Is the pressure in the seal chamber of a centrifugal pump the pressure at the pump inlet?
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Please let the sea friend know
Are the centrifugal pumps you mentioned those with packing, mechanical seals, or some other type of sealing mechanism? And what exactly do you mean by the sealed chamber – which location are you referring to? If it’s inside the mechanical seal, then it depends on your method of flushing the mechanical seal.
It depends on the flushing scheme you use; in some schemes, sealing is achieved by introducing fluid from the pump inlet, while in others it is done from the outlet； In the external flushing approach, a medium is introduced from the outside; its pressure can be either higher or lower than that of the medium being pumped. For example, in the pharmaceutical industry, the pumping medium must not be contaminated, so leakage can only occur from the pumping medium to the seal medium. In contrast, with some chemical pumps – such as those used for methanol, which is toxic, flammable, and explosive – the requirements regarding cleanliness are not particularly strict, allowing leakage to occur in the opposite direction.
Whether the flush pipe leads from the pump outlet to the seal or from the seal to the pump inlet, the pressure inside the mechanical seal chamber is always higher than that at the inlet. The extent of this increase depends on the pump’s head, with certain empirical coefficients involved. If high precision is not required, the seal chamber pressure can be considered as equal to the inlet pressure plus head * (0.1~0.3).
That’s roughly the same as the export pressure, I guess
Because the seal chamber of a conventional centrifugal pump is connected to the inlet through the impeller’s balance hole.
The empirical value should be the pump inlet pressure + 1~2 bar