Propane! Filling direct from a 13kg tank

[ejovrh]

Here's a few pic's

 

Fill valve right from centre of Coleman  and standard Tyre Shrader Valve on the left

 

Coleman pressure relief valve

 

Coleman Tank top. Notice how the valve housing isn't flush hence you will never get all the liquid out while its inverted. Also notice the rust!

 

I'd not consider refilling without the use of scales as overfilling could end in a catastrophic failure!

 

Remember Safety Third !   

 

this is the essence of gravimetric filling.

one has to determine by weight how much liquid gas gets into the bottle that is being filled.

this ensures that you have a sufficiently large gas pocket in the tank.

 

by contrast, if one fills by volume, one typically overfills.

 

yes, the is a pressure relief valve - but, why rely on it?

[renegadecow]

So there really is no anti refill mechanism. Just the valve getting crudded up if not filled with nitrogen.

[MadMax]

Disposable propane bottles are filled after they have been evacuated. Drawing a vacuum first facilitates filling with a large liquid charge. It also excludes oxygen, which is something you don't want in a pressure vessel to be filled with a flammable gas.

[bankz5152]

Good info! According to US forums on the likes of refilling the rule of thumb is no more than 1 minute, I never fill more than 45 seconds however you can hear them when they are full around the 30 - 35 second mark.

 

When weighing after average propane inside has been around 400 - 450 grams. Less than the standard 465, never had a fill above 450 but in all honesty Ive not weighed every tank.

 

on my phone, my spelling will suck

[sir naggedalot]

 

 

yes, the is a pressure relief valve - but, why rely on it?

 

Exactly! Safety third remember at all times!   

[MadMax]

Trying to get a considerable, and consistent, amount of liquid into a compressed gas container is not specific only to airsoft.

 

Your leaky sounding TM or other Japanese GBB magazines have 2 port fill valves. When you push on the fill stem, you open two passages in the valve. One connects the center hole in the stem that you plug your adaptor tip onto to a pipe that goes down the bottom of your mag (notice how JP valves have longer pipes attached to the hub?). Through this center hole, liquid is conducted from your propane bottle or green gas can into the mag. A second passage opens up that allows gas to escape from the top of the mag (inverted mag, means that top is baseplate end). This second passage allows the escape of gas so the pressure in the magazine will always be lower than the pressure in your bottle which assures that liquid can transfer into the mag. At some point the liquid level in your mag gets high enough that it overflows out the 2nd passage and you get a spurt of visible mist out of your mag that indicates that it's full.

 

If you're ever bored, try taking your fill valve out of your TM magazine. You'll see a small hole that's drilled into the side of your valve hub. That's the gas venting 2nd port I'm talking about that makes that valve seem so leaky when filling. It's not a flaw, it assures a consistent liquid liquid transfer.

 

What you have in your propane tank is a single port valve. Once pressure equalizes between your BBQ tank and your propane bottle, liquid transfer ceases.

 

I'm not going to tell you how to get a consistent fill into your disposable bottles (I don't want the liability), but I can tell you what was done to overcome the same problem when filling CO2 bottles for paintball. Pball CO2 stations are connected to bulk bottles with liquid draw tubes. You don't flip them upside down to draw liquid because the outlet valves are connected to long tubes that draw from the bottom of the bottle. When filling, a CO2 fill station would transfer liquid until the pressure equalized between both containers (pball bottle, bulk bottle). The operator would flip a handle over on the fill station which would close the valve from the bulk bottle and open a valve leading to the pball bottle which would dump some CO2 from that bottle resulting in a rapid cooling of the pball bottle and a subsequent drop in saturated vapor pressure in that bottle. A subsequent fill cycle would transfer more liquid into the pball gun bottle because it started off much colder than the bulk bottle which allowed a significant liquid transfer before pressure between both bottles would equalize. For convenience, an empty pgun bottle would be hung on a scale so the operator could observe how many ounces (weight) of liquid CO2 they transferred to the bottle. Hang the bottle and vent it to empty. Tare the scale and transfer liquid. If insufficient liquid is transferred by the time that both vessels equalize, dump some CO2 from the pgun bottle to chill it and resume liquid transfer until enough weight has been transferred.

 

Notionally, pgun bottles could have been disconnected and chilled in say a water/ice bath instead of dumping CO2, but it wasn't really worth it because CO2 is so cheap and inert. It wasn't a flammability hazard to intentionally dump CO2 from bottles to chill them so that's the way the industry went.

