Propane tank recertification?

[NotCook]

That's a great explanation by @JamesG161 . I bought an adapter to refill my small, green disposable propane cylinders for my Magma and found out that I could only fill them half way, and decided the time and hassle wasn't worth the minimal savings so now I'm back to paying $3+ per can.

Down here the 1# cans are more like $5-6, each, I think. Even if "only" $3, thats still paying $3 per pound - nearly 3 times the price we're paying to have the 8# or 20# tanks refilled at $1.20 per pound. I'm going to look into the transfer hose, and consider getting one of the 20# tanks just so i can refill my smaller tanks from it.

 

[Scott B]

Interesting. I have 2 10 Lbs. tanks that fit into the propane locker. Last year both went out of date, 10 yrs. up here, and bought a new one, unfortunately is too tall to properly close the lid. Had both tanks re-certified for $ 35 ea. Not sure what all they had to do, but replaced the valve and now are good for another 10 years.

Also had very bad experiences with propane filling stations with students only familiar with bbq 25 lbs. tanks and overfilling the smaller tanks. Had 2 of them freeze up the regulator due to too much pressure. Royal PITA when you're out in the middle of nowhere and a very nice rib-eye that you can't cook.

 

[JamesG161]

i can refill my smaller tanks from it.

The key to the hook up is to match the connections. Those adapters I linked have the Big USA type female ends [For big source tanks} and the matching end for the Receiver Tank. Note: my first link was to match 1 pound receivers tanks with the source Big Boys .

You might even get a local Propane supplier to make up that hose for you.
______

So, it's interesting because he checked and rejected hers, but did not seem to have checked ours.

There is a very specific safety reason why he rejected her [20#] versus your 10#.

The Diameter of the Tanks!

The smaller the diameter of tank, the longer a tank expiration date. Since I cannot speak confidently on all standards, you should call your local Propane supplier to inquire.

Note: the actual re-cerification is done by putting a testing band around the mid section of a tank. That tank is then put in a failure proof box. The tester then pressurizes that test tank at 125% [ 150% in some services ] of rated pressures, and hold it for +30 minutes. The pressure is then let down, and if that test band moved more than the Safety standard, they will cut a hole in the tank and return to you with a sad face.
_____
I do refill my smaller so called disposable tanks, but the minute that those tanks shows any corrosion, dings or damage...

I TOSS IT!

Not worth the risk
So far I have used 5 tanks for 4 years and only tossed one.
Jim...

 

[JamesG161]

Had 2 of them freeze up the regulator due to too much pressure

I would suggest your grill was taking a lot of propane vapor and/or it was way cold outside.

The Pressure in a propane tank is set by the surrounding Temperature!

To use propane gas [vapor] you cause the liquid to" boil" or Vaporize inside the tank. When you "boil" the propane it takes outside heat to do that.

Don't try to externally heat your tank PLEASE!!

You cannot over pressurize a Propane tank by filling with a reputable dealer. The tank has a relief valve to stop it.

The reason Propane is called LIQUID Petroleum Gas --- LPG... is that you are buying it in a liquid and smaller pressures than liquified Butane.
____
Sorry if I am boring you all.
Jim...

 

[JimInPB]

No way.!
I don't mean to argue, but this has Safety involved.

You cannot cause propane to liquify at household freezer temperatures.

You can never over pressurize with this procedure, if the fill tank is at outside temperatures and the receiver is just freezer cold.
Jim...

Actually, with enough time, you can fill the little tank 100% just from gravity, with the tanks at the same temperature, & no venting. I have done it accidentally when the phone rang while I was filling a tank & I walked away for too long. I had to dump some back into the big tank to get down to a safe level in the small tank.

As for the freezer trick, with multiple freezer passes you can suck down enough liquid to overfill from a room temperature 20# tank, even with the two tanks just connected at the vapor end. With a single pass, you might also be able to do it if the tanks are connected at the liquid end & the outside temperature is high enough. When I lived in AZ, the outside temperature sometimes got pretty high.

In any event, as long as the 20# tank is warmer than the 1# tank, liquid will continue to accumulate in the 1# tank, even if they are just connected at the vapor end. It happens much more quickly if they are connected at the liquid end of the big tank.

I understand that you have a strong background in chemistry, so I will assume that you understand combined gas law. I therefore need to assume that you & I are envisioning different physical connections or something like that, since we both seem to be fairly certain that we are correct, but our statements are pretty different.

 

[JK_Boston_Catalina310]

Interestingly, that's what prompted my interest in the thread. I was getting our 10# refilled at the local gas company. The guy brought back our filled tank and handed it to me, and another lady walked up with a 20# tank. He looked at it and said, "I'll fill it this time, but you need a new tank. They have to be less than 12 years old." I thought that was interesting, because ours came with the boat when we bought it in 2003, and has a date of "10 00". So, it's interesting because he checked and rejected hers, but did not seem to have checked ours. We have three of these 8# tanks (in turns out, not 10# as I had thought), in a lazarette for the galley stove. We also have two more even smaller tanks, for the grill, that we bought (at Fawcett's in Annapolis) when we bought the boat, and they would have to be expired by now, too. I've never been challenged while having any of them filled, any time in the past 15 years, in Ohio, Virginia, or down here...

