Site Buddy PROFESSIONAL SERIES 30TP, Owner'S Manual, Page: 17 / 26

OPERATION
Operating condition
The water pumps operating range should be based upon the NPSH (net positive suction head).
A more precise definition of available NPSH is “the difference between the total suction head
and the vapor pressure of the liquid, in feet of liquid, at the suction flange”. We can measure
the total suction head of the pump and we can find vapor pressure from the liquid temperature.
The difference between these two values is the available NPSH. The following equation is the
mathematical expression of the definition for available NPSH:
hsv = has - hvpa where:
hsv = available net positive suction head, in feel of liquid
hsa = total suction head, in feet of liquid, absolute
hspa = vapor pressure of liquid at suction nozzle, in feet of liquid, absolute
The approximation will be based at an altitude less than 250 meters or 820 feet. Subtracting
10 meters or 32.8 feet from the net positive suction head can approximate the suction head of
the pump. When increasing the altitude of operation, the atmosphere should be decreased as
well as the suction head of the pump. The amount of decrease can be estimated by subtracting
10 meters from the local atmosphere value. If you are using sour pump at high altitudes and
having difficulty obtaining NPSH values, please consult your local power equipment dealer.
It is better to use a straight and short pipeline when operating the water pump. A short and
straight pipeline will minimize the frictional loses in the pipeline. The pipeline should be
fixed to something to avoid vibrations. Before operating the pump, you must check the
connections between the pump and pipelines to verify that everything is installed properly and
that there are no leaks of any kinds.
The filter net should be kept at a certain distance between the river surface, river bottom, and
riverbank. The net must also be submerged at least 0.3 meters or 1 foot below the water
surface to avoid sucking air into the pipeline. The net must also be 0.2 meters or 0.7 feet
above the river bottom or riverbank to avoid sucking stones or weeds into the pipeline.
If the gap between the impeller and flow guidance surface is over 1 mm, an adjustment shim
can be added on the shaft shoulder to reduce the gap. This will permit continuous use of the
water pump. Please refer to figure 2-2 for a diagram of the water pump and a listing of the
components.