Propane tank filling problem

[NY_Dutch]

Dutch; my LP supplier told be his pump is high volume, high pressure, and if he didn't open the bleeder valve the pressure and volume would cause the OPD to bounce around so much the tank could not fill correctly.
Fill valve and OPD are approx. same height on side of the MH tank(mfgr. Bruner Engineering) but separate.

If your LP supplier thinks that 0.0550" (#54 drill) opening bleeds off enough pressure to make a difference when filling, especially with a high pressure pump, he needs to go back to school. As for high volume, the volume is limited by the size of the opening in the fill valve.

 

[Brad Buchanan]

Today, I took my Class A to fill the gasoline & propane tank for the trip I am taking next week. Also, to test things out at the Gold Run Rest Stop.

The first place I went to was a U76 gas station on I-80.
They could not fill my propane tank. Not even with my adapter. The guy there said he has filled at least fifty motorhomes there and had this problem only once before. We finally gave up after many tries with and without my adapter. Again, this guy was saying something is wrong with my RV tank.

From there, I go to an Ace Hardware store near here that sells propane. It worked--kinda-- at less than one tenth the normal speed. I told him to stop and try my adapter. Not a big difference, but perhaps a little faster now, perhaps about a fifth the normal speed. Watching the 1/10-gallon digits on their equipment move not much faster than what would be normal for the full gallon.

This guy says he has filled up hundreds of motorhome propane tanks and has never seen this issue.


And the slow is a new one to me, but at least we got it filled to 80% even if it did take around 20 minutes, instead of the usual two to three minutes max.

Any guesses of what is going on? At the first place, I think I could see the problem. It was his adapter that my adapter screws into. There was no way in his adapter for the pin thingy in his to push in on the center valve to push in on my inlet on my propane tank.

I would ask if motorhome RV tanks changed in year 2022, but I have also had these propane issues with my Y2K Class C, but soi far, my adapter has always worked on it when the propane place didn't have it.

My propane inlets on each of my motorhomes:

2022 Class A:
View attachment 1059926


Y2k Class C:
View attachment 1059927

Do these look normal?


-Don- Auburn, CA

I am going to guess that those are not fixed tanks. the fill valve on my rig is remote and seems to have a brass plug in the middle which I am thinking is an anti-backflow valve. Also there is no rubber o-ring or gasket on the fitting. is this normal? I tried two places and the guy at the last place said that it wouldn't take propane. It didn't appear to be leaking though.

 

[uchu]

I am going to guess that those are not fixed tanks. the fill valve on my rig is remote and seems to have a brass plug in the middle which I am thinking is an anti-backflow valve. Also there is no rubber o-ring or gasket on the fitting. is this normal? I tried two places and the guy at the last place said that it wouldn't take propane. It didn't appear to be leaking though.

They do look like fixed tanks.

 

[DonTom]

I am going to guess that those are not fixed tanks. the fill valve on my rig is remote and seems to have a brass plug in the middle which I am thinking is an anti-backflow valve. Also there is no rubber o-ring or gasket on the fitting. is this normal? I tried two places and the guy at the last place said that it wouldn't take propane. It didn't appear to be leaking though.

The problem at this end has to do with heat. My motorhome (fixed) tanks cannot be filled when it is much over 100°F. And the stupid design of my Class A blows engine heat right on the propane tank.

I have been back to the same propane place on a cool day, and they were able to fill my propane tank quite quickly. The hotter it is, the slower it fills. If too hot, it will not fill at all.

IIRC, this could be a CA problem, AZ has a different procedure WRT releasing the pressure or something like that--I read that somewhere in this forum.

If too hot, I cannot use the propane anyway, even if the tank is filled. (see link above).

-Don- Auburn, CA

 

[Gary RV_Wizard]

Just a reminder that you guys have resurrected a 15 month old thread.

 

[DonTom]

Just a reminder that you guys have resurrected a 15 month old thread.

I could never figure out why that is an issue.

Not much difference between that and a new thread with the same old info.

-Don- Auburn, CA

 

[DonTom]

Another propane story for today.

I stop at the ACE Hardware in Eureka, where they have a large propane tank that should be able to fill up motorhomes. There is a woman there before me who had four large portable propane tanks. They filled those four up fast with no problem at all.

I am next, they cannot get an ounce of propane into this motorhome. But the guy knew why, because he has seen the problem many times before when it is hot. My tank was too to fill--too hot to get even an oz pumped in. He expected a problem, because it was around 100F at the time, but tried anyway. No go.

But he told me something I question, he said part of the issue is his tank, some tanks fill hot motorhome tanks better than others. He said his works at a lower pressure than most others, and that I might be able to fill up elsewhere.

My propane tank is a little less than half full, so not a big worry. I will not need the furnace in this heat, but I know east of Ely, there is no propane available for motorhomes for many miles. But I first tried the place in Eureka, next stop is Ely. I got to the Cal-Ranch store in Ely (where they sell propane for motorhomes) a little too late, they were already closed, it is Sunday.

So I never did get my propane tank filled today and it looks like I will not be able to for a while if I keep on going east.

Motorhome propane tanks are one big hassle, IMO.

-Don- Sac Pass, NV

 

[John From Detroit]

I have filled at ACE many times (Seneca SC)

Only one time was a vendor not able to put gas (well liquid) in the tank.

He'snagged the cable for the emergency cut off valve on his pump system and well it worked as designed.

 

[DonTom]

I have filled at ACE many times (Seneca SC)

So have I. But this was the first time at 100F, with the tank even hotter from engine heat. blowing on it from underneath.

Dumb design.

-Don- Sac Pass, NV

 

[Lou Schneider]

You're transferring liquid propane in a sealed system once the hose is connected. Propane pressure does increase with temperature but if the source and destination tanks are at the same temperature there won't be any pressure difference between them.

