Steam Heat

Hi all

We are pretty aware of most of the fittings used in the steam heat system, and how they operate, one thing we are not sure of is the purpose of what we refer to as the "Sheeps head" (due to its appearance) Its a large cast iron fitting with two flanges either side located underneath the typical mk1 within the 2" main steam pipe with a drip valve threaded into the base of it. Does anyone know its purpose?
The mk2 version is the same but different in appearance.

Many Thanks

Dan Smith
Ecclesbourne Valley Railway

 

I'm no expert on either steam heat or mk.1 coaches but haven't you answered your own question by saying it has a drip valve in its base? Purpose to remove water?

 

its at the lowest point of the steam heat pipe run, so i would say its a collector, when the steam cools, it needs somewhere to condense and then as the drip valve vents to air, the water needs to be able to escape, otherwise it will rot out the pipe i can't remember seeing a casting, most of ours were on a bent section of pipe with the valve at the lowest point most likily a later mod to replace the casting

 

When steam heating is connected to the train and turned on, a lot of water and quite often rust and crud makes it way through the train steam heating pipes from the direction of the engine. A lot of carriages have a large casting (I referred to it as the turkey) at the lowest point of the steam pipe on each carriage. The steam pipe on a carriage will (should) have a small fall towards the middle where the turkey is. This allows an amount of condensate water to accumulate at the lowest point and drain off through a condensate drain valve (eg Spirax) while leaving the upper section clear for the steam to pass through. Quite often a filter is included to trap crud to stop it clogging drain valves. This all helps the steam to pass through faster and reduce the time to heat the train. On vans etc with shorter pipe runs quite often there is just a tee with a drain valve which is cheaper.

 

Dan - I've seen it referred to as a sediment trap on LNER drawings, and when you look at the internals, and the fact that there is also a bsp plug in it, you would think it does this. Never found any scale in one though, and suspect BR didn't remove plug to empty scale out periodically, although I did a load of work to 26043s heatin at one point, including cleaning out this drip valve. I must have knocked a load of scale down in the pipework though, as sometime later, after a frost, I found the drip valve blocked, and the sheeps head split open from ice in it.... Changed it anyway. No scale in the bit meant to catch scale, just the drip valve.... Some Mk1s weren't fitted, 4623, just half inch pipe between main and auxiliary pipes, and a drip valve in the vicinity. Late LMS seem to be like this, early just have main steam pipe and outlets off that.

Some end valves have drip valve moved further from the steam pipe, just with pipe, bigger - 3" - assume to make drip valve colder.

Just been welding up holes in main pipe around headstocks on 1835, pending making a new bit for the end sections (as have done on 9404, 26043...), take valve off, knock it about a bit, then shine a torch round it to make pinprick light through where holes are, then weld up from the inside where you can get to it!.....

 

The Heritage Railway Association has a guidance note on the subject of steam heating which is available via the HRA web site in the documents section. Because this is a safety related subject this particular guidance note is available to all and you do not have to log in to view it.

see:- www.hra.uk.com

Most of the information covers the locomotive fittings but there are some details of coaching stock items. The central casting in the steam heat pipe acts as a reservoir for condensate which is then drained via the steam trap. It also provides the branch pipe to the secondary pipe which connects to all of the heating elements within the vehicle.

If not kept clean the steam trap is liable to become inoperative and the iron casting may well fracture due to frost damage in cold weather.

Andy.