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Converting Pump Head to Pressure

Since pump curves often are in head - feet or meters, its may be necessary with a conversion to the common pressure scales used in pressure gauges - psi or bar.

Converting Head to Pressure

Converting head in feet to pressure in psi

Pump curves in feet of head can be converted to pressure - psi - by the expression:

p = 0.434 h SG (1)

where

p = pressure (psi)

h = head (ft)

SG = specific gravity

Converting head in meter to pressure in bar

Pump curves in meter of head can be converted to pressure - bar - by the expression:

p = 0.0981 h SG (2)

where

h = head (m)

p = pressure (bar)

Converting head in meter to pressure in kg/cm²

Pump curves in meter of head can be converted to pressure - kg/cm² - by the expression:

p = 0.1 h SG (2b)

where

h = head (m)

p = pressure (kg/cm²)

Converting Pressure to Head

Since pressure gauges often are calibrated in pressure - psi or bar, it may be necessary with a conversion to head - feet or meter, commonly used in pump curves.

Converting pressure in psi to head in feet

h = p 2.31 / SG (3)

where

h = head (ft)

p = pressure (psi)

Converting pressure in bar to head in meter

h = p 10.197 / SG (4)

where

h = head (m)

p = pressure (bar)

Converting pressure in kg/cm² to head in meter

h = p 10 / SG (4b)

where

h = head (m)

p = pressure (kg/cm²)

Example - Converting Pump Head - feet - to Pressure - psi

The pressure - psi - of a water pump operating with head 120 ft can be expressed as:

p = (120 ft) 1 / 2.31

= 52 psi

Feet of Head Water to psi

Feet Head	psi
1	0.43
2	0.87
3	1.30
4	1.73
5	2.17
6	2.60
7	3.03
8	3.46
9	3.90
10	4.33
20	8.66
30	12.99
40	17.32
50	21.65
60	25.99
70	30.32
80	34.65
90	38.98
100	43.31