Pulsafeeder PulsaPro 900 EN - Manual (Page 56)

52
Variable
Units Set
English Metric
NPSH psi bar
P
A
psia bar(a)
P
H
psi bar
P
V
psia bar(a)
L
S
feet meters
R strokes/min strokes/min
G
no units no units
Q gallons/hr liters/hr
d inches millimeters
µ centipoise centipoise
L
D
feet meters
P
T
psi bar
P
P
psi bar
V
P
feet/sec meters/sec
C
1
24,600 640
C
2
45,700 1.84
C
3
46.8 0.91
Table 2. Unit sets and constant values for use in Equations 1 through 5.
If piping sizes vary throughout the suction line, different additive values may be used for
the pressure losses attributed to the liquid’s acceleration and deceleration.
Use the last term of Equation 1 or 2 as many times as needed in the equation to adjust for
different lengths/pipe diameters in the suction line. (Everything but the pipe length and
diameter will stay the same in the equation.)
All reciprocating metering pumps also require that a minimum absolute pressure,
minimum suction head (MSH), be maintained at the pump inlet throughout the pumping
cycle to ensure a stable hydraulic system and proper pump operation.
MSH
English, (psia) 5.0
Metric, (bar(a)) 0.35
Table 3. Minimum values for the sum of NPSHA and vapor pressure. (MSH)
The sum of the NPSH
A
and the vapor pressure (P
V
) must be greater than the values shown
in Table 3.