SpectraPure
SpectraPure®Inc.
480.894.5437 Call us toll-free 1.800.685.2783
2167 East Fifth St, Tempe, Arizona 85281
®
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Although RO membranes are capable of maintaining high water quality
over extended periods of time they eventually will begin to deteriorate.
Normally, the conductivity of the permeate water will increase as the
membranes age. By comparing the difference in TDS readings between
the Tap water conductivity and the RO water conductivity, the per-
centage of rejection of the RO membrane may be calculated and the
resultant number may then be used to determine the condition of the
membrane and thus the operator will know when the membrane needs
to be replaced. Membrane failure will be indicated by a reduction of the
percentage of rejection which will be determined by calculating the
differential between the input and output numbers.
In order to accurately determine the condition of the RO Membrane, a
conductivity tester (TDS meter) capable of reading the tap water
conductivity and the permeate water conductivity has been provided
with this system. With the assistance of the TDS meter you will be able to
easily determine the RO membrane’s condition.
Before performing the diagnostic test on the RO membrane, make sure
that the RO system has been “ON” and producing pure water for a
minimum of 10 minutes. Also check the brine (yellow) line to make sure
that water is flowing and that the flow ratio between the permeate
water and the brine water is at a ratio that is > 4 to 1. (NOTE: The
pressure gauge should indicate a pressure reading of > 40 PSI during this
15-20 minute test period.
Procedure:
1. Turn on the meter 1 ( left meter) by depressing the on switch.
2. Locate the meter slide switch on the front of the DM-1 TDS meter.
3. Slide the switch to the Left “IN” and read the Tap water conductivity
then record the reading ________ .
4. Next, slide the switch the to Right “OUT” and read the RO water
conductivity then record the reading ________.
5. See page 15 on “TESTING THE RO MEMBRANE REJECTION RATE ”
RO MEMBRANE DIAGNOSTIC:
