Propane tank filling problem

[NY_Dutch]

Thanks again!

Today, I went to a Chevron gas station about 50 miles north of here to get propane. They could NOT fill it.

Then I found my adapter, it worked perfectly. The ONLY reason I was able to get propane there today was because of that adapter. I told them they need to invest $66.00 as I did. I am going to order another, so I will always have one in each motorhome and will no longer have to remember to check if I have it.

IMO, every motorhome with a nonremovable propane tank like mine should carry such an adapter.

-Don- Wesco, CA

A couple of years ago, I pulled into a refill station where I've gotten the onboard tank filled before. The manager apologized, and said he couldn't fill it because a new employee had accidentally left the adapter on a motorhome fill valve when he unscrewed just the POL side and their LP distributor hadn't replaced it yet. I pulled out my adapter so he could fill my nearly empty tank, and when he finished, he offered me the $54 cost of the fill-up plus $20 for the adapter. Worked for me! A week later I had a new adapter onboard for $62...

 

[DonTom]

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:

Y2k Class C:

Do these look normal?


-Don- Auburn, CA

 

[Arch Hoagland]

What was the outdoor temperature? Tried to fill a tank when it was a hundred degrees and it wouldn't take. Happened to be near the main refilling company office so I went and ask them. They said at high temperatures the propane tanks won't accept propane. Waited until the next morning when temps had dropped and it worked fine.

 

[DonTom]

What was the outdoor temperature? Tried to fill a tank when it was a hundred degrees and it wouldn't take. Happened to be near the main refilling company office so I went and ask them. They said at high temperatures the propane tanks won't accept propane. Waited until the next morning when temps had dropped and it worked fine.

I think you figured out my propane issue today. Perhaps at both places.

It was very hot in the propane compartment because I was going uphill all the way there and it was close to 100°F outside today. A lot of the engine heat gets inside there. It's hotter inside the propane tank area than the ambient outside temperature.

The place that didn't work at all was all uphill to get there. The place that was slow was downhill from there, so things were a bit cooler.

That explains why it was so slow. But at least it worked, and the job got done.

Good thing I got it filled up today, because here is what is coming to Auburn. 106°F/41°C is expected here on Wednesday, July 3.

I had no idea they would not fill up high temps.

Thanks, now I know not to try to fill up my propane tanks on very hot days.

BTW, how come the guys who fill the propane tanks don't know this stuff?

BTW, it is 80°F here right now at 2300 hrs.

-Don- Auburn, CA

 

[Lou Schneider]

This is the vapor pressure inside a propane tank a pump has to overcome to push more propane into the tank. 40 PSI @ 0 degrees F, 100 PSI @ 50F, 200 PSI @ 100F and so on.

Propane - Vapor Pressure vs. Temperature

 

[DonTom]

This is the vapor pressure inside a propane tank a pump has to overcome to push more propane into the tank. 40 PSI @ 0 degrees F, 100 PSI @ 50F, 200 PSI @ 100F and so on.

Propane - Vapor Pressure vs. Temperature

How much PSI are the propane pumps capable of?

Perhaps around 200 psi?

BTW, would I have this same issue for my house propane here? Normally only needs filling in the wintertime anyway. But I wonder if they will not refill houses on hot days.

-Don- Auburn, CA

 

[Kirk]

How much PSI are the propane pumps capable of

The following comes from the website of Ferrell Gas:
Propane pressure levels exceeding 200 psi are likely to trigger a release from the safety relief valve commonly installed on propane storage tanks. This device allows propane gas to safely vent out of the tank if there’s excessive pressure.

 

[John From Detroit]

How much PSI are the propane pumps capable of?

Perhaps around 200 psi?

I have seen much higher pressures on Propane pumps.

 

[John From Detroit]

Only once were they not able to fill my tank.. . I went elsewhere and trust me the price difference between the park and the Wholesaler was more than the cost of the fuel (This is not always the case.. This was in Flint, MI A RV park v/s Parker's propane. In Seneca SC the Wholesaler is very high priced, park was cheaper LOVES cheaper still but LOVES is new park no longer sells propane (Fair Play is park and Loves)

Turns out when the tech pulled the hose out of the cabinet. He snagged the Emergency cut off cable and closed the Emergency valve.

 

[DonTom]

Only once were they not able to fill my tank..

I was finding it to be 50-50 before I had the adapter. Perhaps I have worse luck that most with the places I stop for propane. I had no problems with the adapter, so that did the trick.

I just didn't know that I couldn't fill the tank when the propane compartment was so hot inside it. That is very handy to know.

What surprises me is how none of the propane guys knew the problem. Are those guys licensed? If so, how does that work? I have found a lack of knowledge to be the norm for the propane fillers. But I also know that not all the employees at these gas stations and other propane places are NOT allowed to fill up propane tanks.

All the good info, about such things I get here in this forum!

-Don- (Truckee/Tahoe Airport--getting a free 10KW charge on my Tesla for a change--but came here for their delicious lamp curry burrito, to discover the airport restaurant is closed on Sundays!)

 

[darsben]

These are but a few of the reasons that I fill at home, if at all possible. If there’s a screw-up....I don’t have far to look!

How do you fill your motor home tank at home

 

[John From Detroit]

Are those guys licensed? If so, how does that work?

They are supposed to have some kind of certification but I'm not sure what all it covers. I know it covers some things like discolored brass fittings (And (I know what that indicates) and I know one of the questions had to do with what happens if you get a just right mixture of air and propane there is a spark.. I know this because they were reviewing the test in the same room I was doing my morning internet run and before anyone else could answer I piped up with "You land two counties over" and the instructor.. after the laughter died down, said "EXACTLY".

But I really was not paying attention to the questions and answers that much.

 

[Mark_K5LXP]

the vapor pressure inside a propane tank a pump has to overcome to push more propane into the tank.

This makes sense, to a point. But during a fill the tank has to be vented somehow, either to atmosphere or via some path through the fill port. No matter what pressure the tank would start out at, it will only become more pressurized as liquid is pumped in and it will stop flowing at whatever the pump pressure is. Seems implausible the fill pressure would be near or at the safety vent release point, and in practice the tank is vented during fill, so I don't see how static vapor pressure at any ambient temperature would limit flow. If anything would limit liquid flow it would be the volumetric rate the vent is purging, and that would be irrespective of temperature. Would be interesting to learn from someone that knows propane systems to maybe explain what the controlling factors are.

Mark B.
Albuquerque, NM

 

[NY_Dutch]

Liquid propane

This makes sense, to a point. But during a fill the tank has to be vented somehow, either to atmosphere or via some path through the fill port. No matter what pressure the tank would start out at, it will only become more pressurized as liquid is pumped in and it will stop flowing at whatever the pump pressure is. Seems implausible the fill pressure would be near or at the safety vent release point, and in practice the tank is vented during fill, so I don't see how static vapor pressure at any ambient temperature would limit flow. If anything would limit liquid flow it would be the volumetric rate the vent is purging, and that would be irrespective of temperature. Would be interesting to learn from someone that knows propane systems to maybe explain what the controlling factors are.

Mark B.
Albuquerque, NM

LP tanks and cylinders are not "vented" in any way unless over pressurized triggering the relief valve. The gaseous element in the tank/cylinder is reduced to liquid under pressure from the refilling pump. The small "vent" some refillers open is actually the "Fixed Liquid Level Gauge" that changes from gas to liquid when the container reaches the 80% full mandated limit.

 

[Lou Schneider]

Liquid propane

Would be interesting to learn from someone that knows propane systems to maybe explain what the controlling factors are.

