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Old 12-13-2016, 03:24 PM   #29
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[QUOTE=ScottyBye;3372354]So what you are trying to say is that 20% of the tanks is NOT for expansion. It's there for expansion... Really![/QUOTE

What expands you don't add nothing to the tank or the tank don't get bigger, the only thing that change pressure. Really
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Old 12-13-2016, 06:12 PM   #30
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Ok let's get back on topic please, this is not a science class.
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Old 12-13-2016, 06:25 PM   #31
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[QUOTE=tacaem;3372388]
Quote:
Originally Posted by ScottyBye View Post
So what you are trying to say is that 20% of the tanks is NOT for expansion. It's there for expansion... Really![/QUOTE

What expands you don't add nothing to the tank or the tank don't get bigger, the only thing that change pressure. Really
Just like car gas does it expands as it warms( gets larger) so the 20% is
for the liquid expansion
when you fill your fuel tank too full it expands and leaks out and leaves a hole in the pavement but you never added any after filling it now did you?
same deal
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Old 12-13-2016, 06:26 PM   #32
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No it does NOT.
When a propane tank is new there is AIR (Atmosphere in the tank) which can and will absorb moisture as temps and pressures change both inside/outside the tank.
This is why you ALWAYS purge a tank before filling with Propane for the 1st time or when excesive moisture is suspected or present.
If the purge is done properly you should have no atmosphere or moisture left in the tank.

In most cases if moisture is found in the tank, it most likely came from the LPG Supplier... and small amounts can be removed through a anhydrous methyl alcohol injection into the tank, which should be done by a reputable propane distributor/supplier

Absolutely.... Moisture in the tank = problems.
Example - frozen regulators, insufficient/irregular burning of the fuel gas thus reducing the efficiency of any/all LP appliances, tank rusting internally, and many others...

.
Moisture in the tank = problems
Ok, well this is kinda scary. I have no idea whether it was was purged correctly in the beginning or whether any supplier has introduced water etc.

OP here...We bought this MH 3 going on 4 months ago and this is just one item in a plethora of things I'm checking and going through to insure all systems are serviced properly and up to snuff. All appliances work fine. When I flushed & serviced the Atwood HWH a few weeks ago I adjusted the flame and have a real nice flame now, stove works fine and I'm going to run & check the furnace tomorrow. This MH was purchased new here in TX by the original owner, then we bought it and there are no indications, clues or evidence that he ever took it way up north or subjected it freezing cold temps. But that's my guess, not fully based on known FACTS.

So without knowing the history of the propane tank:
• Do I need to worry about the possibility of water in the tank?
• Are there any signs I need to look for or symptoms that would indicate water in the the tank or warrant taking it in and having it looked at?
• Is taking your MH in and having the tank checked for this a common practice?
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Old 12-13-2016, 06:54 PM   #33
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Originally Posted by tacaem View Post

What expands you don't add nothing to the tank or the tank don't get bigger, the only thing that change pressure. Really

As heat is added or removed the propane expands 370:1 (thermodynamics). The volume doesn't change but the propane still expands. Yes the pressure increases as heat is added. Doesn't matter if you have 5 pounds in a tank. There is still 5 pounds no matter what the pressure/temp. It's still 5 pounds. Although it's state Vapor/Liquid is what changes.
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Old 12-13-2016, 07:36 PM   #34
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Moisture in the tank = problems
Ok, well this is kinda scary. I have no idea whether it was was purged correctly in the beginning or whether any supplier has introduced water etc.

OP here...We bought this MH 3 going on 4 months ago and this is just one item in a plethora of things I'm checking and going through to insure all systems are serviced properly and up to snuff. All appliances work fine. When I flushed & serviced the Atwood HWH a few weeks ago I adjusted the flame and have a real nice flame now, stove works fine and I'm going to run & check the furnace tomorrow. This MH was purchased new here in TX by the original owner, then we bought it and there are no indications, clues or evidence that he ever took it way up north or subjected it freezing cold temps. But that's my guess, not fully based on known FACTS.

So without knowing the history of the propane tank:
Do I need to worry about the possibility of water in the tank?
Are there any signs I need to look for or symptoms that would indicate water in the the tank or warrant taking it in and having it looked at?
Is taking your MH in and having the tank checked for this a common practice?
I have a older MH, 1999, and I haven't had any propane tank checks. It all works fine.

