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The Practical Pumping Handbook ....

Liquid S.G. Head Pressure

Kerosene 0.8 100ft. 34.63 p.s.i
Water 1.0 100ft. 43.29 p.s.i.
Sulphuric Acid 1.8 100ft. 77.92 p.s.i.

Figure 2.3: Pressure-head table

This is why it is much simpler to discuss the performance of a pump in
terms of Head rather than Pressure. The use of Head makes the pump
curve applicable to every liquid regardless of Density.

.1.3 Total dynamic head
The energy added to the system by a centrifugal pump is referred to as
the Total Dynamic Head (T.D.H.) and can be calculated from the
difference in pressure between the Discharge side of the pump and the
pressure on the inlet side.
For example, if the pump in Figure 2.2 is pumping cold water with a
specific gravity of 1.0, the equation for establishing the Differential
Head will be as follows:

Total Dynamic Head = Head at Discharge - Head at Suction

T.D.H. =

= 118.5 - 35.65

= 82.85 feet

2.2 Performance curve

The Total Energy Output of a pump is a combination of the Total
Dynamic Head and the Flow Rate, and the relationship between the
two is shown on a pump performance curve.
For a simplified explanation of how a pump curve is developed,
consider a Centrifugal Pump discharging into a straight vertical pipe.
Eventually the liquid will reach a maximum level, beyond which it is

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