Topics

[Amel Yacht Owners] Dessalator Water Maker Issues & New Photos


eric freedman
 

Gary,
How did you hook the salinity sensor into the watermaker output?
Fair Winds,
Eric
Amel Super Maramu #376 Kimberlite

-----Original Message-----
From: amelyachtowners@...
[mailto:amelyachtowners@...] On Behalf Of amelliahona
Sent: Wednesday, February 15, 2006 6:20 PM
To: amelyachtowners@...
Subject: [Amel Yacht Owners] Dessalator Water Maker Issues & New Photos

15 Feb 2006

Hi all:

I just completed installation of new FilmTec SW30-2540 membranes ($177.00
each from
Air, Water, and Ice, Inc.) in my water maker. Not a difficult job one
accomplished. Hardest
part was getting the end caps off. I have detailed the process in some
Photos that I just
uploaded. My end caps were all ok, the O-rings were all ok, there was some
moderate
corrosion of the stainless interconnect thimble, and a defect in the brine
seal of one of the
membranes. However, I believe the failure mode was the membrane material
themselves.

Output is good, my new Omega EC monitor (220 volt wired to the desalinator
breaker) is
working great. The Dessalator salinity sensor does not work at all despite
testing it three
ways from Sunday with various scenarios. I am still trying to get some
answers from Rod
Boreham and Dessalator. I have spent a couple of hours on the phone with
Rod and a
couple of calls to Dessalator plus about 20 emails back and forth. I will
let you all know
more when I know more.

In the mean time, I would not run my Dessalator watermaker without backup
continuous
monitoring of the TDS (Total Dissolved Solids) or EC (Electrical
Conductivity). Until we
know more there is just no guarantee that the Dessalator sensor will divert
bad quality
water during an operational cycle, thus filling your fresh water tank with
salt water.

Regards, Gary Silver, s/v Liahona SM 2000 Hull # 335






Yahoo! Groups Links


amelliahona <no_reply@...>
 

--- In amelyachtowners@..., eric <kimberlite@...> wrote:
24 Feb 2006
Eric:

I purchased 3/8 inch quick connect fittings at Home Depot (white plastic, push together
fitting that are good to 100 psi) and cut the blue 10 mm product water line. There is
virtually no pressure on this line . The sensor for the EC system that I mentioned
previously plumbs into a 1/2 in pipe thread fitting. I bought a 1/2 inch PVC pipe "T"
fitting, and plumbed it with the quick connects. So the sensor is just immersed in the
product water as it flows by. I'll post photos after my next trip. I took 220 volt 50 Hertz
Power from the circuit breaker for the water maker.

I have noticed that upon startup the EC briefly goes to somewhere above 2000
microsiemens but then within 30 seconds it comes down to about 350. If you run the
watermaker below green range pressure the EC is actually higher than if run in the normal
operating range. I don't quite understand that but it is consistent. I inquired of the Wafer
Fire and Ice people that I bought my membranes from and they tell me that this is normal.
They call it TDS creep. Evidently when the system is shut down the high TDS on the sea
water side draws the product water back across the membrane by osmotic pressure. This
then concentrates the solulte in the product water side as more and more water is drawn
back across the membranes. The longer the system sits idle the more TDS creep there is.
So the initial minute or two of product water will be high in TDS (EC). Perhaps that is why
the Dessalator system had a timer. I have spent hours corresponding with Dessalator and
they will not provide me with schematics or a logic diagram for the system. I plan to take
detail digital photos of the circuit boards next month when I get on the boat and reverse
engineer the electronics. It doesn't appear to be that complicated. Dessalator says that
they do have spare logic circuit boards for sale and will install one if I ship my system to
them but they at the same time make no guarantees that the system will behave as
advertised even with a new board installed. This is about the goofiest company policy that
I have ever run across.

Regards, Gary


Gary,
How did you hook the salinity sensor into the watermaker output?
Fair Winds,
Eric
Amel Super Maramu #376 Kimberlite


eric freedman
 

Gary,
Thanks for the info.
Where is your boat now?
We are in St Martin.
Fair Winds,
Eric

-----Original Message-----
From: amelyachtowners@...
[mailto:amelyachtowners@...] On Behalf Of amelliahona
Sent: Saturday, February 25, 2006 12:24 AM
To: amelyachtowners@...
Subject: Re: [Amel Yacht Owners] Dessalator Water Maker Issues & New Photos

--- In amelyachtowners@..., eric <kimberlite@...> wrote:
24 Feb 2006
Eric:

I purchased 3/8 inch quick connect fittings at Home Depot (white plastic,
push together
fitting that are good to 100 psi) and cut the blue 10 mm product water line.
There is
virtually no pressure on this line . The sensor for the EC system that I
mentioned
previously plumbs into a 1/2 in pipe thread fitting. I bought a 1/2 inch
PVC pipe "T"
fitting, and plumbed it with the quick connects. So the sensor is just
immersed in the
product water as it flows by. I'll post photos after my next trip. I took
220 volt 50 Hertz
Power from the circuit breaker for the water maker.

