$upport your local store, until....

[mac_1103]

All new tanks, as well as refurbished ones, have over-pressure fill valves that won’t allow filling in excess of 80%. That’s to avoid expansion due to thermal increase in the gas.

I know that. I was inspired to weigh mine because of a comment to the effect that they don't even fill to 80%.

Blue Rhino openly states they only fill them to 15lb to "control costs".

Well, they gave me 16+.

 

[Snuffy]

Don’t be too critical of safety “paranoia.”

About 15 years ago I routinely went to a local outlet of a major gas supplier to get my bottles filled. They’d check the tare weight or the bottle, put it on an industrial scale and fill it to the weight of the gas. As I said, they did ‘industrial’ fills of virtually every gas imaginable in any capacity tank, even mixed gases if you wanted beer gas or nitrogen. They also did bottle exchange, but I was jealously possessive of my shiny aluminum tanks, especially my 5 lb one. They usually didn’t have 5# available for exchange unless you called ahead anyway, and were willing to wait a day or two to get one from the central distribution center. They’d always be heavy, ugly steel ones anyway.

So one day I load up my truck (king cab configuration) with my empty 5#er strapped in, drive 12 miles to the gas distributor, leave the bottle on the loading dock and head inside to pay. By the time I get back, the loader has my bottle filled and ready to go.

Looking back on the incident, there’s a bit of cryptic foreshadowing. He jokes about the aluminum bottle being so small and so light that the gas filler hoses and mechanism probably weighs more than the CO2 bottle. Obviously he’s more frequently filling those huge steel tanks mounted on roller wheels.

Anyway, it’s a hot summer day and I’m anxious to get home and hook up the gas to the kegerator and have a frosty one. I strap the bottle in the back seat and head on down the highway. A few minutes later I’m cruising down the Interstate in moderate traffic when suddenly there’s a muffled ’pop’ and the cab is engulfed in a fog. Immediately I “four-ganged” the electric windows to “Open,”correctly analyzing that the over-pressure frangible disk had burst and dumped all the CO2 into the enclosed space. At 70 MPH. In moderately heavy traffic.

The fog quickly cleared, and the CO2 induced ’brain fog’ was dissipating, and I’d somehow maintained not only control of my pickup but my lane as well, without loosing my wits, my consciousness or my life.

Gaseous CO2 is not considered HAZMAT, but although not toxic it is more readily absorbed in the blood stream and will displace oxygen. In a confined environment it can result in loss of consciousness. Luckily, disaster averted.

The cause was over-filling on a hot day, as well as my transporting it in an enclosed space. Had it been a bigger bottle (10# or 20#), and had I been in a regular sized pickup cab, the outcome may have been quite different. Although CO2 (unlike CO) won’t kill you outright, it can cause unconsciousness and eventual suffocation. It is odorless and tasteless (as is CO), and needs to be handled and stored and transported in a well ventilated space. Maybe in a car, with all the windows rolled down? You decide.

I’ve since switched to bottle exchange rather than refilling for not only my 5# ‘portable’ but also my 10 and 20 pounders. Plus, the outlet no longer does on-site refilling.

I guess I used the term "paranoia" because my usual procedure has been to stick the tank in the floorboard where it can't roll around and then tote it into the LHBS and clunk it down for refill. I chat with the proprietor while he fills it and then pay up, take my frosty bottle home the reverse of the way I brought it in and all is well. I did not really consider that they may overfill it or some safety mechanism kicks in to release pressure or something could rupture. They guy weighed it as he filled it and I assumed he has lots of experience at that sort of thing. Sure seemed competent at it anyway.
Did you ever figure out what exactly failed with your tank? Did it blow the valve off or rupture or what? You got me kinda eyeing my fresh tanks like sweaty TNT now...

 

[Broothru]

I guess I used the term "paranoia" because my usual procedure has been to stick the tank in the floorboard where it can't roll around and then tote it into the LHBS and clunk it down for refill. I chat with the proprietor while he fills it and then pay up, take my frosty bottle home the reverse of the way I brought it in and all is well. I did not really consider that they may overfill it or some safety mechanism kicks in to release pressure or something could rupture. They guy weighed it as he filled it and I assumed he has lots of experience at that sort of thing. Sure seemed competent at it anyway.
Did you ever figure out what exactly failed with your tank? Did it blow the valve off or rupture or what? You got me kinda eyeing my fresh tanks like sweaty TNT now...

I’ve always tried to be respectfully paranoid around all pressurized fluids, even those that are non-toxic or unlikely to go boom. I may only have half my wits, but I still have all my digits.

 

[JohnDBrewer]

Blue Rhino openly states they only fill them to 15lb to "control costs".

