Please reply regarding the pump issue
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What happens if the diameter of the pump’s inlet pipeline is smaller than the diameter of the pump’s outlet? Will it empty the inlet pipeline, causing cavitation?
The key factor is the diameter of the pump’s inlet and outlet. If the diameter of the inlet pipe is smaller than that of the pump’s inlet, it may lead to insufficient suction, resulting in vacuum conditions and cavitation. If the diameter of the outlet pipe is smaller than that of the pump’s outlet, it can cause the pressure at the pump’s outlet to be too high, with a low flow rate; this can lead to a sharp increase in the pump’s temperature and ultimately damage to the pump.
The inlet and outlet diameters of the pump are generally larger than the pump’s outlet diameter, to prevent vacuum formation and cavitation caused by insufficient suction volume
The suction pipe has a small diameter, which increases the flow rate and prevents vacuum formation; however, the flow resistance is high, and it is necessary to determine through process calculations whether cavitation will occur.
The inlet diameter of the pump is generally larger than the outlet diameter. Meanwhile, the length of the inlet pipe should be shortened as much as possible, and bends should be reduced in order to minimize the resistance in the inlet pipeline and prevent cavitation. However, I don’t agree with the statement that cavitation will definitely occur when the inlet pipe diameter is smaller than the pump’s inlet diameter (as mentioned on floor 2), because whether cavitation occurs also depends on the pump’s installation height and the pressure at the suction side.
It depends on the specific location and situation, but pumps such as shielded pumps and magnetic drive pumps must not run idle at all; it’s best to enlarge the pipes.
What happens if the diameter of the pump’s inlet pipeline is smaller than the diameter of the pump’s inlet?------------------It’s not designed that way; the diameter should be larger. The exact value depends on the suction resistance. Whether cavitation will occur depends on the specific flow resistance. Will this result in the inlet pipeline being emptied and causing cavitation? It’s necessary to conduct specific calculations to find out.
Do I need to calculate the pipe resistance to determine cavitation?
Inhaling large amounts and exhaling small amounts is the standard design; using the same diameter for inhalation and exhalation is also common. But the situation described by the poster has never been seen.
The inlet diameter of the pump is generally larger than the outlet diameter, and bends should be minimized as much as possible to reduce resistance in the inlet pipeline and prevent cavitation. The length of the inlet pipe should definitely be chosen to be as short as possible, so as to minimize investment
When installing a pump, in order to increase the allowable installation height, it is common to use a larger suction pipe diameter in order to reduce resistance. If the suction pipe is short and thus the resistance is low, and the installation height remains within the allowable range, the diameters of the inlet and outlet pipes can be the same. Cavitation is not caused by vacuum; it occurs when the air pressure at the center of the centrifugal pump’s impeller is lower than the saturated vapor pressure of the fluid, resulting in the vaporization of the liquid at the center of the impeller and thereby causing damage to the pump.