richard5933

Frozen LP Tank Leaking??

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Noticed a strange smell around our bus today while checking on it. Finally realized it was the smell of LP.

I checked on the tanks, which I'm positive I had firmly shut off before the recent cold spell. We have two horizontal tanks. One was about 2/3 full last time I looked. When I opened the cover on the tanks, the tank which was full has a coating of frost on the end of it, with a small pile of what looks like fine snow built up under the fill valve. Pressure gauge on both tanks now reads zero.

I'm assuming that the tank which was partially full leaked out.

Is this something that can be connected in some way to the sub-zero weather or just coincidental? Can tanks leak like this because of extreme cold? If so, any precautions to be taken?

First time having LP so I'm not sure which way to go on this. I'm guessing that one of my stops once the weather warms and I'm back on the road will be to the local propane dealer to have the tanks serviced, but I sure would like to know what's going on and what to expect.

UPDATE: I did a little more looking and inspecting this evening. The fill valve is definitely the source of the leak. In fact, I was easily able to push in on the center of the fill valve and open it. I'm thinking that either the pressure was much lower than I thought and the super cold weather brought it down even further, which allowed the valve to let loose and seep, or possibly the rubber seal got too hard in the cold to continue to make a tight seal. Or, if there is a spring in the valve possibly it no longer has then necessary umph to keep the thing closed properly.

Anyone have any experience changing out the valves on these older tanks? I'm wanting to avoid changing them out totally since I don't think I'll easily find a new one that fills on the end like ours.

20180102_200827.jpg

Edited by richard5933
Additional information added.

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Richard, The fill valve is replaceable. see the frost and wonder if there is a cover missing from the current valve  ? dirt or other contamination at the vale set is always a possibility.  The tanks always need to be empty to replace any of the tank parts. The fact that the valve failed and that most of the LP has discharged.

Manchester Tanks is a good possible source for the parts, but a good LP service center should be able to test and repair the tank.

http://www.mantank.com/products/rvproducts.htm

Rich.

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manholt   

As Rich said, most of the gas has discharged, does not mean that all is gone.  As the weather warms up the liquid that is left will turn into gas vapor and be under pressure.  Yes, your missing your fill valve cover.  What you are smelling is a pungent additive ethanethiol, LPG has no odder, therefore a smell is added so you know you have a leak.

How old are your tanks and when was the last time they was serviced?  Laws have changed over the years and now, you can only use 80% off volume.  If you have a 100 gallon tank, you have to have a valve that only allows 80 gallons....actually they go by pounds, I have forgotten what a gallon of LP=in pounds!  Do not attempt to purge the tank yourself. 

I don't know what your mixture % is between Butane and Propane, that's why it's important to know, when it was last serviced.  LPG will revert back to a liquid at low temperature and then go back to gas vapor, as the temperature increase...expansion is 250:1 How low that temperature is, depends on your mix % of the 2 gasses and how well your tank is insulated.  On most Motor Homes and outside tanks, there is no insulation.  Look on the back of a TT and a lot off times you will see a cover that fits over the tank/tanks, that protects the tank and can also be fitted with insulation!

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Richard,

You may have had a considerable amount of water build-up inside the tank and that's what froze and caused the valve to fail.  Then the pressure of the propane caused the water to spit out and the propane followed.  Which in turn caused local condensation at the leak (super-cold condition) thus the icing. 

You can check to see if there's any pressure on the tank through the bleed/spit valve on the top.

If the tank is small enough to remove, I would take it to a LP service center like Rich mentions and have the valve replaced and the tank recertified.

Blake 

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manholt   

I zoomed in on the gauge  and it shows a 50/50 mixture of Butane/Propane...that's a first for me.  Normal is 20/80!  Since Butane has 3x the energy of Propane.

Joe Leamont's coach had a tank that was very well insulated by the original owner, and it had a 40/60 mix...the owner lived in it in Alaska, while working.  Blake may remember that ordeal, better than me.    

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I'll be going to a local propane vendor today to see if they have any advice. The cover is missing in the photo because I had just taken it off for the photo. It was in place and clean prior to this issue.

The LP furnace is the only thing using propane in the coach, and it has not been used in years. I'd suspect that the LP in the tank has been there for years. I'll report back once I hear from the propane place in town.

