Propane tank filling problem

[Mark_K5LXP]

That looks like a weather station. How does that measure tank temperature?

Mark B.
Albuquerque, NM

 

[DonTom]

That looks like a weather station. How does that measure tank temperature?

With the remote sensor on top of the tank.

-Don- Sac Pass, NV

 

[Mark_K5LXP]

That's air temperature at the top of the tank, which might get you close to the vapor temperature but not the liquid at the bottom. An IR gun will show what the bottom side of the tank is.

My money on your situation is it's nothing to do with temperature, but a hardware issue on your tank or filler misconnection. If temperature really was a root cause I think we'd be seeing far more postings about difficult filling than just yours.

Mark B.
Albuquerque, NM

 

[DonTom]

That's air temperature at the top of the tank, which might get you close to the vapor temperature but not the liquid at the bottom. An IR gun will show what the bottom side of the tank is.

My money on your situation is it's nothing to do with temperature, but a hardware issue on your tank or filler misconnection. If temperature really was a root cause I think we'd be seeing far more postings about difficult filling than just yours.

Mark B.
Albuquerque, NM

I will try moving the sensor to the bottom of the the tank before the next time I get propane, if I can find a good way to hold it there where it is more likely to fall off.

But I have heard from several sources that hot propane tanks cannot be filled. But perhaps in very hot areas, they have ways to deal with it better such as having a much stronger pump at their tanks or having a much hotter tank to pump from.

I was not the only motorhome that they could not fill on hot days at that ACE Hardware, but they have no trouble filling the portable tanks that are a lot cooler than my tank on this Class A with engine heat blowing on it as a drive.

-Don- Sac Pass, NV

 

[Mark_K5LXP]

Through an unforeseen series of events I found myself getting the propane tank on my class A filled this afternoon. We were coming back from a camping trip and were back to town a little early, discussions of fall camping were occurring, and it made sense to top off the tank so we would be ready for cold(er) camping (despite having an extend-a-stay, separate topic). I pulled into the propane place, no waiting. It was 98F per the dash gauge when I stopped. I got my IR gun and measured the tank, nominally half full. 125F at the top (vapor), 120F at the bottom (liquid). Mine also receives hot engine air as DonTom describes. I observed the tech as he did his job - connected the nozzle to the fill port, and before doing anything, he opened the tank vent. He then successively "bumped" the fill valve on the hose assembly a few times and then went between watching the numbers roll on the pump and looking for liquid from the vent. There was no mistaking when liquid started coming out, he closed the vent, shut off the hose, and disconnected. It was then I asked some questions. Do you always open the vent when filling? Yes. Why the on-off when first filling? To help unstick stuck OPD valves. Have you ever had a situation where no gas would flow due to high tank temperature? No, it can affect delivery rate but not stop it. I checked the tank temps after it was filled and they were just a few degrees cooler, not sure if from the fill process or just the natural cooling from being parked/no hot engine air for a while. Could be implied that the liquid entering the tank was not significantly cooler than what was there. When I got home I checked the gauge on the tank and it was on the high side of the 'F', but below the 85% tick. So 'full' by any casual measure. Per the intertubes the vapor pressure of 120F propane is 200PSI, so at least this data point shows at 120F a fill up is possible with seemingly standard station equipment. This was as ordinary a fill experience as I've ever had, no inordinate time or operator distraction observed during the process. I think if I were to encounter a situation where there was no flow, I'd be suspecting equipment (nozzle/fill port/OPD) before I'd suspect elevated tank temperature.