Purging a new propane tank involves pumping propane in, while letting the air escape thru the valve.

Unless yours sat empty AND with the valves open, it should be fine.
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Old 12-13-2016, 08:05 PM   #35
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Quote:
Originally Posted by marjoa View Post

So without knowing the history of the propane tank:
Do I need to worry about the possibility of water in the tank?
NO... This is not overly common
Are there any signs I need to look for or symptoms that would indicate water in the the tank or warrant taking it in and having it looked at?
The only symtom that I know for is a Frozen Regulator
Is taking your MH in and having the tank checked for this a common practice?
NO...Unless you are experiencing problems. As listed above
.
.
.
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Old 12-13-2016, 08:33 PM   #36
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Okay everyone, thank you again so much for the info, cut away pic and the science class to understand the propane tank system.

I just love making my brain "Great Again".
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Old 12-13-2016, 10:35 PM   #37
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Okay everyone, thank you again so much for the info, cut away pic and the science class to understand the propane tank system.



I just love making my brain "Great Again".

OMG. I have a doctorate in frigging chemical engineering. I practically had a cow over the disinformation and incorrect interpretations in this thread regarding "space" versus "pressure" . I just looked up the physical properties of liquid propane . No science class - but my interpretation of the numbers are ( FWIW):
1) the 80% fill rule makes sense to try to avoid actual liquid (versus vapor) coming out of the tank as temperature varies between say freezing and 150F (not that we want to be using it at those temps )
2) if the tank has been reasonably used (I.e. Consistently filled by a reputable dealer before it is dead empty) the risk of moisture accumulation in it is low (but not zero)
3) if you are worried about moisture , find a dealer willing to do a purge fill (ie fill a little, vent, fill a little again, vent, then do a real fill). No guarantee .. but the vent cycles should help to carry out moisture in the tank .

Ok ... I am done venting (pun intended)
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Old 12-14-2016, 07:46 PM   #38
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As heat is added or removed the propane expands 370:1 (thermodynamics). The volume doesn't change but the propane still expands. Yes the pressure increases as heat is added. Doesn't matter if you have 5 pounds in a tank. There is still 5 pounds no matter what the pressure/temp. It's still 5 pounds. Although it's state Vapor/Liquid is what changes.
Apologies if this confused anyone in the way it was worded....
Here is a better explanation as I am sure you will agree.

If you raise the temperature of a closed tank (i.e. "add heat") the liquid does NOT expand 370:1 (that only happens when you go from liquid to vapor). ....and the degree of volume difference between liquid and vapor is not really a part of thermodynamics ... more like physical chemistry. I'll grant the poster that "its state Vapor/Liquid is what changes" ... but to me that statement is very misleading ... the entire contents of the tank do not change regarding vapor/liquid ... as said above a small amount of liquid goes in to vapor to raise the vapor pressure above the liquid

C/P from a better source
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Old 12-14-2016, 08:07 PM   #39
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Apologies

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OMG. I have a doctorate in frigging chemical engineering......
I want to apologize to this thread, and to the Forum in general for my last post here. I fear that I am too much of a nerd and did not acknowledge clearly helpful attempts to explain what is going on in the face of differing statements of the "science". Yes ... I was frustrated by the confusion of the conflicting statements - but that does not excuse arrogance and disrespect on my part.

Please accept my apologies. I will try to be better
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Old 12-14-2016, 08:22 PM   #40
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Not necessary,,, we are all human after all.
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Old 12-14-2016, 08:40 PM   #41
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Reading this conversation implies that you stop filling the propane tank at 80% on the gauge. The propane gauge in my 2016 Phaeton is calibrated to 100% gauge reading when the tank is physically 80% filled with liquid, which also agrees with the gauge in the coach. Since the tank is located horizontal their is adequate vapor space. We always fill to 100% gauge reading without any problems.
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Old 12-14-2016, 08:54 PM   #42
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Reading this conversation implies that you stop filling the propane tank at 80% on the gauge. The propane gauge in my 2016 Phaeton is calibrated to 100% gauge reading when the tank is physically 80% filled with liquid, which also agrees with the gauge in the coach. Since the tank is located horizontal their is adequate vapor space. We always fill to 100% gauge reading without any problems.
My gauge is not calibrated like that.

The fill vavle shuts down and it spits gas out the vent, when the gauge is around 3/4, outside and in.

There doesn't seem to be any adjustment, to change it.
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