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MAINTENANCE
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TESTING EFFICIENCY OF RO MEMBRANE
NOTE: The RO membrane should be replaced annually or when the removal of Total Dissolved Solids - TDS
becomes less than 80% efficient. Contact your local Hobart Service office for TDS efficiency testing of your
Reverse Osmosis system.
NOTE: To determine grains of hardness delivered to equipment, divide the measured RO TDS by 17.1.
1. Ensure bypass valve is closed.
2. Measure inlet TDS before water enters RO filtration system.
3. Measure RO TDS through sampling line.
4. Determine efficiency percentage using the equation:
Efficiency Percentage =
Inlet TDS
!
RO TDS
x 100
Inlet TDS
Example: The inlet water to an RO filtration system is sampled and found to have TDS equal to 198 ppm. A
water sample is then taken from the output of the RO system and it measures a TDS of 17 ppm. Find the
efficiency percentage using the above equation and the gathered data.
Solution:
Efficiency
Percentage
=
198 ppm
!
17 ppm
x 100 =
181 ppm
x 100 = 0.914 x 100 = 91.4%
198 ppm 198 ppm