Hey folks, we had our local gas heating company come out and fill our propane tank that is used to heat our home. My question is, when I checked it this morning and yesterday after it was filled, the gauge only read 80%. I’ve read some confusing material online, so does it mean it is full and just adjusted for temperature changes? Or.. is it 20% less than full. It’s a 500 gallon, underground tank.
Home Propane Tank Gauge Question
- Thread starter Toro50cutter
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80% is the normal maximum fill. If you have a 500 gallon tank, it currently contains 400 gallons. The top 20% is propane vapour. It’s propane vapour that your furnace burns, not liquid propane.
They fill to 80% to leave room for expansion in the summer heat.
Okay. This is our first home which heats off of propane. Good to know & thank you very much
What 'amount' did they charge you for? / check the bill.
Like car tires where the pressure increases in the Summer.
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When its January and we are in a cold snap I have tried to get them to fill mine to 90 percent, they just will not do it. By the time there was any problem with expansion I would have burned thru a tank!
I have also had mine filled to 80 percent in May and thru the brutal heat of the summer while not burning any propane the level increase was almost not noticeable.
I believe it to be the real reason it will only be filled to 80 percent is to maximize profits by getting more trip charges. Don't laugh, if they short everybody from a full fill and end up with 1000s of extra trip charges you better believe they are making more money!
I have also had mine filled to 80 percent in May and thru the brutal heat of the summer while not burning any propane the level increase was almost not noticeable.
I believe it to be the real reason it will only be filled to 80 percent is to maximize profits by getting more trip charges. Don't laugh, if they short everybody from a full fill and end up with 1000s of extra trip charges you better believe they are making more money!
I don't know how large your tank is. (I'm assuming it's very large if it is used to supply the furnace of your home in a cold Winter climate). And while I'm not familiar with how the gauges work on these large tanks, I can say EVERY propane gauge I've seen on smaller tanks, (20, 30, and 40 pound), doesn't read well at all.
Most base their readings on pressure, not volume. The pressure is quite constant with these smaller type of tanks, until the liquid is all but exhausted. So what most always ends up happening, is the gauge shows the tank to be full, or else near full until it is all but empty.
Then the gauge responds by dropping. But by then the propane in the tank is all but exhausted. I've had this happen to many different gauges on various 20 pound tanks used on barbecue grills. I would start grilling because the gauge showed the tank to be full, or near full, only to run the tank dry when the food was only halfway cooked.
For these situations the bast "gauge" is a scale type of gauge, that constantly reads the weight. Then, as the liquid propane burns off, you have a direct decreasing reading that is relative to the amount of liquid propane left in the tank. But these "Full / Empty" screw on the tank gauges that are pressure activated, are all but totally useless. And I've had many of them over the years, that ended up in a drawer directly because of there uselessness.
Most base their readings on pressure, not volume. The pressure is quite constant with these smaller type of tanks, until the liquid is all but exhausted. So what most always ends up happening, is the gauge shows the tank to be full, or else near full until it is all but empty.
Then the gauge responds by dropping. But by then the propane in the tank is all but exhausted. I've had this happen to many different gauges on various 20 pound tanks used on barbecue grills. I would start grilling because the gauge showed the tank to be full, or near full, only to run the tank dry when the food was only halfway cooked.
For these situations the bast "gauge" is a scale type of gauge, that constantly reads the weight. Then, as the liquid propane burns off, you have a direct decreasing reading that is relative to the amount of liquid propane left in the tank. But these "Full / Empty" screw on the tank gauges that are pressure activated, are all but totally useless. And I've had many of them over the years, that ended up in a drawer directly because of there uselessness.
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This is a 1000 gallon above ground tank
This is why these tank exchange places like "Blue Rhino" short fill ALL of their 20 pound tanks. They're basically charging you for a 20 pound fill, but you're getting only 15 pounds of propane.
This is why I always purchase my own tank, and get it filled in town. If the guy knows what he's doing, you should get 4.7+ gallons of propane in a 5 gallon, (20 pound) empty tank.
The older tanks that didn't have the internal float shut off were capable of getting a bit more. But most of those are all out of date, and can't be filled anyway.
I do on
Ours has a Mechanical float. They had too replace it as it sprung a leak.
80% fill is considered a full tank. Filling above that value is a safety violation. All propane tanks are designed for 80% as the full capacity even the tank on the delivery truck. Your ticket from the delivery will show gallons delivered which is what you are charged for. Even if the guy only fills the tank to 70% you are being charged only for the gallons delivered. The tank must have room for the liquid to vaporize and as mentioned above your propane devices burn the vapor not the liquid.
