7
Sizing Requirements
Water Pressure
The water system must have a pump big enough to deliver the recommended backwash
rate with a minimum pressure at the inlet of the filter of 30 psi. If the existing system can-
not do this, it must be upgraded to do so. Whenever possible, the water system should be
adjusted to deliver at least 30 psi for even more satisfactory results.
Backwash Flow Rates
The most important criteria in sizing a filter is the capacity of the pump. The water must
pass through the filter media at the proper service flow rate. The filter must also be back-
washed at a flow rate sufficient to dislodge and remove the captured particles. Failure to
provide sufficient water will cause a build-up of particles in the filter media, impairing its
ability. In order for your filter to backwash and rinse properly, your pump must be capable
of providing the backwash flow rates indicated on page 4.
Check Your Pumping Rate
Two water system conditions must be checked carefully to avoid unsatisfactory operation or
equipment damage:
1.
Minimum water pressure required at the filter tank inlet is 20 psi.
2.
Measuring the pumping rate of your pump:
With the pressure tank full, draw water into a container of known volume, and measure the
number of gallons drawn until the pump starts again. This is draw-down. Divide this figure
by cycle time and multiply the result by 60 to arrive at the pumping rate in gallons per min-
ute (gpm). To aid in your calculation, insert the date in the following formula:
DRAW-DOWN ______ ÷ CYCLE TIME _______ x 60 = PUMPING RATE ________ (gals)
(secs.) (Gpm)
EXAMPLE:
CYCLE TIME is 53 seconds. DRAW-DOWN is 6 gallons; then, PUMPING
RATE equals:
6 gallons ÷ 53 seconds x 60 = 6.8 gpm
See chart on page 4 for minimum flow rates.
NOTE:
If your pumping rate is inadequate for the model, do not install your filter until
the problem has been corrected.
