Propane question

[joshuabardwell]

I am running a gas range off a 20 lb propane tank. I've got a two stage regulator on the tank and have converted the stove's regulator, orifices, etc... Everything was working fine up until yesterday, when the stove began acting starved for fuel. The burners have small flames. The oven looks like only one side of the burner is on. Most tellingly, if I turn on a top burner and then turn on the oven, the top burner shrinks near to nothing.

When I was first testing this setup, I ran the stove on a nearly empty tank to ensure that the pressure would be adequate. It worked fine. The tanks I'm using are both full. Same issue on both tanks. The only thing I can think of that's changed is it was a little colder last night than the night before, and all my testing was done in the summer. Would a ten degree difference in ambient temperature make enough difference in the tanks' vapor pressure to cause this effect? The only other thing I can think is that the regulator or stove has malfunctioned, but that really seems unlikely. Nothing else changed between when it was working last night and now.

I really want to figure this out if possible. I have a bunch of people to cook for tomorrow. I limped through tonight, but it was slow and the oven didn't get hot enough to cook the food like it really should.

 

[SPIKER]

COLD will cause this as the propane liquid can not turn into vapor fast enough to maintain the pressure without freezing up. The regulators and lines and openings will form solid crystals if there is not enough area above the liquid to dissipate the cold when the tank/liquid is already cold from lower temps. heating the tanks up can help but would suggest a 30 or 100 lb tank for regular house size stove. Most BBQ's have the tank rather close to a lot of the heat so that helps, very short hoses and the like topped with cookign outside in heat (usually.)


Mark

 

[mikehaugen]

COLD will cause this as the propane liquid can not turn into vapor fast enough to maintain the pressure without freezing up. The regulators and lines and openings will form solid crystals if there is not enough area above the liquid to dissipate the cold when the tank/liquid is already cold from lower temps. heating the tanks up can help but would suggest a 30 or 100 lb tank for regular house size stove. Most BBQ's have the tank rather close to a lot of the heat so that helps, very short hoses and the like topped with cookign outside in heat (usually.)

Mark

Would 10º be enough to cause this?

I would think it could also be your tanks maybe? Some tanks will shut off if the gas flows too fast, maybe some have flow limiters on them. Just a guess.

BTW... where have you been? I haven't seen any posts from you in a while.

 

[mrmikey]

Some tanks will shut off if the gas flows too fast, maybe some have flow limiters on them

I was thinking that also, might be a combination of the temp and the tank freezing up and it was just working at it's max before the temp drop. If it is the flow check in the nipple, you can drill it out, I just did to use a 20lb on my cutting torch using an acetylene regulator.
I unscrewed the acetylene nipple from the regulator and used the nipple from an old barbecue, they're both 1/4" npt. Couldn't get a thing thru the regulator as there was too much flow until I removed the check by drilling out 3/16", from the nipple......Mike

 

[IXLR8]

I run a 5 burner cooktop off a 20 propane tank outside, no issues down to -10dF. Not sure if it would handle an oven as well though. I have had issues with the regulator at the cooktop sticking closed. I have had to remove the cover from the valve so I could push on it to unstick it. It does seem to stick more when the bottle pressure is getting low.

 

[joshuabardwell]

A little more information, guys: tried opening the valve slowly and no difference. Ambient temp is only 50 degrees, so I'd be surprised if temperature was the issue. The oven burner is rated for 16,000 BTU. Seems like it should really be working.

 

[joshuabardwell]

I run a 5 burner cooktop off a 20 propane tank outside, no issues down to -10dF. Not sure if it would handle an oven as well though. I have had issues with the regulator at the cooktop sticking closed. I have had to remove the cover from the valve so I could push on it to unstick it. It does seem to stick more when the bottle pressure is getting low.

Do you mean then cap that you flip to convert the regulator from natural gas to propane and vice versa? With the spring and diaphragm under it?

 

[jinman]

I would think it could also be your tanks maybe? Some tanks will shut off if the gas flows too fast, maybe some have flow limiters on them. Just a guess.

That's my guess. The tanks flow limiter is closing down the flow. Most bbq tanks have a regulator very close to the tank. An oven probably has a regulator very far from the tank. When the valve is cracked open, the tank valve senses too much flow and shuts down. I would try a double open procedure. Open-close-slowly open to see if the 2nd time around didn't do the trick. I had that happen to me before I knew about it and was super frustrated to have a full tank and hardly be able to cook four burgers. I was ready to throw that grill off the cliff before I discovered the tank valve was shutting down.

 

[charlz]

I have had something similar. I had to close the tank valve, disconnect what I had attached to it, reattach and open the valve. I believe part of the design on the new tank valves is something has to be attached before it will open. If not seated correctly it won't open or open fully. I know horizontal tanks are exempt, 100lb tanks might be exempt from the new valves as well. If this happens now and then it might be worth a tank upgrade just to avoid it.