If you read the small print at any propane exchange place, usually where the price is, it will tell you what amount they fill to. There was huge lawsuit years ago when the "exchange industry" started specifically about the short filling, so now they disclose it so as not to deceive the customer.
I only exchange when my tank(s) when it is close to expiring. Most places will let you pick a tank so I look for a pretty one, otherwise, I go to a local filling place (tractor supply) and only pay for what they put in.

 

[4min33]

I wish I had that option. The only one I can find near me is an Airgas place that only swaps out tanks I think I paid close to 35 to 40 bucks for a 5 gallon tank. I wish I could find a place close that would just refill the one I have. But, I guess that is the best I can do for now.

SF Garden Supply isn't too far away from you and according to my SF Homebrewers Guild buddies they offer $25 20-lb exchanges. By far the cheapest I've heard of in the area but you'd need a 20-lb tank.

 

[beren]

A 20 pound tank is designed to hold 20 pounds of propane safely. The only reason to ever use an exchange is if your tank is out of date because they will Hydro test it and put it back in the system.

I have had places that do a 20 pounds refill only put in 15 pounds and tell me that’s all that will safely hold. I argued with them made him fill it and never went back there again.

 

[Agent]

A 20 pound tank is designed to hold 20 pounds of propane safely. The only reason to ever use an exchange is if your tank is out of date because they will Hydro test it and put it back in the system.

I have had places that do a 20 pounds refill only put in 15 pounds and tell me that’s all that will safely hold. I argued with them made him fill it and never went back there again.

Not quite.

20lb propane tanks hold 20lbs at 100% capacity. OPD valves will limit you to a maximum fill of 90% capacity (18lbs). You need room for the liquid to vaporize anyway.

The rule of thumb for safely filling propane tanks is 80% capacity (16lbs) to cover extreme scenarios. So you'll never see exchange tanks offer more than 16lbs.

 

[rlrohan]

Not quite.

20lb propane tanks hold 20lbs at 100% capacity. OPD valves will limit you to a maximum fill of 90% capacity (18lbs). You need room for the liquid to vaporize anyway.

The rule of thumb for safely filling propane tanks is 80% capacity (16lbs) to cover extreme scenarios. So you'll never see exchange tanks offer more than 16lbs.

That's not quite right either. All newer propane tanks 4-40 lbs have an OPD valve in them that shuts off filling when the tank is at capacity. The OPD shuts off filling when full and still leaves a 20% safety space for expansion. When a 20 lb tank is full it will hold 20lbs of propane and still have the 20% reserved head space. A 20 lb pound tank will weigh about 37lbs full. 20 lbs propane and about 17lbs for the tank. The tank will vary from 16-17lbs (Tare weight).

 

[Snuffy]

I’ve always tried to be respectfully paranoid around all pressurized fluids, even those that are non-toxic or unlikely to go boom. I may only have half my wits, but I still have all my digits.

I've spent time around lots of pressurized tanks. Scuba, propane, CO2, paintball, compressors. Never heard of one failing. Leaking, sure. Boom, no.
Did yours just pop something internal or actually fail externally somehow? Did you trash it or was it capable of refurb? I guess you'd never trust it again after something like that - even if it could be rebuilt.
Just curious.

 

[Broothru]

I've spent time around lots of pressurized tanks. Scuba, propane, CO2, paintball, compressors. Never heard of one failing. Leaking, sure. Boom, no.
Did yours just pop something internal or actually fail externally somehow? Did you trash it or was it capable of refurb? I guess you'd never trust it again after something like that - even if it could be rebuilt.
Just curious.

This was before OPD devices which limit fills to 80% capacity. But compressed gas bottles (all fluids, all gases, whether flammable or inert) have always had frangible blowout discs as a fail safe for over-pressurization.

That’s what blew on mine (CO2) which had been grossly overfilled, then heated by the local 100+ F summer weather. It fully discharged in what seemed like mere seconds.

The bottle was O.K., and passed the hydrostatic test after replacing the blowout disc.

 

[beren]

I've spent time around lots of pressurized tanks. Scuba, propane, CO2, paintball, compressors. Never heard of one failing. Leaking, sure. Boom, no.
Did yours just pop something internal or actually fail externally somehow? Did you trash it or was it capable of refurb? I guess you'd never trust it again after something like that - even if it could be rebuilt.
Just curious.

My dad has gotten tanks refilled at truck stops where they filled it until the overflow vented. They still held gas just fine. It sounds like something internal really failed hard if the entire propane tank vented.

Co2 tanks have a burst disk which is different and will let the tank empty.

