The Home Machinist!

Men, have any of you ever taken a look at those automatic air compressor reservoir drain valves that supposedly work by automatically allowing the condensation to drain out?

I'm wondering if this might be usable as a 3"- 6" scale automatic cylinder cock. This part could potentially be modified and probably do a very good job of replicating an air-operated cylinder relief valve, and/or an automatic cylinder relief valve (opening incase of condensate accumulation is excessive and needs to be released.

The best part is that these components only cost $6 -$10 each and that is in CNC machined brass! I'll buy a case of spares at that price.

This might turn out to be the best looking part on my locomotive and the least expensive if it can be made to work!.

Loco112

Check the sheet that comes with these units, I seem to recall they only list a 100 PSI rating. But I could be wrong.

Here is a guy that shows how to install the drain;

http://www.paragoncode.com/shop/compressor/

He also shows how he replaced the plastic tubing with brass tubing, he refers to the 100psi max. recommendation. I also think that the 100psi is the failure pressure of the cheap plastic tubing, and not the brass parts so it should not apply to the way I'm going to use it with brass tubing to control it nstead of the stock plastic tubing, but I'll look into it.

Thanks for the reply!

David Loco112

These won't take steam service.
d.

These won't take steam service.
d.

Please elaborate on why you think that is so.

Is it the seal or the spring, because both can be changed. Its the outside that is the attractive part, fixing the internals would be the simple part, I think, you may differ.

David Loco112

Has anyone thought of using regular relief valves set slightly above MAP for the boiler? Normally they would stay closed unless you get a liquid lock, then they would open to relieve the pressure (protect the cylinder, etc.) and then reclose automatically. Just a thought. Bill

Yes, the inside parts, ie. the seals and the springs would have to be changed.
But brass is brass so the body should be ok. I would say the time you spent redoing these, the ones on the market are already there. Depends where you want to put your efforts.
My 2 cents.
d.

Men, Has anyone had a chance to look at one of these things yet?

I will buy one this weekend and I'll report on it soon afterwards.

How much could a steam seat and a stainless spring cost to upgrade this thing?
My guess is about < $5. Is that overly optomistic or does that sound about right to everyone?

David

It's been a while since I installed this valve on my air compressor, so my memory regarding the 'innerds is a bit vague. I think the plastic diaphram and a seating o-ring would have to be replaced. Definately the control-line hose, which could not take the heat of the compressed air -it got soft and blew out after less than one hours use.

Men, my digital camera has "gone black" and come up with a factory defect, so its on its way back to the mfg'er. Does anyone else have one of these valves that they can take apart to photgraph and post photos of the parts? It will take me a few weeks to get my camera back.

I think this will be a great valve for us and it will be a neat project for you "modifiers" in the forum who like to start with something cheap and end up with someting different and better than the original component. Its going to take two new (simple to make) little poppet valves, maybe a new spring & maybe not, and some valve seat cutting. Then you'd have a valve that functions both as a pneumatically controlled cylinder relief valve, and at the same time as an automatic (hands off) emergency condensation relief valve, giving cylinder condensation a place to escape before it damages your cylinders (just like Bill "bcody" asked about, so to answer your questin Bill, yes I've been thinking about that function and this valve can do that!).

You will get two functions for the price of $6.00 ea. plus the labor to make a couple of simple parts, and you'll not find a better large-scale cylinder cock valve at any price.

I need some help with this men, so shell out the $6 and get yourself one and lets discuss this. If it fails as a base for our relief valve, you can always put it on your shop air-compressor and prevent the manual draining of it, so you will get your $6 out of it either way.


This will be fun for some of us.

David, AKA-Loco112

Lets follow up on these valves. I'll attach photos of the parts sequentially assembled.

I think this would finction "as is". Anyone have a boiler to test these with?

Here is the layout of the new valve the way I visualize it;

Our cylinder port should be connected to the side 1/4" NPT hole (on the side of the body in the central section). The valve would still be controlled though a copper pressure line to the same end port (photo left) that it uses now to pneumatically pressurize it and control it as the "auto drain" valve. The second 1/4"NPT (photo right), on the opposite end of the pneumatic control end, would be the emergency condensation escape and the regular steam escape when having the cocks opened for normal "cocks opened" operation.

All that is needed to have it operate like I suggest is a new stainless spring to give a pressure on the area of the smaller internal valve which would offer an opening at the pressure of BP+10psi (Boiler Pressure (whatever you run) plus 10psi,). The +10psi is to insure that the boiler pressure could not open the valve by itself. This new spring would be inserted where the present weak spring is now; on the (photo right) 1/4" NPT end, or drain end.

We can test this valve at a test pressure of whatever pressure the weak spring will not unseat its valve at, minus about 10% pressure, probably just a few psi of air, that would allow a short test of the vales functions. Anyone game?

i'm not exactly sure just how this is supposed to work. i have one on the air bag suspension system on my old GMC motorhome. it looks like if there is pressure in the air tank the valve is forced shut. when the pressure is gone the spring pushes the valve open to allow the tank to drain; and when air pressure first builds up it pushes water out but shuts off as pressure builds and over powers the spring.

so for our use it would be open and allow the cyl. to drain until you open the throttle and let steam in, then the valve would close. this would trap condensate in the cold cyl. as it forms. now when the valve shifts and pushes the piston the other direction the valve would open and allow the piston to push water out.

does this sound right? i don't know if it will work or not. let us know.
fred v