[modeleng] Re: Automatic Drain Cocks
- From: "Eric Walker" <eric@xxxxxxxxxxxxxxxxxxxxxxxxxx>
- To: <modeleng@xxxxxxxxxxxxx>
- Date: Fri, 1 Oct 2004 21:25:06 +0100
Phill, I would certainly like details of the steam operated draincocks.
E.W.
----- Original Message -----
From: "Phill Smith" <steam@xxxxxxxxxxxxxx>
To: <modeleng@xxxxxxxxxxxxx>
Sent: Friday, October 01, 2004 2:39 PM
Subject: [modeleng] Re: Automatic Drain Cocks
> Unfortunately there is no such thing as a fool proof drain cock. The laws
of
> physics prevent it.
>
> Though I have seen the patent drawings to one that came close.... The tube
> section with the ball was verticle (not horizontal) with the back end
> attached to the cylinder, and the outlet at the top. Hence with any drop
in
> pressure, the ball would drop. Unfortunately, it was still not perfect, as
> with every stroke there would be some weapage of steam, and it still
> couldn't prevent blowing of off the cylinder cover due to priming except
at
> low speed.
>
> Some of the gents over here make steam opperated drain cocks that come
> closer than many designs. This is purely an accedent of design, but it
> serves the purpose. And the best bit, is they are really simple to make
and
> fit. If you want details let me know.
>
>
> Cheers,
>
> Phill.
>
> ----- Original Message -----
> From: "Clif Walker" <clif.gwr@xxxxxxxxxxxxxx>
> To: <modeleng@xxxxxxxxxxxxx>
> Sent: Friday, October 01, 2004 4:23 AM
> Subject: [modeleng] Automatic Drain Cocks
>
>
> > Hi All,
> > I dont know if any of you saw the recent article in one of the Model
> Engineering magazines regarding automatic drain cocks.I didn't see it
myself
> but I was sent a photostat copy of the design.
> > The article I believe was submitted by someone in South Africa and
> basically consisted of a short horizontal tube with a loose SS ball in it,
> sealed at one end and a hole at the other with a seating. A connection off
> of the top of the tube was made to the cylinder as a normal drain cock
would
> connect.
> > Now the idea seemed to be so simple and the best thing since sliced
bread.
> > The principle explained was that when the tube filled with water the
ball
> dropped off of the seating and allowed the water to drain out,but when
steam
> entered the tube it's velocity pushed the ball along the tube and onto the
> seating.
> > I made a couple of the said beasts and gave them a test by putting a bit
> of plastic tube on the top connection,filling my mouth with water and then
> blowing.I found that the initial water in the cock blew out but as soon as
> an air bubble went through, the ball popped onto it's seating but would
not
> release untill all pressure was released no matter how much water was in
the
> pipe.
> > Now this is not good news for a drain cock as even on a exhaust stroke
> there is still pressure in a cylinder,so it seems that these drain cocks
> would not release no matter how much water was in the cylinders once the
> ball has seated.
> > In such a small dia tube I do not see the difference in velocity between
> water and steam being much different which is the supposed operating
> principle.
> > I did think at the time that how something so simple not been discovered
> before but has anybody else tried playing with these things?
> >
> > Regards
> >
> > Clif
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