Polythene drop pipe can be selected by reference to the pump curve and its suitability can be checked on site
by checking the maximum pressure read at the top of the bore reference to the maximum depth allowed.
An unstrained safety rope must be connected to all pumps suspended on polythene pipe. This line should be
fastened to the lifting hook of the pump. The other end should be fastened at the top of the bore casing or
bore cap. The safety rope should be affixed at three metre intervals by a suitable underwater tape with the rope
having some slackness between each interval to compensate for the expansion of the polythene pipe when
under load.
Care should be exercised to ensure that the polythene pipe is securely fastened to reliable fittings.
If galvanized steel drop pipe is used, it is best installed in three meter lengths to enable easy handling and all
threads should be treated against corrosion.
It may be necessary, as a safety precaution to install a non-return valve at the top of the bore. This is in addition
to the non-return valve fitted in the pump. This will assure a break down of the water hammer and
consequently a reduction of shocks on the hydraulic components (which occurs in any pump system)
immediately after each shutdown.
This non-return valve is mandatory where the pump heads (pressure at the top of the bore plus pump depth)
exceed 80 m (785 kPa or 262 ft) or where the pump is part of an automatic pressure system.
WIRING
Wiring should conform to the requirements of local and national electrical codes. If in any doubt, contact your
Electricity Supply Authority.
CAUTION
The use of smaller cable than specified below may cause premature motor failure and will void the warranty.
Larger sized cables may be used.
The use of old drop cable or white flat is not recommended. Use water-proof cable only, i.e,
Aquaflex AQM rated for immersion to 100 m (500m immersion rated also available) obtainable from White
International.
The tables on the next page indicate the correct size electrical drop cable and maximum lengths to be used.