 

[Broothru]

My dad has gotten tanks refilled at truck stops where they filled it until the overflow vented. They still held gas just fine. It sounds like something internal really failed hard if the entire propane tank vented.

Co2 tanks have a burst disk which is different and will let the tank empty.

There’s a bleeder valve on the fill device, or sometimes plumbed in to the tank fill line like on my RV, that can be used to determine the fill of a tank. When it stops bleeding gaseous fluid and starts venting liquid, you’re pretty much as full as you’re gonna’ get.

 

[shoengine]

Everything I am reading about propane (https://duckduckgo.com/?q=how+full+can+propane+tanks+be+filled&t=vivaldim&ia=web) is that you start with the nominal size of the tank (eg. 20lb) and multiply by 0.8 to get the total filled capacity. Of course these are all coming from suppliers, but I'm not sure why any other source would matter more.

I'm having a harder time finding info on CO2, but at least one place says 34% of capacity (https://www.kegerators.com/articles/CO2-Tank-Guide/), while a Federal guide for shipping maxes out around 70% (https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-173/subpart-G)

Is there a hard and fast rule for refilling or exchanges? For propane it seems 80%, but temperature can play a role. I think that all propane tanks are steel, but with CO2 aluminum is quite common. Should an aluminum tank be filled to the same density as a steel tank? I assume the relief systems on an aluminum tank will be set to a lower pressure than that of a steel tank. My takeaway is that none of these tanks are ever going to be filled to 100% of their volume.

 

[Bobby_M]

https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.2200-01.pdf

 

[beren]

Everything I am reading about propane (https://duckduckgo.com/?q=how+full+can+propane+tanks+be+filled&t=vivaldim&ia=web) is that you start with the nominal size of the tank (eg. 20lb) and multiply by 0.8 to get the total filled capacity. Of course these are all coming from suppliers, but I'm not sure why any other source would matter more.

I'm having a harder time finding info on CO2, but at least one place says 34% of capacity (https://www.kegerators.com/articles/CO2-Tank-Guide/), while a Federal guide for shipping maxes out around 70% (https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-173/subpart-G)

Is there a hard and fast rule for refilling or exchanges? For propane it seems 80%, but temperature can play a role. I think that all propane tanks are steel, but with CO2 aluminum is quite common. Should an aluminum tank be filled to the same density as a steel tank? I assume the relief systems on an aluminum tank will be set to a lower pressure than that of a steel tank. My takeaway is that none of these tanks are ever going to be filled to 100% of their volume.

There is so much bad information online that seems identical and written by ai. A tank size in pounds is how much the tank can safely hold. A total size in gallons is the real size of the tank and you can put 20% less in. So a 500 gal tank can hold 400gal of liquid propane. A 50lb propane tank can hold 50lb of propane safely.

https://www.amerigas.com/about-propane/propane-tank-sizes

 

[shoengine]

There is so much bad information online that seems identical and written by ai. A tank size in pounds is how much the tank can safely hold. A total size in gallons is the real size of the tank and you can put 20% less in. So a 500 gal tank can hold 400gal of liquid propane. A 50lb propane tank can hold 50lb of propane safely.

https://www.amerigas.com/about-propane/propane-tank-sizes

Kind of a throw-away reply there.

 

[beren]

Kind of a throw-away reply there.

Not really. If the tank is sized in pounds, that’s what you put in if it’s sized in gallons you put in 20% less.

This link makes it clearer: https://www.amerigas.com/commercial-propane/propane-tank-sizes

 

[mac_1103]

My totally non-expert WAG is that big propane exchangers like Blue Rhino are intentionally underfilling to give themselves a little extra speed (for $) and margin of error (for liability). If you do a bit of digging, they do tell you that you're only getting 15 lbs in a 20 lb exchange tank, so it's not exactly a rip-off, but they certainly could make that information easier to find.

 

[Bobby_M]

My totally non-expert WAG is that big propane exchangers like Blue Rhino are intentionally underfilling to give themselves a little extra speed (for $) and margin of error (for liability). If you do a bit of digging, they do tell you that you're only getting 15 lbs in a 20 lb exchange tank, so it's not exactly a rip-off, but they certainly could make that information easier to find.

The entire class action lawsuit was predicated on the lack of transparency. People thought they were still getting the totally safe and customary 20 pound fills but they weren't. The labels now say 15lb net weight and that was not their choice to do it.

 

[mac_1103]

The entire class action lawsuit was predicated on the lack of transparency. People thought they were still getting the totally safe and customary 20 pound fills but they weren't. The labels now say 15lb net weight and that was not their choice to do it.

Thanks. ISTM that some people still think they're getting 20 lbs.