Steam heat technology questions

[eastwestdivide]

The 10-min pause of Earl of Mount Edgcumbe at Rotherham today, with a copious steam leak from the middle of the train...

 

... led us to seek the answers to a few questions. Google wasn't very forthcoming, and searching the forum, I couldn't see any comprehensive roundup of the technology, which seems to have gone out of use as late as 1987-ish.

 

So, a few questions from someone who grew up in the "high tech" electrically heated Southern Region, for whom steam heating was a novelty:

 

1. How was it controlled in the loco? As far as I can see, steam locos had a valve in the cab diverting some of the steam to the train. Was this adjustable for colder weather? Or could the crew turn off the train supply for a tough gradient?

 

2. Were all coaches and locos fitted with the same pipes? Any compatibility problems between different companies' stock?

 

3. Presumably the train was normally warmer towards the front. But was there any circulation of steam designed into the system? Did it just randomly leak out, or did the last vehicle have an "escape valve" to regulate the flow of steam through the entire train?

 

4. With boiler-fitted diesels, did the boiler have a separate fuel tank? Did the crew have much work to do tending the boiler?

 

 

Thanks in advance.

[Raffles]

I can speak for 47105 as far as boiler usage goes.

 

Generally, you'd fire up and build up a working pressure of steam and then open the valve to feed it in to the train. As you are filling you can wind it out a bit but once the train steam pipe pressure starts to build, you wind it back in and leave it (for load 6) at around 15-20psi. From there, it should require little attention (you should, however, keep an eye on the water level sight-glass) although when approaching a station where the loco would be detached, you would shut off the feed to the train early to allow time for the pressure to drop before the pipes between loco and coaches are split.

 

I'll double check the fuel question but I think, from memory, that the boiler has a pump that draws fuel from the main tank(s).

 

You can guarantee that there will be at least one leak in the train

[eastwestdivide]

Thanks Raffles for the diesel answer.

 

One more question:

5. Presumably steam locos intended for freight trains wouldn't have the valves and fitments for steam heating.

[sixteen 12by 10s]

Hi

 

A few photos taken on 37190 that may explain. The job of controlling the heat was that of the second man. Later locos became fitted for driver only operation, then an auto steam  valve was fitted to allow the driver to control the steam from his driving position.

 

Second mans side, gauges for, water level and boiler pressure, the fuel gauge is for the main tank

 

 

 

 

The auto steam valve, above the drivers head. (four buttons on the right)

 

 

 

 

Clayton steam generator

 

[Chameleon]

Also the system was designed, for some part, to leak. Supposedly at the rear of the train as it needed some degree of throughput through the pips to keep the steam passing through, otherwise it would just condense back into water throughout the train.

[Guest Phil]

Quite often known as CWA "carriage warming apparatus" in steam days, the system wasn't fitted to all classes. Just a steam cock on the firebox manifold via reducing valve, with pipes to each end of the loco / tender.

 

With diesels, I believe most classes just drew the boiler fuel from the loco fuel tanks. The primary exception was the Brush type two (class 30/31). From memory these locos had a separate fuel tanks of different capacities, which was identified by a TOPS codes - "FA", "FB" and "FC".

 

This link is a help to steam heating boilers on class 31s ; http://www.a1alocomotives.co.uk/31162/31162-boilers-and-steam.htm

[Lady_Ava_Hay]

As a bit of an educated guess, I think that the loco's steam was reduced to 20psi of saturated steam, If the pressure in the system dropped below 15psi then a valve would open and steam would be introduced to re-pressurise the system. Because this is red hot saturated steam at low pressure, there would be little condensate and it would be the loss of heat into the pipework and radiators that would cause pressure loss and replacement of the heated steam.

 

Obviously leaks would reduce the efficiency of the system and possibly make the radiators beyond the leak inoperative.

 

One wonders whether there was a feed and return pipe and/or whether there was a pressure controlled bleed valve to vent air from the system but for certain, steam locomotives were fitted with steam heating apparatus ( or not ) and there were apparently some goods vans that had a steam heat connection ( banana vans ).

[45125]

Steam generators/boilers once fired up generally are automatic in operation. Once the boiler has fired up and steam pressure is built up and all the secondmans checks have been done, the main steam valve will be opened and pressure regulated with regards to its length ( 60psi rings a bell for 8-12 coaches). Once pressure is reached the boiler will then cycle between on and off ( Claytons will cycle between high/low fire and off).

 

The secondman will have in front of him a steam pressure gauge, alarm light (dim normal bright fault) and an emergency shut down switch. There may be a water tank contents gauge.

 

The steam heat bags are standard, this was laid down by the RCH in the dim and distant past.

