PUR40E watermaker - what is normal performance?

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Ric

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I've just installed a used PUR Katadyn 40e watermaker and am in the process of investigating and testing its various idiosyncrasies. Overall I am very happy with the performance which I have been testing methodically (and still gathering data). But I am also surprised by some of my observations.

At anchor, in water of about 22-23C, it produces 4.4-4.8 litres/hour with a current draw of 3-4 Amps which is broadly in line with the manufacturers claims. The output is of good quality generally and tastes ok.

However, underway in the same waters at around 4-7 knots, the output drops to about 3-4 litres per hour - this is with forward-facing dedicated 1/2" through-hull fitting as per manufacturer recommendations. Why does performance drop off underway? I would have thought the opposite would be the case.

I have a TDS meter which I regularly test the output. Sometimes this is as low as 160ppm (less than bottled water) but at other times (with only a few hours of shutdown) the ppm will go back up to about 440ppm (about same as tap water). So what is causing this fluctuation?

I left the system unattended for 48 hours (manufacturers recommendations is no more than 72 hours without pickling - so well within). I restarted with a 2l freshwater flush (i.e. carbon-filtered water through the pickling inlet). I was anticipating that there might be a bit of bad "rotten egg" anaerobic bacteria taste- - but on the contrary the output water was salty. How would salt get through the membrane? The taste and ppm did get back to normal after about 20 mins- but I don't understand how salt could have got through the membrane.

It would be interesting to hear about any other observations about the behaviour of these units.
 
Ric said:
I've just installed a used PUR Katadyn 40e watermaker and am in the process of investigating and testing its various idiosyncrasies. Overall I am very happy with the performance which I have been testing methodically (and still gathering data). But I am also surprised by some of my observations.

At anchor, in water of about 22-23C, it produces 4.4-4.8 litres/hour with a current draw of 3-4 Amps which is broadly in line with the manufacturers claims. The output is of good quality generally and tastes ok.

However, underway in the same waters at around 4-7 knots, the output drops to about 3-4 litres per hour - this is with forward-facing dedicated 1/2" through-hull fitting as per manufacturer recommendations. Why does performance drop off underway? I would have thought the opposite would be the case.

I have a TDS meter which I regularly test the output. Sometimes this is as low as 160ppm (less than bottled water) but at other times (with only a few hours of shutdown) the ppm will go back up to about 440ppm (about same as tap water). So what is causing this fluctuation?

I left the system unattended for 48 hours (manufacturers recommendations is no more than 72 hours without pickling - so well within). I restarted with a 2l freshwater flush (i.e. carbon-filtered water through the pickling inlet). I was anticipating that there might be a bit of bad "rotten egg" anaerobic bacteria taste- - but on the contrary the output water was salty. How would salt get through the membrane? The taste and ppm did get back to normal after about 20 mins- but I don't understand how salt could have got through the membrane.

It would be interesting to hear about any other observations about the behaviour of these units.
Click to expand...

Since water output relates to water temperature, the drop in output as you are on the move, could be the drop in water temperautre due to being in deeper cooler water when on the move. You could also be getting some air into the system.
If you are using 2litres to flush after use, then this is likely to be insufficient to flush the salt out. Your pre-filter and pipes are likely to be about this volume without the RO membrane volume. Do you not flush after use? This would be better than flushing before you use it as it removes the salt water before it starts to decompose
 
Thanks for the input. The water temperature while underway was the same to within a few percent, so I don't think that is a factor. I've realised now better to flush with fresh chlorine-free water immediately after use rather than before use - I have installed a loop after the carbon-filter to facilitate this.

But I am concerned that I might have an air leak. The pre filter always has some air in it - I guess that is inevitable. But I can see (through transparent tubes) that there are is air in the brine outlet tube and filtered inlet tubes. Should these be all be completely bubble free after a period of running?

