I'm in the process of building a new control panel for my watermaker.
While I'm at it I want to replace the kludged Total Disolved Solids (TDS)
meter setup that I have. Right now I have a portable TDS meter stick that
is epoxied into a block of aluminum that I milled out with a cavity for the
meter probes and threaded holes for the in/out water.

When I checking the meter, I saw that it had some water intrusion, probably
from water working up through the prongs in the base of the tester. I also
have no way to clean the probes, so I'm looking for a better solution.

Does anyone have a source for a (panel mountable) TDS meter that's either
12V or battery powered?

-- Geoff
www.GeoffSchultz.org

For an R/O system you want something with a sensitivity to reliably know
when you get below 200 ppm. Hanna makes a series of TDS meters that you can
find at many aquarium supply sites. The HI9833318 is a $185 high range
panel mount meter. With an HI7634-00 probe remote sensor it has a range
from 1 to 2,000 ppm. You can set the relay to trip at any level and it is
sensitive enough for R/O purposes and it comes in 120VAC or 12VDC. I think
the probe is 3/4 NPT so you will probably have to add an adapter to your
product line.

When I was building my system I found the older 983319 in an aquarium supply
site. Talked to the Hanna engineers who recommended the 120V model over the
12V model because voltage fluctuations could cause reading errors. The
983318 is the new model and even if they haven't figured out the voltage
errors it would be a simple matter to put a $20 buck/boost regulator on the
supply line.

Since I put up a picture of my panel on the web site I have seen several of
the pro systems add the same model.

BTW, for a really nice looking panel check out
http://www.frontpanelexpress.com/. High quality reasonably priced
professional looking custom aluminum panels and free software to design it
with. Delivery in 2 weeks or less.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Geoff Schultz" wrote in message
.. .
I'm in the process of building a new control panel for my watermaker.
While I'm at it I want to replace the kludged Total Disolved Solids (TDS)
meter setup that I have. Right now I have a portable TDS meter stick that
is epoxied into a block of aluminum that I milled out with a cavity for
the
meter probes and threaded holes for the in/out water.

When I checking the meter, I saw that it had some water intrusion,
probably
from water working up through the prongs in the base of the tester. I
also
have no way to clean the probes, so I'm looking for a better solution.

Does anyone have a source for a (panel mountable) TDS meter that's either
12V or battery powered?

-- Geoff
www.GeoffSchultz.org

"Glenn Ashmore" wrote in
:

For an R/O system you want something with a sensitivity to reliably
know when you get below 200 ppm. Hanna makes a series of TDS meters
that you can find at many aquarium supply sites. The HI9833318 is a
$185 high range panel mount meter. With an HI7634-00 probe remote
sensor it has a range from 1 to 2,000 ppm. You can set the relay to
trip at any level and it is sensitive enough for R/O purposes and it
comes in 120VAC or 12VDC. I think the probe is 3/4 NPT so you will
probably have to add an adapter to your product line.

When I was building my system I found the older 983319 in an aquarium
supply site. Talked to the Hanna engineers who recommended the 120V
model over the 12V model because voltage fluctuations could cause
reading errors. The 983318 is the new model and even if they haven't
figured out the voltage errors it would be a simple matter to put a
$20 buck/boost regulator on the supply line.

Since I put up a picture of my panel on the web site I have seen
several of the pro systems add the same model.

BTW, for a really nice looking panel check out
http://www.frontpanelexpress.com/. High quality reasonably priced
professional looking custom aluminum panels and free software to
design it with. Delivery in 2 weeks or less.

Glen,

Thanks for the info. I'll check out the Hanna series.

I had book-marked the Front Panel Express site quite a while ago (probably
from a posting from you) and have been using their software to lay out the
panel. I was quite amazed at the low cost. I just need to fill in a few
more components such as the TDS display.

-- Geoff
www.GeoffSchultz.org

Where do you find a $20 buck/boost regulator??

Hanz

Geoff Schultz wrote:
"Glenn Ashmore" wrote in
:


For an R/O system you want something with a sensitivity to reliably
know when you get below 200 ppm. Hanna makes a series of TDS meters
that you can find at many aquarium supply sites. The HI9833318 is a
$185 high range panel mount meter. With an HI7634-00 probe remote
sensor it has a range from 1 to 2,000 ppm. You can set the relay to
trip at any level and it is sensitive enough for R/O purposes and it
comes in 120VAC or 12VDC. I think the probe is 3/4 NPT so you will
probably have to add an adapter to your product line.

When I was building my system I found the older 983319 in an aquarium
supply site. Talked to the Hanna engineers who recommended the 120V
model over the 12V model because voltage fluctuations could cause
reading errors. The 983318 is the new model and even if they haven't
figured out the voltage errors it would be a simple matter to put a
$20 buck/boost regulator on the supply line.

Since I put up a picture of my panel on the web site I have seen
several of the pro systems add the same model.

BTW, for a really nice looking panel check out
http://www.frontpanelexpress.com/. High quality reasonably priced
professional looking custom aluminum panels and free software to
design it with. Delivery in 2 weeks or less.


Glen,

Thanks for the info. I'll check out the Hanna series.

I had book-marked the Front Panel Express site quite a while ago (probably
from a posting from you) and have been using their software to lay out the
panel. I was quite amazed at the low cost. I just need to fill in a few
more components such as the TDS display.

