Hey guys, designing my water table right now and I want to make sure I'm not overlooking anything with this setup. I'm going to be using three 55G drums laying on their side under my table. They already have fittings on the top and bottom that I will be using to run the PVC lines.

To fill the table I would close valve 2, open valve 3, open valve 1. When full, close valve 1, close valve 3.

To drain the table I would open valve 2, open valve 3.

Hopefully my professional drawing makes sense. :o

http://img.photobucket.com/albums/v240/reallyfastz28/cars/wt1.jpg

Most water tables use a chamber in the bottom.
Bend a steel plate and put some notches on one end.
Weld it to the floor(notched end) and the other to the wall. this chamber will fill with water.
Put a pipe in about 1-2 inches below the top of the chamber. Add air to the pipe and it will force the water out the lower slots and raise the warter level. Vent the pipe and the water level will drop down.
Much simpler than piping and 55 gal drums.

Most water tables use a chamber in the bottom.
Bend a steel plate and put some notches on one end.
Weld it to the floor(notched end) and the other to the wall. this chamber will fill with water.
Put a pipe in about 1-2 inches below the top of the chamber. Add air to the pipe and it will force the water out the lower slots and raise the warter level. Vent the pipe and the water level will drop down.
Much simpler than piping and 55 gal drums.
I like this idea but not the welding of all the seams that would have to be water tight...

So does the layout look like it will work to you guys?

It is exactly the same concept....displacing water with air. I think it will work...however you may want to ensure (with blow-off safety valves) that you do not exceed mmore that 2 or 3 psi in those barrels.....especially after they get rusty in a few months.

Most steel air bladders (like the one Alan Bradford describes) are made from 3/16 to 1/2" steel.....with reinforcing plates every few feet.

If valve 1 is open...and vales 2 and 3 accidentally remain closed....expect the end to blow off one of your barrels...could be dangerous...and could dump water on the shop floor!

Jim

You have more valves than you need, and in the wrong configuration.

You do not need to have a valve between the water table and the storage tank/bladder, though it won't hurt anything.

The connection from the bottom of the water table should connect to the bottom of the storage tank / bladder as you have it.

The top connection to the storage tank / bladder does not need to connect back to the water table at all.

The top connection from the storage tank / bladder needs to connect either to two valves or a 3 way valve in such a way that there are three possible states: Add presurized air to the tank / bladder, no air flow, and vent air from the tank / bladder.

When you add air to the tank / bladder it will displace the water up into the water table. When you shut off the air supply the water level in the water table will hold constant (ignoring evaportation, thermal expansion, etc.). When you vent air from the tank / bladder the water will flow from the water table back down into the tank / bladder.

I have a similar setup on the table I built, only I used a 100# LP tank (new) for my storage tank / bladder.

A filter on the connection between the bottom of the tank and the water table is a good idea to help keep sludge out of the tank. I used an inexpensive inline strainer intended for RV use.

Additional thought: Use plastic 55 gal drums and you both eliminate the tank rust issue and should be able to visually see the liquid level in the tanks.

WP1: Thank you for your insights. I'm using plastic 55G drums. :)

I'm working on a revised design and will post it when finished.

OK, much simpler this time around. Close valve, add air till full. Open valve to vent air and the water drains back to the drums. Here's the revised drawing. Let me know what you think.

http://img.photobucket.com/albums/v240/reallyfastz28/cars/wt3.jpg

Presumably you have a valve on the air input to control that side since you need to be able to shut it off to hold the water level constant?

An inline filter / strainer on the connection from the table to the tank would be good.

Presumably you have a valve on the air input to control that side since you need to be able to shut it off to hold the water level constant?

An inline filter / strainer on the connection from the table to the tank would be good.

Yes, there would be a valve and filter. Other than that, it looks good?

It looks reasonable to me. Pretty much how I have my small table setup.

So far you have 2 valves: Valve 1 air in to tanks, Valve 2 tanks to vent. Each to their own but personally I would put a 3rd valve where you originally had it. The valves are cheap and this way you pressurise the system until desired water level is acheived, then close valves 1 (air inlet) and 3 (water level) then depressurise the system by opening valve 2 (vent). By doing this you only have the tanks, lines, and valves under pressure at the time of filling or increasing water height. Although I wouldn't bother, you could possibly use a single "T" valve in place of valves 1 & 2 but you'd have to find one capable of 3 positions instead of the usual 2, i.e. pos1: air in to tanks open and vent port closed (filling), pos2: vent to tank open and air in port closed (venting) and lastly pos3 all ports closed. (most cheap ball valves aren't capable of having all 3 ports closed)

