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5.7 Coping with Dirty Water Conditions
PS pumps have good resistance to quantities of sand
and fine sediment that can normally occur in a well.
However, any amount of abrasive material will reduce
the life of this pump, like any other pump. Extreme
sediment can cause the pump to stick. Sediment can
also settle inside the drop pipe each time the pump
stops, and block the flow. For water sources that contain
high amounts of sand, clay, or other solids, consider the
following suggestions.
To avoid pumping dirty water
1. Have your well purged, developed, or otherwise
improved by a water well contractor before install-
ing the pump.
2. Temporarily install a more powerful pump to draw
at a high flow rate until the water looks clean.
3. Set the pump as high as possible in the well. If the
pump can be placed higher than the perforations
in the well casing, it will probably avoid all but the
finest suspended silt.
4. After lowering the pump in a well, wait at least
15 minutes for sediment or debris to settle down.
5. If the water source is at the surface, dig a shallow
well next to the water source to obtain clean
water.
6. If the water source is at the surface, use a fabric
screen to protect the pump. See section 5.5
If dirty water cannot be avoided
1. Use a reduced size of drop pipe. This will maximize
the velocity of water flow in order to exhaust sand
particles. Refer to section 12.3, Water Pipe Sizing
Chart. Select the smallest size pipe that does
not impose excessive friction loss. Use a reducer
bushing on the pump if necessary, to adapt it to
a smaller pipe size. See the caution about plastic
bushings in section 5.3
2. Monitor the situation regularly by observing the
volume of water pumped and/or the current draw
of the pump. For AC amps, see sections 8.3 and
12.8. As a pump wears, its flow rate (and current
draw) will decrease gradually. Replace the pump
end when reduced performance is observed, or
before your season of greatest water demand.
Increased current draw may indicate debris stuck
in the pump and/or pipe.
Before opening a pump that is clogged with dirt, see the
CAUTION about removing check valve, see section 8.1
QUESTION What effect
does hard, mineralized,
alkaline or salty water have?
— ANSWER Generally, none. Dissolved
minerals and salts are not abrasive.
QUESTION How is a pump
damaged from “dry run”? —
ANSWER If the pump runs
completely dry, parts will overheat and be
damaged. However, if water is only trickling
into the pump, it will usually provide enough
lubrication and cooling to prevent damage.
5.8 Utilizing a Low-Production Water Source
PS pumps can make the best of a limited water source,
even if the pumping rate can exceed the recovery rate.
You want to draw the most water possible, without run-
ning dry. PS-Pumps can handle this in two ways.
The low-water probe The low-water probe allows
the pump to work to its full potential until the water
level drops, see section 4.10. This is a good strategy
because you get all the water you can while the sun
shines. Place the pump near the bottom of the well to
utilize the storage of water in the well. When the pump
is stopped by the low-water probe, it re-starts after a 20
minute delay. The Low Water OFF light will slowly flash
even after the water recovers and the pump restarts,
to indicate that the level got low at some time during
the day. See section 4.10, Low Water Probe. It may be
feasible to hang the probe independently and use it to
locate the water level at any moment. See section 5.4,
Safety Rope and Binding
Reduce the Maximum RPM setting If the well has
little storage capacity, the supply may recover before the
20-minute restart delay. In this case, reduce the “Maxi-
mum RPM” setting in the controller. See section 4.6
WARNING Do not use a valve as a
means of reducing the flow. With a
helical rotor pump, excessive
pressure may result. Use the
Maximum RPM setting instead.
Add a stilling tube if operation in dirty water
conditions cannot be avoided Use a stilling tube
to protect the pump from dirt. This design prevents dirt
to enter from top or from the sides of the borehole into
pump. The large inner diametre of about 115 mm allows
the water to rise only very slowly, so that sand or other
heavy particles cannot be sucked into the pump.
Figure 23: Stilling tube for HR pumps
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