Teral NSVM 25 Series, Installation & Operating Manual

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NSVM, NSVMN
2
WARNING
warranty.
WARNING
4.3 Minimum inlet pressure-NPSH
Ø To avoid cavitation, make sure that there is a minimum pressure on the suction side of the pump.
NPSHA (Net Positive Suction Head Available)
--The net positive suction head available is a function of the pump
suction system.
NPSHR (Net Positive Suction Head Required)
--The net positive suction head required is a function of the pump
design at the operating point on the pump performance curve.
NPSHA=Ha-Hs-Hf-Hv-Hst (in Feet head)
Ha: Barometric pressure.(That can be set to 33 ft)
Hs: Suction lift.
Hf: Friction loss in suction pipe.
Hv = KT+KH: Vapor pressure
KT: Flow resistance due to liquid temperature.
KH: Flow resistance due to elevation above sea level.
If the liquid is water, you can consult the tables to determine the
values of
KT and KH.
T (
°
C) 20 30 40 50 60 70 80 90 100 110 120
KT (ft) 0.656 1.312 2.624 4.264 7.216 10.824 16.4 24.272 36.08 49.2 72.16
H (ft) 0 500 1,000 1,500 2,000 2,500 3,000
KH (ft) 0 1.804 3.608 5.412 7.216 9.02 10.824
Hst: Safety margin. (minimum: 2 ft head)
NPSH
A
≧
NPSH
R
: Pump running will be fine.
NPSH
A
NPSH
R
: The pump will be dry running or cavitating.
Stop operation of the pump if cavitation occurs. Cavitation will cause pump damage and the resultant damage is not subject to
4.4 Minimum nominal flow rate
To prevent overheating of the internal pump components, the pump should not be used at flows below the minimum flow rate.
Do not run the pump against a closed discharge valve for longer than a few seconds.
The curve below shows the minimum flow rate as a percentage of the nominal flow rate in relation to the liquid temperature.
4.6 Electrical data
See the motor nameplate.
WARNING
Make sure that the supply voltages, phase and frequencies correspond to the motor specifications.
4.7 Number of starts per hour
Motors up to and including 5.5HP: Maximum 100 times per hour.
Motors of 7.5 HP and up: Maximum 40 times per hour.
.
WARNING
If you use another brand of motor then check the manufacturer’s instructions for the maximum frequency of starts.
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