I have noticed that upon startup the EC briefly goes to somewhere above 2000

microsiemens but then within 30 seconds it comes down to about 350. If you
run the
watermaker below green range pressure the EC is actually higher than if run
in the normal
operating range. I don't quite understand that but it is consistent. I
inquired of the Wafer
Fire and Ice people that I bought my membranes from and they tell me that
this is normal.
They call it TDS creep. Evidently when the system is shut down the high TDS
on the sea
water side draws the product water back across the membrane by osmotic
pressure. This
then concentrates the solulte in the product water side as more and more
water is drawn
back across the membranes. The longer the system sits idle the more TDS
creep there is.
So the initial minute or two of product water will be high in TDS (EC).
Perhaps that is why
the Dessalator system had a timer. I have spent hours corresponding with
Dessalator and
they will not provide me with schematics or a logic diagram for the system.
I plan to take
detail digital photos of the circuit boards next month when I get on the
boat and reverse
engineer the electronics. It doesn't appear to be that complicated.
Dessalator says that
they do have spare logic circuit boards for sale and will install one if I
ship my system to
them but they at the same time make no guarantees that the system will
behave as
advertised even with a new board installed. This is about the goofiest
company policy that
I have ever run across.

Regards, Gary


Gary,
How did you hook the salinity sensor into the watermaker output?
Fair Winds,
Eric
Amel Super Maramu #376 Kimberlite






Yahoo! Groups Links


Steve Constantine <maramu_49@...>
 

Gary,

I may have a possible answer to your question about the higher EC reading when the pressure is below the green range.

According to Rod Boreham, the membranes are not perfectly cylindrical. They have a slightly larger diameter in the center than at the two ends. The reason for this is to allow for distortion when the pressure is applied.

The membranes are not constructed by rolling a square sheet of material from one side to the other. They are rolled corner to corner. This creates angular seams along the length of the tube. They are actually rolled with enough slack to account for a perfect fit under pressure. If you run the water maker below the prescribed pressure, you are squeezing salt water past the unsealed seams. In other words, they have to be fully pressurized to seal properly. The good news is that your EC appears to be finding it.

Rod was quite emphatic that the Dessalator should only be operated entirely within the green zone. Any higher or lower will result in problems. You should check with Rod to be sure though. I think I interpretted his recommendations correctly, but one never knows.

It may also be due to something else entirely, but this seemed to make sense to me.

Regards,

Steve and Donna. SM#340 Summer Love



amelliahona <no_reply@...> wrote:
--- In amelyachtowners@..., eric <kimberlite@...> wrote:
24 Feb 2006
Eric:

I purchased 3/8 inch quick connect fittings at Home Depot (white plastic, push together
fitting that are good to 100 psi) and cut the blue 10 mm product water line. There is
virtually no pressure on this line . The sensor for the EC system that I mentioned
previously plumbs into a 1/2 in pipe thread fitting. I bought a 1/2 inch PVC pipe "T"
fitting, and plumbed it with the quick connects. So the sensor is just immersed in the
product water as it flows by. I'll post photos after my next trip. I took 220 volt 50 Hertz
Power from the circuit breaker for the water maker.

I have noticed that upon startup the EC briefly goes to somewhere above 2000
microsiemens but then within 30 seconds it comes down to about 350. If you run the
watermaker below green range pressure the EC is actually higher than if run in the normal
operating range. I don't quite understand that but it is consistent. I inquired of the Wafer
Fire and Ice people that I bought my membranes from and they tell me that this is normal.
They call it TDS creep. Evidently when the system is shut down the high TDS on the sea
water side draws the product water back across the membrane by osmotic pressure. This
then concentrates the solulte in the product water side as more and more water is drawn
back across the membranes. The longer the system sits idle the more TDS creep there is.
So the initial minute or two of product water will be high in TDS (EC). Perhaps that is why
the Dessalator system had a timer. I have spent hours corresponding with Dessalator and
they will not provide me with schematics or a logic diagram for the system. I plan to take
detail digital photos of the circuit boards next month when I get on the boat and reverse
engineer the electronics. It doesn't appear to be that complicated. Dessalator says that
they do have spare logic circuit boards for sale and will install one if I ship my system to
them but they at the same time make no guarantees that the system will behave as
advertised even with a new board installed. This is about the goofiest company policy that
I have ever run across.

