[Ian Lancaster]

Hi all,

Even though I've tried to give good advice on another thread, I've got to admit I'm having problems myself.

Maybe someone can think of something I've missed:

We have a few 300gpd (pumped and unpumped) systems.  Recently we have had a problem with membranes failing prematurely.  On one of our systems the membranes failed after about a year - we replaced them on the 23rd April this year and followed Gaps advice by thoroughly washing all housings/pipework etc in a strong bleach solution and then thoroughly rinsing in fresh water.  All prefilters were replaced at the same time.

Up until a week ago the membranes were producing at around 13-15 ppm (95% rejection on input tds of 300 unpumped incoming pressure of 60psi).

Suddenly (in a matter of 2-3 days) output tds rocketed to 37ppm.  There was no change in any conditions (input tds/pressure/average temperature etc).  If these membranes are about to fail, that's a life of just over 3 months

Another system that was run exactly the same way had a failure of membranes after just 13 months.

At this rate we will be replacing membranes as often as prefilters!!

Our other 300gpd systems seem to be OK, and the one 40-40 we have (supplying 3 operatives) has been running on the same HF5 for over 3 years and still producing at 4-6 ppm.

All are running on the same water supplier (Southern Water) and all are single user, approximately 300lt per working day.

I tried to ring Gaps for June's opinion but they're shut till 6th August

Anyone got any ideas?

Thanks,

Ian

[paul saunders]

The main reason for premature failure is chlorine. Is there any chance you can get hold of a chlorine tester and test your water after the pre filtef but before the membranes? This will tell you if your carbon filter is working properly.

[andyM]

So the 4040 has been ok all this time then?
Could it mean that the problem is not the incoming water supply but inferior membrane quality from the manufacturer?
Just a thought.   

[Ian Lancaster]

The main reason for premature failure is chlorine. Is there any chance you can get hold of a chlorine tester and test your water after the pre filtef but before the membranes? This will tell you if your carbon filter is working properly.

Thanks Paul,

I've just spent half an hour trying to find a 'chlorine tester' on Google.  Bewildering array of products/opinions etc.  Anyone know what I should be looking for?

[Ian Lancaster]

So the 4040 has been ok all this time then?
Could it mean that the problem is not the incoming water supply but inferior membrane quality from the manufacturer?
Just a thought.   

Very possible - the same thought occurred to me.  The offending membranes were from Gaps, I've always regarded them as the authority on these things.

Anyone got any advice as to the best make of membrane?

[Spruce]

Hi Ian

The 'old' RoMan told me that the membranes that were made in China and Korean weren't up to the quality of the USA manufactured ones. But that info is old. I bought 3 x 150 GPD Filmtec membranes from RoMan 6 years ago and they are still going strong. We also have a 60psi water pressure, and these membranes produce to an efficiency of 98-99% from a tap tds of between 90 and 100.

I also can't believe that Gaps would sell suspect stuff.

I would start looking at your r/o unit to begin with. The first thing would be to identify if all the membranes are faulty or just 1. So I would test each unit individually. If you have 1 suspect membrane that is contaminating the pure produced by the others then problem identified.

However, if all the membranes are giving bad readings then I would focus in on the Carbon block filter as has been suggested. I don't know if this is normal or not, but the unit I have (bought second hand 7 years ago) always had 2 rubber sealing washers on the carbon block filter. Its as though the carbon filter housing was a fraction too small.

Another couple of questions - how old is the unit? Has it worked fine for years before the last batch of membranes? Where is it located (ie is it at an operatives home)? If so , could its location be an issue? Could the membranes have been 'swopped' for an older set. (I'm not implying anything, but many years ago we had a sales rep working for our company whose company car was the same make and model and their private car. The company car was paying for tyres, brake parts, exhaust etc for the private car - parts being exchanged whenever necessary. He got caught out with the tyres on a car inspection days after having new ones fitted.)

As regards chlorine testers, the best place to look for 1 is a swimming pool equipment supplier. We had one that we used to use. It consisted of a test tube and a colour chart. We put the water in the test tube up to a mark and then put a couple of drops of another liquid into the water from a 'dropper' and shook it to mix it. The resulting colour of the water was compared to the chart to identify chlorine concentration in the water.
http://www.ebay.co.uk/itm/Pool-hot-tub-tester-for-pH-bromine-chlorine-alkalinity-/260577548646?pt=UK_Swimming_Pools_Hot_Tubs&hash=item3caba1d966

Is see there are digital ph testers, but these aren't what you want.

[richard jagger]

I agree with spruce as the chlorine colour match meter.They are good and work well. Water companies do backwash  water pipes and flush with chlorine, which would go up so its quite normal for this to happen in the summer as there would be more algae in the supply system. A Mate ( waster engineer) told me if we saw the water pipes we would not drink the water.
    I also run a 300 lt ro but at 100 psi and not problems and I get all membranes (£ 23 ) and filters from Extend to Wash , cheaper and never had a problem with Johns products.John told me the higher the pressure the better the flow and quality of water and I have found this works for me. ON my old booster pump at 50/60 psi always problem.

[Ian Lancaster]

Thanks Spruce and Slumpy,

I'll try individual testing of the membranes - good advice, thankyou.  I'll also get one of those chlorine testing kits.

Thanks for all the help

Ian

[Spruce]

Please keep us updated as you work through this Ian. It would be interesting to hear the results.

If Gaps do have a faulty manufacturing batch, then they will be very aware of it a few days after they return to the office.