 

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manholt   

They may have a truck and driver that will come out and certify your tanks after they purge them and change out what is needed.

Good Luck

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Just got back from the propane dealer in town, one that I trust.

The valve is apparently leaking. Obviously it shouldn't be. Once the weather warms to the point I can work outside for at least a few minutes (still in single digit temps here) I will pull the two tanks and take them in for repair/inspection/etc. I'll bring the regulator along with me so that it can be inspected as well. My only concern with removing them is in getting the connections made again when I reinstall so that nothing leaks. I just don't seem to have good luck re-using fittings or resealing plumbing once it's opened.  If the tanks are still deemed serviceable, I'll ask them to replace the plumbing (hoses) between the tanks and the regulator to minimize failure points.

If necessary, I will replace with something else. By the way, these tanks do have a vapor tap and based on how the plumbing is connected I'd guess were designed to be refilled in place (not removed for filling). Not sure how that worked, and not sure if it can still be done that way.

I suppose that the two horizontal tanks could be replaced with two vertical tanks if necessary. I'll have to take measurements to be sure and bring them along with me when I take the tanks in in case we go that route.

Anyone know what the proper regulator setting is for these things? My only appliance running off of propane is the furnace, so I assume that I'll need to have them set the pressure regulator for that. If they are checking we might as well check everything.

Oh - the joy of old machinery! If I didn't love it so much this would be a real pain.

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49 minutes ago, manholt said:

All the ones I have had, before I got all electric, where horizontal tanks!

Horizontal would be my first choice since that's what's in place at the moment. Should the tanks need replacing however, I'm seeing mixed information about whether or not it will be possible to find replacements that will fit into the space where the current tanks are kept. Most of the newer tanks I'm seeing have the fill valve located midway down one of the sides. I've got two tanks, stored one above the other, with only the ends exposed to the outside. They are very similar in appearance to forklift tanks. I'll need to find new tanks with a similar setup if I have to replace them. That's the main reason for considering vertical - more options and easier to retrofit with something other than what's in there now. I'm not in the mood to reconfigure half the coach just to position new tanks somewhere else, and there is surprisingly little unused space in the bays.

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Richard, I would check with Manchester. Give them a call. 

The Forklift style tanks are still in use and Manchester's RV tank list is dedicated towards the newer coaches. They very well could also have the same style tanks still in the pipeline. Not likely a mainline item at the time. Our first coach had 2- 20 lb. Horizontal tanks mounted in an outside bay.  They where setup so they could be slid out from the securing system to be filled.

Rich.

 Other suppliers that might be of help.

          https://vikingcylinders.com/products/

           https://worthingtonindustries.com/Products/Propane-Cylinders

 

Compressed Motor Fuel Tanks.pdf

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Richard,

Apologies for late response.  When I first looked at your photo I thought your tank looked like an old forklift tank based on the crash handles around the fittings.  Once the sun is up here I'll go out to the garage and take a photo of the tank on my forklift and send a picture.  It sits horizontal.

I bought a spare tank for the forklift on Craigslist for $80 (if I remember right).

Blake

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Richard, have you filled the tanks since you acquired the coach, or possibly may have been quite a while since it was filled? Reason for asking, butane is / was cheaper to obtain than LP "liquid petroleum" and at one time was sold during the summer months here in the southeast. Problem with butane is that in extreme cold weather, it will freeze, and if read it will show a zero reading due to no pressure. Not saying that is your problem, but in a warmer climate if the gauge starts mysteriously showing a partial tank, then this should help solve the mystery. I had written the above statement after your first post, but did not press the submit button. I used the vertical tanks in my conversion because of the ease of removal for refilling. Also the vertical style are much less expensive than the horizontal. Pressure is about 10# on LP but the regulators are normally preset, natural gas is 4#, this is why the orifice hole is much larger for natural gas.

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manholt   

Kay.  The tank pressure gauge says 50/50 mix, so it would freeze at the temps Richard has had.  Normal for North America (Canada included) is a 20/80 mix.

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I am not sure that the temperature where Richard has much to do with his issue. I feel that he has a leaking filler valve and need to go to a Propane dealer and have them draw off his remaining gas and replace the valve. Just IMHO 

How Does LPG - Propane Turn from Liquid to Gas?

