Automatic drain cocks

[baritoneplayer]

Hello.

Does anyone have any information on automatic drain cocks for a 5" gauge B1. Do they work? Any idea on who may sell them? How much would be a reasonable amount to pay for a set of four?


Any info on these would be gratefully received.

Many thanks

[Boadicea]

Not sure about the scale, but this diagram may help.
Do they work - yes, just about. They do drain water from the cylinders but, in my experience, sometimes stick open - the way round this is to close the regulator and open it again sharply.
I think they are not as impressive to look at as operated drain cocks.

Only my opinion, others may love them!

Attachments:

[steam4ian]

G'day all

Will they open if you prime?

With manual drain valves you can open them if you sense priming or the boiler gets too full. A great trap is having the pump on through the tunnel where you can't see the glass, opening the throttle to lift the train out raises the water and priming can/will follow. Don't ask me how i know?

Regards
Ian

[sncf141r]

Jun 10, 2011 8:54:18 GMT steam4ian said:

Will they open if you prime?

Ian; I took these off of my piston valved locomotive and put on steam operated drain cocks (steam keeps a ball closed, like a spring on a safety valve) because, I, too, was worried about them.

Slide valved locomotives, no problem (the valves can lift in case of hydraulic pressures) but not so piston-valved locomotives.

Now, I could be wrong, and someone can come up with the math showing how, when the ball is closed, and water comes along that it opens, but until then...

(and, I'm very willing to be proven wrong, but the math is beyond me)

JohnS.

[fostergp6nhp]

Jun 10, 2011 8:54:18 GMT steam4ian said:

G'day all

Will they open if you prime?

Regards
Ian

No

[pault]

Hi All
i can't see that design opening under any condition other than zero pressure or a vacuum ie they would work as a sniffting valve but thats it
Regards
Paul

[pault]

Hi
Cylinder relief valves are basically small safety valves, and in my book should only be in addition to normal drain cocks. They need to be set slightly above boiler pressure, so they do not vent small amounts of water, and will often struggle to get rid of all the water if you prime.
Regards
Paul

[baggo]

I've got them on my Helen Longish and they work well. Any water in the chamber causes turbulence which prevents the ball from seating - it rattles around until all the water is expelled and the steam pressure then seats them. They can sometimes stick if they get gummed up with steam oil and may need the occasional clean. They perhaps are not as effective as 'proper' drain cocks but are a lot easier to fit as they require no linkage for manual operation. It is possible to make them both automatic and manual by having a pin operated by the usual linkage which holds the ball off the seat until they are required to shut.





Note the above are a 'scale' size based on those fitted to a Crab. The balls are only 3/32" diameter but for a larger loco the usual size is 1/8".

Helen has piston valves and I occasionally suffer priming due to lack of attention to the water level and never had any problems.

I think the original idea came from Bill Van Brocklin over in the USA who used them on many of his 3½" locos. They are still popular over there and used on many locos of various gauges.



John

[baritoneplayer]

Thanks to you all. It seems to be one of those topics that best fits into the catagory of "try it and see!".

Having done some further research it appears that they 'work' due to the fact that steam and water travel at different velocities. ie steam travels at a higher velocity causing the ball to lift and seal against the seat. On two different sources of information I found it appears that the dimensions are critical. So I guess it's time to get in the workshop and get to work.

Many thanks for your replies.

[Deleted]

I had considered a set of automatic valves for Tich, however I am concerned that they would defeat the object of having a snifter valve on the loco. I will probably go for a set of plug cocks like in shop, shed and road - once I get far enough to see how much room there is for linkages etc. Might be a bit ticklish!

PS Baritone player are you saxophonist or bari. horn?

James.

[baritoneplayer]

intheshed:... I play Baritone Sax... www.theundercoverband.co.uk

[Boadicea]

Looks as though I am no the only at least part-dissenter then, although I always respect what Baggo says. I do have them and have never had any problems other than the sticking.

Just a for-and-against conventionally operated valves, for - they look very impressive when open and working (to me anyway), against - they are sometimes vulnerable when placing the loco on the track if you have to do it manually.

I have seen slide valve 3½" locos without drain cocks - the only downside being a load of water from the chimney at the start - their owners say cylinder drain cocks are more trouble than they are worth.

If I started from scratch, I think I would go for steam operated conventional cocks. Drawings for these are difficult to find, but I have driven a loco with them and it was the DBs.

[leighsailor]

Hi, I have recently coverted my A3 to steam operated drain cocks as suggested by Boadicea, and they work splendidly, and the pipe work was straight forward, compared to trying to get mechanicial linkage cocks to work together.
mine came from an ME drawing, via a recommendation from this forum.
They have proved very reliable.
Leighsteamer

[sncf141r]

Jun 11, 2011 7:25:18 GMT baritoneplayer said:

Having done some further research it appears that they 'work' due to the fact that steam and water travel at different velocities. ie steam travels at a higher velocity causing the ball to lift and seal against the seat. On two different sources of information I found it appears that the dimensions are critical....

That's what I mean by my "maths is beyond me" in my posting above!

Jun 12, 2011 10:56:56 GMT Tony K said:

For interest, and because any addition to knowledge is an expansion of the power of mankind, there is an alternative in the Northampton Club magazine...

These are very similar to what I put on my 3.1/2" gauge 2-8-2; I really like the "pfffft" when I open them via my valve in the cab. I used annealed brass rather than the pfte; I think the pfte would be a lot simpler than the brass, even if it does not last as long...

JohnS.

[Boadicea]

Jun 12, 2011 15:44:26 GMT leighsailor said:

mine came from an ME drawing, via a recommendation from this forum.
They have proved very reliable. Leighsteamer

Leigh, is this the thread you used please?

sncf141r - please be careful with those pffft noises!

[steamjohn248]

Re my last post on this subject, we have fitted steam operated drains on three of our locos and intend so to do on the fourth ( a Garrett), they are simple to make, require only one pipe from the cab to a four outlet manifold at the front end and seem foolproof and virtually damage proof.
Ours are based on a very much simpler design than the one in ME. being merely a stainless shuttle in a brass housing. I could look out the fag packet drawing if required.

John

[Shawki Shlemon]

John , on my Garratt (a little engine ) I used automatic drain cocks for simplicity and lack of room for flexible pipes. You can note ( on my website page 7 ) how I transfered steam to the cylinders using rigid copper pipes ,This engine I have sold and it has change hands again , its now back to our club , these joints have never given any problems . I thought you may be interested . ;D

[Boadicea]

Jun 12, 2011 23:08:14 GMT steamjohn248 said:

Ours are based on a very much simpler design than the one in ME. being merely a stainless shuttle in a brass housing. I could look out the fag packet drawing if required. John

Yes please mister.

[russell]

+1

Russell.

[ewal]

Me too steamjohn248.

E.W.