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Old 01-31-2013, 07:05 AM   #21
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Quote:
Originally Posted by rwidman View Post
From my post above:

"While there are several ways to determine how much propane is left in a steel tank, I just weigh mine with a fish scale. The tank's empty weight should be stamped on the tank, anything more than that is propane."
Well aware of the weight thing for checking Ron, but where my tank is fixed in place it is totally impractical to weigh it, and a major hassle to detach and remove it do do so. Most of the gauges that measure the level pick up the temp difference, and require one to pour hot water down them to indicate, (briefly), where the level is. Also not really feasible in my case. But I have heard of one magnetic strip one which does not require hot water poured on, so am investigating that.
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Old 01-31-2013, 10:30 AM   #22
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Maybe I'm missing something but if the question is "how much propane is in the tank" I've been using this for years, without a hitch.

"Gas Watch"
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Old 01-31-2013, 01:06 PM   #23
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Originally Posted by SeaHorse II View Post
Maybe I'm missing something but if the question is "how much propane is in the tank" I've been using this for years, without a hitch.

"Gas Watch"
That won't fit in my propane locker.
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Old 01-31-2013, 01:13 PM   #24
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Originally Posted by SeaHorse II View Post
Maybe I'm missing something but if the question is "how much propane is in the tank" I've been using this for years, without a hitch.

"Gas Watch"
Any secrets? Most people I know and my own experience is they are wildly inaccurate.

It's...gas...gas...gas...no gas or about 10 minutes worth....

They are good for checking leaks though..
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Old 01-31-2013, 01:38 PM   #25
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Any secrets? Most people I know and my own experience is they are wildly inaccurate.

It's...gas...gas...gas...no gas or about 10 minutes worth....

They are good for checking leaks though..
It's just a pressure gauge and makes no measurement of the liquid left in your tank. As long as you have liquid you will have pressure. No liquid and the pressure goes away quickly.
You are correct about checking for leaks. Pressurize the system, shut the tank off and you should maintain pressure indefinitely.
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Old 01-31-2013, 01:57 PM   #26
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For checking the amount of fuel in a metal tank just spray some water on the outside. It will freeze to the level of the fuel inside. Spray bottle with water works good.
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Old 01-31-2013, 02:08 PM   #27
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For checking the amount of fuel in a metal tank just spray some water on the outside. It will freeze to the level of the fuel inside. Spray bottle with water works good.
Say what? You might want to re-think that.
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Old 01-31-2013, 02:10 PM   #28
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Greetings,
Mr. OFB. Thanks, good tip. Can you still see that effect if the tank is not in use? Say it's been sitting, properly positioned and secured of course, on an open deck unused for a period of time. Wouldn't the gas inside the tank be the same temperature as the surrounding air?
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Old 01-31-2013, 10:27 PM   #29
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Quote:
Originally Posted by RT Firefly View Post
Greetings,
Mr. OFB. Thanks, good tip. Can you still see that effect if the tank is not in use? Say it's been sitting, properly positioned and secured of course, on an open deck unused for a period of time. Wouldn't the gas inside the tank be the same temperature as the surrounding air?
That about sums up the issues with measuring what liquid gas is still there. The gauge Walt showed only starts to warn you once all the liquid has turned to gas, so warns only when there is just minutes or at best a couple of hours of gas left.
The temp difference thing is what most of the other gauges use, and the water sprayed on has to be hot, so the difference between the level of liquid gas (colder), will show up on a special magnetised, (to stick to the side of the bottle), strip with a special agent which changes colour with the hot/cold difference marking the level. You won't see ordinary water freeze just sprayed on tho in my experience, they are not that cold to start with, even over the liquid gas portion.
That's why the composites where you can see the level are soooo good. Damn, I wish I'd kept mine anyway. I could have probably convinced someone to fill it for me if I wasn't so law abiding. There was nothing wrong with it. And no corrosion issues is the other huge plus.
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Old 01-31-2013, 10:34 PM   #30
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Greetings,
Well, my point is I don't think there will be a temperature differential if the tank has been static for any length of time. Once the gaseous propane reaches an equilibrium with the liquid propane, I think everything inside, outside and the tank itself will be at the same temperature. It's only when the gas is being drawn off (used) that the liquid propane cools due to evaporation thus creating a temperature differential. Do I understand the situation properly?
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Old 02-01-2013, 01:26 AM   #31
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Yup - pretty much RT. Good comment.
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Old 02-01-2013, 05:19 AM   #32
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I
The fiberglass tanks are better in a fire, as they are not subject to exploding like a grenade as a steel tank can.

Why? What do they do instead?
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Old 02-01-2013, 12:49 PM   #33
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Say what? You might want to re-think that.

