4
8
Ÿ
When positioning the pump it is important to ensure adequate motor
cooling through water flow past the motor.
Ÿ
It is recommended that the complete pump is submerged at least 3m below
the dynamic water level and if possible the pump should be installed at least
3m from the bottom of the borehole to prevent silting damage.
iii) Pump Lowering
For shallow boreholes (less than 50m) a manual tripod arrangement can be
used while a more elaborate lowering mechanism may be required for
deeper boreholes. When moving the pump the following procedures should
be followed:-
Ÿ
Before pump lowering it is important to check well depth and straightness
to ensure there is unobstructed passage. The pump shall be carefully
lowered into the well and if an obstruction is encountered the pump
should be removed and the cause investigated to avoid pump or cable
damage.
Ÿ
Fit the first starter pipe into the pump outlet and ensure a tight leak free
joint while the pump is on the surface. The thread on the starter pipe
should not be longer than the threads in the pump outlet or it will interfere
with operation of the non-return valve.
Ÿ
Screw the starter pipe into a robust adaptor hook attached to the winch or
tripod cable and lower the pump and pipe section into the borehole.
When fully lowered hold the pipe below the socket with a clamp,
disconnect the lifting hook and attach to the next pipe length ensuring a
water tight connection. Ensure the pipe joint is fully home and repeat until
all pipes are lowered.
Ÿ
While the pipes are being lowered bind the drop cable, low level cable (if
fitted), and airline (if fitted) to the drop pipes with a PVC cable clip at 2m
centres.
6. PUMP OPERATION
When the pump has been connected correctly and is submerged in water proceed
as follows:-
Ÿ
The pump should be run with the discharge valve restricted to
approximately 1/3 of its maximum volume of water. Observe if there are
impurities in the water and then gradually open the valve until the water is
observed to be clear. If the water continues to be silted the pump is
installed too low in the borehole it should be raised until it is in a position of
clear water availability. Alternatively a borehole problem is indicated and
the driller should be consulted.
