How can you tell how much propane is left in a tank?

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On Tue, 24 Jan 2012 18:13:05 -0500, "Robert Green"

tank is to use a scale and weigh it.
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snipped-for-privacy@snyder.on.ca wrote:

I've seen a setup on older BBQs that employed a sprung carriage to hold the tank. The carriage has a hinge on one end, and a compression spring on the other.
When the tank is full, it compresses the spring, and the indicator needle on the carriage points to the "Full" line. As the tank gets lighter, the spring lifts up the indicator needle, and it starts heading up towards the "Empty" line, letting you know it is emptying.
I'm usually too lazy to bend over and look at the indicator, so I just keep a one pound bottle of propane handy should I run out of gas in the middle of a cook. I can usually avoid that, however, by noting that when the tank is on it's last legs, the pressure appears to actually increase, giving a much more aggressive flame pattern.
That's what usually lets me know it's time to go get the tank filled.
Jon
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On Jan 25, 2:50 pm, "Jon Danniken"

years ago machines I serviced use 1 gallon cans of liquid stored in the base cabinet of the machine.
Ditto machine can weighing unit.
_______________________________________________________________________________
I REALLY DONT UNDERSTAND why the OP doesnt just keep a spare tank, and swap it out when needed.......
I mean you gain nothing weighing the tank when its empty doesnt matter its still empty and must be changed...
just run till empty and change
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We do a lot of RV camping and here are two suggestion that can be used without dismounting the tank:
1) Pour some very warm water down one side of the bottle. then feel the bottle. The part that still contains propane will be noticeably cooler than the empty area.
2) Higher tech version of the above - I bought one of the cheaper laser touch-less thermometers from Harbor Freight. They sell them in the $15 to $60 range. I opted for one of their mid range pistol type that was around $25. Otherwise it is the same procedure as above except, if the bottle is not in direct sun you might not even need hot water. In very cool weather you will need to use the water.
Besides that, when you get the laser thermometer you will play with it for days. And no, for $25 you are not buying laboratory grade instrumentation. Those go up way up in price. Just use it to gage differential temp.
Ron
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wrote:

<<We do a lot of RV camping and here are two suggestion that can be used without dismounting the tank:>>
Ah, a man who understand that dismounting the tank makes the weighing method less than optimal - although looking at the porch I did find a way to mount a sturdy eyebolt without it being terribly ugly - that might be the ultimate solution.
<<1) Pour some very warm water down one side of the bottle. then feel the bottle. The part that still contains propane will be noticeably cooler than the empty area.>>
Brilliant. The empty section will dissipate heat far more quickly than the propane submerged part. The only problem I see is adding anymore water to an already frozen-over porch. I might be able to achieve a similar result in reverse by hitting the outside of the tank with a can of Dust-off sprayed upside down. I am sure the tank will get colder where it's empty for the same reasons warm water works.
Of course, I could just hit the side of the tank with a blast from the torch nozzle if I wanted to live *very* dangerously. (-:
<< 2) Higher tech version of the above - I bought one of the cheaper laser touch-less thermometers from Harbor Freight. They sell them in the $15 to $60 range. I opted for one of their mid range pistol type that was around $25. Otherwise it is the same procedure as above except, if the bottle is not in direct sun you might not even need hot water. In very cool weather you will need to use the water.>>
Already have two of the suckers. One by the microwave to insure safe cooking temps and the other on the toolbench. I'll see now if I can see any difference.
<<Besides that, when you get the laser thermometer you will play with it for days. And no, for $25 you are not buying laboratory grade instrumentation. Those go up way up in price. Just use it to gage differential temp.>>
They're very useful for finding air leaks. I know there are "issues" with all IR thermometers, cheap and expensive. I am sure my dogs big spots aren't really that much cooler than the rest of her. It's an artifact of IR reflection from different colored surfaces. (-: (They are brown spots that appear jet black under IR light.)
-- Bobby G.
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You missed "Lazy". Our trailer has the bottles inside of a plastic housing. In order to check bottle levels on a daily basis, I would have to remove the housing which takes a little time. Opening the top panel and pointing the laser down into the opening is easy.
Lazy.
RonB
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wrote:

