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bdickson · 10-28-2012, 11:30 AM

We are all hooked up for the winter at a National Wildlife Refuge volunteer campground in New Mexico. They provide us with free Propane which comes in a "one hundred pound" cylinder that attaches to the "Extend a Stay" adapter I installed on the on board tank. My problem is knowing when the cylinder is going to need refilled (other than waking up cold in the middle of the night). Weighing the cylinder beside the MH is impracticable although I know weight is one of the most accurate methods. I have a gas gauge I bought in camping World for my barbecue bottle, but that uses the "new' style threads (the fat external thread on the tank valve). The valve on the 100# bottle is the "old" style with just the left hand internal thread. BTW, the bottle stands 5 feet tall and weighs 170 pounds full, so any solution involving lifting it isn't going to work.

What would be the best way of measuring or estimating the remaining content of the cylinder?

paz · 10-28-2012, 12:20 PM

When the propane is in use (such as when the furnace is running or DW is using the stove to cook dinner), pour hot water down the outside of the tank. You should be able to feel the temperature of the tank wall and detect a transition where the warm area (vapor above the liquid) and the cold area (liquid) meet to give you an approximate idea of where the level is.

DonDee · 10-28-2012, 12:27 PM

X2 for hot water.

Arch Hoagland · 10-28-2012, 12:40 PM

Sunbeam Rotating Dial Bathroom Scale, White - Walmart.com

Simply mount the tank on top of this scale. You will always know how much you have.

jesilvas · 10-28-2012, 03:26 PM

Temperate differential gauge, weight, or get a float valve.

Tony Lee · 10-28-2012, 06:15 PM

No fancy gizmos - just pour boiling water in a stream down the outside, wait a couple of seconds and run your hand up from the bottom and see where the tank gets hot.
(no need to be using gas at the time). Accurate to about 1/2"

Don't forget that "full" is actually only up to about 80% of the height of the bottle)

newmar10 · 10-28-2012, 07:47 PM

put it on a scale. Should weigh about 168 Lbs full

bdickson · 10-28-2012, 08:22 PM

Quote:

Originally Posted by newmar10

put it on a scale. Should weigh about 168 Lbs full

My original request was for a way of measuring the cylinder contents WITHOUT lifting it (to place on a scale for example). I'm well aware that weighing is the most accurate way, that is what we use when we fill the cylinders from the central storage tank. I am looking for an ongoing visual indication of what is left in the bottle while it is in use. Lifting it on to a scale is not an option. Nor is placing a personal weigh scale under it, as a previous poster suggested. The cylinder is way too big to fit.

bdickson · 10-28-2012, 08:24 PM

Quote:

Originally Posted by Tony Lee

No fancy gizmos - just pour boiling water in a stream down the outside, wait a couple of seconds and run your hand up from the bottom and see where the tank gets hot.
(no need to be using gas at the time). Accurate to about 1/2"

Don't forget that "full" is actually only up to about 80% of the height of the bottle)

OK, so thinking this out, would an infra red temperature gun work without the boiling water? Would it see the temperature difference at the liquid/gas line?

KIX · 10-28-2012, 08:35 PM

Quote:

Originally Posted by bdickson

OK, so thinking this out, would an infra red temperature gun work without the boiling water? Would it see the temperature difference at the liquid/gas line?

Yes, I think so. You will get a more pronounced temp diff. when using a higher BTU consuming appliance such as a water heater or furnace.

Gas companies used to sell a magnetic strip of a material that would change color to indicate the liquid level inside the tank. That's been several years ago and they probably don't have the item any longer. Your temp gun may just do the trick. You could verify whenthe tank is at a know quantity like after fillling it.
Good luck.

Dunner · 10-28-2012, 09:28 PM

What about a high volume auto switch-over regulator with a 5-7 gallon tank sitting next to the main one? The one I had on my 5er showed red when one tank was empty. You could periodically check it and have the main one re-filled as needed. The one I needed fed my propane generator and furnace and cost about $100 from a propane dealer.

BFlinn181 · 10-28-2012, 10:12 PM

Here's a magnetic strip with temperature sensitive markings. Pour hot water on tank and a color change will show the level.

http://www.amazon.com/21st-Century-B.../dp/B0001UZRBG

I'm sure they are available elsewhere, this was the first I found. I've had a similar product for years and it gives a good idea on how much LP you've got left.

Arch Hoagland · 10-28-2012, 11:13 PM

Quote:

Originally Posted by Arch Hoagland

Sunbeam Rotating Dial Bathroom Scale, White - Walmart.com

Simply mount the tank on top of this scale. You will always know how much you have.

My thought was to permanently mount the tank on the scale. Not lift it on each time.

I like the IR gun idea and will test it out soon.

Tony Lee · 10-29-2012, 01:57 AM

Why use the IR gun when your hand has some pretty IR sensors already in it.

Yes, checking when a high volume appliance is running will give you a fairly good indication and if the dew point is right, you might even get a ring of frost below the liquid level. I - and others - suggest the boiling water because if you run your hand up the cylinder soon after pouring the water, the boundary between hot and cold is very distinct, but after a time the boundary becomes broader because of conduction.

How accurate do you need it anyway since you just want a rough idea when it is going to run out so you can refill it in time.