Float Valve / Water Level Control Selection for Closed Tank

[JasonNicholson]

Known:
The tank size and configuration is fixed. The inlet of the water is fixed. The water level needs to be maintained at 2500 gallons by a float valve or some other control. The float valve or control must be in the tank. The fluid is demineralized water at 180F +-20. See picture below.

Problem:
The tank was sized incorrectly but cannot be changed. The float valve / water level control is only thing that can be changed. A person cannot service or adjust the float valve from the manhole because of the scalding water. Basically, as soon as the valve is installed and the tank is in use no adjustment is allowed.

Do any of you have a suggestion for appropriate float valve or other controls that can be implemented? Where do I find them/it?

-Jason Nicholson

 

[Ashereng]

Can you move your control valve to the pipe outside the tank? If you can, the application seems to be straight forward.

OR, is the problem that you only have one opening on the tank and it is for the pipe, which is why you need the float and valve assembly inside the tank?

In this case, what you need is sort of like the float and valve system inside the water tank on typical household toilets. If this is the case, I have seen floats and valves. I believe Fisher used to make such a mechanical float and valve system. I will have to check further.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[JLSeagull]

Someone in the "Measurement and Control" forum may know the model of an old Fisher lever operated level device like that. Most operating companies have design criteria that excludes the use of something like this for several maintenance reasons.

Can you provide a bubbler connection for a level tranmsitter and control with a valve in the outlet piping?

Is instrument or plant air available?

 

[dickon17]

Why not put an electrically operated solenoid valve (fully open/fully closed) in the water inlet pipe and control this valve from a non contact ultrasonic level controller separately mounted through the tank roof. The set points can be easily adjusted from outside the tank.

 

[toothless]

I agree with the above. You are using old technology. Move the valve to the outside of the tank, and use a radar level indicator.

 

[zuccus]

I definitely agree with dickon also. Having a valve where you can't access it because of scalding water is asking for big time trouble.

Float valves have a tendency to break quite often. Make sure you have a block valve outside the tank either way. Plus you want to make sure high level alarm on there.

Zuccus

 

[JasonNicholson]

Guys I am restrict to INSIDE the tank. This is what we were stuck with. The tank is already built and the piping is already finalized and approved. Really the tank was not designed well. Basically, I am trying to find a band aid for a cut that needs stitches.

-Jason Nicholson

 

[itsmoked]

Be interesting when you need to fix that float/valve and have to wait for that water to cool to 100F.. Probably take a month!

How about you modify the system so essentially you have a rod from the valve come out a ways towards the float then rise on a shaft out a hole in the top/manhole cover. There it descends back down to the float now mounted vertically. This allows the float adjustment to occur above the tank not in the tank. If you have a problem with the smalllll penetration hole this would require, then build a small little cover unit out of the same material the tank is fabricated with, essentially 'extending' the tank, hence the adjustment would still be "inside" the tank while now being accessible safely.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[dickon17]

Can anything powered by electricity be mounted to the underside of the manhole?

 

[Oldliar]

Visit the plumbers:

http://www.aquaticeco.com/index.cfm/fuseaction/listings.categories/ssid/353

http://www.metalfloat.com/

http://www.floatvalve.net/default.htm

 

[Ashereng]

Jason, I think the best solution to your particular problem is the Fisher float control valve setup.

Maybe look atthe Fisher Type 171F level regulator and 171L lever valve.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[4Pipes]

Just to add to other posts.

What about adding a spool to the manhole. Say about 600 mm high. i.e. Increasing the standout of the manhole.

Build the float valve in this. Use a stainless steel flex hose with quick connect couplings and suitable isolation valves outside the new "valve chamber". To access the float valve you would take off the manhole cover. To access the tank when it is cool enough, you would unclip your quick connect couplings and unbolt the whole assembly at the existing face of manhole flange.
If you are using a float valve, I would suspect that you should also be using a stilling chamber for the float which could also be built into the assembly.

 

[Newmanite]

How about taking it all out and where the tube is drilled and welded into the position for the float fit a tube with a float type device in that.As it rises vertically within the tube a pin or indicator arm could react with a magnetic switch outside the tank.If it becomes faulty you only have to unscrew it from the socket and remove the whole assembly?

 

[JasonNicholson]

We ended up using a Keckley no 7 1.5" float valve. Thanks for all your suggestions.

-Jason Nicholson