Draw a 250 ml water sample pie from brine hose at backwash tank and check for a pH reading of 5 to 8
(para. 230). 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.
Set CITRIC ACID PUMP valve to PRIME. Feed is completed.
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 most often, is to feed citric acid solution through the vessels (para. 2-29a). The
second method is to circulate Triton X-100 soapy cleaning solution through the vessels (para. 2-29b). Triton
X100 is more effective for removing dirt and silt. The R.O. elements must be cleaned:
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.
BRINE FLOW increases noticeably, and the adjustment of REGULATE PRODUCT FLOW valve
does not correct the BRINE FLOW indication.
d. When R.O. vessels pressure increases by 20% over initial reading.
R.O. ELEMENT CLEANING PROCEDURE.
Citric Acid Method.
R.O. ELEMENT CLEANING switch (fig. 2-42) must be in OFF position except
while cleaning R.O. elements.
(1) First backwash multimedia filter (see para. 2-26).
Be sure that the drained brine water runs toward lower ground as far
downstream from the raw water source as possible.