Steam Heating (3)

Following on from Steam Heating (2), I've fitted the carriage warming equipment to Sentinel 7109 ready for a steam test with a train in a few days time.

I began with the boiler connection and isolating valve.

Isolating valve plumbed into the boiler orifice

Having removed the boiler orifice plug and cleaned out the threads, I checked the 1/2" BSP thread type using a parallel tapping tool. The thread was clearly a parallel type and the BSPT tapered thread of the hex nipple was loose unless tightened firmly. This was as expected so I converted the thread to a tapered type using a tapered tapping tool. Now the BSPT tapered thread of the hex nipple fitted much more positively.

I completed the joint using Rocol steam seal. Total loco unavailable time: about half an hour!

I then fitted the standard buffer beam equipment using the purpose-designed flange.

Standard buffer beam equipment fitted to buffer beam (1)

Standard buffer beam equipment fitted to buffer beam (2)

The blue Spirax Sarco Pressure Reducing Valve (PRV) and Safety valve assembly came next followed by the flexible hose to link the isolating valve to the buffer beam equipment.

Blue PRV and safety valve attached to rear of flange (1)

Blue PRV and safety valve attached to rear of flange (2)

Also showing above is the narrow copper pipe to link the buffer beam outlet pressure to the gauge on the cab's rear panel near the roof on the fireman's side.

Steam Heating Pressure Gauge

The weight of the PRV assembly is supported by a clamp between the PRV and safety valve linked to the footplate above by M10 studding.

Having fitted the buffer beam equipment and attached the hose, I hitched up the hose end using the standard support links. It then became obvious that the assembly was somewhat lower than expected. On examining a MK1 carriage for comparison, the assembly is 6 to 8 inches lower.

Hitched with shortened support linkage

To avoid the end dragging on the ground or catching the rails, by wiring the two end parts of the support links together, I've pulled it up to a safe height above the rails as shown above. A more permanent version will be devised in due course.

Prior to steaming, the first test was to to check that the lower height would not prevent a connection being made to a carriage. As shown below, it is all OK.

May be low but fits perfectly.

Now all we need to do is a steam test. I anticipate that the carriages will be too cold, too hot or somewhere in between. If these are the pass criteria, then all should be fine!

Steam Heating (2)

After some pretty hectic weeks, I have most of the sub assemblies ready to fit. Rapid progress has been made possible by Amanda and Rob at South West Engineering Supplies at Bumpers Farm industrial estate near my home in Chippenham. Without them, I'd have been struggling to obtain all the bits and pieces in a short time and they have given me ready access to trial and error items. So a big thank you to them.

Following on from 'Steam Heating (1)', this is how it's developed.

What equipment is needed?

1. High pressure pipework and an isolating valve able to withstand the Sentinel boiler temperature & pressure (212DegC & 275psi).

High Pressure Pipe Fittings and Valve

In the photo above, the steel 'T' fitting's leg links to a 3000psi stainless steel union and thence to a taper threaded hex nipple which will screw into the boiler orifice. This union allows the angle of the 'T' to be set after securely fixing the nipple into the boiler orifice. The plug at the top of the 'T' fitting is to provide another steam outlet for future use.

The second union below the 'T' fitting allows the valve to be orientated appropriately. The valve is a three-part ball valve made by Valtac. I've written about these before. The hex nipple below the valve will connect to flexible braided hose to take the steam down to the buffer beam. Although the nipple in the photo is a steel type, I will be using a parallel threaded hydraulic fitting machined to take a copper washer sealed mating connector.

2. Pipework to carry the boiler pressure steam to the buffer beam apparatus.

Purists might criticise me for using modern flexible stainless steel braided hose instead of copper pipe with braized end fittings. I can order and receive the flexible hose with welded end fittings and a pressure test certificate within a week and be confident in the result. Using copper pipe, I cannot do this. (In fact, the hose arrived in four days!).

I've covered this before in detail here.

3. A pressure reducing valve to take the boiler pressure down to the carriage requirements (about 40psi).

Blue Pressure Reducing Valve (centre) (and one assistant)

Blue Pressure Reducing Valve (and other assistant)

The blue Spirax Sarco PRV is a 1/2" BRV2S with a Green Spring to allow a range of 20-60psi.

Arguably, to reduce the length of high pressure hose, I could have put the pressure reducing valve below the ball valve instead of behind the buffer beam. However the PRV needs to be mounted upright and would have taken up too much space in the cab.

4. A safety valve to prevent exceeding the carriage maximum pressure.

Gunmetal Safety Valve

The safety valve is a 1/2" ART 642 type made by Albion.

Safety Valve Detail including 3 bar setting.

5. A pressure gauge to allow the carriage pressure setting.

3" Steam Pressure gauge

The safety valve has been delivered certified to 45psi (3 bar) so 100psi full-scale is fine. I purchased it new from "thegaugeman61" on Ebay".

6. Heavy duty bracketry to fix the pipework and standard buffer beam equipment to the buffer beam itself.

Flange made to fit the standard buffer beam equipment to the buffer beam

The flange's central hole is tapped to 1.25" BSPT (tapered) to take a 1.25" section of pipe. The pipe section is then held by a Stauff clamp with an additional supporting bar screwed to the bottom edge of the buffer beam. A third bolt fixes the flange through the buffer beam. It is pretty strong and intended to survive heavy handling.

The flange 3-point mounting to the rear buffer beam

The Complete Assembly

I've pre-assembled the 'flat-pack' version of the equipment to show it all together before it disappears out of sight in and under Joyce's metalwork.

Complete 'flat-pack' and assistants

The boiler fitting is at the top. It passes steam via a 'T' fitting to a ball valve and thence to the braided flexible hose. The hose links to the blue PRV which passes lower pressure steam to the safety valve and pressure gauge pipe. Finally the pipe connects to the back of the flange and to the standard buffer beam equipment.

Now all I have to do is fit the kit and test it. Initial fitting will be quite quick for test purposes. I'll clamp the pipework properly when I'm happy it performs satisfactorily. The assistants will not be allowed on site at Midsomer Norton as they haven't passed their Personal Trackside Safety exam (honest!).