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Model
F74C1015
3/4
F74C1023
1
Table 3. MV876B Timer Selections.
Program Value
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Planning the Installation
The F74C should be sized based on the required flow
rate and the resulting pressure drop across the filter. As a
guideline for most applications, the F74C should be sized
for a pressure drop between 3 psi and 7 psi.
EXAMPLE: What size F74C is required to provide a flow
rate of 20 gpm? Reading Table 2 at 20 gpm, a 3/4 in.
model has 5 psi drop and a 1 in. model has 4 psi drop.
As both models meet the 3 to 7 psi range, the selection
should be based on size preference.
An increased pressure drop across the filter results when
higher velocities are maintained to increase the capacity
through any given size filter. Severe pressure drops will
be encountered as capacity approaches that of the pipe
size. To ensure the backwash cycle operates properly
and cleaning action is not reduced, follow all
recommendations in Fig. 3. Refer to Fig. 3a for an ideal
installation.
All filter installations are different. The size, type and
amount of dirt and debris and the flow rate must always
be considered when choosing a screen and deciding to
install multiple F74C Water Filters in parallel.
F74C REVERSE RINSING FILTER; MV876 AUTOMATIC-BACKWASH CONTROLS
Table 2. Flow Capacity of F74C in Gallons per Minute (gpm).
Size
1
9.0
12.7
10.1
14.3
Backwash Interval
4 minutes
8 minutes
16 minutes
32 minutes
1 hour
2 hours
4 hours
8 hours
17 hours
34 hours
3 days
6 days
11 days
23 days
45 days
3 months
Pressure Drop in psi
2
3
15.6
18.0
17.5
20.2
Fig. 3. Ideal F74C installation. A funnel
mounted directly under the backwash
port is the best installation layout.
Fig. 5. Make sure the backwash outlet pipe
is not downsized, long or crimped. Instead,
install a short oversized pipe on the backwash
outlet. Do not use a low capacity solenoid
valve to automate the backwash cycle.
3
4
5
20.1
34.9
22.6
39.1
M17705
Fig. 4. Make sure the inlet pipe
is not downsized.
M17707
15
Cv
9
10.1
M17706
62-0165
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