 

Whatever method you use to mitigate the equalization of pressure between your two reservoirs, it is important that you do measure how much you have transferred into your portable container. Get a scale and tare it on an empty bottle and assess your fill so you can partially vent an overfilled bottle before it warms up to room temp. The safety regulations applied to your pressure vessels are not there only to protect you. There are also there to protect those around you who may not be aware of how you manage your pressure vessels. Relying on the overpressure relief valve to cover for your negligence is not responsible behavior. The relief valve is a failsafe which means you only have single factor safety if you intentionally rely on it by not assuring that you haven't overfilled a bottle by observing fill weight.

[sir naggedalot]

 Once pressure equalizes between your BBQ tank and your propane bottle, liquid transfer ceases.

 

 

Not so sure,when I've filled using a translucent tube I can see the bubbles of gas transferring up as the some volume of liquid flows down,very slow but the weight still increases. If nothing transferred when we have equal pressures how come we can pour water from a bottle?

[renegadecow]

Because bottles have much larger holes. Make that hole the same size as the hole on the side of the fill valve shaft and nothing gets through unless you pressurize the bottle.

[sir naggedalot]

Because bottles have much larger holes. Make that hole the same size as the hole on the side of the fill valve shaft and nothing gets through unless you pressurize the bottle.

No,get two bottles that are identical and fill one with water. Join them with a airtight seal and turn them so the full bottles on top on top! Watch what happens!

 

Better still watch this as its got one of my favourite subjects at work! The Golden Ratio!

 

https://www.youtube.com/watch?v=dv6vQU94wws 

[renegadecow]

Same thing applies. You're comparing the neck of a bottle to a pin *beep* unless you mean to use 1/2" coupling valves on your magazines. Some might still pass through but it will be a negligible amount unless assisted by pressure.

[sir naggedalot]

 Some might still pass through but it will be a negligible amount unless assisted by pressure.

It might well be tiny but its still a amount !  You just proved yourself wrong as you said "NOTHING"  

[renegadecow]

Nothing in the practical sense. That "something" that goes through which you're so adamant in arguing about won't be nearly enough to even cycle virtually any GBB.

[sir naggedalot]

LoL I never said it was practical! I was just pointing out yours and MadMax's inaccurate statements about liquid transfer ceasing when the pressure in both tanks equalise! I was discussing it not arguing about it and I'm sorry if you don't like me pointing that out to you and others!

 

Lets also remember a tap dripping at one drip per minute  equates to 1,440 drips per day or 34 (US) Gallons per year! :0)

[sir naggedalot]

I trawled the web for a while but this was relevant so I thought I'd post it!

 

Its a Coleman tank that has failed,only one I could find and its possibly because of improper storage/handling!

 

 

  Link to source: http://redrockstore.com/tag/jiffy-pro-4-auger/

[sir naggedalot]

I also found this. I have had the valve leak on a old Green Gas can as the rubber seal inside the valve had perished but I'm thinking of making the the end part so I can screw it onto my adapter that I use to refill my Colemans as I've lost my P-Force propane adapter :0(

 

Would be ideal for the rig that Bankz5152 is thinking of constructing!

 

http://www.instructables.com/id/Propane-to-Green-Gas-Converter/?ALLSTEPS

[ejovrh]

Trying to get a considerable, and consistent, amount of liquid into a compressed gas container is not specific only to airsoft.

 

Your leaky sounding TM or other Japanese GBB magazines have 2 port fill valves. When you push on the fill stem, you open two passages in the valve. One connects the center hole in the stem that you plug your adaptor tip onto to a pipe that goes down the bottom of your mag (notice how JP valves have longer pipes attached to the hub?). Through this center hole, liquid is conducted from your propane bottle or green gas can into the mag. A second passage opens up that allows gas to escape from the top of the mag (inverted mag, means that top is baseplate end). This second passage allows the escape of gas so the pressure in the magazine will always be lower than the pressure in your bottle which assures that liquid can transfer into the mag. At some point the liquid level in your mag gets high enough that it overflows out the 2nd passage and you get a spurt of visible mist out of your mag that indicates that it's full.

 

If you're ever bored, try taking your fill valve out of your TM magazine. You'll see a small hole that's drilled into the side of your valve hub. That's the gas venting 2nd port I'm talking about that makes that valve seem so leaky when filling. It's not a flaw, it assures a consistent liquid liquid transfer.

 

What you have in your propane tank is a single port valve. Once pressure equalizes between your BBQ tank and your propane bottle, liquid transfer ceases.

