propane tank question

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repomanz

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I took my empty propane tank to get refilled and it only filled to 3.8 gallons. The guy said something about an overflow valve auto shuts off the pump.

Is this bs or truth? Any links about thus topic? Is something not functioning properly on my tank?
 

Nateo

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what size was the tank? A "standard" bbq 20-lb tank only hold about 3 gallons of LP, IIRC. My propane pump shuts off when the tank is full, or if I don't open the valve correctly, it'll kick off right away.

We have a scale and fill the tanks by weight. You could overfill them if you tried to, but it's not a good idea.

A 20lb tank should hold about 18 pounds of LP. So the total weight of the tank, when full, would be about 38lbs. I believe the law is to fill the bottles by weight, and unless your OPD (overfill protection device) is faulty, it should still fill to capacity. If you OPD is faulty, I don't think they should have filled the tank.

If the OPD trips the pump off, it's pretty hard on the pump. We lease our pump, so it's not a big deal if it breaks, except for the lost revenue while our pump is down.
 

Catt22

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A 20 lb propane tank will hold 20 lbs of propane if it's completely empty when filled. I recently verified this with my propane supplier when I last filled my tanks. The tare weight (weight of the empty tank) should be stamped on the collar and it's typically about 18 lbs. I used a digital bathroom scale to check the fill and, indeed, I received a full 20 lbs. in my empty tank.

Propane weighs about 4.2 lbs/gal, so the OP's fill was 4.2 x 3.8 = 15.96 lbs which is a short fill unless the tank was not completely empty.

here's a link for more info: http://www.propane101.com/propanecylinderfilling.htm
 
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repomanz

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A 20 lb propane tank will hold 20 lbs of propane if it's completely empty when filled. I recently verified this with my propane supplier when I last filled my tanks. The tare weight (weight of the empty tank) should be stamped on the collar and it's typically about 18 lbs. I used a digital bathroom scale to check the fill and, indeed, I received a full 20 lbs. in my empty tank.

Propane weighs about 4.2 lbs/gal, so the OP's fill was 4.2 x 3.8 = 15.96 lbs which is a short fill unless the tank was not completely empty.

here's a link for more info: http://www.propane101.com/propanecylinderfilling.htm
Thanks for this link. So, does this mean my OPD valve on my propane tank is defective if it only gave me 15.96lbs?
 

Catt22

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Thanks for this link. So, does this mean my OPD valve on my propane tank is defective if it only gave me 15.96lbs?
Not necessarily. The most likely explanation is that the tank was not completely empty. My supplier sells propane by the pound and only charges for what actually goes into the tank. The only way to know for certain is to weigh the tank yourself. I refuse to do the exchange thing as they nearly always give you a short fill. I also don't do business with dealers that charge per tank and not by the pound as you don't get any credit for a partially empty tank.
 

malkore

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I wonder if your tank wasn't completely empty too, but due to heat and usage and the way the liquid phases to gas, coupled with all the safety devices, it kicked off the flow to the regulator 'for safety'.
 

Nateo

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Double-checked my propane safety books. All tanks between 4 and 40 pounds are required to have an OPD. The OPD should limit the fill to 80% of capacity. If the temperature is above 60*F when you fill the tank, you won't hit 80%.

Blue Rhino or one of the other big propane exchange companies had a lawsuit over the OPD issue and the 20lb "name" on the cylinders. Since a "20lb" cylinder with an OPD will only hold 16lbs, they changed the name of their cylinders to 16lbs.

Some people have older tanks without OPDs, but it's illegal to fill those tanks.
 

Catt22

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FWIW, the 20 lb cylinders will contain 20 lbs of propane when filled to 80%. You can easily check this by weighing a properly filled cylinder. The tare weight (TW) or empty cylinder weight is stamped on the valve collar as is the water capacity in lbs (W.C.). I have checked with my supplier who confirmed that the tanks will indeed hold 20 lbs when filled to 80% capacity. When I pay for 20 lbs of propane, I expect to get 20 lbs of propane. I never do the exchange thing. That's a blatant rip off IMO.
 