LPG (Propane) Vaporisation

Did you know that every time you turn on one of your gas appliances, the LPG in your gas bottles starts to boil?

If you could see though the steel, you would also notice that it looks just like water boiling.

The big difference is that it happens at -42°C or -44°F.

This is vaporisation, which is how LPG – propane – goes from liquid to vapour (gas).

How LPG - Propane Turns from Liquid to Gas

LPG (propane and/or butane) turns from liquid to gas when it boils.

Propane boils at a lower temperature than butane, making it more suitable for cold climates.

On a cold winter day, outdoor butane cylinders may not reach their boiling temperature, leaving the user with no gas.

Temperature - Propane & Butane Turn to Gas
How LPG - Propane Turns
from Liquid or Gas?
LPG (1atm)
Liquid
Vapour (Gas)
Propane
< -42°C or
< -43.6ºF
≥ -42°C or
 -43.6ºF
Butane
< -0.4°C or
< 31.28ºF
≥ -0.4°C or
 31.28ºF

 

LPG (Propane) Vaporisation - How LPG Boils

To boil, the liquid LPG draws heat from the steel walls of the gas bottle which, in turn, get heat from the ambient air.

How LPG (Propane) Turn from Liquid to Gas - LPG (Propane) Vaporisation

LPG liquid boils and turns back into gas vapour when you release some of the pressure in the gas bottle by turning on your gas appliance.

As with water, the more heat that is applied, the more rapidly it boils, vaporising at a faster rate.

The vapour pressure in the bottle also increases with temperature, as explained below.

So, as the steel of the bottle draws heat from the ambient air heat, cold weather will slow down the rate of vaporisation.

Vaporisation also makes the gas bottle feel colder than the ambient temperature.

The gas bottle gets even colder when you are actually using the gas.

LPG Boiling Point

Water boils at 100°C or 212°F, becoming a gas (steam). 

In contrast, LPG (propane) boils at -42°C or -44°F, becoming gas vapour. 

LPG stays liquid because it is under pressure in a gas cylinder.

As a liquid, it looks a lot like water.

It is colourless and odourless in its natural state. 

Unlike water, 1 kilogram of LPG does NOT equal 1 litre of liquid LPG.

LPG density or specific gravity is about half that of water, at 0.51.

In Australia, where LPG is propane, 1kg of LPG has a volume of 1.96L.

Conversely, 1L of LPG weighs 0.51kg.

Vaporisation Must Match Consumption

The amount of gas that the appliance or appliances are drawing from the gas bottles must be matched by the rate of vaporisation.

If a gas bottle ices up regularly, it simply means that the vessel is too small for the vaporisation load placed on it. 

Switching to a larger vessel can provide a higher rate of vaporisation.

Heat is absorbed through the vessel shell and into the liquid.

This is known as the “wetted area”.

The larger the tank or the fuller the tank, the more gas that can be vaporised at a given temperature.

Vaporisation tables (as shown below) are used to match the required vaporisation rates to the corresponding vessel size.

Vaporisation tables show the maximum continuous vaporisation rates, in MJ/hr, at different ambient temperatures for each available vessel size.

In instances where a larger vessel is not an option, the only alternative is to supply some artificial means of increasing vaporisation.

The units used are very appropriately call vapourisers.

Lower Fill Equals Less Vaporisation

Keeping in mind the concept of "wetted area", the maximum rate of vaporisation drops as the fill level drops.

If there is less LPG in the vessel, there is less contact area between the liquid LPG and the steel that provides the heat for vaporisation.

Depending on the consumption rate of the attached appliances, this may make no difference at all, if the consumption rate is low.

However, if the consumption rate is high, the vaporisation rate may not keep pace with the consumption.

Depending on the appliance, this starvation may cause the appliance to function poorly or not at all.