 

I'm not going to tell you how to get a consistent fill into your disposable bottles (I don't want the liability), but I can tell you what was done to overcome the same problem when filling CO2 bottles for paintball. Pball CO2 stations are connected to bulk bottles with liquid draw tubes. You don't flip them upside down to draw liquid because the outlet valves are connected to long tubes that draw from the bottom of the bottle. When filling, a CO2 fill station would transfer liquid until the pressure equalized between both containers (pball bottle, bulk bottle). The operator would flip a handle over on the fill station which would close the valve from the bulk bottle and open a valve leading to the pball bottle which would dump some CO2 from that bottle resulting in a rapid cooling of the pball bottle and a subsequent drop in saturated vapor pressure in that bottle. A subsequent fill cycle would transfer more liquid into the pball gun bottle because it started off much colder than the bulk bottle which allowed a significant liquid transfer before pressure between both bottles would equalize. For convenience, an empty pgun bottle would be hung on a scale so the operator could observe how many ounces (weight) of liquid CO2 they transferred to the bottle. Hang the bottle and vent it to empty. Tare the scale and transfer liquid. If insufficient liquid is transferred by the time that both vessels equalize, dump some CO2 from the pgun bottle to chill it and resume liquid transfer until enough weight has been transferred.

 

Notionally, pgun bottles could have been disconnected and chilled in say a water/ice bath instead of dumping CO2, but it wasn't really worth it because CO2 is so cheap and inert. It wasn't a flammability hazard to intentionally dump CO2 from bottles to chill them so that's the way the industry went.

 

Whatever method you use to mitigate the equalization of pressure between your two reservoirs, it is important that you do measure how much you have transferred into your portable container. Get a scale and tare it on an empty bottle and assess your fill so you can partially vent an overfilled bottle before it warms up to room temp. The safety regulations applied to your pressure vessels are not there only to protect you. There are also there to protect those around you who may not be aware of how you manage your pressure vessels. Relying on the overpressure relief valve to cover for your negligence is not responsible behavior. The relief valve is a failsafe which means you only have single factor safety if you intentionally rely on it by not assuring that you haven't overfilled a bottle by observing fill weight.

 

excellent and technically sound post.

[MadMax]

Not so sure,when I've filled using a translucent tube I can see the bubbles of gas transferring up as the some volume of liquid flows down,very slow but the weight still increases. If nothing transferred when we have equal pressures how come we can pour water from a bottle?

 

Joining two bottles together and transferring liquid (like an hourglass) only works because the openings are large enough for gas to bubble around the liquid and exchange their displacement. This doesn't work very well when you get down to small passages like the little Schrader valve in a disposable bottle because bubbles don't float up through the valve to exchange with liquid very well. Maybe if you shook the out of it you'd get somewhere, but it'd still be pretty slow.

 

I just shot some high speed footage of a transparent polycarbonate gas reservoir being filled via a 2 port fill valve and a 1 port fill valve to illustrate how the two valve types behave so differently. I'd getting a lot of flak for our 2 port fill valves sounding leaky so I'm putting together an informational video to show how a 2 port fill valve assures a more consistent liquid transfer than a 1 port valve.

 

I think I've been making this explanation for maybe 10 years now. I started with a scan of a KSC G17 manual page showing a magazine cross section that I doctored up with MSPaint. The picture link for those forum posts has gone bad so I guess I should put together a good technical video finally.

[sir naggedalot]

Look forward to the vid and great to see more interesting relevant posts from you unlike SO MANY pointless post one here!

 

I just wanted to correct the statement that "Once pressure equalizes between your BBQ tank and your propane bottle, liquid transfer ceases."  as someone might read this and leave their set-up connect thinking its going to stop filling of its own accord when in fact even though "This doesn't work very well when you get down to small passages like the little Schrader valve in a disposable bottle" and it might well be very slow the transfer is still taking place and this could lead to a dangerously over filled pressure vessel !   

    

 

I hope no offence was taken as none was intended :0) 

[sir naggedalot]

Here's a couple of pics of a pics of a KJ Works Para Ordnance P14.45 magazine body that almost blew the base plate off as I over filled it!

 

IMO a good reason why single port fill valves are dangerous!

 

[paranoiddroid]

In a practical sense leaving it connected won't do much at all because he actual amount that's overfilled is so minimal that if you leave it connected whilst setting up and don't disconnect until you put everything away you aren't going to see an issue.

 

If you leave it connected for like a year with the valve open then you MAY see it overfill to a dangerous level but practically speaking when something reaches equilibrium what goes through one way only really ever equals what's lost going the other way.

 

Pointing out the single drip that goes through as some kind of GOTCHA moment that discredits RC isn't doing anything more than making you look stupid..

