Desalator interconnect Bobin


Nick Newington
 

I have a small leak from the watermaker outboard end membranes on my 160 litre per hour unit. I believe it is the stainless inter connector between the membranes.
Had a look at Desalator website and it looks like the new one is a plastic material not stainless. This makes sense if one pickles the watermaker when not in use as “they say” that the sodium metbisulfite is corrosive.

Has anyone bought one of these connectors?
Just simple push fit right?
Nick
s/v Amelia
AML54-019


 

Nick,

Hopefully, the cause is the O Ring(s) on the Bobin but could be the endcap itself. That said, take a look at your endcaps. If they are white, it is very likely the endcaps have eroded at the Bobin connection. About the time that the A54 was introduced, Dessalator changed the material used to make the endcaps to a stronger material. They did this because the pickling agent caused erosion of the Bobin connection hole.

I think the plastic will work, but the solution I like is to rarely pickle the watermaker, rinsing instead, and when pickling, to use 1/2 of the sodium metabisulfite recommended by Dessalator.

I show these sizes:
O-RINGS FOR DESSALATOR D160 MEMBRANE ASSEMBLY (N70 = Nitrile (Bun)):
  Interconnect Bobbin O-Rings: 9.0 by 1.5 mm N70
  Membrane Nipple O-Rings: 19.0 by 2.5 mm N70
  End Cap O-Rings: 53.0 by 3.5 mm N70
  Dessalator High-Pressure Hose: E740100 SAE100R7 5/16" MAX W. P. 253 BAR

Bill


CW Bill Rouse Amel Owners Yacht School
720 Winnie, Galveston Island, Texas 77550 
   


On Sun, May 29, 2022 at 4:23 AM Nick Newington via groups.io <ngtnewington=aol.com@groups.io> wrote:

I have a small leak from the watermaker outboard end membranes on my 160 litre per hour unit. I believe it is the stainless inter connector between the membranes.
Had a look at Desalator website and it looks like the new one is a plastic material not stainless. This makes sense if one pickles the watermaker when not in use as “they say” that the sodium  metbisulfite  is corrosive.

Has anyone bought one of these connectors?
Just simple push fit right?
Nick
s/v Amelia
AML54-019






Bill Kinney
 

When working on these end caps and bobbins, be REALLY careful.  Even a little bit of torque on the opposite end of the housing is multiplied by the leverage of the long housing.  It is really easy to crack the endcaps or bobbin.  That is the voice of experience...

I agree with BillR, it is unlikely that the bobbin itself is the issue, but when I replaced my endcaps, they came with a new, plastic, interconnect bobbin which I used just to be sure they hadn't changed dimensions anywhere.

Bill Kinney
SM160, Harmonie
Le Marin, Martinique


Nick Newington
 

Hi Bill and Bill, 

Thanks for the reply. 

My end caps are black. So good news there. I guess they are carbon fibre?

I am running the unit now and the leak is almost certainly the interconnect. I have had a very good look and a small drop appears between the two tubes. 

I am not going to do this project now as we have friends arriving and a busy schedule. I have stuffed a rag to catch the drip. There is no particular hurry.


The first thing to decide is whether or not to buy a whole set of end caps and the interconnect bobbin before embarking on the job.” Por su caso “as they say in Spanish or just the o rings and bobbin, or even just the two outboard end caps.

The next question is whether to change the membranes all at the same time; I bought Amelia in 2017 and am pretty sure that the Desalator was original. It has 687 hours on it. The product water is good and in 20 degrees C water makes 160 litres an hour with pressure at the bottom of the green on the gauge.  My wife Cat, who is quite particular to the quality of watermaker water, and is generally someone to pay attention to, says that we make the best water she has ever tasted from a desalinating unit and that we should leave them be. In the face of that logic I am inclined to agree with her.

Any thoughts?

Nick
Fethiye Bay Turkey
AML54-019








On 29 May 2022, at 16:53, Bill Kinney <cruisingconsulting@...> wrote:

When working on these end caps and bobbins, be REALLY careful.  Even a little bit of torque on the opposite end of the housing is multiplied by the leverage of the long housing.  It is really easy to crack the endcaps or bobbin.  That is the voice of experience...

I agree with BillR, it is unlikely that the bobbin itself is the issue, but when I replaced my endcaps, they came with a new, plastic, interconnect bobbin which I used just to be sure they hadn't changed dimensions anywhere.

Bill Kinney
SM160, Harmonie
Le Marin, Martinique


David Vogel
 

When I recently replaced the interconnects at the same time as the end-cap and membranes, I received plastic interconnectors from Dessalator France - previously these were stainless steel. I am unaware of why Dessalator changed the material.

