TM 10-4610-240-10
TM 08580C-10/1
T.O. 40W4-13-21
b. Fill CITRIC ACID pail with 3 gallons o f brine.
c. Stir chemical and brine with wooden paddle, and pour solution into 5 gallon chemical container.
d. While the ROWPU is operating normally, set the citric acid chemical feed pump valve to RUN; chemical feed
control knob should already be set to maximum setting (100).
e. Wait for 10 minutes.
f.
Draw a 250-ml water sample from brine hose at backwash tank and check for a pH reading of 5 to 8
(paragraph 2-15). If that reading is over 8, feed a new batch of citric acid chemical mixture, using 1. 5 pounds citric acid
mixed with 3 gallons brine
g. Set CITRIC ACID PUMP valve to PRIME. Feed is completed.
2-12. R.O. ELEMENT CLEANING METHODS.
It will be necessary to clean the R. O. elements to improve total dissolved solids (TDS) rejection, and reduce operating
pressure (P. S. I. ). Two methods of cleaning elements are available. One method, used to remove mineral deposits
such as iron and calcium carbonate, is to feed citric acid solution through the vessels (paragraph 2-13a)
The second method is to circulate Triton X-100 soapy cleaning solution through the vessels (paragraph 2-13b)
Triton X- 100 is more effective for removing dirt and silt. The R.O. elements must be cleaned:
a. Whenever the pressure shown on R.O. PRESSURE P.S.I. indicator rises to above 960 for seawater or 500 for
fresh water.
b. Product water output drops several gallons per minute on PRODUCT WATER FLOW indicator, with no change
in raw water temperature.
c. BRINE FLOW increases noticeably, and adjustment of REGULATE PRODUCT FLOW valve does not correct the
BRINE FLOW indication.
d. When R.O. vessels differential pressure increases by 20% over initial reading.
2-13. R.O. ELEMENT CLEANING PROCEDURE.
a. Citric Acid Method
CAUTION
R.O. ELEMENT CLEANING switch (figure 2-4) must be in OFF position except while cleaning R.O. elements.
(1) First backwash multimedia filter (see paragraph 2-10).
WARNING
Be sure that the drained brine water runs toward lower ground as far downstream from the raw water source as possible.
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