Can anyone tell me the difference between a stove fuel valve that meters a gas like butane or propane as opposed to one that meters a liquid fuel? I don't have two to compare.
Having stripped down a lot of both, I've invariably seen (in both butane/propane and liquid fuel examples) a conical valve spindle tip screwing down onto the circular rim of a hole (occasionally a tapered valve seat) to shut-off, unscrewing it to allow the fuel to get to the burner and all points in between to regulate the fuel. Differences arise in spindle shaft sealing arrangements - graphite ring in 'classic' liquid stoves and nitrile 'O'-ring (or rings) in the butane/propane ones. Some liquid fuel stoves have a cam or rack and pinion arrangment to operate a jet pricker and that's about it. John
Thanks. I'm mostly wondering how a valve designed to meter liquid would work to meter gas provided it sealed properly, etc. I would guess that a liquid metering valve would have coarser threads or rack and pinion and because of that it wouldn't be very easy to "fine tune" gas flow. For example if used for gas as soon as you cracked it open a bit it would be nearly full on. That being said, I really don't know. I've had one of each apart at one time or another and aside from the diffs you pointed out I remember that the threads to adjust the flame on the liquid valve were very coarse.
Actually, depending on the pressure, the opposite may be true. Liquid fuel expands something like 270 time it's liquid volume when vaporized, so a tiny amount makes a LOT of gas. But gas will flow faster through a like passage, so I think it all balances out pretty even. But practically there's not much difference at all other than those stated above. Mike
Hi Litetrek, In most "classic" liquid fuel stoves that have a regulating valve, the valve is just underneath the burner head (or part of the burner), where the fuel is already vaporized. I believe the stuff that flows through the valve is extremely hot fuel vapor. I am not sure at what point in the fuel path you can mark the boundary from liquid to vapor, but I suspect it is before the valve, or inside it. There are other designs that might work differently. Coleman stoves typically have the valve before the generator, and I assume most of the vaporization takes place within the generator, so the valve would control very hot liquid fuel. MSR and other "separate tank" stoves have a valve on the pump in the tank, and those would be regulating cold liquid fuel. And still, some of them are multi-fuel that can be used with propane and white gas through the same valve. Regardless, most liquid fuel valves that I disassembled conform to the principles described by Presscall above here, namely a conical spindle moving in and out of a conical seat. I did not have a chance to disassemble any pure butane / propane valves, so I don't know if they differ. Yonadav
Yes, Yonadev makes an excellent point on the classic type burners. That's why you can shut them off immediately, whereas a Coleman type will continue to burn for a short time until the remaining fuel in the generator is vaporized and burned.
Thanks everybody. I'm modifying a coleman xpert stove to accept the current "standard" threaded fuel canister since the powermax canisters aren't available here anymore (except at highly inflated prices). The xpert feeds liquid fuel through the valve I believe. I don't want to use the adaptor coleman sells. I bought a valve for a liquid fuel stove from China. Those valves seem to be very popular on this site and they look like they will work for me. I would like to be able to use the coleman Xpert in either regular or canister inverted mode and have the flame be easily adjustable (useable) in either mode. Since my stove still works AND I have a few canisters left I don't want to tear it apart until i'm fairly confident my plan will work. I appreciate everyone's input. It has given me some confidence that my plan is feasible. i am not so confident the part I ordered will show up. however, the low price was worth the gamble.
Hi litetrek, I believe there was an ADAPTOR (click this link) marketed to allow the stove to be used with lindal type canisters instead of powermax canisters. Ron
Litetrek, you said, "I'm mostly wondering how a valve designed to meter liquid would work to meter gas provided it sealed properly, etc." Answer is, from practical examples I've worked on, just as well, or in some cases better. For the stoves on a flexi-hose supply, shutting down is pretty much instantaneous on the control when the burner cartridge is right way up, and just the same as on 'regular' liquid fuel when the cartridge is inverted and providing a liquefied butane feed. Juwel petrol stove on butane Coleman 500 on butane Coleman 501 on butane Coleman 502 on butane MSR Whisperlite on butane Optimus Nova on butane I've used quite a few of those imported valve/flexi-hose components and they work fine on inverted (liquefied gas feed) cartridges. Some of the stoves they're supplied with (they're sold as spares for stoves) are petrol burners in any case. The valves have the usual conical tip control spindle and valve seat arrangement and have a couple of 'O' rings as spindle seals. The manufacturer is supplying flexi-hoses with a larger diameter, thicker-walled, rubber inner core of late, but I've not had any problems with the thinner flexi-hoses. When you place your order, you could perhaps ask for the later specification type however. John
