Propane Tank Math Equation

I'm still a little new to the whole propane tank brewing and I wanted to make sure I understand this. I'm trying to tell how much I have left in my tank.

Here's the info:

I have an Ameri-Gas Tank that says Net Weight- 15 pounds on front of tank

The Tare Weight on the handle of the tank says 17 pounds

I just weighed the tank and it weighs 26 pounds even.

How much propane do I have left??? Thanks!

You have 9 lbs remaining in the tank. The Tare Weight is the empty weight of the container. The net weight is the weight of the contents. In this case your supplier is saying that 15 lbs is what the contents should be for a full tank. Normally, the 20 lb propane tanks hold 20 lbs of propane when full. The exhange places have been playing a shell game lately and only fill the tanks 3/4 full, or 15 lbs. This is a scam IMO. The suppliers claim they are doing this so that they don't have to raise the price. Duh? So, we get screwed out of 25% of the fuel and are required to fill the tanks more frequently. I guess they figure our time and effort are worth nothing to us.

The calculation is simply to subtract the tare weight from the total weight to arrive at the remaining gas weight. ie 26-17=9

It would weigh 32 lbs when filled with 15 lbs and 37 lbs if filled with the max 20 lbs.

To avoid this, take your empty tank to a refill station if you have one near where you live and they will normally give you a true fill of 20 lbs. You may also discover that the price will be lower than the exchange price. I get 20 lb fills for roughly $20 currently. I am surprised and disappointed that the state bureau of weights and measures has not come down hard on the tank exchange people, but they have found a loop hole by putting up a sign saying that the net weight is 15 lbs for their tanks. It's still pretty slimy IMO and I refuse to give them my business. The average idiot on the street is usually too stupid to realize they are getting screwed and it's pretty obvious some in the government are getting kick backs somehow. You can bet on it.

Wow, Catt...I never paid attention to the whole 15lbs vs 20lbs filling. I have noticed recently that my tanks dont last as long. I've also wondered why someone would go through the pain of taking a tank to get filled when it is the same price to exchange it and less hassle. Make sense...unfortunately there are no spots that fill tanks around here.

Good info...

And if you use blue rhino you are getting raped. I fill my own tanks, have been for years, and those blue rhino tanks do not hold #20lbs.

Thanks Catt. Good information here.

So I should have plenty left to do at least 2 more 60 minute boils if I heat the mash and sparge water on my stove, right??

Does anyone know how many gallons of LP make ~20#, I have my tanks filled for the same reason, it is about $30 after tax with an exchange here, and it costs me about 15 bucks or so to have my tank filled, normally I don't allow them to run dry, but when I have them filled they will take about 4 gallons give or take. Does 4 gallons equal ~20# of LP?

HarryHood1 said:

Thanks Catt. Good information here.

So I should have plenty left to do at least 2 more 60 minute boils if I heat the mash and sparge water on my stove, right??

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Yes, but it might be close. A lot depends on your burner design and how you use it. It's possible to waste a lot of propane by turning the burner up higher than necessary. Some burners are more efficient than others. I have multiple propane tanks so always have a backup on hand. The damn things seem to accumulate. Someone's always giving me one and I occasionally find one discarded at the curb or buy them for a few bucks at garage sales. I think I have seven at the moment and I didn't buy any of them at retail price. I make a run with four at a time when I get them filled.

It's a real drag to run out of gas in the middle of a brew session. You should do some more looking for a bulk propane supplier. I'm almost sure there is one somewhere in your area.

Schnitzengiggle said:

Does anyone know how many gallons of LP make ~20#, I have my tanks filled for the same reason, it is about $30 after tax with an exchange here, and it costs me about 15 bucks or so to have my tank filled, normally I don't allow them to run dry, but when I have them filled they will take about 4 gallons give or take. Does 4 gallons equal ~20# of LP?

