Propane tank+Kovea Adapter+Optimus Vega flame dwindles to nothing

[Eugene Hollingsworth]

I purchased a Kovea propane tank adapter to run a Optimus Vega. The initial light up and flame is good, but after a few minutes the flame dwindles as if running out of gas.  The little screw adjuster thingie on the Kovea adapter made little difference.  Continually adjusting the stove valve back and forth seems to help but that’s not a solution. I tried 2 different tanks, both have lots of gas in them.

The tank is used both upright (preferred anyway) and inverted just to see if I can leave it lay on it’s side. This was in my garage, probably 40 deg f.

Isobutane and Kovea butane/propane mix with adapter work fine. I’ll try to link videos in the next post. Here are pictures of the adapter and stove valve looking a little frosty.

[Eugene Hollingsworth]

This is the Optimus Vega not running so well on the propane tank:  (skip to about 1:30 where I have it inverted then turn the tank upright)  Initially it looks like I’m just being impatient and not waiting for the delays caused by having the hose buffering the fuel flow, but I tried to make sure I wasn’t doing that.

https://geneh.smugmug.com/Public-Shared-/Shares-to-Public-Forums/BackPackingLight-Content/i-KNr6fg3/A

This is the Optimus Vega running on a isobutane canister. Flame controls are as good as I could ask for.

https://geneh.smugmug.com/Public-Shared-/Shares-to-Public-Forums/BackPackingLight-Content/i-X5hmKr4/A

[Roger Caffin]

Hi Eugene

Here are pictures of the adapter and stove valve looking a little frosty.
??????
How did you get the valve to look frosty? That frost implies the fuel was vaporising at the valve, which should only happen if the green bottle is lying on its side or inverted. OK, I will assume that.

If tweaking the valve changed things for the better, I would guess that the valve might have a lot of muck around it. That can happen with a liquid feed. It might need cleaning – both needle and seat.

The first video definitely looks as though something is dirty – most likely the jet in the stove, but possibly the needle valve at the end of the hose. That happens, often, with an inverted feed. I would suspect that the dirt did not come from the propane bottle but from a screw-thread canister.

The second video also looks like a blockage somewhere.

Cheers

[Paul Wagner]

The canister does NOT need to be inverted to work well. But what you are doing here is running a refrigerator…expanding a liquid and turning it into a gas. It’s an evaporative cooler powered by propane. We have this issue with our little Coleman butane stove any time the temperature gets below 45 degrees or so…the solution is to make sure the valve doesn’t get frozen.

We don’t bother with the butane stove in those conditions—we switch to our MSR Pocket Rocket, But there are a number of creative ideas on this site for how to get a little bit of heat to that valve…

[Eugene Hollingsworth]

Agreed on all counts.  Yep, the green propane bottle was inverted.  And yep, with the green propane it was acting as if there was a blockage. Possibly the inverted isobutane canister was acting as if there was a blockage I did not recognize. I suspected frosty blockages with the propane bottle because I continually move the valve more open and closed to make it work, but that didn’t make sense to me because it takes moisture (or so I thought) to get a frosty blockage inside the valve.

I’ll retry this test without inverting the green propane bottle. Which BTW goes back to earlier threads – I prefer upright bottle and canister operation to minimize junk getting into the stove valve – hence the desire for propane when the temps are lower than optimal for isobutane and because propane is so cheap.

[Roger Caffin]

I prefer upright bottle and canister operation to minimize junk getting into the stove valve –
and into the jet.

But yes, I entirely agree with the wish. 100% propane in a fly spray can (like the Powermax or BOSS ones) would be ideal. They could be equipped with the Lindal valve fitting from one of the butane cans, to allow them to be run on their side but with a gas feed.

Why a Powermax style rather than a screw-thread canister style? Because the narrower the can or bottle, the easier it is to get the pressure rating. An engineering issue.

Cheers

[Eugene Hollingsworth]

Tonight I ran the stove using only the upright green propane bottle for about 15 minutes without any hint of frosting on the stove valve. The flame control was easily adjusted and predictable. I guess running the stove with a liquid propane feed isn’t a good idea.

Thanks folks for setting me straight.

[Roger Caffin]

Hi Eugene

What sometimes happens with a NEW fuel bottle is that any dirt in the bottle gets flushed out in the first few minutes of inverted operation. This means you have a lot of trouble at the start, then things settle down when the dirt has been flushed.

You see, the gas filling operators (naturally) do everything as cheaply as possible, AND they assume that all containers will be used upright. The percentage of users with inverted canister stoves is very very small. So any residual dirt does not matter for the vast majority.

Which is why I transfer my fuel from whatever source canister to my preferred destination canister (ousually a Powermax can) through a custom chem-lab standard filter system. To be sure, some ‘dirt’ may still get through, but it will be at the micron size level. My stoves can tolerate that.

Caution: refilling is technically illegal, you must know what you are doing, and it should always be done outdoors.

Cheers

[Eugene Hollingsworth]

Thank you Roger. I hadn’t thought filters would be available so hadn’t pursued that line of thinking. I see that I can purchase filters for propane tanks which I might get just for peace of mind when using my Mr. Buddy heater, even though the tanks sit upright. Apparently oil can get into propane tanks and foul heaters also, though it’s unlikely unless incorrect hoses are used for refilling.

PS PM sent

[Roger Caffin]

Well, filters are not ‘available’, but I make a lot of my own gear.

Cheers

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