So far you have 2 valves: Valve 1 air in to tanks, Valve 2 tanks to vent. Each to their own but personally I would put a 3rd valve where you originally had it. The valves are cheap and this way you pressurise the system until desired water level is acheived, then close valves 1 (air inlet) and 3 (water level) then depressurise the system by opening valve 2 (vent). By doing this you only have the tanks, lines, and valves under pressure at the time of filling or increasing water height. Although I wouldn't bother, you could possibly use a single "T" valve in place of valves 1 & 2 but you'd have to find one capable of 3 positions instead of the usual 2, i.e. pos1: air in to tanks open and vent port closed (filling), pos2: vent to tank open and air in port closed (venting) and lastly pos3 all ports closed. (most cheap ball valves aren't capable of having all 3 ports closed)

I'll add a valve on the water side just incase I need it. My tables only 30" tall so it shouldn't take more than 2-3 psi to raise the water but it's better to be safe than sorry, right!

The 3 way valve is interesting but I think it might increase operator error...

You really only need two valves, (and I'm also using a regulator). The first valve is a shutoff between the regulated pressure and the top of the barrels. The other valve is the air pressure drain. Any air pressure that is in the barrels will equalize with the atmospheric/head pressure, so there is no residual pressure to isolate other than head pressure (which is eliminated during storage by emptying the table). I'm using this same type of setup, and it works fine (but only with one barrel so far). I also would consider running these barrels in series rather than parallel, as it's possible to drain one barrel and start blowing out air prior to the second barrel being empty (any hydrostatic or hydrodynamic friction between the barrels can create flow differences that will create this situation. The hard part for you is that you're using plastic barrels, so changing the one bung from a 3/4 NPT to a larger one (like the 2" NPT on the large bung) to get sufficient flow, will create issues.

I'm running a steel coolant barrel (soon to be two) and there have been no issues at all.

You really only need two valves, (and I'm also using a regulator). The first valve is a shutoff between the regulated pressure and the top of the barrels. The other valve is the air pressure drain. Any air pressure that is in the barrels will equalize with the atmospheric/head pressure, so there is no residual pressure to isolate other than head pressure (which is eliminated during storage by emptying the table). I'm using this same type of setup, and it works fine (but only with one barrel so far). I also would consider running these barrels in series rather than parallel, as it's possible to drain one barrel and start blowing out air prior to the second barrel being empty (any hydrostatic or hydrodynamic friction between the barrels can create flow differences that will create this situation. The hard part for you is that you're using plastic barrels, so changing the one bung from a 3/4 NPT to a larger one (like the 2" NPT on the large bung) to get sufficient flow, will create issues.

I'm running a steel coolant barrel (soon to be two) and there have been no issues at all.

I might as well add a valve to the water side, they're cheap enough. Then if I ever need to clean out or repair a line I could lock the water in the table while I release the system pressure and work on it.

The bungs are both 2" but one side is coarse buttress threads and the other is fine nps threads. I just dont see how running them in series would increase performance?

I might as well add a valve to the water side, they're cheap enough. Then if I ever need to clean out or repair a line I could lock the water in the table while I release the system pressure and work on it.

The bungs are both 2" but one side is coarse buttress threads and the other is fine nps threads. I just dont see how running them in series would increase performance?

By having the barrels in series, you are forcing the system to empty the first barrel before emptying the second.

If you have the barrels in parallel, there is a potential for friction slow the fluid leaving the furthest barrel from the table inlet, to the point that the closest barrel empties first and negates the benefits of having all of the volume. This can be aggravated by any dross that ends up building up in the piping. I would guess that inevitably the dross will end up in that piping (Murphy's law).

At least by running the system in series, you pretty much know where the dross will end up......in the first barrel.

By having the barrels in series, you are forcing the system to empty the first barrel before emptying the second.

If you have the barrels in parallel, there is a potential for friction slow the fluid leaving the furthest barrel from the table inlet, to the point that the closest barrel empties first and negates the benefits of having all of the volume. This can be aggravated by any dross that ends up building up in the piping. I would guess that inevitably the dross will end up in that piping (Murphy's law).

At least by running the system in series, you pretty much know where the dross will end up......in the first barrel.

That makes sense. Guess I'll run them in series then. Thanks for the suggestion!

Tofi1

Here is my table on youtube...

YouTube - Water table Filling up


I think your design will work fine. Pressure valves are a must!

Clean up my be an issue.

My system is 11 years old and I clean the bottom of tank with a magnet

Luck,

Tom

Tom, Your water table looks well made, thanks for the video!

Here's the final revision. :)

http://img.photobucket.com/albums/v240/reallyfastz28/cars/wt4.jpg