 

On each buffer beam cock there will be condensate trap which will allow condensate to be blown out by steam. Coaches generally have other condensate traps on them, main steam pipe and on the feed pipe to the relevant heaters. There will all also be an isolating cock between these pipes.

 

The steam that is often seen under coaches comes from these valves. By the looks of your photo that is a leaking pipe.

 

Boiler water will come from an either an external or internal tank, (Peaks have both). Fuel will come from either the main tank or a separate boiler fuel tank (26, 27, 31 40 spring to mind).

 

Regards

Al Taylor

[The Stationmaster]

Steam locos fitted for train heating had a separate reducing valve to feed the steam pipe and I think (but am not certain) the initial feed would be set at around the 40 -50 lbs (per square inch) mark although probably reduced as the stock was considered to be warming up. Steam heating was seasonal and applied basically between September and mid June on overnight trains and for a shorter winter period on other trains except sleepers - which were supposed to have a supply available if need all year round.

Having checked the WR Instructions the pressure was supposed to be set according to the length of the train - 40lbs for 5 coaches, 50lbs for 6 - 8 coaches, and 60lbs for more than 8 coaches. The reason for increasing the pressure for longer trains is basically along the lines you surmised - the pressure (and therefore amount of heat) drops the further you are from the engine because the steam went in at the loco and made its way along the pipe until it lost its pressure and could get itself no further.

As far as I know the connections were standardised in BR days on wide ranging stock - possibly earlier - and as the pipes were removed from most stock during the non-heat period and returned to stores for examination and repair it was a relatively easy matter to ensure standardisation over a short period. However although connections were probably standard the arrangement of the valve on the coach headstock did vary a bit. The only connection I have any direct working experience with is the one used on BR built stock and in later years these were also fitted with some sort of drip valve to deal with surplus water (and perhaps also excessive steam pressure?).

Uncoupling a loco from a steam heated train could always be something of an adventure as whoever went in between was reliant on the loco crew shutting off the steam supply some time previously to reduce the pressure in the pipe when it was - carefully - parted although it was sometimes difficult to avoid a drop of hot water down your trousers even if you did everything absolutely correctly. Mind you I can honestly say that I usually found steam pipes a darned sight easier to deal with than recalcitrant ETH jumpers

[jamie92208]

Steam heating could actually draw quite a bit of steam and sometimes you read of the heat being turned down if the loco was struggling. Most freight locos were unfitted and passenger locos were. For minstance the 9F's (Which didn't have steam heat pipes) could only be used on the Somerset and Dorset in the summer.

 

Certainly the 47's had a separate water tank and if I remember correctly the 47/8's were long range locos that had their boiler water tank converted to be an extra fuel tank when they were converted to ETH machines and the boilkers removed.

 

Jamie.

 

PS In the US steam heat could be as high as 140psi and I've got a photo somewhere of the connections which were heavy steel pipes with articulated joints.

[melmerby]

 

Having checked the WR Instructions the pressure was supposed to be set according to the length of the train - 40lbs for 5 coaches, 50lbs for 6 - 8 coaches, and 60lbs for more than 8 coaches. The reason for increasing the pressure for longer trains is basically along the lines you surmised - the pressure (and therefore amount of heat) drops the further you are from the engine because the steam went in at the loco and made its way along the pipe until it lost its pressure and could get itself no further.

 

 

According to GWR 1936 rules pressure was up to 8 carriages = 60lb and above 8 carriages 70-80lbs, 80 lbs to be maintained in severe weather.

 

Interesting fact about the precise times it was used on the GWR:

 

Sleeping cars and Boat trains - heating on from first Monday in September. Express trains running late evening, night or early morning or Business trains - third Monday in September, all other trains 1st October.

Steam heating to be discontinued on all trains 31st May.

 

Keith

[melmerby]

Most freight locos were unfitted and passenger locos were. For minstance the 9F's (Which didn't have steam heat pipes) could only be used on the Somerset and Dorset in the summer.

 

 

 

A couple of Stanier 8Fs were fitted, one of which was allocated to the S&D.

I'm a little surprised that the 9Fs weren't fitted when on the S&D as the equipment appears to be fairly simple to fit.

 

Keith

[45125]

On short trains the last steam heat valve was often cracked open with diesel traction, so as to allow the boiler to cycle properly and stop excessive condensate build up.

 

Al Taylor

[eastwestdivide]

Thanks to everyone above for the info and experiences. So to sum up,

 

1. How was it controlled in the loco? As far as I can see, steam locos had a valve in the cab diverting some of the steam to the train. Yes

Was this adjustable for colder weather? Yes

Or could the crew turn off the train supply for a tough gradient? Yes

 

2. Were all coaches and locos fitted with the same pipes? Yes

Any compatibility problems between different companies' stock? No, standardised early on.

