Purging new tanks

[ScottG]

So I've got two new PP tanks. Tried to have them filled but they could only get gas into one bottle. The other tank took a tiny amount and just wouldn't take any more. The guy opened the bleeder screw to let air out as gas tried to flow in but no joy.
I understand there's some kind of "purging" that has to be done. Is this something more than just opening the vent screw thingy?

Thanks.

[GASMAN6674]

Proper purging procedure for ALL New LP gas Tanks (5# to 90,000 gallon)
On a new cylinder/tank or a cylinder/tank that has been opened to atmosphere for repair you need to introduce LP gas VAPOR at 15 psi, once the tank equalizes you need to vent or purge this to atmosphere, this procedure needs to be done 5 times. Then the tank can be filled with Liquid. It is also recommended that methanol be added on initial fill to combat moisture. Improperly purged tanks will cause freeze ups, pilot/flame outages and premature relief valve operation. A vacuum purged tank can forgo this procedure and be filled the "first" time. Also you cannot count on an opd for filling they are a safety measure mandated by the CPSC and they sometimes fail. The only proper procedure is to fill by weight (tare + cylinder volume)

[Old-Biscuit]

ScottG wrote:
Found a real service station (an actual shop) that sold PP and they knew exactly what to do. He unscrewewd the brass coupler from the fill hose and used it to relieve the pressure in the tank. It took several minutes for the pressure to disapate. After that he filled it in the regular manor by loosening the bleed screw.
No wonder PP wouldn't go in, there was a LOT of pressure in there.

He went on to explain some have pressure and some are "pre-purged". The latter are under a vacuum and ready for filling.

Thanks everyone for all your input!

Still wasn't purged....just relieved the shipping air (up to 100#) and filled it.
Now you have a cylinder with liquid propane, propane vapor mixed with air.
Could result in popping noises, moisture in the air freezing up in regulator, moisture in air rusting out inside of cylinder, improper mix of propane/less btu, odorant fade (mercaptan oxidizes)----
That is why purging requires exchange of Vapor 3-5 times to REMOVE the air.

Sorry but that service station got it filled but not purged.

[mobeewan]

To properly Purge a propane cylinder they use what's called a purge rig. They connect another propane cylinder with liquid propane to your empty cylinder. They then transfer propane gas from their cylinder to yours. They then vent the gas from your cylinder. They may do this a couple times. After the purging process they then fill your cylinder with liquid propane.

Nowadays propane cylinders are usually vacuum purged at the factory before being shipped. These vacuum purges are only good for about 6 to 12 months per my conversation with somebody at Worthington, a company that manufactures propane cylinders. However, if the vent screw on the cylinder valve is opened air will be introduced into the tank negating the vacuum purge. If the hand wheel is opened on the cylinder valve air could be introduced into the tank through the check valve.

As long as the cylinder has been vacuum purged at the factory, is under 12 months old and no one is screwed with the valve hand wheel or vent screw it should be okay to fill a new cylinder with liquid propane without purging it. Otherwise it must be purged with propane gas prior to filling with liquid propane. It's up to the individual whether they get the cylinder purged or not. However my personal bad experience with two of my cylinders that had to be emptied and then purged properly has taught me to always have new cylinders purged regardless of how much the idiot filling them insists they don't need purging.

[ScottG]

Found a real service station (an actual shop) that sold PP and they knew exactly what to do. He unscrewewd the brass coupler from the fill hose and used it to relieve the pressure in the tank. It took several minutes for the pressure to disapate. After that he filled it in the regular manor by loosening the bleed screw.
No wonder PP wouldn't go in, there was a LOT of pressure in there.

He went on to explain some have pressure and some are "pre-purged". The latter are under a vacuum and ready for filling.

Thanks everyone for all your input!

[dougrainer]

ScottG wrote:
On top of all that, a buddy of mine just had a (used) tank refilled where the person didn't even open the purge vavle - just forced the gas in.
Doesn't seem like you would get a full load that way.

You are not forcing GAS in. LP is LIQUID PROPANE. So, you are filling with a Liquid. The 80 percent(purge?) valve is used as a secondary safety device when filling. The CORRECT and ONLY safe way to fill DOT tanks is by WEIGHT. You fill by weight and when the Tare weight matches the tank sticker weight, your tank is FULL to the safe liquid level. Now, you also have a OPD device, but THAT is also a 2nd/3rd safety device. If the 80 percent spews liquid you stop. If the tare/tank weight hits the mark you stop. IF you fail to follow this, then the OPD hopefully stops the fill. Also. if the tank was correctly purged on first/new fill, then there is NO WAY for AIR to get in the tank, so air in the tank is a none existent problem. Doug

[CJW8]

Take it to a propane supplier and not the local gas station or RV fill station. They'll know what is going on.

[Old-Biscuit]

time2roll wrote:

ScottG wrote:
On top of all that, a buddy of mine just had a (used) tank refilled where the person didn't even open the purge vavle - just forced the gas in.
Doesn't seem like you would get a full load that way.

Very common method to just use the OPD to stop the flow.
Mine have been filled with this method and virtually the same seven gallons goes in.
Actually with the bleeder open you are losing propane the entire fill time so it may take a bit more to make it full.

Actually using 'bleeder valve' is correct method along with weighing to refill propane vessels.
Bleeder valve is connected to a dip tube that is right at the 80% liquid level line.....vapor comes out until 80% FIXED liquid level then it will begin spewing liquid out of bleeder valve. Time to close and stop filling.

Even if two cubic feet of propane gas is lost through the bleeder valve, this is only .05 gallon of gas. At $2.00 per gallon, this would be equal to ten cents worth of propane expelled through the bleeder valve.

OPD Mfgs do NOT recommend relying on the 'float' as means of when to stop filling...it is a 'secondary' method.


Purging of propane depends on 'shipping method' of the cylinder.
As mentioned....
Filled with air (up to 100#)
Shipped with a vacuum (as much as 26")

LP Gas method..special fittings/extra supply tank for 'vapor'
Vacuum method....special fitting, vacuum source and purge 'vapor'

Vapor is used to Purge. Once purging is done THEN liquid propane is used to fill

[time2roll]

ScottG wrote:
On top of all that, a buddy of mine just had a (used) tank refilled where the person didn't even open the purge vavle - just forced the gas in.
Doesn't seem like you would get a full load that way.

Very common method to just use the OPD to stop the flow.
Mine have been filled with this method and virtually the same seven gallons goes in.
Actually with the bleeder open you are losing propane the entire fill time so it may take a bit more to make it full.

[time2roll]

If the bleeder was open the propane should flow regardless of what is in the cylinder.
Seems like operator error to me.

[ScottG]

On top of all that, a buddy of mine just had a (used) tank refilled where the person didn't even open the purge vavle - just forced the gas in.
Doesn't seem like you would get a full load that way.

[SaltiDawg]

Seems there is "purging", "venting," and "evacuating."

Some new tanks come evacuated - virtually no air in them. Simply fill them with propane.

Some tanks come with air in them at atmospheric pressure. Some simply fill them while simultaneously bleed a combination of air and propane from the vent. 3-5 refills and the tank would be virtually air free. (Others might take them to a place where they would use a special fitting to evacuate the tank prior to filling.)

I have no idea why a bottle with air in it could not be vented.

[ScottG]

Ahh, a special fitting - that explains it.
Thanks DTR, I'll take it to Suburban Propane.

Scott

[downtheroad]

My new tanks...new Arctic Fox also, had to be purged. Took them to a local propane distributor (not just a refill outlet). They purged them and filled them.

The guy used a special fitting during the purge process...then they took a full amount of propane.