[modeleng] Re: Automatic Drain Cocks
- From: "Phill Smith" <steam@xxxxxxxxxxxxxx>
- To: <modeleng@xxxxxxxxxxxxx>
- Date: Fri, 1 Oct 2004 21:39:26 +0800
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
> MODEL ENGINEERING DISCUSSION LIST.
>
> To UNSUBSCRIBE from this list, send a blank email to,
> modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject
line.
>
>
>
MODEL ENGINEERING DISCUSSION LIST.
To UNSUBSCRIBE from this list, send a blank email to,
modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.
Other related posts:
