Testing Membrane Quality - SpectraPure 4-Stage Compact DWS-CLS-3 Operation Manual

Ro drinking water system for coffee lovers

Hide thumbs

Table Of Contents

Table of Contents

SpectraPure

The performance of a RO membrane is measured in terms of its rejection characteristics. Note:Test the quality of the

membrane once every 6 months.

Method 1: Using a test kit

The rejection of the membrane is measured using the following procedure.

1. Turn the right-angled ball valve on the top of the pressure tank to the OFF position. Flip the faucet lever into the UP

position.

2. Measure tap water conductivity* (Call it X).

3. Run the system for 30 minutes.

4. Rinse test instrument cell 2-3 times with RO water.

5. Measure RO water conductivity* (Call it Y).

6. Subtract RO water conductivity* from tap water conductivity* (X - Y) .

7. Divide this quantity by tap water conductivity* (X - Y) ¸ X .

8. Rejection = [(X - Y) ¸X ] ´ 100 .

9. Put the faucet lever back to the DOWN position and then turn the right-angled ball valve to the ON position.

* Conductivity in the above procedure could be replaced by hardness, alkalinity, nitrate, phosphate, silica etc. (measured in

ppm or mg/l). These test kits are commonly available at aquarium stores.

Example: Calculation of Rejection of the RO Membrane.

1. Tap water hardness = 150 ppm (X).

2. RO water hardness = 7 ppm (Y).

3. X - Y = 143 ppm.

4. (X - Y) ÷ X = 143 ÷ 150 = 0.953

5. Rejection = [ ( X - Y) ÷ X ] ×100 = 0.953 ×100 = 95.3

Membrane Hardness Rejection = 95.3 % Þ Membrane OK.

Depending on your tap water chemistry, the rejection characteristics of the membrane may vary significantly.

Following tips will ensure a good membrane life. They are:

1. Replacement of 0.5 micron Micro-Tec TM sediment filter once every 6 months OR when the pressure indicated by the

pressure gauge drops by 15-20% (whatever happens first). This will prevent membrane fouling due to silt or sediment

depositing on the membrane.

2. Replacement of 0.5 micron carbon block filter at least once every 6 months OR when the pressure indicated by the

pressure gauge drops 15-20% (whatever happens first) OR when chlorine breakthrough occurs *. This will ensure

good membrane life and prevent membrane from chlorine damage.

3. Membrane should not be operated at lower than 4:1 waste water to product water ratios. If you have a lower ratio,

change the length of the flow restrictor to adjust to at least 4:1.

4. Running reverse osmosis systems on softened feed water reduces the chances of membrane fouling.

* Method to check for chlorine breakthrough : Detection of chlorine levels > 0.1 ppm in brine (1/4" yellow waste water

line). USE PART #: CTK-05 (Total Chlorine Test Kit).

No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical,

photocopying, recording or otherwise without the prior written permission of SpectraPure Inc.

TESTING THE QUALTIY OF THE MEMBRANE

Tips for good membrane life

SpectraPure®Inc.

2167 East Fifth St, Tempe, Arizona 85281