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The specific gravity of propane is about .495 which equates to roughly 4 lbs per gallon. It will vary some depending on the temperature, but that should be close enough for our purpose. So, your four gallons would be about 16 lbs. which indicates you still had about four lbs in the tank when you had it filled. The fill stations usually weigh the tanks when filling them in order to avoid overfilling. This is the other advantage of getting refills. Normally, the fill stations only charge you for what they put in the tank. The exchange places don't allow credit for any gas remaining in the exchanged tank. This is a PIA for some as you must run your tank completely dry before you exchange it or you get additionally screwed.

SOB said:

Wow, Catt...I never paid attention to the whole 15lbs vs 20lbs filling. I have noticed recently that my tanks dont last as long. I've also wondered why someone would go through the pain of taking a tank to get filled when it is the same price to exchange it and less hassle. Make sense...unfortunately there are no spots that fill tanks around here.

Good info...

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I just used the googles for "Propane Delaware Ohio" and came up with quite a few propane suppliers in your area. Here's one:

Delaware Rental Center
1050 Bowtown Rd, Delaware, OH
(740) 369-9661

and another:

Alum Creek RV & Marine
5742 State Route 37 E
Delaware, OH 43015
740-363-4068

There are some others also.
‎

So I just called a propane place in town and they refill tanks for $1 per pound.

Is this a decent price for propane refills??

HarryHood1 said:

So I just called a propane place in town and they refill tanks for $1 per pound.

Is this a decent price for propane refills??

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Yes, that's the going price in my area at the moment. It will vary according to the market much like gasoline and diesel does. It's a fuel just like those are.

Tanks with a gauge on them are key. Costco was blowing some out last week.

Catt22 said:

I just used the googles for "Propane Delaware Ohio" and came up with quite a few propane suppliers in your area. Here's one:

Delaware Rental Center
1050 Bowtown Rd, Delaware, OH
(740) 369-9661
‎

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I'm a flippin' tool! Thanks for doing the "dirty" work for me and finding a couple places. This Rental Center is basically in my back yard!! Even closer than the gas station where I exchange my tanks.

The exchange companies claim they decreased the fill to maintain the price as the cost of propane rose. Of course they have not increased the fill and maintained the price as the cost of propane has fallen. Its a legal scam as they are informing the consumer regarding the amount of propane they are buying. But how many consumers would expect that they are not getting a full cylinder? I exchange only when my cylinder goes out of date or the valve fails. Then I find the newest date coded cylinder on the rack and keep it; refilling it at my local hardware store.

Catt22 said:

Normally, the 20 lb propane tanks hold 20 lbs of propane when full. The exhange places have been playing a shell game lately and only fill the tanks 3/4 full, or 15 lbs. This is a scam IMO.

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This is not a scam. Ok, maybe a little bit of a scam. Propane tanks can only be filled to 80% capacity. This means that a 20# tank can legally only accommodate 16# of fuel. All current portable propane tanks must have an Overflow Protection Device (OPD) installed, and the OPD prevents the tank from being filled to more than 80% capacity.

Does this mean that the exchange places put 15-16# in a 20# tank? I don't know. It would make sense to decrease the volume in order to keep the posted price the same when the cost went up. It would be more expensive for YOU if they have to reprice everything every time the price of propane changed...

Certainly the best way is to find a place that refills YOUR tank and charges for the amount filled. Assuming they charge a reasonable price for it...

Schnitzengiggle said:

Does anyone know how many gallons of LP make ~20#, I have my tanks filled for the same reason, it is about $30 after tax with an exchange here, and it costs me about 15 bucks or so to have my tank filled, normally I don't allow them to run dry, but when I have them filled they will take about 4 gallons give or take. Does 4 gallons equal ~20# of LP?

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Around 4.71 gallons. Propane weighs 4.24pounds per gallon at 60F. So your close. The tanks I use for work have overflow valves on them so at most you can get it is about 4.5 gallons.

Those crappy Blue Rhino tanks only hold 3 to 3.5 gallons.

ruffdeezy said:

Tanks with a gauge on them are key. Costco was blowing some out last week.

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I have a dedicated bathroom scale in my garage, it works just as well.

HarryHood1 said:

So I just called a propane place in town and they refill tanks for $1 per pound.

