Propane Usage Calculation

[Dave Smith]

Ok I know one of you will enjoy doing this more than me

So what's the conversion of lbs of propane to minutes of burn time?

I know you have to take btu's in a lb of propane x btu's of the buner x number of beers x yada, yada.......

[prophet]

just keep it on high please

[Dave Smith]

Seems like I heard that was the best way to reheat chicken spaghetti

[Jody]

mmm...i love me some toasted chicken sketti!

[AR-Nimrod]

I always use the "shake" calculation

[Mike B]

Dave,

These numbers are approximant but will get you pretty close.

Propane is sold in pounds. Each pound of propane has about 21,400 BTU.

20 lb. tank x 21,400 BTU = 428,000 BTU.

So, if running one 20,000 BTU burner at full blast it would last 21.4 hours with a 20 lb. tank. (428000 / 21,400)

If running four 20,000 BTU burners at full blast it would last 5.34 hours with a 20 lb. tank.

Of course you rarely cook at full blast so you have to figure about how long it takes to cook meals, heat dish water, etc. Of course, keep in mind ambient temperature, elevation and all the other factors that make this question so easy to answer.

Other notes:

Most tanks under 40 lbs. have a built in 125,000 BTU flow restrictor so it may not run multiple burners if you exceed 125,00 BTU of flow.

The most accurate method to monitor use is a set of hand fish scales. Weigh your bottle empty [it should actually have a Tare Weight (ex. TW 17)], and establish the empty tank weight. Then weigh it when filled (should be TW + weight of propane). Then you can weigh it at any time and know what you have.

There are also new composite tanks (about $100.00) that weigh much less and you can actually see the amount of propane left in the bottle.

Consider taking two or three small tanks as opposed to one large tank and maybe even a few small Coleman tanks with the appropriate adapters.

[Crane]

... or, take two 20 lb tanks and big rafts to haul them on. On our recent 8-day trip, we used pretty much all of one 20 lb tank and a smidge of another... but, we never hooked up a blaster.

[paddledog]

One 1 lb tank to one blow log..
Thats the only formula I know.

[Dave Smith]

Thanks Mike B just the trivia I was looking for!

I actually have one of those 8lb tanks (I think anyway) and just trying to guesstimate if I have enough propane to make it through this weekend.

[Shark Attack]

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That just puts a tear in my eye

[Mike B]

The Partner Blaster is a great tool but it eats up propane at about 120,000 BTU per hour on full blast.

Be careful or you can burn through a 20 lb. tank in about 3.5 hours!

[Crane]

Dave, if you miscalculate, I have a spare tank (with some propane in it!)you can come fetch... Crane

[GaryPaladino]

You may also note the fine print at those 20# tank bottle exchange places like Lowe's and Walmart sell say "17 pound fill".

It's kinda like when the $1 10# bag of ice suddenly started to weigh 8# but still cost a $1.

[KimL]

I just read that all the big retailers are now filling 20-lb. tanks with just 15 lbs. of propane, and they've been doing it for a year "in order not to raise prices." Not knowing that you are leaving on an 8-day trip for 20 people with 15 pounds instead of 17 or 18 pounds of propane in a 20-lb. tank could be bad--really, really bad.

[Eric Esche]

If you really want more gas in your bottle, you can always take it to an individual/independent refiller and have them fill it there, rather than doing an exchange somewhere. When I did this in North Carolina, the fill bill was by the pounds filled, not on a stock exchange. You won't gain more than a pound or two at the most as you are still unlikely to get them to give you more than an 80-90% fill as there is usually a limit set by their insurer's, just like they will no longer fill tanks with the old style valves.

Bottom line - if you got to have "x" amount of gas, take more tanks, and then plan on having a larger reserve in addition to that.

Eric