressure at the water inlet or at the water outlet? Where or where should the pressure gauge be installed? 4. How should the pressure range be selected for the several flushing pressures that need to be controlled? Some say it should be 1.2–1.3 times the outlet pressure – is this appropriate?
【2. Is a control valve needed to be installed at the rinse water outlet? 】They are generally controlled by valves.
【1. Is there any difference in whether the water for flushing enters and exits through the inlet and outlet from top to bottom, from bottom to top, or from side to side?】 】All I’ve seen are those that enter and exit from the side.
【Where or where should the pressure gauge be installed?】 】It should be installed on the inlet side.
Thank you. I don’t have a control valve at the water outlet here, and there’s also no pressure gauge behind the valve on the inlet side. The water flows in from above and out from below, which makes it quite tricky to connect the pipes.
OP, what are the components of filtered water? It is recommended to use water that is cleaner and less prone to scaling
OP, what kind of sealing solution are you using? Generally, single-face mechanical seals come in types such as P01/P11/P21/P23/P32. However, in the case where there is one inlet and one outlet on the seal, as you mentioned, the P23 type is usually used; a cooler should be present outside. This situation differs from what you described, so it is recommended to contact the pump manufacturer to determine which type of seal is suitable.
Similar to p32. But there are differences
1. For flushing water, an inlet at the top and an outlet at the bottom is generally used; if there are impurities inside the pump, the flushing water will push these impurities out. However, there are also special cases. 2. A control valve should be installed on the flushing water supplied to the mechanical seal; generally, no valve is installed at the outlet. If pressure is required in the flushing chamber, a valve should also be installed at the outlet. 3. The pressure of the rinse water is generally determined by the inlet pressure. 4. A pressure higher than that at the pump outlet will suffice; there’s no need for it to be several times higher. Since this is a low-pressure pump, a pressure of over 1 kilogram is enough.
The P32 scheme has only an inlet on the mechanical seal, with no outlet. The flushing fluid goes directly into the interior of the medium. Typically, the inlet pipeline of a flushing line includes components such as pressure gauges, check valves, filters, and globe valves.