Is this a decent price for propane refills??

Click to expand...

Totally off topic... we have a ton of Phish fans on this message board... hooray for us.:rockin:

shoebag22 said:

Totally off topic... we have a ton of Phish fans on this message board... hooray for us.:rockin:

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Very cool. I want to do some fall shows but I'm not sure if it's going to happen. Too many hobbies.

wildwest450 said:

Around 4.71 gallons. Propane weighs 4.24pounds per gallon at 60F. So your close. The tanks I use for work have overflow valves on them so at most you can get it is about 4.5 gallons.

Those crappy Blue Rhino tanks only hold 3 to 3.5 gallons.

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Yeah, I have a Blue Rhino, and an old tank that is expired that they continue to fill at my local gas station. I have noticed the BR rarely takes more than 3.5 gallons.

DNW said:

This is not a scam. Ok, maybe a little bit of a scam. Propane tanks can only be filled to 80% capacity. This means that a 20# tank can legally only accommodate 16# of fuel. All current portable propane tanks must have an Overflow Protection Device (OPD) installed, and the OPD prevents the tank from being filled to more than 80% capacity.

Does this mean that the exchange places put 15-16# in a 20# tank? I don't know. It would make sense to decrease the volume in order to keep the posted price the same when the cost went up. It would be more expensive for YOU if they have to reprice everything every time the price of propane changed...

Certainly the best way is to find a place that refills YOUR tank and charges for the amount filled. Assuming they charge a reasonable price for it...

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Dunno, but mine will all hold a full 20 lbs and they are all equipped with the OPD valves. I still think it's a scam.

Just called...$14.95 to fill my tank. The gas station across the street from the filling station was charging my $24 for an exchange! Damn glad I got involved in this thread...

First: My understanding of the OPD device is that it prevents any tank so equipped from being charged with more than the maximum amount of propane......so if the tank's OPD is functioning properly, it should be impossible to overfill it.

I fill at a local Sunbelt Rentals. They fill the 20# cylinder for $12, which is a bargain in our area. Their fill is simply to set the scale at 2X the tare weight stamped on the handle, and cut it off there. That's sensible and very reasonable.

There is another stamp on the cylinder marked W.C followed by a number. For example one of mine has W.C 47.6 stamped on it. This is the water capacity of the cylinder in lbs. You can easily do the math to convert this to lbs of propane or you can use this chart that I found on one of the propane sites:



So, for the W.C 47.6 it says the tank will hold very nearly 20 lbs of propane. W.C. 47.8 would be 20 lbs according to this chart. That would be like a 0.4% difference and I suppose that's due to tolerance variations during manufacturing. The W.C. capacity is the allowable capacity for that particular tank. Blue Rhino might install some type of device to reduce the capacity and I would not be surprised if that were the case.

SOB said:

Just called...$14.95 to fill my tank. The gas station across the street from the filling station was charging my $24 for an exchange! Damn glad I got involved in this thread...

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Good for you! That's a considerable savings for sure.

DNW said:

This is not a scam. Ok, maybe a little bit of a scam. Propane tanks can only be filled to 80% capacity. This means that a 20# tank can legally only accommodate 16# of fuel. All current portable propane tanks must have an Overflow Protection Device (OPD) installed, and the OPD prevents the tank from being filled to more than 80% capacity.

Does this mean that the exchange places put 15-16# in a 20# tank? I don't know. It would make sense to decrease the volume in order to keep the posted price the same when the cost went up. It would be more expensive for YOU if they have to reprice everything every time the price of propane changed...

Certainly the best way is to find a place that refills YOUR tank and charges for the amount filled. Assuming they charge a reasonable price for it...

Click to expand...

This is bad information a 20# tank holds 20# of propane at 80% I have my tanks filled at costco and always get 20# of propane

jspence1 said:

This is bad information a 20# tank holds 20# of propane at 80% I have my tanks filled at costco and always get 20# of propane

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+1 This has been my experience too. The exchange thing is a scam and a blatant one at that.