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Mud Pumps 73

6000
Maximum working pressure
5000

Pressure (psi) 4000 P h = 1,714

qp
3000

2000

1000

0
0 200 400 600 800 1000 1200
Flow Rate (gpm)
Figure 3.5 A theoretical pump performance curve.

The constant 1,714 in U.S. units is 44.14 in SI units.
For a given pump having a horsepower rating P H , the value of the
right-hand side of Eq. (3.8) should not exceed P H ;thatis, P h < P H .Ifa
pump runs at the maximum working pressure p pm , the maximum avail-
able flow rate is expressed as

q max = 1,714E p P H (3.9)
p pm
where
3
q max = maximum mud flow rate, gpm or m /min
P H = Horsepower rating of pump, hp
E p = pump efficiency, dimensionless
p pm = maximum working pressure of pump, psi or MPa
If apumprunsataflowrate q < q max , the maximum available pump
pressure is expressed as
p max = 1,714E p P H (3.10)
q

However, the pump pressure should always be kept lower than the maxi-
mum working pressure—that is, p max < p pm .