Regards, Gary


Gary,
How did you hook the salinity sensor into the watermaker output?
Fair Winds,
Eric
Amel Super Maramu #376 Kimberlite





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amelliahona <no_reply@...>
 

Steve:

Thanks for your thoughts. I have inquired of several sources about these issues and this
is what I have distilled:

There are two separate phenomenon both of which are applicable to any RO membrane
system:

1. TDS CREEP. Imagine that on once side of the membrane you have very high TDS
(seawater with about 32,000 ppm TDS) and on the other side you have product water with
a TDS of about 400-500 ppm. Water is forced across the membrane by the 55 bar (800
PSI) pressure gradient established by the high-pressure piston pump. This high-pressure
gradient overcomes the natural osmosis and drives the physics of osmosis in the reverse
direction (RO). When the system is shut down the pressure equalizes on both sides of the
membrane but there remains still a very high gradient in solute (TDS) across the
membrane. At this point natural osmosis begins to occur with water being drawn back
across the membrane to the high TDS side in an effort to try to equalize the osmotic
pressure on both sides of the membrane. The longer the membrane sits idle the more
water is drawn back across to the high TDS side. As more and more water is drawn back
across the membrane there is an ever-diminishing amount of pure water on the low TDS
side (but still the same amount of solute) so the TDS measured in ppm actually increases.
When the system is restarted there will be a brief period of relatively high salinity product
water. My experience with my continuous EC meter is that this high salinity, TDS Creep
water with a TDS of about 2500 to 4000, only last less than a minute before it is diluted
with the new 400-500 ppm TDS product water.

2. PRESSURE DEPENDENCY OF PRODUCT WATER TDS. That is, as the pressure of the RO
process is increased the TDS of the product water decreases. This phenomenon is much
less clearly understood. Rod Boreham gave me a similar description to what he gave you
but he also implied that without pressurized water on the chevron seal in the tube that
seawater could leak by. This just didn't seem logical to me for two reasons; a) the chevron
seal that seals the seawater side of the membrane in the tube from the product water side
is very tight. It is all you can do to get the membrane in or out of the tube because it is so
tight. Also, b) the membranes are robotically produced (hence their dramatically reduced
price and better performance than the old style membranes) and the edges and seams are
absolutely sealed. Again, what I can best understand from several sources is that on a
molecular level the angstrom size pores, that allow water to pass and not the solutes,
actually are squeezed even tighter (made smaller) when under pressure and up to the
rupturing pressure of the membrane the pores become smaller and smaller. This allows
less and less solute to pass. All RO membranes exhibit this quality and there is an
optimum pressure for highest quality water and least potential for harm to the membrane.
By running in the green zone the highest quality water will be produced while staying
safely below membrane rupture point.

Related to the salinity sensor and other questions I have raised on this forum regarding
the Dessalator control system suffice it to say that I am still trying to ferret out the truth. I
have been in touch with Amel, Joel, Dessalator and Rod Boreham. I have gone around and
around with Dessalator. Rod has attempted to be helpful but his information comes from
Dessalator and either because of language barriers or just reluctance by Dessalator to be
fully forthcoming he has been unable to come up with a satisfactory answers for me. I
have asked Dessalator for schematics and logic diagrams for their circuit board so that I
might understand the system and know how to trouble shoot it but they tell me that they
have neither available because the board was produced by a subcontractor that is no
longer in business.

This much I know for sure:
1) Amel believed that the system operated as advertised when we took delivery of our
boat. I am still unable to determine if indeed it did live up to Dessalator's claims.
2) There evidently is no way to know if the original equipment salinity sensor is working
correctly or not. The two-minute timer idea may or may not be accurate. I have so far
received no assurance from Dessalator that a properly functioning machine will sense and
divert high TDS water during water production following system start-up.
3) I reiterate my belief that the Dessalator monitoring system cannot be relied on and that
a secondary monitoring system is necessary. I will stick with that statement until
Dessalator or Amel can tell me how one can determine if their original equipment salinity
monitor is functional.
4) Amel has been very good to work with and remains one of the finest companies I have
ever done business with.

Sincerely,

Gary Silver


Gary,

I may have a possible answer to your question about the higher EC reading when the
pressure is below the green range.

According to Rod Boreham, the membranes are not perfectly cylindrical. They have a
slightly larger diameter in the center than at the two ends. The reason for this is to allow
for distortion when the pressure is applied.

The membranes are not constructed by rolling a square sheet of material from one
side to the other. They are rolled corner to corner. This creates angular seams along the
length of the tube. They are actually rolled with enough slack to account for a perfect fit
under pressure. If you run the water maker below the prescribed pressure, you are
squeezing salt water past the unsealed seams. In other words, they have to be fully
pressurized to seal properly. The good news is that your EC appears to be finding it.

Rod was quite emphatic that the Dessalator should only be operated entirely within the
green zone. Any higher or lower will result in problems. You should check with Rod to be
sure though. I think I interpretted his recommendations correctly, but one never knows.

It may also be due to something else entirely, but this seemed to make sense to me.

Regards,

Steve and Donna. SM#340 Summer Love