Gas lamp adjustments

[Andrew Gabriel]

Does anyone know of any resources or instructions for setting the gas rate and mixture for a gas lamp? This is the type with a preformed inverted mantle, as used in old gas street lamps.

[meow2222]

Mixture is simple enough, if its too rich the flame gets yellow patches, if too thin it makes a blowing noise.

Re gas rate, I dont think theres any one required setting... efficiency falls off when the flame gets too big for the mantle, so you can choose max output or max efficiency or any setting with less gas & light.

If the above doesnt cover it, can you describe the problem some more?

NT

[Owain]

might be able to help

Owain

[Andrew Gabriel]

The lamp has a variable orifice jet and adjustable airholes, which then feeds on to a second variable orifice jet and second set of adjustable airholes, and then on to the burner/mantle. The large number of adjustment combinations make for something of a complex setup. I suspect this is for dealing with a range of different gases and presures (it's an old gaslamp, well predating natural gas). The two jets seem to allow me to set relatively independently the velocity and the rate of the gas.

I went into my local traditional hardware store and asked for mantles, and they brought several boxes from the back. We tried them until we found the one which fitted on the burner nose, which was actually the largest one they had, so I presume this was quite a powerful gaslamp in its day.

In trying to run it, I can't get the mantle burning as brightly as I see in gaslamps in London. With certain settings, I can get the bottom of the mantle glowing brightly, I think due to adjusting the second jet to let a fine high speed jet of gas through, but there doesn't seem to be enough gas to make the whole mantle glow. By opening the second jet, more gas comes though and causes all of the mantle to glow, but not anywhere near as brightly. Allowing even more gas through just results in a faintly visible flame starting to come out of the top opening of the mantle, with no further increase in light output. It looks to me as though with today's natural gas pressure, I can't get enough gas through the second jet at high enough velocity. (What pressure was town gas?)

I haven't yet played with the first airhole so there's more experimenting to do. For now, I completely closed it to be sure gas wouldn't come out if I closed down the second jet too far. I've not come across a pair of daisy-chained jets and air mixers in any burner before. The first airhole is supposed to be preset and can be completely closed, and the second is user-adjustable. Both jet orifices are user-adjustable.

[meow2222]

I've never come across owt like that. Good luck.

NT