What is the purpose of the pin-indexing system on compressed gas cylinders?

• A. prevent destroying or stripping the threads on the cylinder.
• B. ensure that the correct regulator is used for the cylinder.
• C. help you determine what type of oxygen regulator to use.
• D. reduce the cylinder pressure to a safe and more useful range.

Answer: (B)

The pin-indexing system is a safety feature that ensures you connect the correct regulator to a given gas cylinder. Each cylinder gas type has a unique arrangement of indexing pins on the valve stem, and the regulator’s yoke has matching holes or alignment features. When you attempt to attach a regulator, only the regulator designed for that specific gas and cylinder combination will align and fit. This prevents the wrong regulator from being connected, which could deliver the wrong gas, at the wrong pressure, or in unsafe ways.

So the core purpose is to guarantee that the correct regulator is used for the cylinder, not to protect threads, determine oxygen-only regulators, or reduce pressure.