I suppose that one option would be to take to one of the takes your empty tank and exchanges it for a full tank. They would end up either fixing it or recycling it if not fixable.

Gary

 

Probably just frozen. It can happen in high humidity or if you're drawing a large amount of fuel. Let it sit for a while and warm up, then try it again.

 

Some tanks have a safety that closes if there is no back pressure or line connected. Make sure the appliance valve is off, connect the tank and try opening the tank valve very slowly.

 

All of the above seem reasonable;

Im assuming from your description your van regulator worked with the “test tank”.

@83Grumman is correct regarding the back pressure as a safety & IIRC the regulators can also shut down if too much pressure is applied too quickly (opening up the tank valve too quickly).

but it sounds as if your tank valve is defective. Regardless I would het a new tank or exchange it as you want to eliminate the tank/valve as an issue & who wants those problems while camping

Good Luck !!

 

Thanks for the responses guys. Very helpful. It's probably some sort of safety shut off, though I'm not sure why that would have happened. The propane is liquid inside so it's not frozen. I'll just go exchange it for a new one (hopefully home depot will exchange it because it's not blue rhino).

 

It's not that the propane in the tank freezes, it's that when it expands, going from liquid to gas, it freezes in the line. This happens often in portable outdoor heaters. Annoying as heck and kind of counter intuitive. If it's humid the outside of the valve and the first couple inches of line will get covered in frost.

 

I'm sure Rhino will take it -- I've exchanged tanks with them from other places.

Not that it makes much difference at this point, but Rhino only fills their exchange tanks 3/4's full.
There are some exchanges that provide the full 20 lbs.

Really irritating that Rhino gets away with this, but sometimes not a lot of choice when on the road.

Gary

 

All the Blue Rhino tanks that I have seen are actually 15 lbs and not your standard 20 lbs tanks. This makes an exchange more expensive if you give up your 20 lbs tank. Fixed price refills are also more expensive than most measured fills.
Valves go bad, had a couple that would not flow in the past. Luckily they were older tanks.

 

Hi,
I don't see how propane could freeze in the line. It freezes at -306F and it boils at -44F.
As the propane expands in the regulator it cools, but its never going to reach -306F.

It seems like if some kind of freezing is going on, that there must be some water contamination?

Home Value Plans - ELGAS - LPG Gas for Home & Business

Elgas is one of the best suppliers for convenient and sustainable LPG gas for homes and businesses. Explore local and reliable LPG gas bottle refills today.

www.elgas.com.au

Gary

 

Hi,
I don't see how propane could freeze in the line. It freezes at -306F and it boils at -44F.
As the propane expands in the regulator it cools, but its never going to reach -306F.

It seems like if some kind of freezing is going on, that there must be some water contamination?

Home Value Plans - ELGAS - LPG Gas for Home & Business

Elgas is one of the best suppliers for convenient and sustainable LPG gas for homes and businesses. Explore local and reliable LPG gas bottle refills today.

www.elgas.com.au

Hi,
I don't see how propane could freeze in the line. It freezes at -306F and it boils at -44F.
As the propane expands in the regulator it cools, but its never going to reach -306F.

It seems like if some kind of freezing is going on, that there must be some water contamination?

Home Value Plans - ELGAS - LPG Gas for Home & Business

Elgas is one of the best suppliers for convenient and sustainable LPG gas for homes and businesses. Explore local and reliable LPG gas bottle refills today.

www.elgas.com.au

Gary

I think water contamination is a good answer. In several restaurants I've worked in the patio heaters would shut down and the valves would be frosty. The fix was to put a hot wet towel on the tank valve. Maybe some separation of the layers of the hose combined with water contamination? My first little buddy heater did it a couple of times and replacing the propane line fixed it.

 

Hi,
My understanding is that Rhino exchanges standard 20 lb tanks, but they only fill them to 15 lbs.

One of our local tank exchange services does a full 20 lb fill up on their exchange tanks and they say this in their advertising:

Cylinder Exchange - Madison River Propane

Cylinder Exchange Madison River Propane’s 20 lb BBQ Cylinder Bottles last up to 25% longer. This means you’re grilling longer for the same amount of money! How is this possible? We fill our cylinder bottles up to their 20lb weight as they were intended to be – you can check it out yourself...

madisonriverpropane.com

Article on 15 lb refills in 20 lb tanks...

Propane tank refill vs exchange - eLivermore.com

Gary

 

This gives the propane tank vapor pressure at various temperatures...

Propane Information

Propane Vaporization Chart, Properties and Combustion Data VAPORIZATION RATE - 100 lb. Propane Cylinder (Approx) Pounds of propane in cylinderMaximum continuous draw in BTU/hr at various temperatures in degrees F. 0° 20° 40° 60° 70° 100 113,000 167,000 214,000 277,000 300,000 90 104,000 152,000...

flameengineering.com

As you say, it would have to be really really cold for the propane not to generate enough pressure to work -- at -30F, the vapor pressure is still 6.8 psi.

Gary

 

[...] at -30F, the vapor pressure is still 6.8 psi.

Remember that's 6.8 psi absolute - so about 8 psi below sea level pressure, or about the top of Pikes Peak.

 

@dtwigs

Did you get your problem resolved?

If so can you report back your solution & in your estimate what the problem was?

 

@dtwigs

Did you get your problem resolved?

If so can you report back your solution & in your estimate what the problem was?

Sorry my area has been over taken by wild fires so haven't looked into it in a while. I swapped the tank out with another and it works fine, but I havent been able to bring the faulty one to the propane guys.

 

Most likely it's your OPD valve a new one can be bought for $20 there are U-tubes for more info.

