Equivalent Lengths of Valves and Fittings in Pipeline Pressure
Drop Calculations  Calculating Pressure Drop ives pressure drop
in terms of feet of head is given below: The term is commonly
referred to as the Velocity Head.  The total pressure drop in
the pipe is typically calculated using these five steps. (1)
Determine the total length of all horizontal and vertical
straight pipe runs. (2) Determine the number of valves and
fittings in the pipe. For example, there may be two gate valves,
a 90o elbow and a flow thru tee. (3) Determine the means of
incorporating the valves and fittings into the Darcy equation.
To accomplish this, most engineers use a table of equivalent
lengths. This table lists the valve and fitting and an
associated length of straight pipe of the same diameter, which
will incur the same pressure loss as that valve or fitting. For
example, if a 2” 90o elbow were to produce a pressure drop of 1
psi, the equivalent length would be a length of 2” straight pipe
that would also give a pressure dro