2023 Online Catalog - Flipbook - Page 507
Feed Pump Sizing 17
Polyphosphate Treatment For Water Systems
In order to size a MEC-O-MATIC feed pump for
polyphosphate feeding it is necessary to know:
a) the polyphosphate residual (ppm), and
b) the well pump rate (gpm).
Rule 1: One pound of polyphosphate per 10 gallons
water = 12,000 ppm (solution strength)
Rule 2: One pound of polyphosphate typically
treats 40,000 gallons of water at a 2 ppm
concentration (residual).
Formula: [Well pump rate (gpm) x polyphosphate residual (ppm) x 1440 (conversion factor)] ÷ solution
strength = required feed pump output (gpd)
Example:
Well pump rate = 10gpm
Polyphosphate residual = 4 ppm
(10 x 4 x 1400) ÷ 12,000 =
56,000 ÷ 12,000 = 4.66
feed pump output (gpd), with 10 = well pump rate;
4 = the desired concentration of polyphosphate;
1440 = the conversion factor to change gpm to gpd;
12,000 = the solution strength based on the above Rule
1; and 4.66 = the feed pump output (gpd) based on well
pump rate and polyphosphate residual.
It is advisable to slug the system initially at 10 ppm
for approximately 30 days to clean out the lines at a
faster rate.
Useful Data:
Polyphosphate @ 1 lb/10 gal = 12,000 ppm
5.25% bleach = 52,500 ppm
12.5% bleach = 125,000 ppm
Potassium Permanganate @ 0.25 lbs/gal = 30,000 ppm
• It requires 3 ppm chlorine for each ppm of
hydrogen sulfide.
• It requires 1 ppm chlorine for each ppm of iron.
• It requires 0.7 ppm potassium permanganate for each
ppm of hydrogen sulfide or iron.
• Do not neglect the residual required for
chlorine applications.
• Do not mix potassium permanganate stronger
than 0.25 lbs/gal or the maximum solubility will
be exceeded.
Sizing Feed Pumps
In sizing feed pumps for iron and hydrogen sulfide removal using chlorine bleach or potassium permanganate,
the following formula can be used:
x
Required
dosage
x
in ppm
Solution
(1440)
in ppm
÷
strength
=
Feed rate
required
in ppm
Size the chemical feed pump so that its maximum capacity is double the required feeding.
Technical & Engineering
Well pump
flow rate
in gpm
23
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