Dankoff Solar SunCentric Series Installatie- en onderhoudshandleiding - Pagina 4

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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.