Why is it important to know the change in pressure accross the RO membrane? What can pre and post membrane pressure tell you that a conductivity/TDS/percent rejection meter cannot?
Posts: 3 | Location: Philadelphia, PA USA | Registered: 09 September 2002
<B.R>
Posted
Hi!
First, what means TDS?
About the pressure, I think the main reason to check the pressure before the RO membrane is to prevent it from getting too high.
RO membrane can get blocked from dirt, Ca and bacterial growth. If it gets too blocked, the pressure sure rises and finally the membrane will be damaged.
There is sure different kinds of systems used in the world, in our hospital we have Gambro CWP-100, where we don�t check pressure across RO & UF membrane at all, but we check the flow from the rejection line. If the flow gets too low, we know that membrane is getting blocked.
We clean our RO and UF membranes 2 times a week with both Dialox and with alkaline solution. So usually it is very clean. If we see the flow has decreased from the rejection lines, then we adjust the valves at the rejection line, and so we decrease the pressure across the membrane.
<B.R>
Posted
Sorry, I did a mistake in my last mail.
It was wrong when I wrote: if the flow gets too low from the rejection line that we know the membrane is getting blocked.
No not at all! I meant that then we know that the pressure is getting too high. In our system the rejection flow should be high enough, so the membrane is not damaged.
In our system the membrane doesn�t get blocked, because of the cleaning twice a week.
Originally posted by Lorna G: Why is it important to know the change in pressure accross the RO membrane? What can pre and post membrane pressure tell you that a conductivity/TDS/percent rejection meter cannot?
Its important because if you get an increasing difference between the pressure on the first membrane in comparison with the last one this tells you that you are fouling the membranes.
