Stuart Wheel and Stop Valves

Hello all,

Long time reader, first time poster from Australia - G'day!

As we head into winter I thought it timely to set about restoring a 5" gauge LSBC Virginia I have. It arrived with a dicky weir pump (unreliable, and seized), a hand pump, and an axle pump.

After many years in full size preserved steam circles I am looking to re-plumb the locomotive with two injectors, tidy up the manifold, and fit steam operated cylinder drain cocks (the current geyser is quaint but a nuisance).

I am looking for some manifold valves that are threaded 1/4" x 32tpi and accept a 3/16" OD pipe on the outlet - I have found that Stuart Models produce just the ticket as a 'stop valve' and a 'wheel valve' variety.

Can anyone explain the difference between the two? Is one a coarser action than the other, or does the stop valve just back seat?

As I am looking to use these for injector steam valves for two injectors (one Number 2 (11oz) and one Number 3 (3/4 pint)), which valve would be the more suitable for the application?

Many thanks in anticipation,

David

Not into model railways but IIRC isn't a stop valve known as a tapered plug valve... 90* turn, & the wheel valve operated via wheel handle with a back seat as in globe / gate valve.

George.

What the website does not show is that their wheel valves are straight through 180degree and the stop valves are angled 90 degree valves

I don't actually think there is any difference internally, both are screw down type fittings (not 90degree turn cocks) and its only the fact Stuarts give them a different name.

As to what is more suitable then I would base it on the best plumbing run as to whether you need a straight or 90degree valve.

Edited By JasonB on 06/06/2016 11:02:14

I think Stuarts are about the only ones who do them with 1/4 x 32tpi, all the other suppliers of boiler fittings tend to use 40tpi on the 1/4" fittings

Welcome to the Forum, David.

I'm afraid I can't answer your question, but someone will be along in a minute!

Hi David,

Stuart have always used non standard threads so far as us miniature loco builders are concerned. IMHO 1/4" x 32 tpi is far too coarse, and in the interests of standardisation I wont use it.

As Jason points out, the Stuart 'wheel' valve is a straight through valve, and has very tortuous small passageways, when compared to a 90 degree valve in miniature.

Be careful of using them on injectors as the pipe size may mean you still have a valve that isnt big enough with the 'wheel' type.

Avoid steam valves that do not have the handle fitted onto a square on the spindle.

Next point...

Why 3/16" dia pipe for your small and very small injectors? If of thinwall, 5/32" copper pipe is quite adequate for a medium sized injector on the steam side. Your 11 oz injector ought to have the cone in the union nut made to accept only 1/8" dia pipework, with the delivery and water connections being for 5/32" dia pipe.

I make all my own fittings - they are not difficult and personally I would follow the LBSC instructions for Virginia and also stick with the thread sizes he advocates for boiler fittings (ie no 1/4" x 32 tpi stuff).

If you dont want to make them yourself I would endorse 'here agains'' recommendation of Macc Models, usual disclaimer

Cheers,

Julian

Hello all, thanks for your replies.

Short of manufacturing a new manifold (which I'd rather not do), I'm stuck using the 1/4" x 32tpi mounts in the existing unit. I have discovered that Clevedon Steam make little male x female adaptors for 1/4" 32tpi to 40 tpi, which would then permit the use of Macc Steam valves and fittings - excellent, and for the sake of a few pounds saves a few hours of machining.

Julian, at the present I don't have time to manufacture my own fittings, so am looking at how best to purchase commercial fittings to suit what hardware is already there. Recall this is a 5" gauge locomotive, so the LBSC fittings described in the Virginia book at generally too small.

The drive towards 3/16" OD pipe is to suit the advertised union sizes on Macc Steam's website for the 11oz and 3/4pint injectors - listed as 3/16" - is this not the case? Would appreciate your feedback.

I have a preference to use larger pipe wherever possible - particularly with injectors, to prevent any constriction.

Kind regards to all,

David

Hi David,

I suggest you contact your proposed injector supplier. There may be an error in the online details for pipe sizes.

I checked 2 12oz injectors I have yesterday. Steam connection for 1/8" dia pipe, and water and delivery connections for 5/32" dia pipe. A standard medium injector 26 oz per min requires 5/32" dia pipe on the steam supply side.

The small injectors (eg your 11oz per min) will also have smaller 1/4" x 40 tpi connections and union nuts.

Your constriction argument for pipes applies equally to the valves. It will also apply especially to the filter for a 11oz per min injector which must be very fine and large enough not to restrict the water supply to the injector. The annular gap between steam cone and combining cone is only 4 or 4 1/2 thou on this size of injector.

Cheers,

Julian