We have a 10 pound aluminum and a 10 pound steel. The aluminum is original with the boat, so 2001 and I was getting problems with it in the states so I got it re-certified, I think that is up now as it was only good for 5 years. I have never had a problem filling the aluminum tank here. I am shocked they filled the steel tank last time. The date is fine but it is rusted pretty bad despite sanding and painting it every year or so. I actually told myself that was the last time I would fill it and bought another 10 pound aluminum since. But the gas companies over here in Crumb Bay don't even know what the aluminum ones are. I get strange looks all the time. So I'm not surprise they didn't give yours another look.

Where are you in STX? In late May we sailed over for a 10 day vacation. A friend who lives there set us up with a mooring at Green Cay and then we were at Buck. We have lived off of STT for about 4 years and that was our first visit. I liked it and could see living there, my Bride wasn't as sold.

 

[JimInPB]

...There is a very specific safety reason why he rejected her [20#] versus your 10#.

The Diameter of the Tanks!

The smaller the diameter of tank, the longer a tank expiration date. Since I cannot speak confidently on all standards, you should call your local Propane supplier to inquire...

That is new news to me. I thought that all tanks of the same material & pressure class got the same range of expiration date. I do seem to remember that there was a minimum diameter below which the pressure testing & date stamping requirements do not apply. That is why the little Whippet cylinders don't need stamps in them. Off the top of my head, I think the diameter limit was around 2", but that is a foggy memory from back when I was designing high pressure helium cylinders for medical equipment back in the 1980's, so take that information with a grain of salt please.

 

[JimInPB]

Actually, one other quick thing should probably be mentioned for those of us who want to refill tanks ourselves. If you do that, you want to burp the air out of the line before you fill the little tank. Air in the tank with the propane can be a bad thing. That is why new propane cylinders need to be purged before they are filled the first time.

 

[JimInPB]

If anybody want's to be legal when they refill a 1# tank, the option does exist -

https://www.homedepot.com/p/Flame-King-1-lb-Refillable-Propane-Cylinder-YSN164/305539511


https://www.homedepot.com/p/Flame-K...e-Cylinder-with-Refill-Kit-YSN1LBKT/305539519

 

[BigEasy]

I noticed on the Home Depot link that it showed the 22# tank inverted when filling the 1#cannister.
Is that correct??

 

[kloudie1]

Inverted is correct when filling.. gets the liquid from big tank into small one.. like inverting the butane cylinder to refill a cigar lighter..

 

[JimInPB]

Upside down 20# tank feeds liquid into the little tank & gives you a quick fill. Right side up, gives you vapor into the little tank, which then needs to condense into liquid, which requires a temperature difference & is much slower.

 

[JimInPB]

Some general information on propane cylinder filling - http://www.propane101.com/propanecylinderfilling.htm

 

[Gunni]

Make sure you stick around until 1:30 for the big-boom!

 

[JamesG161]

I did like the $44 set up at home depot.
I would never fill the smaller cylinder by gravity dips.
Why?
1) NEVER fill the small cylinder liquid full.
2) The cylinder relief valve is vapor designed. It is a simple open/close valve.
3) Never leave the fill system unattended [gravity drips may take hours.]
4) You will introduce wet AIR into the larger tank by gravity displacement. Use Vapor Pressure differences only.
5) Never let your small cylinder go empty. See #4
6) The cold method takes more time to set up, than to recharge it, and doesn't introduce wet air in the Big Unit.
7) Any air put into the smaller receiver will be purged on the first use.

Please understand that this is a Safety concern.

Call your local Propane supplier about why they don't gravity fill your tanks.

Use the quick, partial fill, cold method only.

Jim...

 

[JimInPB]

...
4) You will introduce wet AIR into the larger tank by gravity displacement. Use Vapor Pressure differences only.
...

???
Assuming that you burp the adapter fitting when you hook up the small cylinder, where does the air come from??? If air was already in the small tank, how would vapor transfer prevent the air from moving to the big tank better than liquid flow?

 

[JimInPB]

...Call your local Propane supplier about why they don't gravity fill your tanks.
...

Perhaps because they have pumps that work much faster?

 

[JimInPB]

...2) The cylinder relief valve is vapor designed. It is a simple open/close valve.
...

Are you saying that the over pressure relief valve will not vent liquid???

 

[JimInPB]

...
6) The cold method takes more time to set up, than to recharge it, and doesn't introduce wet air in the Big Unit.
....

Please explain this. I really don't see how cooling the small tank will prevent air from getting into the big tank.

 

[JimInPB]

...
7) Any air put into the smaller receiver will be purged on the first use.
...

Are you saying that the air in the small tank will be consumed first as the small tank is partially used? Or are you saying that by the time the contents of the small tank are used up, the amount of air remaining will be negligible because they air will seep out with the gas at an equal rate & the percentage of the air in the tank will have been small by comparison?