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Figure 2.1: Total head in tank

In more general terms, the relationship between Pressure and Head
when dealing with water at 60 ~ F, is as shown, when Pressure is in PSI
and Head is in Feet.

Head (in feet) = Pressure (in p.s.i.) x 2.31

When other liquids arc in use, however, it is necessary to consider the
different densities of these liquids. The ratio of the Density of any
liquid to the Density of Water at 60 ~ Fahrenheit is called the Specific
Gravity. Consequently, the following formula will apply.

Head (in feet) x Specific Gravity
Pressure (in p.s.i.) =
2.31

2.1.1 Pressure terminology
Of the various terms used to identify pressure in the pumping field, all
of these are compared to some specific base pressure, and arc clarified as
follows:
Absolute Pressure relates to the complete absence of pressure, as in a
perfect-vacuum. It is the amount by which the stated pressure exceeds a
perfect vacuum.

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