Mark B.
Albuquerque, NM

 

[DonTom]

Through an unforeseen series of events I found myself getting the propane tank on my class A filled this afternoon. We were coming back from a camping trip and were back to town a little early, discussions of fall camping were occurring, and it made sense to top off the tank so we would be ready for cold(er) camping (despite having an extend-a-stay, separate topic). I pulled into the propane place, no waiting. It was 98F per the dash gauge when I stopped. I got my IR gun and measured the tank, nominally half full. 125F at the top (vapor), 120F at the bottom (liquid). Mine also receives hot engine air as DonTom describes. I observed the tech as he did his job - connected the nozzle to the fill port, and before doing anything, he opened the tank vent. He then successively "bumped" the fill valve on the hose assembly a few times and then went between watching the numbers roll on the pump and looking for liquid from the vent. There was no mistaking when liquid started coming out, he closed the vent, shut off the hose, and disconnected. It was then I asked some questions. Do you always open the vent when filling? Yes. Why the on-off when first filling? To help unstick stuck OPD valves. Have you ever had a situation where no gas would flow due to high tank temperature? No, it can affect delivery rate but not stop it. I checked the tank temps after it was filled and they were just a few degrees cooler, not sure if from the fill process or just the natural cooling from being parked/no hot engine air for a while. Could be implied that the liquid entering the tank was not significantly cooler than what was there. When I got home I checked the gauge on the tank and it was on the high side of the 'F', but below the 85% tick. So 'full' by any casual measure. Per the intertubes the vapor pressure of 120F propane is 200PSI, so at least this data point shows at 120F a fill up is possible with seemingly standard station equipment. This was as ordinary a fill experience as I've ever had, no inordinate time or operator distraction observed during the process. I think if I were to encounter a situation where there was no flow, I'd be suspecting equipment (nozzle/fill port/OPD) before I'd suspect elevated tank temperature.

Mark B.
Albuquerque, NM

Mark, I got my propane tank filled in Delta, UT. And as usual, a story comes with it. I first went to the Ace Hardware, but they told me their motorhome adapter was broken. I said "I carry one with me". So we go to check it out. My adapter is threaded on the inside. His cracked motorhome adapter is threaded on the outside, otherwise looks the same. IOW, mine would not fit his machine.

Here is mine:

I didn't know there was another type.

But then he told me the good news, there are only two places in all of Delta, Ut that can fill up a motorhome and the other place is a propane place (they only do propane) just across the street. So I asked the guy there if he ever had a problem filling hot motorhome tanks, he said "no, not yet, but it can then be very slow to fill". So that is exactly what happened with my tank. He got it to the full (~80%) but it must have taken a good 20 minutes from when it first started pumping. Very slow, but it got the job done.

-Don- Richfield, UT

 

[Mark_K5LXP]

Did he open the vent? I can see with a hot tank opening the vent may not make a huge reduction in internal pressure but stories abound of this not being done or necessary. I've never seen it done any other way but I haven't had my various tanks filled at very many different places. First pass observation is that if you have to supply your own adapter, then maybe they might not be the ideal place to fill an RV. It works out that by using grill tanks on most trips I only need the main tank filled once a year, so I'm glad I don't have to deal with it often.

Mark B.
Albuquerque, NM

 

[DonTom]

Did he open the vent? I can see with a hot tank opening the vent may not make a huge reduction in internal pressure but stories abound of this not being done or necessary. I've never seen it done any other way but I haven't had my various tanks filled at very many different places. First pass observation is that if you have to supply your own adapter, then maybe they might not be the ideal place to fill an RV. It works out that by using grill tanks on most trips I only need the main tank filled once a year, so I'm glad I don't have to deal with it often.

Mark B.
Albuquerque, NM

Yes, they always open the vent for at least a while. I don't think In have ever seen them not do such.

I have found NM to be the most difficult state to find propane for a motorhome. I don't think NM allows it to be sold at gas stations (unlike CA, AZ and other states I have been to) or least I have not yet seen propane sold at a gas station in NM and that makes a big difference in many areas. At least a few hardware stores and KOAs have propane for motorhomes there in NM.

I have propane issues perhaps more than 50% of the time I stop for propane in this motorhome. Reasons vary greatly, but them not having the correct adapter is a very common one. I wish motorhomes were designed for the portable tanks, it would make life a lot easier.

