Two quick steamie questions...

C

CoggesRailway

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1) why do roundhouse say not to use anything but butane? It seems that mixed is a lot easier to come by... not that straight butane is a problem of course...

2) Interestedly following the Lady Annette thread (one day....) but interested about of talk of a 55psi saftey valve- assuming the boiler is the same on the standard lady anne can I fit one, and if so is there more performance to have. I do find that to haul a train round my gradients effectively i need it more or less blowing off - or wait to gather steam at the bottom of hills if running the burner lower. would a higher saftey valve threshold help this is anyway?
 
CoggesRailway said:
1) why do roundhouse say not to use anything but butane? It seems that mixed is a lot easier to come by... not that straight butane is a problem of course...



2) Interestedly following the Lady Annette thread (one day....) but interested about of talk of a 55psi saftey valve- assuming the boiler is the same on the standard lady anne can I fit one, and if so is there more performance to have. I do find that to haul a train round my gradients effectively i need it more or less blowing off - or wait to gather steam at the bottom of hills if running the burner lower. would a higher saftey valve threshold help this is anyway?
Click to expand...


1) They do say this ? but their gas tanks are designed to hold butane mixed gas as well. This came up on the 16mm egroup when I recommended to someone that they use 'butane only' (cos that is what Roundhouse say in their instructions). In fact i happily use mixed gas in RH locos but would not recommend against RH instructions. Roger Loxely told me, on group, that their tanks are designed for both ? so there you are ? used mixed in a modern Roundhouse and straight butane in older models with the square tanks.


2) The boiler on Annette is a coal-fired boiler with proper smokebox and blastpipe and therefore very different to a standard single flue RH boiler which entrains its own air via the gas burner. Certainly you could raise the pressure to 55psi safely on the standard boiler ? but there is no reason for doing so ? Roundhouse have set the optimum for their model... I am surprised that you need full working pressure for your gradients ? sounds like you have hills rather than railway gradients. The biggest reason for the higher pressure on the coal-fired boilers is to allow some flexibility with the coal fire. If you ran at 40psi then you would have to be very careful not to lose the fire in normal running... You could try a couple of turns of the safety valve ? bring it up to 45psi ? but I doubt that you will find it will make much difference.

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a.) Propane expands to a far greater extent when heated than butane does. This means the pressure in the gas tank, especially in warm conditions, can reach levels greater than the tank is designed to cope with. In practice it shouldn't be a problem, it's just covering their own backs. However using mix can make setting the gas regulator a bit hit and miss. General rule is mix is OK in winter (and sometimes necessary, as the pressure of butane drops too low) and use pure butane in summer.

As for b.) Lady Annette is coal fired, so has a totally different boiler. I'd stick with what Roundhouse has given you- they are pretty good at getting their engines set up right.
 
Thanks chaps. I think I will ask the question underlying one on the saftey valve in another thread... BTW the ruling gradient is 1:35, which you are right is a bit unrealistic- it should go in the rebuild project.
 
1:35 may be a little steep, but I'm running a 1:40 about 15yards long from the end (beginiing?) of the terminus, and I'm not finding it too testing (there's that lovely word again!). Will need a "Chuffer" soon to make it sweet.
 
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