TM 55-1930-209-14&P-3
.
4-7.2.2 Backwashing media filter 1.
a.
Position RO valves as indicated.
o = open
x = closed 1/2
o = 1/2 open.
A = position A
B = position B
C - position C.
RO valve no
1
2
3
4
5
6
7
12
18
19.
Valve position
B
A
A
C
x
1/2o
x
o
o
x.
b.
Start seawater pump by turning pump OFF/ON/START switch on control station to START and then to ON
(Figure 3-1).
c.
Adjust valve RO6 to obtain a backwash flow rate of 162 gpm at seawater pump flow indicator F1 and a
temperature reading of 80°F at seawater temperature gauge T1 Exact flow rate depends on actual
temperature reading and should correspond to readings In table below Cooler water requires less flow.
Temperature
Slow backwash
Fast backwash.
T1 (F)
F1 flow rate (gpm)
F1 flow rate (gpm).
55
115
180
60
125
200
65
135
220
.
70
144
240
75
153
255
80
162
270
85
170
285
90
177
300
95
184
315
100
191
325
105
198
334
110
204
342
115
210
350
120
216
355
125
222
360
.
d.
Observe condition of the water at the flow indicator After 5 minutes or when water is dear, open valve RO6 to
obtain fast backwash flow rate corresponding to water temperature at T1 In the table above.
.
e.
After 2 minutes of fast backwash, partially dose valve R06 to obtain slow backwash flow rate at Fl.
.
f.
After 2 minutes of slow backwash, stop seawater pump by turning pump ON/OFF/START switch on control
station (Figure 3-1) to OFF.
4-16
