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Old 28-05-2015, 03:37   #1
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Is your 440's watermaker earthed?

Just a note to suggest other 440's check their watermaker was earthed when installed.

We recently noticed two pin size leaks when our Idromar system was run.

It turned out that the end caps of the long stainless steel vessels were suffering electrolysis between the tube end caps and the actual membrane housing tubes .... because it was never earthed when originally installed !

Fortunately, our repairer was able to make a series of layered / custom seals to get a suitable pressure seal instead of having to replace the two pressure tubes (which was going to cost many more boat units (ie thousands) if the new seals didn't work!) ..... and earth it properly !

We're probably not the only ones so suggest adding this to your "things to check" list.
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Old 28-05-2015, 07:35   #2
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Re: Is your 440's watermaker earthed?

Thanks for the info Craig.
Mine has been in hibernation, probably far too long, so this is a timely reminder to wake it up, for a while. I'll then check for earthing. Now I'm scared of what I'll find. If there's 'boat units to spend" I generally find myself involved.....
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Old 28-05-2015, 09:02   #3
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Re: Is your 440's watermaker earthed?

Quote:
Originally Posted by Boardshorts View Post
Just a note to suggest other 440's check their watermaker was earthed when installed.

We recently noticed two pin size leaks when our Idromar system was run.

It turned out that the end caps of the long stainless steel vessels were suffering electrolysis between the tube end caps and the actual membrane housing tubes .... because it was never earthed when originally installed !

Fortunately, our repairer was able to make a series of layered / custom seals to get a suitable pressure seal instead of having to replace the two pressure tubes (which was going to cost many more boat units (ie thousands) if the new seals didn't work!) ..... and earth it properly !

W
This is an interesting one; thanks for sharing. "Earthing" can be used to mean many different things and many people who think they know (and charge for that) will get confused and only make things worse.

Are you saying that:

a) there was no (typically black or yellow) wire to connect the battery negative terminal to the part of the unit through which electricity IS meant to circulate: or

b) there was no (typically green or green and yellow) wire to connect the parts of the unit that are NOT mean to carry electricity to a bonding/safety ground bus?

Are tube end caps and the actual membrane housing tubes made of the same metal (presumably 316 SS)?

C
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Old 28-05-2015, 10:38   #4
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Re: Is your 440's watermaker earthed?

I think you may have other issues here. The membrane housings should not be connected to any part of the electrical system. If you are getting electrolysis on the housings or endcaps, the only path I can imagine is through the water connections. If electricity is coming through those, you have a problem that should not be solved by providing a short to ground, and you need to find that electrical leak. You should also be concerned now about the thruhulls being used for the unit, if they are metal.

If this is a galvanic issue, then a ground wire is not going to help that either, and may make things worse. If it is galvanic, then the design is poor, but you should look at physically isolating the different metal components.

Mark
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Old 28-05-2015, 11:18   #5
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Re: Is your 440's watermaker earthed?

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Originally Posted by colemj View Post
I think you may have other issues here. The membrane housings should not be connected to any part of the electrical system. If you are getting electrolysis on the housings or endcaps, the only path I can imagine is through the water connections. If electricity is coming through those, you have a problem that should not be solved by providing a short to ground, and you need to find that electrical leak. You should also be concerned now about the thruhulls being used for the unit, if they are metal.

If this is a galvanic issue, then a ground wire is not going to help that either, and may make things worse. If it is galvanic, then the design is poor, but you should look at physically isolating the different metal components.

Mark
+1 on all counts.
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Old 28-05-2015, 18:56   #6
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Re: Is your 440's watermaker earthed?

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Originally Posted by colemj View Post
I think you may have other issues here. The membrane housings should not be connected to any part of the electrical system. If you are getting electrolysis on the housings or endcaps, the only path I can imagine is through the water connections. If electricity is coming through those, you have a problem that should not be solved by providing a short to ground, and you need to find that electrical leak. You should also be concerned now about the thruhulls being used for the unit, if they are metal.

If this is a galvanic issue, then a ground wire is not going to help that either, and may make things worse. If it is galvanic, then the design is poor, but you should look at physically isolating the different metal components.

Mark
+1

A full galvanic audit may be on the cards. The current flow paths can be insidious and hard to track down.

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