LPG (Propane) Vaporisation Table

LPG Vaporisation Chart of Standard Size Vessels

Nominal LPG Vessel Size

Volume in Water Capacity

Maximum Continuous Vapourisation Rates for LPG (propane) at Indicated Ambient Temperatures. 
(in MJ/hr)
at 30% full
Weight
Volume
-18˚C
-7˚C
-1˚C
4˚C
10˚C
16˚C
45kg
108L
46
92
115
138
161
184
90kg
215L
70
140
175
211
246
281
190kg
499L
106
219
274
328
383
438
0.5t
1.35kL
235
469
587
704
821
939
1.0t
2.2kL
327
653
816
980
1143
1306
2.0t
4.3kL
545
1090
1363
1636
1908
2181
2.5t
6.7kL
826
1652
2065
2478
2891
3304
3.0t
7.5kL
921
1841
2302
2762
3222
3683
10t
23kL
1616
3231
4039
4847
5655
6463
13t
33kL
2214
4482
5603
6724
7844
8965
17t
43kL
2502
5003
6300
7505
8756
10006
21t
53kL
3492
6984
8730
10476
12222
13968
25t
62kL
3502
7004
8755
10507
12258
14009
33t
81kL
4503
9006
11257
13509
15760
18011
40t
100kL
5504
11007
13759
16511
19262
22014
© 2013-2017 Elgas Ltd.

Vaporisation Table Notes:

1. As a simple rule of thumb, when using vessels of say 2.75 or 5.1kL capacities, simply extrapolate between the two nearest size vessels but biasing your calculations on the conservative side. Always consult your supplier’s technical representative for advice.

2. Always check with your supplier’s technical representative that the above vapourisation rates are correct for the particular vessel you have designated.

3. For sites requiring a high vapourisation rate but it is not cost effective to install larger and/or multiple vessels, consider using a vapouriser.

4. Vessels above 3 tonnes or over 7.5kL will be custom designed by supplier to suit customer needs. Figures provided are only rough estimates, based on previous designs.

Condensation Turns to Ice

Condensation and ice on a gas bottle

Initially, condensation forms when the temperature of the gas bottle or regulator drops below the dew point.

This is exactly the same as the condensation you get on a humid day with a glass of ice water.

Under the right conditions, when you are using gas very rapidly, ice can even form on the gas bottle!

LPG Vapour vs Gas

Let's also clarify the terminology.

The two terms, vapour and gas, are used interchangeably by most people in reference to LPG.

Vapour (or vapor in American spelling) is the more technically correct term for LPG, as it is in gaseous and liquid equilibrium at room temperature.

It can be turned back into a liquid by increasing the pressure on it without reducing the temperature.

A gas has one defined state at room temperature.

So, vapours are gases however not all gases are vapours

Gas Bottles Contain Liquid and Gas

Liquid and vapour in a gas bottleThe LPG gas vapour is held in the top of the bottle and the liquid LPG at the bottom, as shown in the accompanying image.

Almost all of the uses for LPG involve the use of the gas vapour, not the liquefied gas.

LPG Pressure Varies with Temperature

As previously mentioned, when LPG is stored in a gas bottle, it is under pressure. 

The term “pressure” refers to the average force per unit of area that the gas exerts on the inside walls of the gas bottle. 

(LPG Pressure-Temperature Chart shown)

LPG Pressure Chart

Pressure is measured in kilopascals (kPa) or pounds per square inch (psi).

“Bar” is yet another unit of measure for pressure. 

1 Bar = 100 kPa, so it is metric based but not an SI unit of measure.

LPG pressure can vary greatly based on temperature, as shown in the chart.

The level of fill in the gas bottle comes into play when the LPG is being used, as it affects the rate of vaporisation. 

As LPG is a liquefied gas, the pressure inside the cylinder will remain the same from full until the last of the liquid LPG is vaporised. 

Then the pressure will fall quickly as the last of the LPG vapour is used, as well.

Final Thoughts

Understanding vaporisation helps explain how LPG turns from liquid to gas. 

It is particularly important for larger commercial installations where the rates of gas consumption are higher.

The technical staff matches the gas load to the appropriate vessel size and, if required, a vapouriser.

 

 

View More LPG Gas Blogs

Comments, questions or feedback?

Please Email us at: blog@elgas.com.au

The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.

Herman

 

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manholt   

:lol::lol: You only forgot, by running your hand from bottom towards the top of a bottle, as it's being used or just shut off, you can feel the cold, then warmth and that is how much liquid is still in bottle(if you don't have a gauge)! 

