Propane pressure gauge

Jan 4, 2006
7,037
Hunter 310 West Vancouver, B.C.
The principle involved here is exactly the one that led to the misconception of the status of the liquid level in the pressurizer at Three Mile Island that then precipitated in manually securing High Pressure Coolant Injection that ultimately led to shifting bubble from the pressurizer to the core and resulted in melting 1/3 of the core at Three Mile Island.
I can imagine trying to get this straight in your mind while sitting beside the reactor as it rocks back and forth.

Not that there's any pressure, mind you :yikes: !
 

dLj

.
Mar 23, 2017
3,878
Belliure 41 Back in the Chesapeake
What I open the solenoid valve on my propane tank the pressure guage drops to zero. Any help on the causes?
@GreenSailor2 - I'm not sure your question has been answered. We've got 6 pages talking about many aspects of propane etc. but I'm not sure this question was ever answered. Have you figured it out?

Just an observation - it's still sailing season in the northern hemisphere and this thread grew rather interestingly. I'm quite looking forward to an entertaining winter when sailing season is slower...

dj
 
Dec 28, 2015
1,886
Laser, Hunter H30 Cherubini Tacoma
I may be totally wrong, but as I recall, the "amount of liquid propane" can be deduced from observing the "temperature" at the tank surface. At the point of liquid level the temperature of the tank surface will be slightly below the temperature of the tank surface where the gas exists. (conductivity of the liquid is more than the gas) An old tank I used to have for my home grill had a strip of temperature sensitive material on the outside of the metal tank. At the level of the liquid propane the strip changed color if you doused it with a little water. Could you not use a non-contact temperature gun to see where the temperature changes on the surface of the tank. Just asking?
Correct but only while the gas is being used.
 
Dec 28, 2015
1,886
Laser, Hunter H30 Cherubini Tacoma
I should have said I have labelled all three of my tanks only for my own estimation of Propane remaining in the tank.



Exactly what we do here in Canada but yours are in US pounds and ours are in metric pounds :biggrin:. We pay with metric dollars.



Nope, nope, and nope. You know how much it agrieves me to disagree with you BUT if you're buying propane by the gallon as per @dlochner, you want cold, cold, cold propane. Get it cold, heavy, and dense and you get more propane in a gallon.

If you're buying propane by the pound, get it hot, get it cold, it just doesn't matter. 5 pounds is five pounds no matter what you do.

And now Mr. JamesG161, for your final question worth $100,000.00,

WHICH IS HEAVIER, A POUND OF HOT PROPANE OR A POUND OF COLD PROPANE ?

You have thirty seconds to answer.
The difference is going to be minimal considering both ways are putting it into a cylinder that is vented to atmosphere ( vapor vent) and the liquid will be vaporizing while the cylinder is filling causing to to cool while it does. The only way to really make a difference is to heavily vent the tank prior ( with liquid still in it) causing it to auto refrigerate then fill it.
 
Jan 4, 2006
7,037
Hunter 310 West Vancouver, B.C.
We've got 6 pages talking about many aspects of propane
We've covered all of the basics here, from heat transfer to duct tape to nuclear reactors to chicken soup. Did we miss anything ?
 
Oct 26, 2010
2,023
Hunter 40.5 Beaufort, SC
Correct but only while the gas is being used.
The "hot water trick" on the outside of the tank will work too. It is taking advantage of the roughly 5 to 10 times greater "thermal conductivity" (depends on pressure in the tank compressing the gas, not so much the liquid) of the liquid propane in the bottom of the tank compared to conductivity of the gas in the top of the tank so the tanks surface cools faster where there is liquid. Of course a completely full tank or a completely empty tank might be hard to tell, but then weight should be a dead giveaway.
 
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JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
7,717
Hunter 430 Waveland, MS
Of course a completely full tank or a completely empty tank
Never let a Propane Tank go empty!!!
Why?
Unseen Internal corrosion begins

Also they can not fill a tank more than 85% of Liquid Propane.
_______
I guess this thread is too long. Seems that no one reads it from the start.
Jim...
 
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Jan 4, 2006
7,037
Hunter 310 West Vancouver, B.C.
By the way..
1 Bara = 1 dyne per square centimeter :pimp:
Damnit Jim, you've been snorting propane again. You know what it does to you.

1662235034838.png



1 bar = approximately one atmosphere (0.986 atm.)

1 bara = 1 bar absolute

1 bara = 1,000,000 dyne/cm²

Now go say ten Hail Mary's and drop a penny in the poor box on your way out.
 
Dec 28, 2015
1,886
Laser, Hunter H30 Cherubini Tacoma
The "hot water trick" on the outside of the tank will work too. It is taking advantage of the roughly 5 to 10 times greater "thermal conductivity" (depends on pressure in the tank compressing the gas, not so much the liquid) of the liquid propane in the bottom of the tank compared to conductivity of the gas in the top of the tank so the tanks surface cools faster where there is liquid. Of course a completely full tank or a completely empty tank might be hard to tell, but then weight should be a dead giveaway.
The stickers I have seen are not sensitive enough to show the contrast in temps between the liquid and vapor space of a static tank when not flowing but if dumping hot water in it gets it to work then fine. Burning some gas off to get there seems pretty easy…….
 
Dec 28, 2015
1,886
Laser, Hunter H30 Cherubini Tacoma
Never let a Propane Tank go empty!!!
Why?
Unseen Internal corrosion begins

Also they can not fill a tank more than 85% of Liquid Propane.
_______
I guess this thread is too long. Seems that no one reads it from the start.
Jim...
A LPG tank is never empty of propane (gas) unless purged. This means it has the same gas mixture in it when filled ( in the vapor space) or when empty of liquid propane (all vapor space). Same gas, same moisture content, same corrosion potential inside. Outside ( at the bottom) is where you need to have concern.
 

JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
7,717
Hunter 430 Waveland, MS
A LPG tank is never empty of propane (gas) unless purged.
Well open one up completely and wait a few years with the valve left open.
Jim...

PS: 1 bara = 1,000,000 dyne/cm² , my calculator broke when set my Propane Tank on it.:facepalm:
 
Dec 28, 2015
1,886
Laser, Hunter H30 Cherubini Tacoma
Well open one up completely and wait a few years with the valve left open.
Jim...

PS: 1 bara = 1,000,000 dyne/cm² , my calculator broke when set my Propane Tank on it.:facepalm:
Yea your right, cut a big hole in it to and leave it. But who does either of those in the normal use of a LPG cylinder?…….exactly, no one……a few years, let’s come up with obserd contradictions to win.
 

LloydB

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Jan 15, 2006
900
Macgregor 22 Silverton
An empty container with an open port will tend to breath in moisture laden air during the normal cooling temperatures of each day and is most likely to be left that way on the last day of normal use until the next season because the fuel was exhausted during the last use. No large hole necessary.
 
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Dec 28, 2015
1,886
Laser, Hunter H30 Cherubini Tacoma
An empty container with an open port will tend to breath in moisture laden air during the normal cooling temperatures of each day and is most likely to be left that way on the last day of normal use until the next season because the fuel was exhausted during the last use. No large hole necessary.
I completely agree on the physics. My initial reply was to a comment that consisted of “ don’t let you tank go empty or corrosion will take place inside”. I should have included in my statement that no valves or opening to the cylinder should be left open when empty ( of liquid). I highly recommend not leaving the valve open on a “empty”cylinder for the reasons you make and also enabling gas inside the cylinder the ability to migrate out. The gas itself inside of the cylinder poses no additional corrosion hazard as it does when liquid is also present.