Re: [Amel Yacht Owners] watermaker,TDS meter

Ian Shepherd <ocean53@...>

Hi Gary & John.

I have now found out why my inline TDS meter continuously gives an 'Error'
reading. It is not to do with the orientation of the probe at all. The
problem is that the water maker output is so polluted that meter is out of
range. It was a guest on board today that refused a glass of water that
aroused my suspicions. I guess I had got used to the taste, but she
convinced me that something was wrong. I thought it may have been a dirty 50
micron filter, but changing it did nothing to the taste. Another test with a
Hanna confirmed a seriously polluted output (860 with an 'E' in the top
right hand corner.

So yet another case of being fooled by the green light, which as we now know
means nothing.

I have disassembled the 160 l/h membranes which have 185 hours use. (For
Eric- if you have not yet removed your membranes, I can confirm that it is
best to remove the whole cradle first, then unscrew the rods. The only nasty
part of the job is reaching the self tapping screws that hold the blower
ducting together. You may need to do this to get to the two outboard roof
bolts, depending on your installation. My 110/220V transformer gets in the
way of the side screw).

Gary, I am concerned that the sea water side of the membranes is only
isolated from the centre output tube by a single 0-ring on the membrane
nipple. Do you really think this seal is sufficient to reliably withstand a
60 Bar or 870 PSI sideways pressure? ( have the nylon end caps). The caps
don't seem to be a very tight fit on the nipple seal, so this may be the
root of my problem rather than the membranes themselves.

I will get some new seals and jury rig the assembly for a trial. I use
silicon grease on seals. Do you think that the seal may do a better job with
sealant perhaps, at the expense of more difficulty in getting it apart
again? If so, can you recommend any particular type or brand of sealant for
this application?

I was interested to read about your flying exploits. Not so long ago Steve
Jones who was a UK aerobatic champ took me up in his Sukoi. After 19,500
hours of commercial flying, it was the most hair raising experience of my
life! I take my hat off to you for being able to stay ahead of the aircraft
whilst the world is a 270 degree per second roll rate blur and the G-meter
is swinging from +7 to -5! Currently I fly hang gliders, paragliders and


Ian Shepherd SM414 'Crusader'

-------Original Message-------

From: amelliahona
Date: 6/14/2006 2:38:47 AM
Subject: Re: [Amel Yacht Owners] watermaker,TDS meter


Have you tried orienting the sensor horizontally or inverted? I found that
sensor didn't give consistent readings when I had it mounted vertically. I
that perhaps the probes weren't long enough and there was an air bubble
trapped when it was upright. See the photo of my installation in the photo
section and you will see that my sensor is now mounted horizontally and in
that orientation any air in the system is washed past the probes yet the
probes remain imersed in product water. Just a thought.

Regards, Gary

--- In, "Ian Shepherd" <ocean53@...> wrote:

Hi John,

Is your TDS meter made by HM Digital? Mine is, and no matter where I put
in the blue output line, all I get is an 'Err' message when the water
is producing water. It does give a reading when the flow is stopped, i.e.
Just after shutdown, and it works fine in a cup of water. It seems not
to cope with a decent flow rate. I have tried just after the membrane
and just after the control panel with the same result. I have waited 5-10
minutes as per Gary's suggestion, but get the same result.

I would appreciate any advice. Like you, I have never used chemicals on my
membranes. Only the occasional back flush with self made water when not in
use for a while.


Ian Shepherd SM 414 Crusader

-------Original Message-------

From: John and Anne on Bali Hai
Date: 06/08/06 09:17:08
Subject: [Amel Yacht Owners] watermaker,TDS meter

There seems to be no doubt that the dessalateur salinity detector is
non functioning.A cheap and easy solution is to fit a simple TDS meter
in the output line.Such a meter is sold by an American company and also sold in the UK for £23.50.
It is very small and has two sensors. I did not use the "in" sensor
and put the "out" sensor in the blue output line which can be found
behind the wooden cover at the front ot the big cockpit locker. This
blue pipe is easily cut with a razor knife and the ends pushed in as
far as they will go into the sensor. The wires from the sensors are
connected to the meter with a plug which is quite hard to pull out.
Once removed the plug can be pushed through the small gap created by
removing the screws holding the panel in place in the galley. The
meter is held in place with velcro.
The actual meter is only 3x2x0.75 inches with a very small screen.It
is powered by two button cells and stays on for about 20-30 seconds
when the on button is pushed. It does not have an alarm. It is sold
either with fittings for a small or a larger tube which is needed for
my 160ltr ph watermaker.Make sure that the tubes are pushed fully in
and the do a freshwater flush of the membranes to make sure there are
no leaks before replacing the coverboard.
I used it yesterday for the first time and got an initial reading of
over 9,000 ppm which soon went down to about 360ppm which is better
than Maltese mains water.
Incidentally I have followed Olivier's advice and never sterilised or
pickled the membranes which are still delivering 160 ltr. ph. even
though the machine stands idle for about five months a year. We do
however always flush it with product water after use if it is going to
stand idle for more than a few days. We never take on shore water and
rely totally on this machine.
With the benefit of hind sight I should have put both sensors in the
product out line !

Best wishes to all, Anne and John, SM 319

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