Finally, when you fresh-water flush, do you lift the cleaning valve at the raw water inlet? The user manual states that this should be lifted when running pickling fluid through the unit - but there is no specific advice about using it for a fresh water flush.

Also, what specifically does this valve do mechanically? I would have thought that if pickling or flushing the membrane, it would be best to force fresh water/pickle solution through the membrane - i.e. use the unit normally. Does this valve really divert throughput overboard after it has gone through the membrane? Given its physical location next to the sea-water inlet, this would appear somewhat unlikely.
 
Ric said:
Thanks for the input. The water temperature while underway was the same to within a few percent, so I don't think that is a factor. I've realised now better to flush with fresh chlorine-free water immediately after use rather than before use - I have installed a loop after the carbon-filter to facilitate this.

But I am concerned that I might have an air leak. The pre filter always has some air in it - I guess that is inevitable. But I can see (through transparent tubes) that there are is air in the brine outlet tube and filtered inlet tubes. Should these be all be completely bubble free after a period of running?

Finally, when you fresh-water flush, do you lift the cleaning valve at the raw water inlet? The user manual states that this should be lifted when running pickling fluid through the unit - but there is no specific advice about using it for a fresh water flush.

Also, what specifically does this valve do mechanically? I would have thought that if pickling or flushing the membrane, it would be best to force fresh water/pickle solution through the membrane - i.e. use the unit normally. Does this valve really divert throughput overboard after it has gone through the membrane? Given its physical location next to the sea-water inlet, this would appear somewhat unlikely.
Click to expand...

From memory the little valve depressurises the system. You could lift the valve and just run you feed pump to flush with fresh water. When I had one of these units ( we are going back many years) I had problems with air coming in via the skin fitting as the boat was shallow draft. I installed a vent off the kingston cock I used and this helped. I just drilled a hole in the top of the kingston cock and ran a hose to high level. Hope this helps
 
Ours is an home made system we getting about 70/80 lts an hour ,
we fresh water flush after every use , we can leave it four days with out using it ,
any longer we just flush it with 10 lts of produce water .
I have been told that other have left it 10 days before re flushing it ,
But being on the safe side we keep to no more then four , any now after four days we usually looking at make more water .
 
Well I've discovered why my PUR40E had such variable performance. The **** who sold it to me sent a filter bowl with no O-ring, so it has just been sucking in air, only occasionally sealing. The next job is to try and find an O-ring for the 8" filter bowl. I presume these are fairly standard so hopefully should be easy to find?

And said **** who sold it to me does not pick up the phone so can't find out from him. He is well known on these pages and some have said positive things about him - I've found him a total **** to deal with, not the slightest bit interested in any after-market service. Will never use him again.
 
I wish I had done the same. The amount of time I have spent chasing all the connectors, o-rings etc which he failed to send (despite endless promises) I could have built my own system.

The first PUR40E he sent me was totally encrusted in salt water corrosion and had a substantial crack in the casting - he claimed to have simply "not noticed it - as it is such a rare failure" (I believed him at the time lol!). The unit had not even been emptied of water before bing posted to me, so all the packaging had gone soggy resulting in damage to the freshwater outlet nipple. I sent it back and - to be fair - the replacement second unit was in far better condition. But still it was fitted with tired and leaky 6mm pneumatic outlet pipes. I had never seen such pipes before so had to start a new learning curve working out what these strange blue pipes were - numerous emails and phone calls to **** were unanswered so I just had to do my own research - I am now an expert in all 6mm pneumatic connectors. I have found that they are literally cheaper than chips on eBay - so why didn't **** just replace them with new before sending them out and save customers the huge hassle of having to research everything from scratch? Now, having been baffled by erratic performance of the unit since installation, and spending days replacing pipes and jubilee clips, I have discovered that the filter housing had no o-ring in it! The guy is a total delboy.

Normally the advice and recommendations on this forum are very good - but I definitely got a bad steer to deal with him...
 
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