 

3. Presumably the train was normally warmer towards the front. But was there any circulation of steam designed into the system? Yes

Did it just randomly leak out, or did the last vehicle have an "escape valve" to regulate the flow of steam through the entire train? Condensate removal and leaks regulated the flow

 

4. With boiler-fitted diesels, did the boiler have a separate fuel tank? Sometimes separate

Did the crew have much work to do tending the boiler? They were meant to be automatic

 

5. Presumably steam locos intended for freight trains wouldn't have the valves and fitments for steam heating. Yes EDIT: or put more clearly, yes they wouldn't have them generally

 

Thanks again, and keep warm!

[Guest Phil]

On the last point I have a feeling that a couple of "duck eights" were fitted with CWA because I'm sure I read somewhere that one was used as the Royal Train heater when the train used to stable at Berkswell. Still looking for evidence of this.

[roythebus]

On the KESR we steam heat to 45-50 psi per 5 car train, depending how cold it is. Steam is taken from a manifold on the back of the boiler, through a valve to feed the steam heat pipe.

[Boris]

 

3. Presumably the train was normally warmer towards the front. But was there any circulation of steam designed into the system? Yes

Did it just randomly leak out, or did the last vehicle have an "escape valve" to regulate the flow of steam through the entire train? Condensate removal and leaks regulated the flow

 

 

SOme passenger locos also had a type of safety valve fitted to the steam heat main that would "blow off" if the pressure in the steam pipe became too great, a blown steam bag is quite spectacular and will probably remove your arm if you are too close to it.

 

Incidentally "hot loosing" is quite easy and safe with steam heat pipes provided the headstock supply valves at either side are closed as steam heat pipes come with a pressure relief button fitted as part of the head, a couple of good presses with the tow of the boot and your as safe as houses - however for some unfathomable people forget it's there or don't use it!

[slilley]

So far as the Class 47s are concerned they had sperate water tanks located between the bogies for the water suply. A number of 47s in later years had one of the tanks used as an additional fuel tank. The 47/7s for the Edinburgh Glasgow push-pull were the first.

 

On the 47s fuel for the boiler was taken from the main supply. I have a test report on D1507 soon after derating in May 1965 when it worked a test train from KX to Newcastle and return. It says " As the boiler was not at full output it is estimated that the fuel consumed was 45 gallons on the Down train and 35 gallons on the up train. The loco used 305 gallons for the Down train and 320 gallons for the Up train giving fuel consumption of .97 gallons per mile and 1.06 gallons per mile respectively overall".

 

Regards

 

Simon

[The Stationmaster]

SOme passenger locos also had a type of safety valve fitted to the steam heat main that would "blow off" if the pressure in the steam pipe became too great, a blown steam bag is quite spectacular and will probably remove your arm if you are too close to it.

 

Incidentally "hot loosing" is quite easy and safe with steam heat pipes provided the headstock supply valves at either side are closed as steam heat pipes come with a pressure relief button fitted as part of the head, a couple of good presses with the tow of the boot and your as safe as houses - however for some unfathomable people forget it's there or don't use it!

 

Having never come across the term 'hot loosing' I'm not at all sure what it means. However while the later ball valve fitting on standard stock is there to release surplus steam and water it would not drain any water from the bags (although the drain hole in the diaphragm iwa supposed to do that) which means there is still a possibility of some water remaining in the bags.

In any event in many cases the pipes would have to be uncoupled within a few minutes of a train's arrival - a lot of the railway wouldn't have worked if that was not the case - and provided the job was done properly there was no risk, apart from that possible drop of hot water washing your trouser legs. But if the steam supply had been shut off in good time hot water was unlikely

 

 

[Swindon 123]