Now I need to look for another adapter to carry in my motorhomes with the threads on the outside, which I never knew existed before this trip.

-Don- 84701

 

[Mark_K5LXP]

My answer is an extend a stay hose. Even in winter I can go for days on a grill tank. So the standard protocol is if we're staying at a spot a couple days or more I hook up a grill tank and run off that. This last trip with just fridge and water heater we used about 1lb/day. So that's almost 3 weeks before needing a refill. When travelling or overnight stops the grill tank is too much fussing around so just run the main tank. Conserving the main tank this way extends my refill interval to about once a year, easy to check that box. Grill tanks can be filled/exchanged many places so easy to keep one on hand. I also fill my 1lb canisters from the grill tank to keep the backstone and gas grill fed. It would be interesting to learn the nomenclature for your (and mine) fill port and understand why there seems to be this disparity in station compatibility.

Mark B.
Albuquerque, NM

 

[DonTom]

Even in winter I can go for days on a grill tank.

What do you do with that tank while on the road driving?

I have no place to store such outside.

-Don- 84701

 

[Mark_K5LXP]

I have 7 basement storage compartments.

Mark B.
Albuquerque, NM

 

[DonTom]

I have 7 basement storage compartments.

This class A probably has room for such. Large doors, some with a lot more room than others.

No such room in my Y2K class C.

Is it considered safe to store propane tanks in such a way?

-Don- Richfield, UT

 

[Mark_K5LXP]

Maybe not. But I have a motorcycle, run with scissors and drink from the garden hose so my judgement is questionable.

Mark B.
Albuquerque, NM

 

[DonTom]

I have a motorcycle,

Did you mention your bike here?

I now own a dozen motorcycles, seven are electric (last 7 bikes below):

1971 Black BMW R75/5
1984 Yamaha Venture
2013 Blue Triumph Trophy SE
2016 Kaw Versys 650 LT
2017 Blk/Gold HD Road Glide Ultra
2017 Zero DS ZF 6.5
2017 Zero SR ZF13 w/ Pwr Tank
2020 Blue Energica SS9
2023 Bormio Ice Energica Experia
2023 Green Zero DSR/X
2025 Red/Black Energica Experia
2025 Black Can-Am Origin

-Don- Richfield, UT

 

[Mark_K5LXP]

Did you mention your bike here?

You wouldn't approve - it's carbureted.

Mark B.
Albuquerque, NM

 

[DonTom]

You wouldn't approve - it's carbureted.

I own a couple of bikes with carbs. My 1971 BMW R75/5 and my 1984 Yamaha Venture. Carbs on old stuff is fine. Carbs on stuff made in 2021 (such as the Onan genny in this RV) means it is outdated junk, IMAO.

-Don- Richfield, UT

 

[Ex-Calif]

I own a couple of bikes with carbs. My 1971 BMW R75/5 and my 1984 Yamaha Venture. Carbs on old stuff is fine. Carbs on stuff made in 2021 (such as the Onan genny in this RV) means it is outdated junk, IMAO.

-Don- Richfield, UT

So your genny is a battery powered ev?

Does Onan have a lot of charge stations?

Kidding obviously.

 

[Mark_K5LXP]

Mine's a hybrid.

Mark B.
Albuquerque, NM

 

[DonTom]

So your genny is a battery powered ev?

Perhaps we will see the day when RVs use a big battery instead of a genny.

A lot can be done with a 100KWH 400 VDC battery and it will last a long time on a single charge. Run your MW oven for around 80 hours continuously on. Or your A/C for around 40 hours continuous before needing a recharge.

And slowly recharge at RV parks--such as with the two Tesla 12KW stations here. Or by then, recharge with DCFC at RV parks.

Hard to say what we will see in the near future. The demand for more and more electricity every year has not stopped since Edison invented the light bulb.

-Don- Richfield, UT