water ingress

[dom253]

I am working on an application where an automatic drain is fitted to a compressor wet air receiver. The drain fills with the condensate (under pressures up to 16 bar) and a float arm (like in your toilet) operates a valve which uses the compressed air in the system to operate a cylinder which allows the water to be drained. The problem is that i need to operate the cylinder using the air from inside the drain, and this has big problems.....As you can imagine compressor condensate cxan contain oily residue in the water, and this is finding it's way into the inlet port of the cylinder, which is not what i want. I came up with an idea of usind a half a cup shaped air lock system. The half cup acts as an air trap around the float valve and is supposed to only let air trapped in this void through the valve. This however is not the case. How can i stop water getting into the air system...??? I can not completely enclose the valve as the float arm would be inhibited, and also no air would get through...HELP...kind ladies and gents

 

[Montemayor]

Dom:

I've put in a lot of compressors, especially multi-staged, reciprocating types with condensate separators between stages and I always installed an automatic condensate drain device which was nothing more than a "commode" float valve working in reverse. These devices were made by such companies as Fisher Governor, Austin, Armstrong, and many others. The best ones had Stainless Steel float, arm, and internal valve plug and trim. They worked very well and I never had a failure.

I've never seen what you describe and I frankly don't see the justification for using the float arm to operate a valve which, in turn, uses the compressed air in the system to operate a cylinder which drains the water. In the drainers I used, the system air pressure directly forces the water out through the drain valve - there is no intermediate "cylinder". I recommend you get such a device, which is a very low-priced one.

 

[dom253]

Montemayor.
The drain i'm trying to develop is a zero air loss drain. The condensate is pumped into a oil/water seperator. If i just let the air pressure force the water out then i would loose all that air. The spec was zero air loss, internal pilot supply. The drain must pump 1 litre of cindensate, then close untill that level is reached again

 

[Montemayor]

Dom:

Direct condensate drainers do not have any air loss. The principle of draining vapor-liquid separators is the same: you keep a positive condensate level in the separator and only drain the condensate that is accumulting.

If you are "developing" a zero air loss drain, you should have the answers. I wouldn't separate the oil/water that way.

 

[dcasto]

Just use an electric time based system, the amount of lost air is nothing.

Back in 1977, a company developed what was suppose to be the dream dump valve. The unit had disks that sealed over a series of concentric rings cut in the equivalent to the valve body. The theory was something about the liquid would lubricat or change the vibration of the disk and the disk woul slide and open a path for the liquid to dump. Didn't work. Get a kidney float valve typically used in older steam condensate system.

 

[zdas04]

This sounds like a blowcase operation. A properly designed blowcase loses approximately zero power gas ("approximately zero" because some small amount of gas will disolve into the liquid). The "dump" signal isolates the blowcase from the vessel being drained, opens a high-pressure source, and opens the dump. An "end dump" signal from the float shuts the dump, shuts the power gas, and opens the vent back to the vessel being drained. The liquid enters the blowcase through a check valve that goes shut when the power gas comes in.

David

 

[dom253]

The drain has to operate with no electrical power source. Thanks for the alternative suggestions guys, but my main problem is i need to stop water ingress from the pressure vessel to the pilot air supply. I can not completely enclose the valve because it has a float arm sticking out the side which has to move up and down. I have been looking at fluorocarbon impregnated porous plastic discs downstream. These work for a while but with the pressure behind them the water finds it's way through.

 

[unclesyd]

Take a look at ISC drains. These two have an electrical connection but it may pay to give the call with your requirements.

Someone help me out here.
There is another type drain that used to be used on natural gas distributions lines that was essentially an upside down steam trap.

http://www.iscsales.com/store.asp?pg=products&grp=1153&wcw=google

 

[dcasto]

http://www.boilersupplies.com/floatvalves/index.html

http://www.generalairproducts.com/pages2/drainvlvs.html

Try something like this?

 

[dom253]

Yes some of these products are on exactly the same lines of what i'm thinking. Unfortunately they don't divulge how they keep their pilot air supply and the condensate seperate. There is quite a lot of turbulence when the drain fires, and water gets everywhere. It would be great to physically seperate the air and water side, but not so easy when you have a float arm triggering the cylinder. It's got me up all night this problem. The costs have to be kept to a min, 'as usual' so that leaves little room for technology....!!!!