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Question:

Why does the GB/T3216 specify the pump performance tolerance as positive and negative?

Assuming that my water pump standard flow is 20m3/h, tolerance value requirements is + 8%, then is not traffic 22m3/h is not qualified?

Answer:

Tolerance coefficient is due in the manufacturing process, will, so each pump products are possible shapes and sizes do not conform to the pattern of the situation, and ensure the test results in the value (operating point) when compared, should be allowed to have a certain tolerance. It should be noted that these tolerances are only relevant to the actual pump and do not involve test conditions and measurement uncertainties.If the pump at a certain working point (the same lift) standard (Design) flow of 20m3/h, the actual flow of 22m3/h, indicating that the pump in the design process has unreasonable place, resulting in waste of power. Deviations from the manufacturing process usually have no positive deviation.
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Tolerance coefficient is due in the manufacturing process, will, so each pump products are possible shapes and sizes do not conform to the pattern of the situation, and ensure the test results in the value (operating point) when compared, should be allowed to have a certain tolerance. It should be noted that these tolerances are only relevant to the actual pump and do not involve test conditions and measurement uncertainties. If the pump at a certain working point (the same lift) standard (Design) flow of 20m3/h, the actual flow of 22m3/h, indicating that the pump in the design process has unreasonable place, resulting in waste of power. Deviations from the manufacturing process usually have no positive deviation.A pump is a machine that transports liquids or pumps liquids. It will be the prime mover of the mechanical energy or other external energy transfer to the liquid, the liquid energy increase, mainly used to transport liquids including water, oil, alkali liquid, emulsion, suspension emulsion and liquid metal, but also transport liquid, gas mixtures and liquids containing suspended solids. Pump performance of technical parameters are flow, suction, lift, shaft power, water power, efficiency, etc.; according to the different principles of work can be divided into volume pumps, vane pumps and other types. Displacement pump is to use its studio volume changes to transfer energy; vane pump is to use the rotating blade and water interaction to transfer energy, there are centrifugal pumps, axial flow pumps and mixed flow pumps and other types.

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