Steam regulator

Could some please advise what issue/s of ME that had an article about using ball valves as steam regulators on steam locos

Sorry John I don't know what issues the articles were in but a good candidate successfully used in North America in many live steam locomotives was the Swagelok brand P4T series valves. They offer versions with stainless steel valve bodies and seals good to 600 deg C and 400 psi.

https://www.swagelok.com/downloads/webcatalogs/en/MS-01-59.pdf

Ball valves can be used on steam lines. We have one on a full size traction engine (180 psi) for controlling the steam to the injector and is good for a couple of years, then needs replacing.

They are not good if you want to accurately regulate the volume of steam. The action is too course, only 1/4 turn from off to full on and would not recommend using one for the throttle valve on an engine. Your engine would accelerate too quickly from a stop position because of the sudden rush of steam as you open the valve.

On my model engine, I have shaped the opening hole on the slide valve as a tear drop shape to stop it jumping when I open the throttle. The slide uncovers the smaller end of the opening first, allowing only a small amount of steam to pass.

Paul

Edited By Paul Lousick on 05/02/2021 01:56:48

The prolific builders at my club all use ball valve regulators. They are excellent.

Hi,

I used to work in a factory which used a ball valve to provide a constant low flow of high pressure air. The ball valve was turned by twisting a pinion which engaged a gear attached to the ball in the valve. The whole thing was contained in a cast aluminium body. The gearing was 4:1 so it took a full turn from OFF to ON. Might make a interesting project.

Mind you, if you use Swagelok valves, the quality is so good and the action so smooth, it's usually fairly easy to set them to give the desired flow.

Regards,

Alan

The article about using ball valves as steam regulators starts in ME Vol 225 No 4645.

Jan

Not being a steam man, I imagined using a push rod to lift a ball a controlled, varying, distance off the seat.

Presumably with the push rod on the regulated side, so that full steam pressure pushes the ball back onto the seat.

Misunderstood again. Or worth investigating?

Howard

Howard, it is actually a valve like this which is mounted vertically within the steam dome to replace the traditional disc type valve but still operated by the same lever and rod arrangement from the backhead. They seem to work well without the problems of getting the older ones to seal or operate without excess friction.

Hi All . Thank you. i now have all the information i need.

I am amazed at how well the system works.

Thanks again,

Regards, John Chappell

Greetings, I would be a little nervous about using the valve specified by Jason, because it lacks a gland on the operating spindle, and whilst rated for 150 psi, at the elevated temperatures found inside a boiler or smokebox, i have found the, I think, PTFE, seals soften and start to leak. ball valves are sold for higher pressure & temperature operation, and they do have a spindle gland. They cost abut 3 times the low pressure ones.

I fitted a cheaper one to a 71/4 Britannia, and it blew after a couple of steaming, replaced with the higher pressure version, it now has 6 years concentrated running, no problems.

The use of a ball valve in this application transforms the controllability of a large locomotive, with finger tip response. Some regulator designs can be all or nothing.

Regards

Brian

Has anyone tried ' plug taper' valves for steam regulation.

Still using PTFE as the seal face as in commercial versions.

The advantage being the opening could be shaped to give proportional regulation and the PTFE seats made to suit.

The one I linked to was purely to illustrate the type of "ball valve" to Howard and was the first that came up on google, not suggesting it is suitable or not for the particular use.

Like the one on our washing machine!

Does anyone use a two valve regulator as used on some full scale locos, to give more sensitive control?

Howard

there was a big post on here several years ago when i mentioned how good ball valves were, several people who clearly had never tried them stated that they did not work well. I assure everyone thet they work incredably well with zero leaks and total control, a few pounds from screwfix

Years ago I was involved in a small amount of commercial steam equipment installation and used Spiral Sarco parts and their knowledge.

Whilst I appreciate that they are concerned with full size things there is a wealth of know how on their website which might prove interesting to some, calculations, visualisations of valve internal etc.

SpiraxSarco

Brian