I thought I'd add a bit about gas supply.
The biggest problem I've had with any of the burners I've done, including those for my little engines, has been controlling the gas supply so I know what is going on.
For my small engines I used camping gas cylinders with the 7/16 screw on connector. Primarily because I had a control valve for these cylinders that came with the original Rob Roy ceramic burner.
This didnt work very well with the loco for two reasons.
- You have no idea what pressure you are supplying to the burner and you cant really see what is going on, as the fire door needs to be shut.
- The gas in these cylinders is 60/40 butane/propane, you really need propane as it provides more heat.
The light began to shine when one of the club members loaned me his driving trolley that is fitted out for gas running. It has gauges so you know what is going on and carries a 2Kg Primus gas cylinder.
The Primus cylinder is ideal as it is a nice size and has a low profile. We get these filled at the local BOC depot and the gas they supply is guaranteed 60/40 Propane/Butane.
You can see the cylinder has a regulator (orange knob on the right) to control the gas pressure and of course the gauges up front to see what is going on. (the grey cylinder on the left is the accumulator for the vacuum brakes.
This led me to get my own set up like this for testing. (I use the loaner trolley for the track)
This has a bottle mounted regulator with a POL connector and input (post regulator) and output (jet) pressure gauges. In addition there is a cut off valve and two gas control valves in parallel. The idea of the parallel valves is one is preset for idle or pilot burning and the second for the main control of the gas supply. The main control can be shut right down without the burner going out. If there is a major issue the cut off valve can be used.
Of course the problem with this is the use of the LPG type bottles with POL (or whatever connectors) they are generally too big and the wrong shape for carrying on a driving trolley.
The other option is the disposable propane cylinders with the MAPP connector. I had one of these for a portable barbecue but had no way of dealing with the regulation issue until I started searching on Ebay and found the Turbotorch STK-R regulator. The trouble was they were expensive (~US$60) and the shipping prohibitive in comparison. http://www.thermadyne.com/IM_Uploads...05_56-1252.pdf
Then I stumbled across this guy in Hawaii who does these and ships worldwide.http://ultimatespudgun.com/propane-m...tor-p-220.html
US$27 and $12 shipping. It regulates 0-40psi which is ideal when I am trying to get 0-20psi for the burner.
This regulator combined with a pressure gauge now gives me a compact solution for gas supply and control.
The regulator itself provides enough control of gas feed but building this into a driving trolley should really also have a cut off valve and two gas control valves in parallel readily available to the driver rather have them fiddle about with the gas cylinder which can be hidden in the trolley.
There are some issues with these small cylinders
- They are probably only suitable for smaller locos.
- They wouldnt supply enough gas at the right rate for larger locos. Theyd cool right down and the pressure would drop off
- These small cylinders are not refillable and they are more expensive than bottle gas. For example one of these 450gm (1lb) cylinders is NZ$11 whereas a refill of the 2kg Primus bottle is NZ$2.50.
- Although these regulators fit MAPP bottles Id suggest dont even thing about using MAPP gas for your loco.
Of course my other option is the Primus cylinder but I havent found a suitable regulator for one of these and these cylinders dont seem to be current in NZ. I do have a Primus to POL adaptor but when the cylinder, adaptor and POL regulator are coupled together its a really cumbersome. Maybe Ill get something sorted in this area but for now it looks like Im going the small cylinder route.
Regulators side by sidePUBLIC SERVICE NOTICE You are on your own with this. Its up to you to make sure you do things safely and within the bounds of your local regulations