The high-speed reciprocating pump vibrated, the crankshaft broke, and it destroyed the pump casing

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Dear sea friends: When calculating the NPSHa of reciprocating pumps, have you taken into account the acceleration loss in those pumps? Some time ago, we used reciprocating pumps from German company SPECK in one of our projects (with a flow rate of 3.5 m3/h, an outlet pressure of 5.8 MPaG, a motor power of 7.5 kW, a rotation speed of 1450 r/min; the fluid handled was an amine-based liquid that caused mild corrosion, and the operating temperature of the pumps was between 60 and 70°C). After the plant was in operation for some time, the springs of the check valves in these reciprocating pumps broke. In one of the pumps, the leakage of fluid due to the broken check valve springs caused the lubrication system to fail, resulting in the crankshaft grinding against each other and breaking. The broken crankshaft then shattered the pump casing. The supplier claims that our installation suffers from cavitation. However, when we first designed it, the flow velocity at the liquid inlet was below 0.5 m/s, and the liquid level in the tower was well above the pump inlet. According to the calculations for acceleration losses in reciprocating pumps as specified in HG/T20570, due to the high speed of the pump itself and the absence of a gearbox, the calculated acceleration head loss is quite large; as a result, NPSHa is less than NPSHr. The manufacturer keeps bringing up this issue, but only one out of the three pumps has problems – the other two function fine under the same conditions. We insist that there is a quality issue with the manufacturer’s products. What do you all think?