What are the two most common sizes of acetylene cylinders used in the HVAC/R trades?

The two most common sizes of acetylene cylinders used in the HVAC/R trades are indeed the MC and B cylinders. The MC cylinder is smaller and typically holds about 10 cubic feet of acetylene, making it well-suited for smaller applications or jobs where portability is essential. The B cylinder is larger and generally holds around 40 cubic feet of acetylene, providing a more substantial supply for tasks requiring greater volume or longer durations of use.

These cylinder sizes are favored by HVAC/R technicians due to their balance of portability and capacity, allowing technicians to select the appropriate size based on the specific requirements of the job. The usage of these sizes ensures efficiency and safety while handling acetylene, which is critical in refrigeration and air conditioning work.