 

The mag being over filled isn't the same thing as the propane to bbq tank thing because the containers make the difference. An air soft gun magazine doesn't carry the same safety systems and will fail more dramatically.

[sir naggedalot]

 1:In a practical sense leaving it connected won't do much at all because he actual amount that's overfilled is so minimal that if you leave it connected whilst setting up and don't disconnect until you put everything away you aren't going to see an issue.

 

2:If you leave it connected for like a year with the valve open then you MAY see it overfill to a dangerous level but practically speaking when something reaches equilibrium what goes through one way only really ever equals what's lost going the other way.

 

3:Pointing out the single drip that goes through as some kind of GOTCHA moment that discredits RC isn't doing anything more than making you look stupid..

 

4:The mag being over filled isn't the same thing as the propane to bbq tank thing because the containers make the difference. An air soft gun magazine doesn't carry the same safety systems and will fail more dramatically.

  1:So the problems only going to happen when you put it away? Is that not the worst time as your handling it or storing it then?

 

2:Yes and that's why when the gas in the lower vessel is replaced by the liquid you could end up with a vessel fully filled with a non compressible  liquid! Any thermal expansion could end in a catastrophic failure! 

 

3: When was it stated that it was only going to be a single drip? 

 

4:A airsoft magazine has no safety systems as far as I'm aware but we shouldn't rely on any safety systems anyway! 

 

Lets remember "Safety Third"   

[paranoiddroid]

The important thing to remember with the safety third style stuff is he main safety is the one between the persons ears.

 

I have never overfilled a magazine to the level it failed hell I don't think I have ever overfilled a mag even a single valve magazine why you ask because I'm not a moron and I understand what I'm doing.

 

I use gases based on what the mag is rated by the manufacturer to take,the temperature and relevant humidity data and I vary the time of my fills based on that as well.

 

For example a gun that's been marketed to the US market as safe to use GG in I know will be safe to use green gas and propane in the UK with as if it's rated safe for Florida cali or HI temperature highs I can know it's going to be safe at a UK 28-35 degrees and Will remain safe if it hits 40c a gun that's rated for 134a in the Japanese market I can be sure that that will be safe for 134a in the UK but I know green gas would need some consideration before I use it due to the risks involved and potential for damage to the weapon system due to part failures caused by the increased power and recoil plus the safety and capability of the mag to handle green gas.

 

It's all about looking at the data and making the correct judgements and safety calls based on what you see.

 

If you were defeated by a single valve magazine and damaged the mag because you weren't paying attention to the environment and the data known about the weapon and that the mag was showing you that says more about you than it does about the 'dangers of the product'.

 

As for the safety aspect, the fact they are pressure rated for a larger psi than created by the max amount GG/propane that can fit in the mag is a safety system meaning that the overfilling isn't likely to do more than blow the seals and dump the baseplate as opposed to exploding like a pipe bomb as is the fact that there's an engineered failure point designed to release pressure before such an incident occurs (the baseplate) is something of a safety measure. It may not be a preventative safety but it serves the same purpose as a blow off valve or burst disk in some commercial setups.

 

 

 

Leaving the kit connected while its in use will be fine so setup, run the gear for the task required and at the end of the day disconnect, shut the main tank off and then vent the hose before packing up for long term storage and you won't have any problems at all. It's what I do with the propane heaters in the workshop, what we did with the bbq setup and exactly what I'd do with the tank setup at the end of the game day. (Though I'd probably use the contents of the hose to put a small amount of gas into my mags for storage before venting the excess. Then vent those mags at home and refill with the abby maintaince gas for peace of mind)

 

 

You know exactly what I meant about the gotcha comment don't be obtuse.

[sir naggedalot]

Were we not referring to overfilling a Coleman Bottle? I thought that was you meant as your point would of been moronic otherwise?

 

I over filled it as I topped off my mags during a game and then brought them home and stored them,a fairly common practice in airsofting I suspect and with the no loss valve fitted on the mag its very easy to over fill as there's no indication when the gas has reached the fill valve but hay hay we live and learn, hopefully from others mistakes and not only ours!  Not all of us are perfect unlike you seem to be when it comes to filling mags!

 

The base plate acting like a blow off valve or a burst disk is nonsensical as both are designed to avoid any projectiles being emitted where as a baseplate could make a great projectile with plenty of mass!    

 

Could you please tell me what relative humidity has to do with filling or are you just being obtuse? :0)

 

As for the hose bulk fill set up I'd just let the liquid drain back into the upright bottle by raising the hose before I shut the valve on the bottle but each to their own.