Mark B.
Albuquerque, NM

The controlling factor is propane's boiling point at atmospheric pressure is -40F. It stays in liquid form at higher temperatures because it's in a pressure vessel where the increased pressure raises the boiling point until it reaches the temperature vs. pressure in the graph I posted above. Pressure cookers and pressurized automotive cooling systems use the same principle - raising the boiling point of their liquid contents by increasing the pressure.

The reverse is also true - if you increase the tank pressure by introducing more liquid propane the tank is now colder than the dew point at that pressure and excess vapor condenses back into liquid until the pressure vs. temperature equilibrium is restored. Since liquid propane is 200x denser by volume than vapor you can condense a large amount of vapor without noticeably affecting the liquid volume.

I fill propane cylinders every week at the RV park. It really doesn't make any difference in the fill rate if the "vent" valve is open or closed. Like NY_Dutch said it's not a vent but an 80% full indicator that discharges a very small amount of vapor. The discharge noticeably changes when liquid propane reaches the level of the dip tube indicating the tank is legally full. Originally this was the only way to tell the tank is legally full unless you weigh the tank as you fill it which is only required in a few states. Now it's backed up by a float activated shutoff on the tank's fill valve.

 

[NY_Dutch]

What surprises me is how none of the propane guys knew the problem. Are those guys licensed? If so, how does that work?

-Don-

In most states, all a refiller needs is a relatively brief training, often conducted with the station owner, manager, or lead refiller conducting the training using material from either CEPT or one of the other training sources. In practice, it's not unusual that a new employee simply shadows a refiller until he's capable of doing his own refilling. Those are the ones we commonly find at RV parks and smaller gas stations.

https://p3propane.com/cetp-and-hand...ng Program,job duties safely and effectively.

https://ohi.org/ohi-blog/are-you-and-your-employees-properly-trained-to-fill-propane-cylinders/

 

[Mark_K5LXP]

The gaseous element in the tank/cylinder is reduced to liquid under pressure from the refilling pump.

That doesn't make sense to me. If we use the example of compressing a refrigerant, what you end up with is a hotter, smaller volume of vapor and it doesn't turn from a gas to a liquid until that heat is removed in the condenser. Given the speed a fill happens in a propane tank, there is no way (in my mind) vapor is compressing, heat being shed and vapor turning into liquid at the rate liquid is being dispensed. Just poking around online any propane fill process instruction includes a vent step, whether it's by tank volume or weight.

Mark B.
Albuquerque, NM

 

[Kirk]

If we use the example of compressing a refrigerant,

Propane occurs naturally as a gas, however, at high pressure or low temperatures, it becomes a liquid. As a liquid, propane is 270 times more compact than as a gas, and it is transported and stored in its liquid state in pressurized containers. What is pumped into an RV tank or bottles is liquid.

 

[Mark_K5LXP]

I get that, but where I'm parting ways with this gas to liquid theory is the pressures this happens at and rates of phase change. It would take a lot of energy at high pressures to make this happen in real time, and require the shedding of heat. None of this happens during any propane tank fill I've seen.

Mark B.
Albuquerque, NM

 

[Lou Schneider]

In most states, all a refiller needs is a relatively brief training, often conducted with the station owner, manager, or lead refiller conducting the training using material from either CEPT or one of the other training sources. In practice, it's not unusual that a new employee simply shadows a refiller until he's capable of doing his own refilling. Those are the ones we commonly find at RV parks and smaller gas stations.

https://p3propane.com/cetp-and-hand...ng Program,job duties safely and effectively.

https://ohi.org/ohi-blog/are-you-and-your-employees-properly-trained-to-fill-propane-cylinders/

All of the members of the propane team at our park have been certified using the CEPT materials. We fill 30-40 cylinders at a time in assembly line fashion during our weekly propane sessions and sell more propane per week than anyone else in Pahrump. Our supplier is the chairman of the Nevada State Propane committee and one day he came by to observe our operation and gave us a gold star on the official state list.