TEMPERATURE CONSIDERATIONS
A potential hazard can occur when cylinders are exposed to excessive temperatures that can cause the pressure of the refrigerant inside to elevate to a dangerously high level. This excessive pressure can cause the cylinder to rupture and present a severe safety hazard. It is generally recommended that cylinders not be exposed to temperatures above 125°F. When storing and transporting these cylinders make sure they are not exposed to temperatures above this value.Also when removing refrigerant from a cylinder, a technician may need to warm a cold cylinder, do not use a torch or any other similar high heat device. The best practice is to place the cylinder in a bucket of warm (not hot) water. Remember: Do not expose the cylinder to temperatures over 125°.
One time I was working on a floral cooler and needed to add refrigerant to the system. I took a brand-new 30-pound cylinder of CFC-12 from my truck. (This was back in the 1980s when R-12 was the refrigerant of choice for coolers). It was wintertime so the cylinder was cold. I did not have a bucket to put the cylinder in, so I decided to warm the cylinder in a plastic utility sink in the back of the floral shop. As I was placing the cylinder in the sink and turning on the hot water, my pager went off. (Remember, this was back in the ’80s when service techs still carried pagers). I left the water running over the cylinder and went to call the office. As I was on the phone, I heard a loud explosion and saw what seemed like smoke coming from the back room. Without any hesitation I (along with the two employees in the store) ran out of the building.
After about five minutes I went back inside to see what had happened. Guess what? The explosion was from my refrigerant cylinder.
The water I used to warm the cylinder was extremely hot and caused the relief valve on the cylinder to blow. This particular cylinder had the relief valve on the bottom of the tank. When the valve blew it dumped its 30 pounds of R-12.
What I thought was smoke was actually a refrigerant cloud that had formed. The force of the refrigerant being released also caused the bottom of the utility sink to crack; I believe this was from the cylinder being lifted off the bottom of the sink and then crashing back down. So not only did I lose 30 pounds of refrigerant, I had to replace the sink for the customer. An expensive safety lesson. Luckily, no one was walking by when the cylinder ruptured.
OLD CYLINDERS
This potential hazard is also possible with old cylinders left outdoors or on a job site. The internal pressure of a cylinder with even a small amount of liquid refrigerant is exactly the same as a full cylinder. An abandoned cylinder will eventually deteriorate and can possibly rupture.Before disposing of non-reusable, non-refillable cylinders, a technician must make sure all of its contents are removed using an approved refrigerant recovery device. Once emptied, the cylinder’s valve should be opened to allow air to enter, and the cylinder should be punctured with the valve still open (rendering it useless). It can then be recycled with other scrap metal.
Working with these refrigerant cylinders is generally not considered a hazardous practice. But, as with many of the components refrigeration technicians handle each day, it can become a safety hazard if carelessly handled.
Publication date:05/03/2010