Did my boiler training at Stratford DRS on the static boiler rig which had working examples of the 4 main boiler types fitted to diesel loco's, these being Spanner 1 fitted to 31's, Spanner 3 fitted to 47 and 46's, Stones fitted to 40 and 47's and lastly Claytons fitted to 37, 40 and 47's. These where the main types of loco's I worked on at "The Cross" so there are other classes fitted with these boilers, (steam generators in the case of the Stones and the Clayton) although saying that I never worked on Claytons a lot, if ever, 37's being rare at KX and only WR 47's seemed to be fitted with Claytons which I also never saw and the only 40's I came across with them never worked or where isolated. The only type of boiler missing from the list is the Spanner 2 which was fitted to Deltics and KX drivers assistants had 2 extra days boiler training to find one to be taught on the job so to speak. Although I did see a couple of loco's fitted with driver remote boiler operating equipment it had all been removed by the late 70's, in fact I never came across a driver who had used one ever. When it came to train operation it could be very hit or miss as to how much steam got back through the train. One trick employed in really cold weather was to very slightly open the valve on the steam heating "bag" on the last coach as this would usually draw the steam down the whole train. Sometimes the train would do it for you. I once had a guard come up and complain to the driver at Peterborough heading north with a 40 I was on that his train was cold. I thought I was doing alright as the steam gauge in the cab was showing nearly 60psi in the train pipe, exceptional for a Stones. One look back at the train told the story. there was steam escaping from everywhere, which was the main reason he was cold. He got even colder after Retford for the loco ran out of boiler water there and the boiler packed up altogether. 40's along with 31's took their fuel from a seperate boiler fuel tank which could be a problem as I found out on a 31 on an overnight train from Doncaster to KX diverted via Lincoln. The loco had come on at York which usually wasn't a problem but it took us so long to go round via Lincoln that the boiler packed up around Hitchen with no fuel. Boiler water wasn't a problem as you could top up, usually Grantham was the favourite. I have topped up various loco's there using the solebar level connection or a couple of times the old steam era water crane opening on the side of the loco. I once blew a steam heat bag apart with a 46 at Doncaster. It made a spectacular hole in the ballast and rattled a few windows in the formans office nearby. One thing you has to be carefull of when uncoupling a steam pipe was the hot water that used to collect at the connections. As well as being made of brass which meant they tended to get hot you could get a lap of scolding hot water if you weren't carefull. To stop this there was a small loose disc in the coupling head which was normally seated by steam pressure but once the steam valves where closed this could be moved and any water collected there allowed to escape. If you could move the disc it was also a good sign that you had remembered to close the steam pipe isolating cocks. It could sometimes be a challange getting the boilers to work properly and a few times I spent more time in the boiler compartment of a loco than the cab but I wouldn't have missed it for the world.

 

Paul J.

 

 

[34theletterbetweenB&D]

3. Presumably the train was normally warmer towards the front. But was there any circulation of steam designed into the system? Yes

To go a little further with this, provided the supply was adequate, the heat will be transmitted along the train efficiently, because the working fluid is a pressurised gas which condenses to vapour and then a liquid, leading to a pressure differential moving the heat supply to the point of condensation. The point of condensation travels along the vessel as far as the supply volume permits; if there is insufficient supply there will be an equilibrium point where the last condensation occurs. Provided the initial rate of steam supply is large enough the rate of propagation can be very fast as the gas/vapour has near as much mobility as a true gas. I have certainly been well warmed at the back of a steam heated 12 coach set!

 

But, there must have been some drill to get most of the air out of the pipe when the steam heat pipe was first connected to stock standing cold. I imagine this would have been by connecting a standing supply, or loco supply from an ECS shunter one end, and opening the connector at the far end of the train, and allowing the steam to come through thus purging the pipe of most of the air in it, before closing off the far end of the train.

[roythebus]

No, there are automatic drain valves under each coach which close when steam pressure is present.

[34theletterbetweenB&D]

Of course, that's the obvious way, a set up that automatically purges when supply is introduced.

[Swindon 123]

34theletterbetweenB&D wrote

But, there must have been some drill to get most of the air out of the pipe when the steam heat pipe was first connected to stock standing cold. I imagine this would have been by connecting a standing supply, or loco supply from an ECS shunter one end, and opening the connector at the far end of the train, and allowing the steam to come through thus purging the pipe of most of the air in it, before closing off the far end of the train.

 

It was usual practice at "The Cross" to heat the ECS in from Bounds Green or Hornsey, especially the sleeper and postal trains that where done all year. That is the reason FP had a large allocation of boiler fitted 31's. On arrival at KX the shunter would unhook the ECS loco and then couple up the train engine which was usually waiting to come on the front. If it was a sleeper or TPO which might stand in the platform for up to an hour it was connected up to the station shore supply from the station heating boiler. If this was out of action for any reason the boiler van was dragged down from FP, along with an attendent fitter, and connected up to the system, usually you would find it on the block in platform 5. I know that some Stratford DA's would go to the back of the train after the loco was coupled up and open the back cock for a couple of minutes to blow the steam thru to get rid of any water that may have collected. Although the system was designed with blow down valves and drip valves built in these could not always be relied on to work and with a train doing 90MPH in freezing temperatures the wind chill would sometimes defeat the best designed systems as I found out on a few occations.

 

Paul J.