Amazon.com : Flame King VOPD20 20 Pound Propane Tank Cylinder Service OPD Valve, White : Patio, Lawn & Garden

Amazon.com : Flame King VOPD20 20 Pound Propane Tank Cylinder Service OPD Valve, White : Patio, Lawn & Garden

www.amazon.com

 

I think so also !

I have purchased many 20lb tanks from Costco over the years @ $36 Canadian including the $20 OPD valve. If one does that then the tank is year stamped & IIRC good for 10 years?

Fill Station People check the age of the tank prior to filling them - or they are suppose to.

 

Hi Wow,
Is that true? I think the vapor pressure of a liquid is 0 when it exactly equals atmospheric pressure -- that is it just starts to boil with air over it.

That's -44F for propane, so at -30F it would have the +6.8 psi above atmospheric?

"The vapor pressure of any substance increases non-linearly with temperature according to the Clausius–Clapeyron relation. The atmospheric pressure boiling point of a liquid (also known as the normal boiling point) is the temperature at which the vapor pressure equals the ambient atmospheric pressure. With any incremental increase in that temperature, the vapor pressure becomes sufficient to overcome atmospheric pressure and lift the liquid to form vapor bubbles inside the bulk of the substance. Bubble formation deeper in the liquid requires a higher temperature due to the higher fluid pressure, because fluid pressure increases above the atmospheric pressure as the depth increases. More important at shallow depths is the higher temperature required to start bubble formation. The surface t"ension of the bubble wall leads to an overpressure in the very small, initial bubbles. "

Vapor pressure - Wikipedia

en.wikipedia.org

Or, maybe I'm wrong?

Gary

 

The atmospheric pressure boiling point of a liquid (also known as the normal boiling point) is the temperature at which the vapor pressure equals the ambient atmospheric pressure.

It's there in the article you quoted.

 

Yes, I think you are right.
So, it looks like vapor pressure of propane gets up to atmospheric pressure a bit lower than -10F.

A now puzzling thing for me is that we have propane heat in our home and some of the piping and the regulator are outside in the air, and we have (rarely) seen -30F and our propane furnace continues to operate (thank goodness!).
Our tank is underground, but some of our neighbors have above ground tanks and I've not heard of anyone having a problem. Maybe the thermal mass of the tank keeps it from getting down to the low temperature.

I can remember from climbing days taking our butane stove into the sleeping bag so it would work in the morning

Gary

 

Hi,

Actually we got that wrong...

The charts on this page give the absolute and gage vapor pressures for propane

Propane - Vapor Pressure vs. Temperature

Vapor pressure vs. temperature.

www.engineeringtoolbox.com

At -44F (boiling point of propane), it produces 14.7 psi (one atmosphere) of absolute pressure and 0 psi gage pressure.
By about -30F its up to 20 psi absolute and about 6 psi gage.

So, its going to be hard to get propane cold enough where it won't produce enough pressure to work -- unless its contaminated with water or something else.

Gary

 

Hi,

Actually we got that wrong...

The charts on this page give the absolute and gage vapor pressures for propane

Propane - Vapor Pressure vs. Temperature

Vapor pressure vs. temperature.

www.engineeringtoolbox.com

At -44F (boiling point of propane), it produces 14.7 psi (one atmosphere) of absolute pressure and 0 psi gage pressure.
By about -30F its up to 20 psi absolute and about 6 psi gage.

So, its going to be hard to get propane cold enough where it won't produce enough pressure to work -- unless its contaminated with water or something else.

Gary

Of course we like 29.92 inches Hg over 14.7 psi

 

I thought you guys liked 760 mm

Gary

 

😜

I was in school during the Canadian Metric Conversion in the 70’s 🙄. I think it is like knowing 2 languages. Metric of course is way easier as it relates to our world with science & has easily usable decimal points. It is easier to to just forget about imperial but the real world does not work like that - go to the lumber store and ask for a straight 38x89 DF#2 or better or a 1220x2440 sheet of standard 18 non T&G and see the look you will receive from the yard guy.

My understanding is you have had a career in aviation, I am just a hobbyist. Inches of mercury, knots, fahrenheit, gallons, pounds, etc & converting fluently at the design table into metric or whatever else needs conversion is one thing; sitting in a cockpit with busted fuel gauges chatting French & English Metric & Imperial converting fluently is also no problem (providing you are an expert glider pilot);

Gimli Glider - Wikipedia

en.wikipedia.org

The story of this fascinates me as life is sometimes way way stranger than fiction.

I always enjoy reading your scientifically presented posts Gary. IIRC it was RD who once wrote you are an invaluable gem of this Forum @ I could not agree more !!

I have not had problems with my propane (van heater or other propane equipment) or my cheap Chinese cabin diesel heater yet both operating at 6000’ “Density Altitude”. I believe “True Altitude” is irrelevant in regard to fuel combustion & what really matters is “Density Altitude”. IIRC @MsNomer set her Wabasto heater to “high altitude” & keeps it on that setting even when at lower elevations. The burners tend to clog up on these units & I would probably operate the same as her if I had a Wabasto changing elevations. Not having a Webasto manual I do no know if they talk about “True” altitude or “Density” altitude, nor do I know if they have more than 2 altitude settings. My rambling point is this; propane or gas or diesel what really matters to your oxygen combustible appliance is what “density” altitude you are at. Have operated @ 6000’ DA when the TA is only 3400’ (the swings can be that great).

 

I’m getting high just reading this🙀

 

My Webasto does not have "altitude" or "density" settings. It has a rheostat with numbers 1-7. If the high altitude procedure is performed, the unit will perform better at higher altitudes—no precise numbers given. Tech Webasto told me that it is not a simple reverse procedure to reset to lower altitude. If I were to mess with it again, I would need someone with a sensor.