Do not hold START BACKWASH switch up for more than 5 seconds to
avoid damage to the controls.
(10) When a steady stream of water flows from backwash pump draincock, close draincock.
Solid-state timer will come on immediately. BACKWASH PUMP ON
lamp will come on, pump will start and backwash water will flow through
the multimedia filter and out the waste water hose. The multimedia filter
gage needle will move fully to right. During backwash, the backwash
water flow rate varies automatically from 0 to 70 to 120 gpm while
washing and rinsing.
Backwask with the solid-state timer lasts about 13 minutes.
(11) When backwash is complete, BACKWASH PUMP ON Lamp will go off and multimedia gage will return
to "0". When backwash pump shuts off, turn BACKWASH valve handle upward to left to NORMAL position. Close valve
at brine water supply tank.
(12) Start up the ROWPU after backwash in the normal manner (para. 2-25).
Since the multimedia filter uses brine water to backwash, it should not be
drained or left inoperative following backwash without first flushing with
raw water for 5 minutes. Flush by operating filter normally.
2-27.CITRIC ACID FEED. After 20 hours of full operation, feed citric acid solution into filtered water in order to maintain
pH recommended for optimum R.O. process:
Chemicals can cause sickness or even death if extreme care is not
taken. Wear protective devices when working with these solutions.
Put 0.75 pounds of citric acid into CITRIC ACID pail, using citric acid measure.
Fill CITRIC ACID pail with 3 gallons of brine.
Stir chemical and brine with wooden paddle, and pour solution into 5 gallon container.
While the ROWPU is operating normally, set the citric acid chemical feed pump valve on RUN, and set
chemical feed control knob to maximum setting: 8.5.
Wait for 10 minutes.
Draw a 250 ml water sample from brine hose at backwash tank and check for a pH reading of 5 to 8. 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.