[Amel Yacht Owners] Re: leaking 3 way valve in dessalator watermaker prefilter


Sv Garulfo
 


Hi Bill, 

Thanks for your reply. Agreed, nothing urgent at this point, and I can run the system ok and not use the automated reverse flush part of the shutdown. According to the manual, that is by switching off the watermaker first and then lower the pressure with the regulatring valve. I understand you would follow the same procedure?

I wouldn't try to fix the valve, but I was enquiring whether it was plausible it would fail by just using it once and I suppose failure in any of the three modes you describe could be triggered that way. Alternatively, and as I read from a previous thread about leaking 3 way valves, I was looking for reports of people who experienced fixing the issue by operating the valve somehow differently. I accept there might be none.


On the subject of performance, i can see the device produces 50L/h, so 50% of nominal capacity, with 23C waters temp, with 530h history. That looks pretty poor to me. No leaks to report, pressure gauge stable in the green zone, output water quality is acceptable to taste, just less volume than expected. This is both running 24V and 230V motors. I looked for air in the filter and I can only see a few bubbles dancing around. I tried to purge them as per Bill Rouse's method but can't get 100% rid of them. I hope that's ok?
Is that symptomatic of anything in particular?

Thanks 
Thomas

Garulfo
Amel 54 #122
anchored near Hyeres, France 


On Tue, 25 Jul 2017 at 16:58, greatketch@... [amelyachtowners] <amelyachtowners@...> wrote:
 

I also have a 2-way valve in my fresh water flush line for the watermaker. (actually two...) that is closed all the time unless I am actually flushing with fresh water.  I might very well have a leaking 3-way valve, and will never know...


I am assuming if you close the 2-way valve in your freshwater flush line the leaking 3-way valve would then have no symptoms.  So my first reaction is, what's to fix? But... if you regularly flush the watermaker and the main seachest seacock stays closed, you could eventually overfill the raw water circuit and flood engine exhaust, so a fix might be a good idea anyway.

There are only three failure modes I can think of for this valve: corrosion of the body, corrosion of the ball, or failure of the seats.  None of these are an easy fix. The valve has shown itself prone to failure, new valves are not very expensive.  Why even try to fix?

Three-way valves like this should not fail this way.  If I ever need to replace mine, I would not consider replacing it "in-kind", but with a more reliable valve. Bronze, 3-way, L-port, ball valves with teflon seats in an appropriate size are easily available.  With a stainless ball and stainless handle, and you're all set for less than US$100.  It will likely last longer than the hull.

Bill Kinney
SM160, Harmonie
Glouchester, Mass

--
GARULFO
Amel 54 #122
Côte d'azur, France


greatketch@...
 

Thomas,

Our system is older, and does not have an automated fresh water flush, I don't know enough about that system to give advice.  We flush our system with fresh water manually for three minutes only if we are not going to be using it for more than two days.  Our normal routine is to make water every day. 

I can not imagine any operating tricks that would "fix" the leaking valve... but other people might be more creative than I am!

If your pump output is low, you can get the pressure up but not make as much water as you should.  This can happen if one check valve in the pump is bad, basically taking one piston out of service. If at all possible, measure the rate of the output brine flow. Directing the hose into a bucket with a timer is good enough. In very round numbers, it should be 10X the product water flow.  

If you expect 100 l/hr of product water, and you are getting 50, and you saw 500 liters/hour of brine flow I'd suspect the pump or salt water supply.  If you had 1000 liters/hour or more brine flow, I'd suspect clogged membranes.

If you find lower than normal brine flow, a mechanical repair of the pump is likely required.  If the membrane is clogged, flushing with the right cleaning solution might restore at least some of the lost capacity.

Bill Kinney


---In amelyachtowners@..., <svgarulfo@...> wrote :


Hi Bill, 

Thanks for your reply. Agreed, nothing urgent at this point, and I can run the system ok and not use the automated reverse flush part of the shutdown. According to the manual, that is by switching off the watermaker first and then lower the pressure with the regulatring valve. I understand you would follow the same procedure?

I wouldn't try to fix the valve, but I was enquiring whether it was plausible it would fail by just using it once and I suppose failure in any of the three modes you describe could be triggered that way. Alternatively, and as I read from a previous thread about leaking 3 way valves, I was looking for reports of people who experienced fixing the issue by operating the valve somehow differently. I accept there might be none.


On the subject of performance, i can see the device produces 50L/h, so 50% of nominal capacity, with 23C waters temp, with 530h history. That looks pretty poor to me. No leaks to report, pressure gauge stable in the green zone, output water quality is acceptable to taste, just less volume than expected. This is both running 24V and 230V motors. I looked for air in the filter and I can only see a few bubbles dancing around. I tried to purge them as per Bill Rouse's method but can't get 100% rid of them. I hope that's ok?
Is that symptomatic of anything in particular?

Thanks 
Thomas

Garulfo
Amel 54 #122
anchored near Hyeres, France