You might want to check with a propane distributor that does home and business delivery and installs and delivers tanks to those homes and businesses. They should have all the equipment necessary to safely empty tanks and cylinders and perform maintenance on them.
I had two brand new 30 lb cylinders that were not properly purged as I requested when they were filled. These cylinders had vacuum purges done at the factory. According to the distributor that eventually helped me, a factory Purge was no longer reliable after 6 months anyway. He said that 6 months after a cylinder was manufactured he would normally purge a new unused cylinder using propane before filling them.
Both places that had filled the brand new cylinders that I took to them did not purge them prior to filling them. I later learned that the persons filling the cylinders thought purging the cylinder was done by opening the spitter valve before putting the propane in the cylinder. So all they did was to suck humid air into the cylinder when they opened the spitter before allowing propane to flow into them.
I was not able to use the cylinders because they would cause my trailer furnace to sputter and pop. When switching over to my other cylinders the sputtering and popping went away.
I didn't have anywhere that I could safely just open the spitter screw on the cylinders and let them bleed off in order to empty them and both cylinders were full.
The propane distributer had a small trailer with a high volume burner on it that they used and could transport where needed to burn off the propane from tanks and cylinders that they needed to empty. I believe they told me it was capable of burning propane at a rate of 1 million BTUs per minute. It was temporarily on loan to the volunteer fire department, so I left the two cylinders with them and picked them up a few days later.
After burning off the propane, they removed the valves in order to put in an alcohol to rinse and remove any moisture still in the cylinders. They then reinstalled the valves, purged the cylinders and refilled them. They only charged me for the propane refills and about 10 or 12 dollars total for the labor. I didn't have any more problems with propane from those cylinders causing the furnace to sputter and pop.