What does matter is if the destination tank is hotter (higher pressure) than the source tank, This means the pump has to work harder to force liquid into it.

You may have the same problem in moderate temperatures if the underchassis heat warms the motorhome tank a similar amount above the ambient temperature. Maybe take a "recharging break" and let things cool down instead of trying to fill the tank immediately after coming off the highway,

 

[Mark_K5LXP]

It's assumed but not known that tank temperature is the issue. I would think if this were the root cause there'd be far more propane problems than RV's on hot days. The place I go to is no effin' around, a dedicated pump/hose for drive ups with a guy older 'n me popping the hatch, screwing on the fitting and hitting the switch. I note that he opens the tank vent - maybe that's the difference.

Mark B.
Albuquerque, NM

 

[DonTom]

What does matter is if the destination tank is hotter (higher pressure) than the source tank, This means the pump has to work harder to force liquid into it.

So it's the difference in temp that makes the difference (as well as their pump pressure) So they need to keep their tank even hotter than mine.

I guess that explains why those in very hot areas can still get their propane tanks filled, as long as the RV tank is cooler than theirs even if when very hot.

Anyway, there was almost an hour wait, but my tank was still too hot. I first got gas there, then went grocery shopping with my rig parked by their tank as I was shopping, it still would not fill. But it was 100F there at the time and no shade around.

So their tank wasn't hot enough, or did not have enough pressure for the hot day. I assume this is a very common issue with motorhomes.

BTW, would I have better luck with getting it filled at a KOA or whatever, where they often fill motorhomes?

-Don- Sac Pass Rec. Area, NV

 

[DonTom]

. I note that he opens the tank vent - maybe that's the difference.

They tried that too, still no go. The 2nd guy who tried to fill my tank seemed very knowledgeable, he was one of the supervisors there, who was called by the first guy who tried, who wasn't nearly as knowledgeable.

He mentioned the vent was warm air that should have felt cold, and that was how he knew what the problem was (if I understood correctly what he was saying).

-Don- Sac Pass Rec. Area, NV

 

[DonTom]

Is the PSI the same at any tank level? Mine was just a little under 50% full. Would it have helped if I had less propane in my tank, as I normally do when I refill?

--Don- Sac Pass Rec. Area, NV

 

[Mark_K5LXP]

Vapor pressure is vapor pressure whether you're at 1% or 99% full.

Looking on the google it shows propane is around 200psi at 100F. Venting will reduce this only if you vent enough to boil what's there and reduce the liquid's temperature, and subsequently reduce the vapor pressure. The chart I'm looking at shows vapor pressure of 150PSI at 75F. If the posited opinion that source and fill tanks are at equilibrium then it comes down to just what the source tank temp/pressure is and what rate you're venting at that can displace enough vapor at your tank's current temp, where liquid can then enter. Based on this premise though, a one PSI difference would be enough.

But I part ways with the premise that the fill system is passive. Maybe there are some that are and a typical tank vent can't purge at a sufficient rate but I have the same engine heated tank and the place I go can fill it in a few minutes. My opinion is that there's an issue with the facility - connection or operator. A place that does more than filling grill tanks may be the solution.

Edit: Found on the google-
"Commercial propane transfer pumps usually generate 100 to 125psi differential pressure (the boost above the source tank pressure) to force liquid propane into the receiving container.

So for the100F hot tank no-flow theory to be true the source tank would have to be less than 50F.

Mark B.
Albuquerque, NM

 

[Kirk]

He mentioned the vent was warm air that should have felt cold, and that was how he knew what the problem was (if I understood correctly what he was saying).

What causes the vent valve to get cold is the expanding of whatever is compressed inside of the tank. It doesn't matter what that is coming out of the vent. If you have ever noticed, a running air compressor gets very hot but if you use an air nozzle to blow things off for long it gets cold. When any gas is compressed it gives off energy as heat and when it expands it will absorb energy get cold. That is how refrigeration in your air conditioning works. If there was anything inside of the tank that was compressed exiting through the valve it should get cool or cold, depending upon the amount and rate of expansion.

 

[John From Detroit]

Dumb design.

That.... I agree with

 

[DonTom]

But I part ways with the premise that the fill system is passive.

I don't see anybody saying such, just that the pump might not be powerful enough for pumping into 200 PSI that could be fine at 150 PSI. But perhaps if their tank is hot enough and mine is cool enough, they would not need a pump at all--but that is not going to happen in reality, especially with this motorhome.

My Y2K RV has a lot less issues than this 2022 Class A.. My Y2K doesn't get engine heat blowing on the propane tank, for one thing. There are others issues also I never experienced in my Y2K, such as I mentioned here.

--Don- Sac Pass Rec. Area, NV

 

[Mark_K5LXP]

Do you have an IR thermometer? Would be curious to know just how hot the tank is. Per the google the minimum vent pressure is 250psi max 375psi. 125F to 175F.

Mark B.
Albuquerque, NM

 

[DonTom]

Do you have an IR thermometer? Would be curious to know just how hot the tank is. Per the google the minimum vent pressure is 250psi max 375psi. 125F to 175F.

Yes, I have a temp sensor on the tank, but I didn't think about setting up the monitor on this trip to check. I have looked at it before, but I do not remember the numbers. But I have three sensors total outside around this motorhome and I have checked the tank temp before.

But I do not now remember the numbers but at the tank it was signifyingly hotter than the other two.

I will set it up now, so I can look at the numbers during my, next drive,

It is a Newentor Model FJ3378 with three external sensors. All I need to do is plug it in to a USB up front and drive a while. But I had it unplugged and under a bunch of other junk the other day and I didn't think about checking it. From now on, when hot, I will always check it before trying to get propane: