Propane Tank Puzzlement

[Iowa Dave]

Hi Mike
I would suspect that thermometer could pick up the tank level fairly easily especially if the draw out of the tank was significant. I know that a large stove like a camp chef with dual 30,000 burners, or a turkey fryer with a 60k burner will ice up the exterior of
a tank if they are full on. Some of the portable campfires will do this too. You can get down low on a tank that would run the stove or refrigerator on an Escape and it will go dry on you. But a maximum draw on a low tank can freeze them up. Once they thaw they'll provide propane again.
Dave

[Mike Lewis]

Dometic makes a device that will measure the level of propane in a tank. It looks like a pen and uses ultrasound; you press it against the side of the tank and it will light up red or green depending if liquid propane is on the other side of the tank wall at that location. There is a sticker on mine that says "Model No. 9108844791".

The drawback is that this thing is expensive: $50 if I remember correctly. I bought it on an early trip two or three years ago because I was frustrated that I kept returning tanks for refill when they were still partially full, or somehow managing to drain both tanks and run out completely. But I don't think the device is worth the cost, since you can buy a propane tank with a gauge for the same price.

[Iowa Dave]

Hi Mike
That's kind of the way of camping for me. Can I justify the cost of something not totally necessary? Frustration, return on investment, upgrading to a real good one that will last all go into the mix. There are also the weird dimensions of pride of ownership, competitive ownership ( I got one of those too) and total convenience ( one for home one for the camper). That's how I see it. I bleed nearly empty tanks off at home cooking on a Weber Q. Low draw won't freeze the tank.
Dave

[Vermilye]

I carry a luggage scale, and use it to weigh the tanks. I've found it very accurate, however is is a bit of a pain to use since you need to disconnect the tank to weigh it. I don't use it ll that often, just when I'm heading to someplace where getting a refill would be difficult, or when the change over hasn't happened when I suspect it should have.

I had an interesting problem with my first regulator. When I disconnected the empty tank, even though the lever was switched to the full one, propane hissed out of the empty connector.

I do carry a dental mirror that I use to see the "red" line in the regulator indicator. Before that I had to remove the entire propane tank cover before I could see the thing. Now all I do is open the top cover.

[Mike Lewis]

I'm not sure my automatically switching regulator works properly. I don't think it completely drains Tank #1 before switching to Tank #2, and it gets confused when both tanks are partially full. This is why I bought two tanks equipped with gauges.

I paid attention when I had my second gauged tank filled for the first time. It took 4.6 gallons. I had the other one refilled when its gauge was pegged on "empty". It took four gallons, so there was a bit left inside. Next time I'll leave the tank on the regulator a few days after it reads "empty", to see if the regulator will drain it dry. I doubt it.

[ReagentGrade]

I use a tank like this one. I saw them recently at Costco for about $25. They have an internal float that accurately measure the liquid level inside. This has nothing to do with pressure.

Mine work very well!

[Brian B-P]

Originally Posted by Mike Lewis

Brian,
Will your infrared thermometer detect a temperature difference between a tank that is being used vs. one that isn't being used? Evaporating propane should cool the tank in use, but I don't know if the cooling would be detectable.

I'm sure it can, if the rate of use is high enough, since the difference can be substantial and the thermometer has a resolution (although not accuracy) of less than a degree. It was past midnight and below freezing when I check before by previous post, so I didn't do more testing; also, infrared thermometer readings depend on the characteristics of the surface (not just the temperature), and the tank in use is painted differently from my other tanks so a comparison wouldn't be ideal.

[Brian B-P]

Originally Posted by Vermilye

I had an interesting problem with my first regulator. When I disconnected the empty tank, even though the lever was switched to the full one, propane hissed out of the empty connector.

Presumably a stuck check valve. I haven't found propane equipment for RVs to be particularly robust, so I wouldn't be surprised by a valve which has mechanically failed, or stuck due to contamination.

[Brian B-P]

Originally Posted by Mike Lewis

I'm not sure my automatically switching regulator works properly. I don't think it completely drains Tank #1 before switching to Tank #2...

I paid attention when I had my second gauged tank filled for the first time. It took 4.6 gallons. I had the other one refilled when its gauge was pegged on "empty". It took four gallons, so there was a bit left inside...

When a tank no longer has any liquid propane, the pressure in it drops below the vapour pressure of liquid and vapour propane in equilibrium. The switchover mechanism is driven by the difference in pressure between the tanks, so when one empties and the other has some in it, the switch occurs. This can go wrong in two ways:

1. the pressure in the primary tank (in use) can drop far enough to trigger the switch due to chilling of the propane, even though there is liquid remaining; or,
2. the pressure in the backup tank (in reserve) can drop far enough to be inadequate to drive the switchover, due to low ambient temperature.

The first problem can cause leftover propane in normal camping conditions. The second problem can be an issue in winter.

Originally Posted by Mike Lewis

... it gets confused when both tanks are partially full.

The pressure in a propane tank depends only on the temperature, as long as there is any liquid, regardless of the level. If no propane is being used, there is no chilling effect of vapourization, so the temperature of two tanks sitting side-by-side is the same, and they will have the same pressure. The auto-changeover device isn't confused by this - it just doesn't care. It has no way to select the "more full" tank - it simply stays on the primary tank (the one the control lever points to) until there is enough pressure difference.

[Mike Lewis]

Originally Posted by Brian B-P

The auto-changeover device isn't confused by this - it just doesn't care.

"Confusion masked by indifference" -- that could be my motto.

Currently my starboard tank is less than half full, according to my ultrasonic pen. My port tank has not been used since refilling-- it is full. The black lever points to the starboard tank.

The red/greeen window right now is exactly that: part red and part green. To me that reads "confused" and I see it like that a lot. My expectation is that as I continue to drain the starboard tank, the window will turn entirely red, and at some point the regulator will start using the port tank. But frequently that window never turns entirely red, and I end up refilling a tank that doesn't need it yet. The system is less than satisfactory.

[padlin]

Originally Posted by Mike Lewis

The red/greeen window right now is exactly that: part red and part green. To me that reads "confused" and I see it like that a lot. My expectation is that as I continue to drain the starboard tank, the window will turn entirely red, and at some point the regulator will start using the port tank. But frequently that window never turns entirely red, and I end up refilling a tank that doesn't need it yet. The system is less than satisfactory.

I swapped out my original change over regulator with a MEGR last fall, have seen the same screwy indicator since. Seems to go half way down then it stops, can't tell when it's really empty.

[cpaharley2008]

Time to get a new Escape, Mike, that is what I do when I run out of propane.....

[cpaharley2008]

Originally Posted by ReagentGrade

I use a tank like this one. I saw them recently at Costco for about $25. They have an internal float that accurately measure the liquid level inside. This has nothing to do with pressure.

Mine work very well!

They want $40 for the same at Sam's Club

[Donna D.]

Originally Posted by cpaharley2008

They want $40 for the same at Sam's Club

Humm, I can see where one indicator would face the front and the other the back wall on a dual-tank setup. Unless it could be turned around. (?)

[Mike Lewis]

Originally Posted by Donna D.

Humm, I can see where one indicator would face the front and the other the back wall on a dual-tank setup. Unless it could be turned around. (?)

My tanks are positioned so that the gauges face the same direction, and I can see both when I open the small hatch on the tank cover. I don't know what the 5.0 TA propane tank compartment looks like, though, so I don't know if you would have trouble seeing them.

[Mike Lewis]

Originally Posted by cpaharley2008

Time to get a new Escape, Mike, that is what I do when I run out of propane.....

Yeah, we've noticed.

As for me, I'm one and done. I intend to wear my trailer out then quit.

[Brian B-P]

Originally Posted by Donna D.

Humm, I can see where one indicator would face the front and the other the back wall on a dual-tank setup. Unless it could be turned around. (?)

No, neither this design (which I believe is from Worthington) nor the one from Manchester allows you to move the gauge position. The two designs are oriented the same way (if you're looking at the gauge, the hose fitting is to the left), so you can't use one of each type to get a mirror-image pair.

Use a mirror for one tank? Try other orientations of the tanks?

[ReagentGrade]

Originally Posted by Brian B-P

Use a mirror for one tank?

That's exactly what I did: used double sided foam tape to mount a stainless steel camping mirror behind the second tank.