hydraulic pump failure modes

	A	B	C	D	E	F	G	H	I	J	K
1		hydraulic failure					mechanical failure

2	cause	pump does not deliver liquid	pump does not deliver sufficient capacity	pump does not deliver sufficient pressure	pump delivers flow intermittently	bearings run hot and/or fail on a regular basis	high rate of mechanical seal failure	packing has short life	pump vibrates at higher-than-normal levels	pump is drawing too much power	wear of internal wetted parts is accelerated
3	pump not primed or prime lost	X	X	X	X
4	suction and/or discharge valves closed or clogged	X	X	X					X
5	suction piping incorrect	X	X	X
6	insufficient NPSH available*	X	X	X			X		X		X
7	excessive air entrapped in liquid	X	X	X	X
8	RPM too low*	X	X	X
9	incorrect rotation		X							X
10	broken impeller or bent vanes		X	X		X			X
11	incorrect impeller or impeller diameter		X	X
12	system head too high		X
13	instrumetns give erroneous readings		X	X
14	air leaks in suction line				X
15	excessive shaft misalignment					X	X		X
16	inadequate lubrication					X
17	lubricant contamination					X
18	inadequate lubricant cooling					X
19	axial thrust or radial loads higher than bearing rating					X
20	improper coupling lubrication					X			X
21	suction pressure too high					X	X
22	bearing incorrectly installed					X	X		X
23	impeller out of balance					X	X		X
24	overheating of seal faces						X
25	excessive shaft deflection					X	X		X
26	lack of seal flush at seal faces						X
27	incorrect seal installation						X
28	pump is run dry						X
29	pump is run off design point					X	X	X	X	X
30	shaft/shaft sleeve worn						X	X
31	packing gland not properly adjusted							X		X
32	packing not properly installed							X
33	impeller clogged	X							X
34	coupling out of balance					X	X		X
35	baseplate not installed properly					X	X		X
36	pump operating speed too close to system's natural frequency								X
37	bearing failure					X	X		X
38	piping not properly anchored					X	X		X
39	pump and/or driver not secured to baseplate					X	X		X
40	specific gravity higher than specified					X	X			X
41	viscosity higher than specified					X	X			X
42	internal clearances too tight								X	X
43	chemicals in liquid other than specified										X
44	pump assembled incorrectly			X		X	X	X	X		X
45	higher solids concentration than specified										X
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47	NPSH = Net Positive Suction Head; difference between liquid pressure and vapor pressure at a certain temperature. Too little of it means your liquid is boiling.
48	RPM = Revolutions Per Minute; speed at which something turns. Too little of it means not spinning fast enough.
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