Here is a quick example to help separate the impact of the safety margin from the impact of businesses that short fill 20 pound tanks.
A typical 20 pound tank has a maximum capacity (ignoring the 80% safety factor) of roughly 5.7 gallons. To confirm this you can divide the water capacity (WC) stamped on the tank by the weight of a gallon of water:
WC / (Pounds per gallon of water) = 47.6 / 8.34 = 5.7 gallons.
Reducing the maximum capacity of the tank to account for the 80% safety factor gives a maximum safe fill of:
.80 x 5.7 gallons = 4.6 gallons.
Converting gallons of propane to weight of propane gives:
4.6 gallons x 4.2 pounds per gallons = 19.3 pounds which is roughly 20 pounds.
As you can see from the work above, businesses that short fill 20 pound tanks with only 15 pounds of propane are doing so for reasons other than the 80% safety factor. In contrast, businesses that fill a 500 gallon tank with 400 gallons of propane are doing so because 400 gallons of propane is the maximum safe fill level for a 500 gallon tank.
I hope this helps.
A typical 20 pound tank has a maximum capacity (ignoring the 80% safety factor) of roughly 5.7 gallons. To confirm this you can divide the water capacity (WC) stamped on the tank by the weight of a gallon of water:
WC / (Pounds per gallon of water) = 47.6 / 8.34 = 5.7 gallons.
Reducing the maximum capacity of the tank to account for the 80% safety factor gives a maximum safe fill of:
.80 x 5.7 gallons = 4.6 gallons.
Converting gallons of propane to weight of propane gives:
4.6 gallons x 4.2 pounds per gallons = 19.3 pounds which is roughly 20 pounds.
As you can see from the work above, businesses that short fill 20 pound tanks with only 15 pounds of propane are doing so for reasons other than the 80% safety factor. In contrast, businesses that fill a 500 gallon tank with 400 gallons of propane are doing so because 400 gallons of propane is the maximum safe fill level for a 500 gallon tank.
I hope this helps.
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It will vaporize if the tank is filled to 90 percent or even 95 percent.
Not exactly on point but relevant to propane tanks:
A propane guy told me there is a "kinda clear goo" which collects in small propane tanks. He said refillers do not empty this goo unless the tank is refurbed. He also said many of the white rental tanks we see are from the '70's!
Does anybody know if there's any truth to these claims?
Will this goo be delivered to our buried tank as well? Does it need to be serviced (removed) periodically?
Our supplier mentioned the 80% fill too.
A propane guy told me there is a "kinda clear goo" which collects in small propane tanks. He said refillers do not empty this goo unless the tank is refurbed. He also said many of the white rental tanks we see are from the '70's!
Does anybody know if there's any truth to these claims?
Will this goo be delivered to our buried tank as well? Does it need to be serviced (removed) periodically?
Our supplier mentioned the 80% fill too.
Thank you. Sometimes it would be better to discuss this over a beer. A guy can write an essay to deliver all the facts. But generally here is a good document to end the discussion and carry on with other things.
My research shows propane expands 1.5% every 10 degrees F
By my calculations it would take a 150 degree F temperature swing from a tank at 80% full to when it would run out of room to expand.
So it would take filling a tank with -30 F propane and it would run out of room to expand when the propane in the tank hit 120 degrees F Seems like a pretty good safety margin.
By my calculations it would take a 150 degree F temperature swing from a tank at 80% full to when it would run out of room to expand.
So it would take filling a tank with -30 F propane and it would run out of room to expand when the propane in the tank hit 120 degrees F Seems like a pretty good safety margin.
The safety factor is there to prevent too much pressure from building up inside the tank as the liquid gas expands. For example, an increase due to expansion from 80% full to 90% full would roughly double the internal pressure of tank. This type of pressure increase will trigger the pressure relief valve to release propane gas into the atmosphere long before the tank fills completely with liquid propane. Anyone that has heard the hissing sound of a propane tank pressure relief valve in action knows what that type of release sounds like.
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If you fill a tank to 95 or even 100 percent the propane will vaporize just fine, it is stored under pressure as a liquid and vaporizes when it leaves the pressurized tank and then turns to vapor since it boils at -44°f. The liquid level of a substance in a pressurized vessel doesn't dictate when and if the liquid will vaporize, pressure, temperature and the boiling point of the liquid dictates if flashes to vapor.