Anode

I do not understand this comment?

I do this to check the level of fuel in a bottle of compresed gas.

Re think that why ?
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Old 02-01-2013, 01:19 PM   #34
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Why? What do they do instead?

Older tanks with older style valves do not release the fuel when under extreme preasure. They wil grenade when heated to extreme. Its a huge bang !

However here in BC tanks must be inspected and the valve replaced every ten years to be filled. Tanks with old style valves can not be re filled here in BC by any retail outlet.

Compliant tanks using these valves will vent when preasure in the tank is too high. With these valves they no longer grenade if over heated and or over filled. They turn into a torch instead.

Composit tanks fall under these regs and that makes them a bit expensive past that ten year's date with inspection and re valve. Here in BC any way.
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Old 02-01-2013, 02:09 PM   #35
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Quote:
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Why? What do they do instead?

Google 'composite propane tank fire safety'

A steel tank in a fire can vent thru the valve's blowoff safety vent, split a seam and spill propane, or explode like a grenade, with shrapnel everywhere.

The propane burns off when vented. This is the best outcome, with the explosion the worst.

A composite tank burns thru, releasing the propane which burns without any explosion.
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Old 02-01-2013, 02:20 PM   #36
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I have a correction to make to my previous post. I found a qualified salesman at the Sure Marine booth at the Seattle Boat Show who explained the situation.

Composite tanks must be recertified after 5 years (USA rule). It's aluminum tanks that are good for 12 years.

After a tank has had propane in it, it can no longer be shipped by UPS, etc. To get a tank re-certified, there has to be a nearby company that can do the work.

After considering all this, a steel tank could be the cheapest way to go. Pay $30-$40, use till its too rusty or out of date, and buy a new one. Re-certifying a composite tank which originally cost $100+, could cost $45 (Seattle price) after 5 years.

An aluminum tank is an option as it is good for 12 years, no re-certification needed.
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Old 02-01-2013, 02:58 PM   #37
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Anode

I do not understand this comment?

I do this to check the level of fuel in a bottle of compresed gas.

Re think that why ?
Sorry if my cryptic comment sounded smart ass but I work with propane for a propane company almost daily in the winter. It's one of my off-season retirement hobby jobs.
Unless you are releasing (using) vapor and decreasing tank pressure at extreme amounts your tank, the liquid and vapor inside will be the same or close to ambient temperature.
A static stored tank will be at ambient.
I agree that tanks will frost if you're releasing vapor at a rate that exceeds their design as propane boils at -41F but a static tank no.
If your tanks are frosting up during your normal usage you should consider a larger tank.
There are those that use hot water in a spray bottle to check liquid levels in tanks as the evaporation rates on the outside of the tank will be different from liquid to vapor. If you want to stand there long enough you can see the liquid level.
The industry excepted method is by weight and that's why the containers are stamped with tare weight.
What are the conditions that you are able to spray water on a propane bottle and get it to freeze?
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Old 02-01-2013, 03:12 PM   #38
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Anode

All I am doing and recieving is the level the liquid propane is at, in the tank by spraying water onto the tank body. I am not using the technique to re fill a tank. To re fill a tank use the stamped wieght for that tank.

But thats how I , test the propane tanks on the boat and the 120 litre tanks hanging off the side of my commercial trucks.

I have yet to find or see an acurate tank guage for a propane system tank. But there just might be one out there somewhere. But the spray bottle is quick and dont lie.

In the trucks if you run outa fuel you get a tow as its not legal to fill or top off road side. Unlike gasoline. As an example.
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Old 02-01-2013, 03:24 PM   #39
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Okay, please clarify. You spray water on the outside of the propane tanks on your boat and the spray freezes on the outside of the tank to the level of the liquid? When the ambient temp is above freezing?
They do make magnetic gauges that are on most road vehicle tanks here but they are not always trustworthy.
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Old 02-01-2013, 03:35 PM   #40
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Sorry Anode I am trying to be way too quick with this.

Yes I spray the outside of the tank, but even a wet rag will work.

No it will not always freeze at the level but the water vapor from the spray hangs around on the tank where the level of liquid propane is even if will not freeze.

Could be a wet coast thing dont know but give it a try.

Also just a quick note. Propane bottles are not filled to the top. Its like 80 % when full.

And another note. From time to time I see the regular 10 and or 20 lb propane bottle used on boats and RVs laid on there side. Folk replace bottles valved to be on there side with regular bottles placed on there side. Not a good thing. The tank "stand" is important for correct use. Uniflite used that set up in the fatcory install and can be replaced with stand up tanks laid on the side. Just an example and an FYI
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