<<You missed "Lazy". Our trailer has the bottles inside of a plastic housing. In order to check bottle levels on a daily basis, I would have to remove the housing which takes a little time. Opening the top panel and pointing the laser down into the opening is easy.>>
Lazy is just the lazy way of saying "efficient." (-:
-- Bobby G.
Lazy.
RonB
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On 1/24/2012 7:45 AM, Robert Green wrote:

the best way is to weigh it. There will be a "TR" number on the bottle. This is your 'tare' weight. That is the weight of your empty bottle. Just weigh yourself, then pick up the bottle and see the difference. Then from that number subtract your tare weight. The difference will be the pounds of propane in the jug.
--
Steve Barker
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On 1/24/2012 9:03 AM, Steve Barker wrote:

correction: The "TR" should read "TW". Tare Weight.
--
Steve Barker
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On 1/24/2012 10:03 AM, Steve Barker wrote:

I agree. A pressure gauge would not give a good answer until it was near empty. The dew line on these tanks are hard to determine and tank has to be in use for temperature differential to exist.
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Two problems: One is that the tank's now quite securely fastened to a small luggage cart that won't easily sit on the bathroom scale unless I make up some sort of platform for it - which I may yet do. That's because even 4 seconds of bone-on-bone contact in the wrist seems to be something a few RCH's short of a crucifiction nail. All it takes is a load shift in the wrong direction to do it. As my MD says, you're now at the age/condition where you can't lift anything larger than your head.
With a little forethough I should be able to design an "interface" to the bathroom scale that allows me to use the collapsible handle on the cart as a lever to angle it onto the scale. The block needs to be high enough to prevent any part of the tank and cart from touching the ground. If that doesn't work, I've mounted a heavy duty screw-eye to the porch overhang where I can pull a rope attached to the scale through and "hoist" the tank and cart up for a weigh-in. Then, I can build a little hangman's scaffold, roll the tank and cart up over a trap door and then kick it loose to do the weigh-in. Well, just kidding, but it does look like I'm going to end up with a weight solution.
-- Bobby G.
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On 1/25/2012 12:17 AM, Robert Green wrote:

It's a lever. Lay the handle on the scale and make a calibration chart.
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years ago i had a gauge that threaded on the tank with a rotary dial.
i couldnt use it anymore when my new grill used a new style fitting........
the gauge appeared to work pretty well....
why not buy one locally and try it? return it if it doesnt work
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wrote:

I'm not sure why anyone would say that you won't have enough advanced notice when using a scale.
It shouldn't be much more complicated than a "weight per time period" calculation.
Using rough numbers here...
The Tare weight of a standard gas grill tank is ~20lbs, as marked on the tank. YMMV
Depending on where you have it filled, they may put anywhere from 15 to 20 lbs of propane in the tank but that doesn't really matter. The only numbers that matter are the overall weight at any given time and the Tare weight. The only number that will change is the overall weight.
As you use the propane the overall weight will go down. If you monitor your usage over some time period, you should be able to determine how long it takes, on average, to use 1 lb of propane.
When the scale reads ~21 lbs, you have roughly whatever "time" left that it takes to use 1 lb, based on average usage.
If 1 lb is too fine of a measure or too short of a time notification, use 2 lbs or 3 lbs or whatever works for your situation.
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.
easiest to just have a spare full tank to transfer to when the primary tank runs out
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...
How does that answer Bobby G's question, which was...
"How can you tell how much propane is left in a tank?"
I always have a spare tank on hand but it has never once told me how much propane is left in the other tank.
Your suggestion may indeed solve the problem of running out and it is most assuredly employed by countless propane users. However, it doesn't answer the question that was asked.
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om...
either way it doesnt matter. when the tank is empty it must be changed....
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.com...
How does that answer Bobby G's question, which was...
"How can you tell how much propane is left in a tank?"
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<stuff snipped>

<<I'm not sure why anyone would say that you won't have enough advanced notice when using a scale.>>
My error. When I said "dial" I meant the dial type pressure gauges. What I was trying to say was: "If the scale idea fails, I am back to the dial-type pressure gauge which a lot of people claim does not give enough advanced warning of an empty tank." I don't expect the scale method to fail, though.
-- Bobby G.
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OP poster could run the torch flat out from full tank to empty, and note the time.
or store a spare tank under a overturned garbage can. i did that years ago with some spare gasoline
or build a ventilated secure container of some sort close to the house for easy tank swap.
while OP is concerned about weight of tank, he may not realize the weighing unit and scale will make moving the unit heavier.......
if OP concrete areas need replaced i would suggest a new whatever with imbeded PEX line to warm the areas when needed
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