I own two Vapalux pressure lamps. They are both WWII era. Is it possible to use a larger mantle than the 300CP that is supposed to be used? I want more light. Why?...Because. Has anyone ever tried this? Will it harm the lamp? Is it a waste of money for a larger mantle? Your thoughts. Thanks for your help.
Answers to your questions are:- Yes; Yes; Yes, to some minor extent; Yes, probably. I'll dig out the lantern tomorrow...
You can only get the light that the vaporiser and burner are designed to give. Do what you will with mantles and the light output is still limited to the rated cp because of the jet size and burner air intake design. Power output has little to do with mantle size. ::Neil::
I think the original idea in something like the Tilley 500 series was that the bigger the mantle, the bigger the area that's incandescing and thus, in theory at least, the greater the light output / illuminance / call it what you will. Naturally, and as Neil suggests, if the vapouriser/burner combination can't sufficiently 'fill' the mantle, then you'll get grey patches which obviously aren't giving out light. Now, as I see it, Tilley's idea was to use the same vapouriser/burner combo as the X246B but to fill the bigger mantle by simply increasing the tank pressure - not a good plan with a flimsy X246B tank! So I thought I'd try the same thing with a Vapalux lantern which is an altogether tougher beast and would withstand the increased tank pressure. I got a bloke I knew at the time to make me a longer spigot for the standard Vapalux burner and fitted a Tilley 500 mantle to that. If I recall correctly, there were still grey patches on the bigger mantle because there's a limit to how much pressure you can put in a tank with a simple hand pump - you have to give up eventually because your thumb hurts! In any case, the maximum tank pressure possible is determined by the pump-tube dimensions - diameter and stroke. So, just like the Tilley 500, my 'Vapalux 500 series' wasn't a huge success either. My presumption, after the event, was that if it was ever going to work, W&B/Bairstow Bros. would have already done it. Still, it was an interesting exercise at the time. I'll chuck on some clothes and try to find the lantern...
The pressure limit in a Vapalux is about 60psi. Best I could get was 56psi if I remember right. There is no doubt that increasing pressure will increase light up to a point but there is always the danger of damaging the fount. Willis & Bates were engineers so we can be pretty confident they applied engineering standards to their product which means with the lamps operating pressure at about 30psi customer test pressure will be 60psi and works test 120psi. I therefore don't think it is a coincidence that the pumps can only generate a max of 60psi. So a bigger mantle and around 50psi will almost certainly give more light but beyond that lies danger. ::Neil::