On the small green portable bottles, most users will throw them away, there is still enough liquid left to grill a steak! :o

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Thanks everyone for the information. I agree with Herman - the fill valve on the one tank is leaking and will be replaced. Can't do it right now since it's just too cold to work outside for more than a few minutes. As soon as I'm able, I'll pull both tanks along with the hoses and regulator and take the whole thing to a local propane dealer. I'll ask them to inspect and repair as necessary.

If they can't repair, then we'll start the process of replacing. I'm pretty confident that the valve's rubber seals have just gotten hard and dry over the years, and the tech at the propane dealer agreed that it could be something as simple as this. Could also be something much more involved. Won't know till he sees the tanks, of course.

Other than this issue, the tanks only show a little bit of wear and surface rust around the very outside parts of the handles. I would doubt that they've been used much and fortunately they are located in a dry bay and have not been exposed to weather. There are gauges on both tanks, and they appeared to function up to just a few weeks ago. The one tank whose gauge showed content a few weeks ago is the one that leaked, and at the moment it is showing nothing. I have a photo taken from when I first noticed the smell which showed '20' on the level. Now it shows '0'.

Regarding the markings on the gauge itself, I don't read them as indicating the actual content of the tank. There are three lines to the text:

             Propane
          50/50 Pro-Bu
              Butane

To my reading, this is information about the rating of the gauge, not the content of the tank. There are other marking & instructions on the gauge about filling, etc. I will have to confirm this when I take the tanks in for service.

That's all I got for now. I'll do my best to report back once I get the tanks in for service and have more information. Maybe others can benefit from whatever I learn.

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Richard,

As promised, here's a picture of the spare propane tank for our forklift.  This is the spare one I got off of Craiglslist.

Herman.....great explanation!

Blake

Forklift Propane Tank.jpg

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Richard, the picture Blake posted.

As promised, here's a picture of the spare propane tank for our forklift.  This is the spare one I got off of Craiglslist.

Just picked noticed the label - and the tank was made by Manchester.

Rich.

 

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jleamont   

That configuration resembles the tank that was in our coach. If it gets down to it I'm certain one of the used RV salvage yards would have one.

5916ddb394e0a114c1029fd2.jpg

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jleamont   
5 hours ago, hermanmullins said:

The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.

Herman

:lol:

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11 hours ago, richard5933 said:

             Propane
          50/50 Pro-Bu
              Butane

I was going to point this out to Carl, those descriptions are only there so you will know how to read, it does not indicate what is in the tank, only the supplier will know that answer. Or an analysis of the substance.

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bm02tj   
On 03/01/2018 at 1:59 AM, manholt said:

I zoomed in on the gauge  and it shows a 50/50 mixture of Butane/Propane...that's a first for me.  Normal is 20/80!  Since Butane has 3x the energy of Propane.

Joe Leamont's coach had a tank that was very well insulated by the original owner, and it had a 40/60 mix...the owner lived in it in Alaska, while working.  Blake may remember that ordeal, better than me.    

That is a temp chart to show expansion of liquid with temperature  

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bm02tj   
On 03/01/2018 at 10:29 AM, richard5933 said:

Just got back from the propane dealer in town, one that I trust.

The valve is apparently leaking. Obviously it shouldn't be. Once the weather warms to the point I can work outside for at least a few minutes (still in single digit temps here) I will pull the two tanks and take them in for repair/inspection/etc. I'll bring the regulator along with me so that it can be inspected as well. My only concern with removing them is in getting the connections made again when I reinstall so that nothing leaks. I just don't seem to have good luck re-using fittings or resealing plumbing once it's opened.  If the tanks are still deemed serviceable, I'll ask them to replace the plumbing (hoses) between the tanks and the regulator to minimize failure points.

If necessary, I will replace with something else. By the way, these tanks do have a vapor tap and based on how the plumbing is connected I'd guess were designed to be refilled in place (not removed for filling). Not sure how that worked, and not sure if it can still be done that way.

I suppose that the two horizontal tanks could be replaced with two vertical tanks if necessary. I'll have to take measurements to be sure and bring them along with me when I take the tanks in in case we go that route.

Anyone know what the proper regulator setting is for these things? My only appliance running off of propane is the furnace, so I assume that I'll need to have them set the pressure regulator for that. If they are checking we might as well check everything.

Oh - the joy of old machinery! If I didn't love it so much this would be a real pain.

Regulator should be set at 11 in WC  

28 in WC = 1 PSI

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