-- Geoff
www.GeoffSchultz.org

Glenn,

I was just looking at your site and was looking at the RO control panel
schematic. One thing that I didn't understand was that it appears that the
fresh water flush tees into the brine water supply line to the pump. How
do you adjust the water pressure so that you're not feeding 800 PSI RO
water to the membranes? I've been told not to run the pressure above 200
PSI when flushing with non-brine water as it will over drive the membrane.

Also, when the solenoid is open, won't you potentially end up with fresh
water back flowing through the pre-filters and out through the seacock? I
suppose that just flushes the pre-filters.

-- Geoff
www.GeoffSchultz.org

That is handled by the 3 way solenoids and the control circuit. When you
hit the backwash button the pressure relief solenoid opens the product side
to waste bypassing the regulator and the backwash solenoid to the intake and
fresh water supply line. House system pressure circulates fresh water
through the membranes for 1 minute with the HP pump running then the HP pump
shuts down and, after 5 seconds to avoid any water hammer effect, the
relief solenoid closes. This forces fresh water back through the
pre-filters for 15 or 20 seconds.

I am estimating about 5 gallons of fresh water for one cycle. Once I see how
it is working I may eliminate the pre-filter backwash from the cycle. I am
afraid it will just push gunk back and forth between filters and strainer
unless I use a lot more fresh water. Probably better to just leave them
alone until the vacuum switch turns on indicating that the filters need
changing/washing.

BTW, disregard that control circuit. It will work but since that one was
built I figured out how to program microprocessors and eliminated 90% of the
chips and all but 2 relays. I can also adjust all the parameters in
software without changing resistor and capacitor values. It works great on
the bench but will probably require some tweaking once in use.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Geoff Schultz" wrote in message
.. .
Glenn,

I was just looking at your site and was looking at the RO control panel
schematic. One thing that I didn't understand was that it appears that
the
fresh water flush tees into the brine water supply line to the pump. How
do you adjust the water pressure so that you're not feeding 800 PSI RO
water to the membranes? I've been told not to run the pressure above 200
PSI when flushing with non-brine water as it will over drive the membrane.

Also, when the solenoid is open, won't you potentially end up with fresh
water back flowing through the pre-filters and out through the seacock? I
suppose that just flushes the pre-filters.

-- Geoff
www.GeoffSchultz.org

Check out the model radio control sites.

The Hanna meters work on less than 100ma so a very small regulator is all
that is needed. I have a pair of miniature switching regulators on my kite
photography rig. One puts out 150ma at 12V for the video down link and the
other 250ma at 5V for the R/C receiver from an 11.1V Li-Po battery. I think
I paid $30 for the pair and they weigh a total of 18 grams.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Hanz Schmidt" wrote in message
...
Where do you find a $20 buck/boost regulator??

Hanz

Geoff Schultz wrote:
"Glenn Ashmore" wrote in
:
For an R/O system you want something with a sensitivity to reliably
know when you get below 200 ppm. Hanna makes a series of TDS meters
that you can find at many aquarium supply sites. The HI9833318 is a
$185 high range panel mount meter. With an HI7634-00 probe remote
sensor it has a range from 1 to 2,000 ppm. You can set the relay to
trip at any level and it is sensitive enough for R/O purposes and it
comes in 120VAC or 12VDC. I think the probe is 3/4 NPT so you will
probably have to add an adapter to your product line.

When I was building my system I found the older 983319 in an aquarium
supply site. Talked to the Hanna engineers who recommended the 120V
model over the 12V model because voltage fluctuations could cause
reading errors. The 983318 is the new model and even if they haven't
figured out the voltage errors it would be a simple matter to put a
$20 buck/boost regulator on the supply line.

Since I put up a picture of my panel on the web site I have seen
several of the pro systems add the same model.

BTW, for a really nice looking panel check out
http://www.frontpanelexpress.com/. High quality reasonably priced
professional looking custom aluminum panels and free software to
design it with. Delivery in 2 weeks or less.


Glen,

Thanks for the info. I'll check out the Hanna series.

I had book-marked the Front Panel Express site quite a while ago
(probably from a posting from you) and have been using their software to
lay out the panel. I was quite amazed at the low cost. I just need to
fill in a few more components such as the TDS display. -- Geoff
www.GeoffSchultz.org

"Glenn Ashmore" wrote in
:

That is handled by the 3 way solenoids and the control circuit. When
you hit the backwash button the pressure relief solenoid opens the
product side to waste bypassing the regulator and the backwash
solenoid to the intake and fresh water supply line. House system
pressure circulates fresh water through the membranes for 1 minute
with the HP pump running then the HP pump shuts down and, after 5
seconds to avoid any water hammer effect, the relief solenoid closes.
This forces fresh water back through the pre-filters for 15 or 20
seconds.

I am estimating about 5 gallons of fresh water for one cycle. Once I
see how it is working I may eliminate the pre-filter backwash from the
cycle. I am afraid it will just push gunk back and forth between
filters and strainer unless I use a lot more fresh water. Probably
better to just leave them alone until the vacuum switch turns on
indicating that the filters need changing/washing.

BTW, disregard that control circuit. It will work but since that one
was built I figured out how to program microprocessors and eliminated
90% of the chips and all but 2 relays. I can also adjust all the
parameters in software without changing resistor and capacitor values.
It works great on the bench but will probably require some tweaking
once in use.

Thanks for the explaination. I personally don't want any electronic
controls on a watermaker. From 7 years of experience with on my own 2+
watermakers and others, they're only a source of problems. I happy
manually turning valves and sticking with the KISS principle. I also
believe that you need to observe the unit while its starting up and
shutting down. 800 PSI has a way of causing problems.

-- Geoff
www.GeoffSchultz.org