rico567

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The supplier I've been using (but probably won't any more, since their price DOUBLED to fill a 20 lb. tank) fills the tank to twice the tare weight. I have been given to understand that these small BBQ type tanks are all filled by weight. Thus, if the tare weight (empty weight) stamped on the handle is 18.5 lbs, they will fill it to 37. From everything I've read, this seems reasonable.
 

brewingmeister

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FWIW, the 20 lb cylinders will contain 20 lbs of propane when filled to 80%. You can easily check this by weighing a properly filled cylinder. The tare weight (TW) or empty cylinder weight is stamped on the valve collar as is the water capacity in lbs (W.C.). I have checked with my supplier who confirmed that the tanks will indeed hold 20 lbs when filled to 80% capacity. When I pay for 20 lbs of propane, I expect to get 20 lbs of propane. I never do the exchange thing. That's a blatant rip off IMO.
I'd like to know where you are getting your tanks filled that they are filling to 20 lbs. With the safety valve a perfect fill at optimal temperature will fill a tank with 16.8 lbs of propane. Found this old thread for reference: https://www.homebrewtalk.com/f11/20-lb-lp-liquid-propane-tanks-77833/

-cheers
 

Nateo

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If your supplier is filling your tank with a full 20lbs of propane, he's probably violating the law. If you're transporting them in your vehicle, that's probably violating the law too. I know it's against the law here in MO.

I don't really care about your safety, but those DOT regulations are for emergency workers in case you're in an accident. Having a greater margin of pressure on a tank may save their lives if your vehicle is on fire and they're trying to save you, inside of it.
 

Catt22

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Oh B.S! The tanks will hold 19-20 lbs with the 20% headroom to spare. The OPD does just that. It prevents overfilling. My dealer has been in business a very long time and I'm fairly certain he would not risk overfilling a cylinder. That would be blatantly stupid.

Like I said, you can check it yourself by weighing your tanks. It's very simple math to figure out. I buy the propane by the pound and I check to see if I'm getting what I pay for.
 

Nateo

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I bought a glass of wine the other day, and it's wasn't filled to the brim. I sent it back and got a glass of beer, and there was all this foam on top. I said "Well I'm not paying for foam!" and threw it at the waiter.
 

iaefebs

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A 20# propane tank with a normal fill holds 20# of propane. I check each time I fill a tank. I know that at one time Blue Rhino was selling tanks that had a longer fill tube and that would only allow a 15# fill. They were sued in Michigan and can no longer do this. The tanks they use have to be able to accept the 20# fill, they are allowed to sell 15# fills as long as the sign tells you it is 15#. I don't know the law in your state I don't know how many 15# only tanks are out there and if they still use the longer tubed tanks in your state. My empty tanks weigh around 18#, when I fill them they weigh 38#. Every time.... If I take in a tank that has 4# of propane remaining it weighs 22# when filled it weighs 38# and I am charged for the 16# for the fill.
 

shelly_belly

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Blue Rhino around here says net weight:15 pounds propane. I take my Blue Rhino tank to the propane guy and he fills it to 20 pounds (I weigh them to be sure). I pay him $15 and change whereas the Blue Rhino exchanges are $19 something + tax. Get more for less!
 

Catt22

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If your supplier is filling your tank with a full 20lbs of propane, he's probably violating the law. If you're transporting them in your vehicle, that's probably violating the law too. I know it's against the law here in MO.

I don't really care about your safety, but those DOT regulations are for emergency workers in case you're in an accident. Having a greater margin of pressure on a tank may save their lives if your vehicle is on fire and they're trying to save you, inside of it.
I care not about your safety as well. Actually, quite the contrary.:D
 

brewingmeister

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Using the 80% rule and assuming everyone is talking about the same standard bbq tank. The tank would have to be a 25 lb tank to be able to hold 20 lbs. Must get the 20lb label from the fill not capacity then? I'm going to have to start weighing my fills.

-cheers
 

Catt22

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Using the 80% rule and assuming everyone is talking about the same standard bbq tank. The tank would have to be a 25 lb tank to be able to hold 20 lbs. Must get the 20lb label from the fill not capacity then? I'm going to have to start weighing my fills.

-cheers
It's 80% of the water capacity (W.C.) which is stamped on the collar of the cylinder, not 80% of 20 lbs. That's where the confusion lies IMO.
 
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