Intake Piping
The most common problems that occur with all non-submersible water pumps are due to
mistakes made in the design and installation of the intake piping. Please follow these
instructions carefully. Most important, it is critical to minimize the suction load on the pump.
Place the pump as low and as close to the water source as you can. In NO case should the
pump be placed any higher than 10 vertical feet (3 m) above the surface of the water in the
source. (Subtract 1 foot from this number for every 1000 feet of elevation above sea level —
1 m for every km.)
Always keep pipe size as large, as direct, and as short as possible as possible. To reduce
friction losses, use a minimum of elbow fittings. Where possible, use 45° elbows instead of
90° elbows or use flexible suction hose. Refer to the pipe sizing chart in this manual, and
select a pipe size that will result in a very low pressure drop for your application.
Suction applications: If the pump must be placed higher than the water level in the
water source, extra attention must be paid to the suction piping. It should slope upward to
the pump without dips or high points, so that air pockets are eliminated. The highest point in
the suction piping should be the pump inlet except where liquid flows to the pump inlet
under pressure. The suction line should be built following the same rules as for a drain line,
to allow it to flow as easily as possible — except that the water will be drawn upward.
Foot valve: A foot valve must be used at the water intake, to keep the pump primed. Foot
valves are available from any local pump supplier, and from many hardware stores. To
prevent air from being drawn into suction pipe due to a suction whirlpool, the foot valve may
need to be submerged as much as three feet (1 m) below the low water level. This will NOT
add to the suction load on the pump. The suction pipe must be tight and free of air leaks or
the pump will not operate properly.
Intake screen: A foot valve that you can buy locally will have a perforated screen with
openings that are less than 1/8” (3 mm) in size. This is adequate to protect the pump.
If you are not using a foot valve, you should have an inline strainer to prevent particles
larger than 1/8” (3 mm) from entering the pump. Such particles may stick in the impeller and
reduce the performance, and may cause damage. An inline strainer can be purchased from
suppliers of pump, irrigation or swimming pool equipment. It should be large enough to
allow a substantial accumulation of material before it blocks the flow.
Discharge Piping
Discharge piping should never be smaller than the fittings on the pump, and should
preferably be one size larger. Refer to the pipe sizing chart at the end of this manual. A gate
valve can be installed in discharge line to serve as a shut-off during maintenance or for
throttling if the pumping rate is too high. With this type of centrifugal pump, it is safe to
restrict the flow in this manner. However, DO NOT run the pump for a long time against a
completely blocked discharge (a closed gate valve or a float valve). To do so can cause the
water to get very hot, sufficient to damage the pump.
