Lesson in physics..and gravity

geshields · 12-06-2004, 04:14 PM

I have been trying to find a place to put my topoff container for my new tank and finally found a great spot for it out in the garage. It all sounded perfect..I could make it as large as I wanted, I had gravity pressure working for me. etc..

I am going to run my Kalk reactor inline betweeen the topoff and the float valve in the sump. Kalk reactor is 8" OD acrylic tubing X 30" Tall.. It was all going to work out great..I knew there had to be a downside, so I called an engineer I know and we figured the pressure out..

The topoff container would be located 10 feet up in my garage...basement floor is approx. 8 feet below the garage. Total head of 18 ft. We proceeded to figure out the PSI that the Kalk reactor would see because I hate leaks.. At 18 feet of head, the reactor would see 7.79PSI...pretty high...to give you an idea of how much pressure that is..at 5PSI, a 3/8" thick acrylic flange will bow upwards 1/8" Needless to say, I will scrap this idea. Total pressure on the flange of the Kalk Reactor would have been 391 pounds trying to push upward...

Now just got to find a place in the basement for it...

Greg

Minnreefer · 12-06-2004, 04:20 PM

probably a stupid idea, but could you reinforce the reactor with a harder substance on the outside of the reactor? It may not be very pretty but it could work.

David Grigor · 12-06-2004, 06:07 PM

So if the Kalk Reactor is also in the garage does the PSI inside the reactor change or still the same as if it were located 18 feet down ?

Other option. Store the water in the garage. Using a float valve fill a smaller container down stairs and feed the Kalk reactor from the smaller (interim ) container.

ksarauer · 12-06-2004, 06:54 PM

Just to give you an idea... I had my holding tank ~6 feet above the Kalk reacotr, and I had leaks from the pressure.

I have moved the Kalk reactor to just below my holding tank.

FYI - You may not want a holding tank that is too big. I recently had a float valve stick, which could have dumped an extra 5 gallons of water on the floor if the holding tank was full.

I am still using a float valve (new one, the old one took on water) with an electronic switch, that controls a RO/DI Solenoid for failover. http://www.autotopoff.com/products.html

Kevin

geshields · 12-06-2004, 10:21 PM

Quote:

Originally Posted by David Grigor

So if the Kalk Reactor is also in the garage does the PSI inside the reactor change or still the same as if it were located 18 feet down ?

Good question...I have no idea. I wrote an answer before I really thought about and initial guess was that it is only the difference in the height between the reactor and the water topoff....but after thinking about it...the whole "chain" of items between the topoff container and the float valve would be seeing the 8 PSI...

Quote:

Originally Posted by David Grigor

Other option. Store the water in the garage. Using a float valve fill a smaller container down stairs and feed the Kalk reactor from the smaller (interim ) container.

Sounds like a pretty good plan...

Greg

marm64 · 12-07-2004, 09:20 AM

You could always use a pressure reducing valve to drop the pressure down to what you want in the basement, do not know if you could get one reef safe though.

For the pressure the equation is P=pgh where P is pressure, p is density of liquid, g is gravity, and h is the height of of liquid. The pressure would be a lot less the closer to the container. The smaller the tubing the less pressure you will also get due to the resistance in the tubing.

geshields · 12-07-2004, 09:43 AM

I found a formula that stated p(pressure in psi)= height(in feet)/2.31

Pressure reducing valve would work because it would be before any saltwater. Size of tubing will not matter at least for static pressure...for dynamic pressure, the larger the hose, the less pressure..

geshields · 12-07-2004, 09:45 AM

http://www.mcnallyinstitute.com/16-html/16-08.htm

geshields · 12-07-2004, 09:58 AM

Just found one that will give gallons per minute....

http://www.geocities.com/gletiecq/theory4.html

GPM = ( 2.56 * X * d^2 ) / sqrt(y)
X = horizontal distance in inches
d = pipe diameter in inches
y = vertical distance in inches

If we plug in that we are using 1/4" R.O tubing with an inner diameter of 1/8"(.125"), topoff(fresh water storage) is 6 feet (72") above the float valve and we will run 10 feet (120") of tubing horizontally to get to the float valve...

Max flow will be .57 Gallons per minute...

And here I thought that I was done with school...

Greg

civil · 12-07-2004, 01:10 PM

Greg,
This system would best be assumed as a static system. Even with a large tank, as you have, there is essentially no flow. At least not enough to start thinking about head loss due to friction of the fluid.

Think of water towers, the same equation will apply. The water is held up in the air to provide head for the system. Water pressure in a city system is provided one of two ways, pumps or towers. Pumps are obviously more expensive and they are much larger than any sequence pump you have ever seen where towers continue to work without electricity. So if you want 60 psi in your system you need a tower about 140' above the mean.

David's idea of providing a small interim tank sounds like the most fool proof, which I know Greg likes

That way all pressure is shut off at the float valve and the only pressure the reactor will see is that from the top of the interim tank to the outlet, which should be sufficiently low for the acrylic end caps.

Havre · 12-07-2004, 02:05 PM

GPM = ( 2.56 * X * d^2 ) / sqrt(y)

???????????????????? This is a warning from your moderator...you guys are getting wayyyyyyyyyyyyy too technical!!

otolith · 12-07-2004, 02:12 PM

Quote:

Originally Posted by geshields

And here I thought that I was done with school...

Greg

You are done with school. You're just not done learning.

I agree with what civil said, since he is a civil engineer and all.

otolith · 12-07-2004, 02:16 PM

Another thought...I suppose you could just put a spigot on the main water container in the garage, and just run some tubing into your container downstairs, it shouldn't be that big of a deal. The only thing is that it's not fully automated, but shouldn't add too much to your routine maintenance.

David Grigor · 12-07-2004, 02:34 PM

Kevin, What type/brand of float valve did you have stick in the on position? I have been using Kent float valves since 1996 and have never seen it stick on only stick off because of Kalk build up. Outside of some foreign object getting caught in there I really don't see how it can get stuck on.

geshields · 12-07-2004, 02:37 PM

Yep..that is what I was planning.

It will be sort of setup like my old 58 but I will never have to carry water across the house...

Also, the RO/DI will not be continually making water. I can get 20G, then it turns on, fills upper container, then shuts off...

Like this..