Pin Index Safety System (PISS) is used to decrease inadvertent misconnections of gas cylinders.

• A. To decrease inadvertent misconnections of gas cylinders
• B. To regulate gas flow
• C. To identify cylinder contents by color
• D. To measure cylinder temperature

Answer: (A)

The main idea is that the Pin Index Safety System is a mechanical safeguard designed to prevent connecting the wrong gas cylinder to a regulator or device. Each gas has a unique pin pattern on its cylinder valve, and only a regulator or equipment with the matching pin holes can attach. This reduces the risk of inadvertent misconnections that could deliver an incorrect or dangerous gas to a patient or system.

It's not about regulating flow (that’s the regulator’s job), identifying contents by color (color codes aid recognition but don’t prevent misconnections), or measuring temperature (temperature isn't part of the safety interlock). The Pin Index System specifically prevents the wrong gas from being connected in the first place.