My experience was that the black Delrin endcaps had become eroded around where the interconnector inserts, resulting in weeping, then leaking, then spraying of HP salt-water. The only solution was not to use the watermaker - very unfortunate timing at the beginning of COVID, no spare parts available from any DESSALATOR agents I contacted, the factory in France was then closed by government decree, and then no international freight. A lesson here about fractured supply chains, and spares holdings for remote area cruising (and I thought I was pretty well set up).

Anyway, I think that the endcap-interconnect failure occurred as a consequence of different rates of thermal expansion/contraction of stainless interconnect versus the delrin end-caps -- hot engine room, higher temps of the pressure vessels then, as the water starts to flow, the stainless steel cools and contracts quicker than the Delrin end-caps. A slight temporary size mismatch compromised the seal of the o-rings, allowing a miniscule amount of water to seep past under pressure. This water (and it also drying out, leaving salt crystals behind) further eroded the Delrin, the water rate increased, more erosion, and so on, leading to eventual failure - just like the shuttle SRB o-rings.

One solution would be to have the interconnector with closer thermal characteristic to the Delrin - hence (perhaps) the change from stainless steel to plastic interconnectors.

In my case, in retrospect I believe that another contributory factor was an intermittent exhaust fan (due to failing capacitor), that resulted in higher-than-normal temperatures in the engine room. So greater temperature differentials to start with.

David
SM#396, Perigee
NZ


On 29/5/2022, 7:23 pm, "Nick Newington via groups.io" <main@AmelYachtOwners.groups.io on behalf of ngtnewington@...> wrote:


I have a small leak from the watermaker outboard end membranes on my 160 litre per hour unit. I believe it is the stainless inter connector between the membranes.
Had a look at Desalator website and it looks like the new one is a plastic material not stainless. This makes sense if one pickles the watermaker when not in use as “they say” that the sodium metbisulfite is corrosive.

Has anyone bought one of these connectors?
Just simple push fit right?
Nick
s/v Amelia
AML54-019


 

Nick,

A couple of things:
  • There is substantial anecdotal evidence that the pickling solution is the cause of the erosion that happens with end caps, more so with the white end caps. The problem begins with a small leak which is almost never noticed and ends with chips of the end cap and a lot of saltwater flying through the engine room. See the black ones below which were victims of a hired technician who believed "more is better." I believe that you know what I mean here!.
  • The membranes operate at 50 BAR pressure and when something lets go, a sudden and without notice catastrophe can happen which will ruin most electrical devices in the engine room.
  • We wanted the TDS to always be below 285. We cruised full-time and used the watermaker for most of our freshwater. We changed membranes every 3 years, on average, or at between 300 - 350 hours.
  • The biggest part of changing membranes is the removal of the end caps.
image.png

CW Bill Rouse Amel Owners Yacht School
720 Winnie, Galveston Island, Texas 77550 
   


On Mon, May 30, 2022 at 12:30 AM David Vogel <david.vogel@...> wrote:
When I recently replaced the interconnects at the same time as the end-cap and membranes, I received plastic interconnectors from Dessalator France - previously these were stainless steel.  I am unaware of why Dessalator changed the material.

My experience was that the black Delrin endcaps had become eroded around where the interconnector inserts, resulting in weeping, then leaking, then spraying of HP salt-water.  The only solution was not to use the watermaker - very unfortunate timing at the beginning of COVID, no spare parts available from any DESSALATOR agents I contacted, the factory in France was then closed by government decree, and then no international freight.  A lesson here about fractured supply chains, and spares holdings for remote area cruising (and I thought I was pretty well set up).

Anyway, I think that the endcap-interconnect failure occurred as a consequence of different rates of thermal expansion/contraction of stainless interconnect versus the delrin end-caps -- hot engine room, higher temps of the pressure vessels then, as the water starts to flow, the stainless steel cools and contracts quicker than the Delrin end-caps.  A slight temporary size mismatch compromised the seal of the o-rings, allowing a miniscule amount of water to seep past under pressure.  This water (and it also drying out, leaving salt crystals behind) further eroded the Delrin, the water rate increased, more erosion, and so on, leading to eventual failure - just like the shuttle SRB o-rings.

One solution would be to have the interconnector with closer thermal characteristic to the Delrin - hence (perhaps) the change from stainless steel to plastic interconnectors.

In my case, in retrospect I believe that another contributory factor was an intermittent exhaust fan (due to failing capacitor), that resulted in higher-than-normal temperatures in the engine room.  So greater temperature differentials to start with.

David
SM#396, Perigee
NZ


On 29/5/2022, 7:23 pm, "Nick Newington via groups.io" <main@AmelYachtOwners.groups.io on behalf of ngtnewington=aol.com@groups.io> wrote:


    I have a small leak from the watermaker outboard end membranes on my 160 litre per hour unit. I believe it is the stainless inter connector between the membranes.
    Had a look at Desalator website and it looks like the new one is a plastic material not stainless. This makes sense if one pickles the watermaker when not in use as “they say” that the sodium  metbisulfite  is corrosive.

