Purging new tanks

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.

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

Scott

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.

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.

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

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 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

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

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

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!