 

[user.69169]

You got the triangle valve blues going for yourself there.
The new propane tanks with the triangle valve handle only let out so much propane per minute, some government genius design made for a fool reason.
Lot of people with the turkey cooker burners find out about them new tanks with the built in limiter every year and give up turkey frying.
Them dang triangle valves on everything short of 100 pound tanks now.
Might too have you case of undersize propane hose. The gas at very low pressure after leaving the regulator, and the hose has plenty of friction to add to the problem.

Far as temperature concerned, you need to get down to about 10 degrees to notice any lack of boil in the tank.

 

[joshuabardwell]

I'll try a double crack procedure. It is about a six foot hose, or maybe more. What's really confusing me is I ran the stove for about ten pizzas at home to test it out, no problems at all. And I ran it for a whole day, on and off, at the event, no problem. Then the next morning, bam.

One difference between the tests and two days ago was that the tanks were near empty for testing, and are full now, but the regulator should equalize that, I would think. The stove seemed to be running hotter two days ago, with some orange tips to the flames, and larger flames, whereas during testing, the flames were blue. I halfway wonder if somehow the stove or tank regulator got messed up.

 

[joshuabardwell]

I got an opinion from a hippie handyman who thinks I've checked all the obvious things and it may be the regulator. He's going to see if he can rustle me up a spare two stage for the tank. If it's the stove I'm obviously out of luck.

 

[Midniteoyl]

A little more information, guys: tried opening the valve slowly and no difference. Ambient temp is only 50 degrees, so I'd be surprised if temperature was the issue. The oven burner is rated for 16,000 BTU. Seems like it should really be working.

Is it actually butane? Butane doesnt like cooler temps, thus the reason why we dont use it up here. And, it takes a different air/fuel mix.. Its is cheaper too, some some place like to sell it instead of the the methane mix to save money. After all, they dont expect you to use a 20lb'er in the fall/winter..

 

[farmgirl19]

I would bet that it is Propane. Butane is heavier than propane, and therefore not allowed in most places now, due to increased explosion hazards. Butane sinks and pools, whereas propane floats up. Propane has one less carbon than butane, and that is the difference in weight.

 

[joshuabardwell]

Definitely propane, unless the Flying J has made a colossal screw up. They sold it as LP.

 

[firedog]

most of the 20 & 30 lb cylinders have flow limitations. When I set my 10K genset up for LP, I was unable to test it using a 30 lb cyl. for that very reason. Combine that with the fact that the more you pull from the cylinder the greater the temperature drop on the LP. (latent heat of vaporization) The lower the temp = the lower the vapor pressure, which in turn gives you less flow. It's not uncommon in 100 degree ambient temperatures to freeze a cylinder to the concrete when boiling crawfish (picture a big ol' ice ring around the bottom of the cyl.)

Also LPG = liquified petroleum gas. Butane, Isobutane, Propane are all considered LPG's, and are sometimes sold mixed; 80% propane 20% butane and such.

Also propane is heavier than air with a vapor density of 1.52. Ethane is nearly equivalent to air with a density of 1.038. Methane @ 0.554 and Natural Gas ranging from 0.60 - 0.70

 

[Midniteoyl]

Also LPG = liquified petroleum gas. Butane, Isobutane, Propane are all considered LPG's, and are sometimes sold mixed; 80% propane 20% butane and such.

Also propane is heavier than air with a vapor density of 1.52. Ethane is nearly equivalent to air with a density of 1.038. Methane @ 0.554 and Natural Gas ranging from 0.60 - 0.70

:thumbsup:

 

[Dr Dave]

There are summer mixes and winter mixes, of butane/propane. I had a 1000 gal tank filled in the summer and on the coldest day in the winter, I thought we ran out. The guage showed 20% no flow in the house. I thought the guage had failed. So I had a 500 gal tank with 65% so I hooked it up. In the spring, I cracked the valve on the large tank and had propane. Called the supplier and he said the summer mix has more butane, the reason they sell it cheaper in the summer.

I would recommend you get a 100 lb bottle and eliminate the 20 lb saftey tank hassle. My grill has issues with these, the wife was having trouble and just changed tanks, she thought they were empty. She asked me to refill them in town, when I went to load them, all 4 had propane in them? She now just opens the valves slow and this seams to help.

Dave

 

[farmer2009]

I agree with the bigger tank. The empty tanks had more head room for the propane to vaporize than the full tank look at a 50 or 100 pounder.

 

[joshuabardwell]

BTW... where have you been? I haven't seen any posts from you in a while.

Now that I'm back from the event and in front of a keyboard, I can answer more easily. I've been posting a little here, but I started posting more over on the Everlast forums because they were having a contest. My latest big project didn't get a lot of response when I posted about it over here, but got a lot of response over there, so I've been doing most of my posting over there, just because that's the project I'm posting about.

Manipulating welder output with Arduino