Replacement Parts

TECHNICAL DATA
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HYDRONIC SOLUTIONS CATALOG
Pressure (psi) = (Head (feet) × Specific gravity) / 2.31
Head (feet) = (Pressure (psi) × 2.31) / Specific gravity
Vacuum (inches of mercury) = Dynamic suction lift (feet) × 0.883 × Specific gravity
Horsepower (brake) = (gpm x Head (feet) × Specific gravity) / (3960 x Pump eciency)
Horsepower (water) = (gpm x Head (feet) × Specific gravity) / 3960
Eciency (%) = (Horsepower (water) × 100 percent ) / Horsepower (brake)
npsh (available) = Positive factors – Negative factors
gpm capacity feet head bhp
Impeller diameter
change
Speed change
Where q = gpm, Head, p = ft, d = Impeller diameter, rpm = Pump speed
pump formulas
npsh (net positive suction head)
npshr (net positive suction head required)
npsha vs. npshr comparison
npsha (net positive suction head available)
npsha basic equation
affinity laws: Eect of change of speed or Impeller diameter on centrifugal pumps.
npshr is dependent upon the pump design and is deter-
mined by the pump manufacturer. npshr is an important
value which greatly contributes to the successful operation
of a centrifugal pump. It is the amount of positive head
in feed of liquid absolute required at the pump suction to
prevent vaporization or cavitation of the fluid. npshr values
usually vary with pump capacity and are based on clear
water with a specific gravity of 1.0.
To prevent vaporization or cavitation of the liquid in the
suction side of the pump and to ensure rated pump perfor-
mance, npsha must be greater than or equal to the npshr
plus a two foot safety margin.
That is: npsha> npshr+ 2 feet 1
npsha is dependent upon the system in which the pump
operates. npsha is the amount of head or pressure that is
available to prevent vaporization or cavitation of the fluid
in the system. It is the amount of head available above the
vapor pressure of the liquid at a specified temperature, and
is measured in feet of liquid absolute.
npsha=1+2± 3-4-5
1 Pressure on the surface of the liquid, measured on the
suction side of the pump, in feet of liquid absolute (or
atmospheric pressure (Patm) for open tank suction
systems):
=
(psig + Patm) × 2.31 ÷ sp.gr
2 Velocity head in feet of liquid at the point of pressure
gauge connection. Where, velocity head = V
2
÷ 64.4;
and, V is the velocity of the liquid in the pipe at the
pressure gauge connection in feet per second (fps).
V=0.32 × gpm ÷ area; Area (Sq. inches) = d
2
÷ 4;
where, diameter (d) is in inches.
3 Strategic height in feet of liquid that the liquid supply
level is above (+) or below (-) the pump centerline.
4 All suction line fiction looses (in feet) between the
suction pressure gauge connection and the pump
suction including piping, valves, and fittings.
5 Vapor pressure of the pumped liquid at the pumping
temperature in feet or liquid.
Q
2
= Q
1
D
2
D
1
( (
H
2
= H
1
D
2
D
1
( (
2
P
2
= P
1
D
2
D
1
( (
2
Q
2
= Q
1
rpm
2
rpm
1
( (
H
2
= H
1
(
rpm
2
rpm
1
( (
rpm
2
rpm
1
(
2
P
2
= P
1
(
rpm
2
rpm
1
(
2
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