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UK Window Cleaning Forum => Window Cleaning Forum => Topic started by: [GQC] Tim on December 27, 2007, 09:43:44 am

Title: Are new membranes coated with a chemical aswell?
Post by: [GQC] Tim on December 27, 2007, 09:43:44 am
I know that the prefilters do, and when installing new filters you have to disconnect final filter output, and let it run for about 2 hours. Do new membranes come coated in a chemical aswell?

Reason I'm asking is, that in the manual of my purefreedom RO, it says nothing about disconnecting final filter output, instead it just says let it run for 2 hours, because the filters are treated with a chemical. Is that the same with the membranes then?

I don't feel comfortable with all the prefilter chemicals going through the membranes, can't be good for them can it?

I'd rather do two hours flushing the prefilters, and if the membranes are treated aswell, another two hours just for the membranes.

Is that correct?

Thank you. :)
Title: Re: Are new membranes coated with a chemical aswell?
Post by: windowwashers on December 27, 2007, 09:50:22 am
I know that the prefilters do, and when installing new filters you have to disconnect final filter output, and let it run for about 2 hours. Do new membranes come coated in a chemical aswell?

Reason I'm asking is, that in the manual of my purefreedom RO, it says nothing about disconnecting final filter output, instead it just says let it run for 2 hours, because the filters are treated with a chemical. Is that the same with the membranes then?

I don't feel comfortable with all the prefilter chemicals going through the membranes, can't be good for them can it?

I'd rather do two hours flushing the prefilters, and if the membranes are treated aswell, another two hours just for the membranes.

Is that correct?

Thank you. :)
you can get membranes dry or with liquid in, I would run it for 2 hours just to be on the safe side, but I am sure if this is a freedom install andrew would have already done this.

Ian
Title: Re: Are new membranes coated with a chemical aswell?
Post by: Ian Lancaster on December 27, 2007, 10:00:38 am
I've had my RO-man 300gp for about two and a half years, changed filters at the correct times and I'm still using the original membranes, even though there are four of us taking supplies from the system, and I've never flushed new prefilters as you describe.

My system still produces water at 5ppm before DI

I flush the membranes every time I start the system up.
Title: Re: Are new membranes coated with a chemical aswell?
Post by: [GQC] Tim on December 27, 2007, 10:04:25 am
Okay cool, I'll just let it flush a bit then.
Title: Re: Are new membranes coated with a chemical aswell?
Post by: Alex Gardiner on December 27, 2007, 10:57:49 am
Hi GQC,

As far as I know the pre-filters are not coated with any chemicals at all it is the membranes that are coated with a preservative that has to be flushed out before using the water to drink from.

When fitting new pre-filters it is best to disconnect to flush as they usually have small particles of loose material in them that needs flushing out so as to avoid blocking the membrane.
Title: Re: Are new membranes coated with a chemical aswell?
Post by: [GQC] Tim on December 27, 2007, 11:05:29 am
Ah I see, that explains that then. So what should I do, seperate flush? Disconnect prefilters first, then flush the membranes? What do you think? :)
Title: Re: Are new membranes coated with a chemical aswell?
Post by: Alex Gardiner on December 27, 2007, 11:10:49 am
If you are doing both together then just switch the valve to flush and flush both together.

If you were only changing the pre-filters then I would recommend disconnecting before the membranes.
Title: Re: Are new membranes coated with a chemical aswell?
Post by: windowwashers on December 27, 2007, 11:16:42 am
does anyone know where to get a small filter from like the ones for the pumps ?
Title: Re: Are new membranes coated with a chemical aswell?
Post by: [GQC] Tim on December 27, 2007, 11:23:57 am
does anyone know where to get a small filter from like the ones for the pumps ?

http://www.cleaningspot.co.uk/acatalog/water_pumps.html

Half way down.


Alex, do you perhaps have a diagram of how a membrane works? I'd like to know how the flushing works exactly, I would say that if you flush both together, then the particles from the filter would damage the membranes a bit? Or when you flush, does it just completely bypass the membrane? if so how does the flushvalve accomplish that? :)

(I've send you an email btw Alex)
Title: Re: Are new membranes coated with a chemical aswell?
Post by: Alex Gardiner on December 27, 2007, 11:29:55 am
HI GQC,

When forcing water through the membrane there is always an amount (waste) that is allowed to flow across the surface of the membrane to take away the dirt particles that cannot go through the membrane.

When you switch the flush valve the restriction on the waste is gone and all the water is allowed to flow across the surface of the membrane helping to clean the surface of the membrane thereby improving its performance.
Title: Re: Are new membranes coated with a chemical aswell?
Post by: [GQC] Tim on December 27, 2007, 11:53:40 am
Oh I think I understand now, that's why you have two seperate outlets, one for the waste, and one for the pure water, one goes through the membrane, while the other flows over it, not going through the membrane, flush valve lets all the water go through the waste outlet, bypassing the membrane, but taking any particles off the membrane to waste. Fully understood now. (Just repeating it for myself lol)

Thanks a lot! :)