Pumps - NPSH (Net Positive Suction Head)

Calculate and analyze Net Positive Suction Head (NPSH) to prevent cavitation and ensure safe pump operation. Includes suction head, vapor head, available NPSHa, and required NPSHr calculations.

Temperature (°C)	Absolute Vapor Pressure (kPa)	Reduction in Suction Lift (m)	Suction Head (m)
0	0.6	0	10.3
5	0.9	0	10.2
10	1.2	0	10.2
15	1.7	0	10.2
20	2.3	0.1	10.1
25	3.2	0.2	10
30	4.3	0.3	9.9
35	5.6	0.4	9.8
40	7.7	0.7	9.5
45	9.6	0.8	9.4
50	12.5	1.1	9.1
55	15.7	1.5	8.7
60	20	1.9	8.3
65	25	2.3	7.8
70	32.1	3.1	7.1
75	38.6	3.8	6.4
80	47.5	4.7	5.5
85	57.8	5.8	4.4
90	70	7	3.2
95	84.5	8.5	1.7
100	101.33	10.2	0

Altitude (m)	Reduction in Suction Lift (m)
0	0
250	0.3
500	0.6
750	0.89
1000	1.16
1250	1.44
1500	1.71
1750	1.97
2000	2.22
2250	2.47
2500	2.71

Fluid	Temperature (°C)	Absolute Vapor Pressure (kPa)
Ethanol	20	5.9
Ethanol	65	58.2
Methyl Acetate	20	22.8
Methyl Acetate	55	93.9

Calculator

Inputs

Static Pressure at Impeller (ps) (Pa)

Fluid Velocity (vs) (m/s)

Vapor Pressure (pv) (Pa)

Liquid Specific Weight (γ) (N/m³)

Acceleration of Gravity (g) (m/s²)

Elevation (he) - Positive if above tank (m)

Head Loss in Suction Pipe (hl) (m)

Atmospheric Pressure (patm) (Pa)

Results

Suction Head (hs)-- m

Vapor Head (hv)-- m

Net Positive Suction Head (NPSH)-- m

Available NPSH (NPSHa)-- m