Q RE: Dual Propane Tanks Gauge Reading

[2KC Seattle]

Hi,
We're just starting to de-winterize our 15A (new Feb 2015) and have a question about how to read/interpret the propane gas gauge. The gauge always seems to "look" the same, with two green quarter triangles (I'm attaching a photo of this) so I can't figure out how full/empty they may be. When I do the old fashioned test of dripping hot water down side of tank for about 10-15 seconds, I can feel down the sides and find that where it's still "hot" it's empty (no cold gas) and where it's cold begins to reveal the gas level. So this results in on tank appearing to have less than 1/4 left and the other about 60-75%. The gauge just stays the same and I've no idea if it is giving my a clue about how full they might be.

I'm planning on taking both tanks to get refilled at gas station and I see in the manual a strong caution DO NOT FILL CONTAINERS TO MORE THAN 80% OF CAPACITY. FAILURE TO COMPLY COULD RESULT IN A DEATH OR SERIOUS INJURY.
This note got my attention, but how does the attendant refilling a given tank know when it hits 80%?
Thanks for any thoughts or advice on monitoring and refilling propane tanks "to 80%".
- King

[bouterse]

The weight of the empty tank is stamped on the tank. If you weigh your tank and subtract the stamped weight, you will know how much is left. This is what the propane attendant will also do.

[KirkB]

The purpose of the tank indicators is to tell you when the regulator has switched to the backup tank, not how much fuel is left in the tank. When the indicator is green, the regulator is using propane from the tank in the direction of the black switch. When this primary tank is empty, the indicator turns red and the regulator uses the propane from the other tank. That is when you can refill the first tank as it is completely empty.

Sometimes I have seen the indicator partly red, in that case the primary tank is almost empty and in the process of switching tanks. Half red would not mean the tank is still half full.

Try turning one tank valve off, then fire up the hot water heater (it runs for a while) then switch the black lever back and forth to see how it works.

I use a cheap luggage scale to weigh my propane tanks before each camping trip.

[barry]

Originally Posted by bouterse

The weight of the empty tank is stamped on the tank. If you weigh your tank and subtract the stamped weight, you will know how much is left. This is what the propane attendant will also do.

This is what they do in Canada but when I've had propane filled in the States they unscrew the little overflow screw and wait until propane comes out of it before they shut it down. In Canada it's sold by the lb but in the States it's sold by the gallon.

Barry

[Greg A]

Kathy and King,
That's the regulator type I had that was bad when I left ETI. It was full of water and froze preventing auto switch. It could be the picture, but yours looks like it has water inside the flag Windows too. Reace sent me a better model regulator when I got home and changed it out. Haven't had any more problems since the change.

[davescape]

Originally Posted by KirkB

The purpose of the tank indicators is to tell you when the regulator has switched to the backup tank, not how much fuel is left in the tank. When the indicator is green, the regulator is using propane from the tank in the direction of the black switch. When this primary tank is empty, the indicator turns red and the regulator uses the propane from the other tank. That is when you can refill the first tank as it is completely empty.

Thanks, this is the first explanation I've seen that makes sense. I never did quite figure out what was going on with the indicator.

[2KC Seattle]

As always, such a helpful bunch of good folks on this forum. Thanks indeed for the good info and advice. I will give it a try. As an aside, my experience filling tanks in US has been the same as Barry's, i.e., they fill it till the relief valve at top squirts out and then stop.

[2KC Seattle]

Thanks Greg - sorry about the upside down picture and you correctly spotted some water drops in the gauges. Don't know if that will impact switching yet, as haven't even gone through one tank. I'll watch it though.

[Brian B-P]

Originally Posted by bouterse

The weight of the empty tank is stamped on the tank. If you weigh your tank and subtract the stamped weight, you will know how much is left. This is what the propane attendant will also do.

This certainly is the most accurate way to determine how much is left.

A propane filling attendant who is filling by weight should check the tare (empty) weight marking to determine what the filled weight will be. Unfortunately, I've never seen an attendant do this - they just assume the same tare weight for all tanks of the same nominal size, and have their scales marked for the corresponding full weight.

Originally Posted by barry

This is what they do in Canada but when I've had propane filled in the States they unscrew the little overflow screw and wait until propane comes out of it before they shut it down. In Canada it's sold by the lb but in the States it's sold by the gallon.

Yes, typically portable propane tanks are filled by weight in Canada and by volume in at least many places in the U.S. That little "overflow" screw is the 80% fill level bleed valve, so when it starts spitting liquid the tank is filled with liquid to the correct maximum level.

[Brian B-P]

Originally Posted by KirkB

The purpose of the tank indicators is to tell you when the regulator has switched to the backup tank, not how much fuel is left in the tank. When the indicator is green, the regulator is using propane from the tank in the direction of the black switch. When this primary tank is empty, the indicator turns red and the regulator uses the propane from the other tank. That is when you can refill the first tank as it is completely empty.

Great explanation!

The mechanism inside these selectors is driven by the difference in pressure between the tanks, so sometimes the switchover is slow or uncertain, especially in cold weather (which lowers propane pressure).

One note: when the primary tank is empty, before removing it to take it away for refilling, turn the selector to the other tank.