    Has anyone bought one of these connectors?
    Just simple push fit right?
    Nick
    s/v Amelia
    AML54-019













Germain Jean-Pierre
 

Hello Gang,

I cured the problem altogether by ridding myself of the Dessalator provided membranes and housings. Procured on Alibaba:

- a one piece housing with SS caps. About 42 inches IIRC
- compression rings from a agriculture hydraulic firm. These compress the O ring better than just the end caps.
- added a single longer membrane. (Water Anywhere) New membrane = US$210… compared to US$200 each for the old ones.

Used the low pressure piping supplied by Dessalator. Worked perfectly since. UNLIKELY to leak.

Good luck


Jean-Pierre Germain, formerly Eleuthera, SM007

On 29 May 2022, at 05:23, Nick Newington via groups.io <ngtnewington@...> wrote:


I have a small leak from the watermaker outboard end membranes on my 160 litre per hour unit. I believe it is the stainless inter connector between the membranes.
Had a look at Desalator website and it looks like the new one is a plastic material not stainless. This makes sense if one pickles the watermaker when not in use as “they say” that the sodium metbisulfite is corrosive.

Has anyone bought one of these connectors?
Just simple push fit right?
Nick
s/v Amelia
AML54-019





<image0.png>


Jason Rutledge
 

On Mon, May 30, 2022 at 08:57 AM, Germain Jean-Pierre wrote:
Water Anywhere
Jean!  we need part numbers or more detailed specs of what you did.  I like your concept.
 
--
Jason Rutledge
SV Liahona
SM 335


David Vogel
 

Hi Nick,

Re yr: My end caps are black. So good news there. I guess they are carbon fibre?
The white end-caps provide by Dessalator originally were (I think) nylon, and eventually replaced with black ones, which are made out of Delrin.

David
SM#396, Perigee

From: <main@AmelYachtOwners.groups.io> on behalf of "Nick Newington via groups.io" <ngtnewington@...>
Reply to: <main@AmelYachtOwners.groups.io>
Date: Monday, 30 May 2022 at 2:39 pm
To: <main@amelyachtowners.groups.io>
Subject: Re: [AmelYachtOwners] Desalator interconnect Bobin

Hi Bill and Bill, 

Thanks for the reply. 

My end caps are black. So good news there. I guess they are carbon fibre?

I am running the unit now and the leak is almost certainly the interconnect. I have had a very good look and a small drop appears between the two tubes. 

I am not going to do this project now as we have friends arriving and a busy schedule. I have stuffed a rag to catch the drip. There is no particular hurry.


The first thing to decide is whether or not to buy a whole set of end caps and the interconnect bobbin before embarking on the job.” Por su caso “as they say in Spanish or just the o rings and bobbin, or even just the two outboard end caps.

The next question is whether to change the membranes all at the same time; I bought Amelia in 2017 and am pretty sure that the Desalator was original. It has 687 hours on it. The product water is good and in 20 degrees C water makes 160 litres an hour with pressure at the bottom of the green on the gauge.  My wife Cat, who is quite particular to the quality of watermaker water, and is generally someone to pay attention to, says that we make the best water she has ever tasted from a desalinating unit and that we should leave them be. In the face of that logic I am inclined to agree with her.

Any thoughts?

Nick
Fethiye Bay Turkey
AML54-019








On 29 May 2022, at 16:53, Bill Kinney <cruisingconsulting@...> wrote:
When working on these end caps and bobbins, be REALLY careful.  Even a little bit of torque on the opposite end of the housing is multiplied by the leverage of the long housing.  It is really easy to crack the endcaps or bobbin.  That is the voice of experience...

I agree with BillR, it is unlikely that the bobbin itself is the issue, but when I replaced my endcaps, they came with a new, plastic, interconnect bobbin which I used just to be sure they hadn't changed dimensions anywhere.

Bill Kinney
SM160, Harmonie
Le Marin, Martinique


Germain Jean-Pierre
 

Hello Jason,  

Alibaba:  https://www.alibaba.com/product-detail/Membrane-Housing-Membrane-Reverse-Osmosis-HIgh_1600174348758.html?spm=a2700.galleryofferlist.normal_offer.d_image.18d545c3zBeZUr&s=p

40 inch housing.

Filmtec 40 inch single membrane


Comment:  The total product volume was reduced marginally but the peace of mind assured by this mod was worth it.  Perhaps the direct path of the water flow increased the efficiency…. I was very satisfied.

The O ring compression fittings were sourced at an agricultural hydraulic shop in Kawakawa New Zealand.  They are installed on the outer side of the O ring before installing the SS end fittings.  Because of the added total thickness, the end caps are a bit of a faff…. :-)

Perhaps the new owner could comment on his experience…


Jean-Pierre Germain, formerly Eleuthera, SM007



On 31 May 2022, at 17:49, Jason Rutledge <jasonrutledge1@...> wrote:

Jason Rutledge