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American Dispensing Company
88 Currant Road / Fall River, MA 02720-4781
24
SECTION VIII
REVERSE OSMOSIS (R.O.) MEMBRANE
In normal operation, a reverse osmosis membrane can become fouled by microorganisms, suspended solids
and minerals in the water. It is time to clean the membrane when these elements cause a 15% drop in the
product water flow rate, after compensating for temperature differences. It is important, therefore, to establish
a base flow rate of a new membrane so future measurements can be compared.
This base measurement is taken during the first 24 to 48 hours into the operation of a new membrane. Every
two months thereafter, the rate of flow of the product water from the membrane should be measured and
compared. It is also important to measure the temperature of the incoming water as the flow rate decreases
with temperature decrease. This is normal and should not be confused with membrane fouling.
A. PRODUCT WATER FLOW RATE MEASUREMENT
Tools required:
Thermometer for measuring water temperature
One (1) Gallon Container
Stop Watch Calculator
1. We need to establish the incoming water temperature. Check if the R.O. pump on the cabinet base is
running. The pressure gauge at the pump should indicate about 160 psi. If the pump is not running, vend
water until the pump starts. System does not produce water until water level is below
the refill level switch. Wait until pump has run for at least one minute and then take a sample of water from
the sampling valve prior to the sediment filter and measure its temperature.
2. Vend three gallons of water to allow the system to charge. During vend, have a stop watch and a gallon
jug ready and disconnect the white 3/8” O.D. tubing going into the water storage tank. To disconnect
tubing, push down on the ring in the fitting and then pull at the tubing (diagram 7). The water coming out
of this tube is the product water from the R.O. membrane. Start the stop watch and measure the time (in
seconds) to fill the gallon container with this water.
3. Replace tubing by pushing it back into the fitting completely.
diagram 7
top of tank
push firmly,
then pull