Safety pin index for oxygen cylinder is
**Core Concept**
The safety pin index for oxygen cylinders is a mechanical locking system designed to prevent the connection of an oxygen cylinder to a yoke or valve that is not specifically intended for oxygen service. This system ensures that oxygen cylinders are used with the correct equipment to prevent accidental exposure to high-pressure oxygen, which can cause fires or explosions.
**Why the Correct Answer is Right**
The safety pin index system uses a specific arrangement of pins on the cylinder valve and a corresponding yoke or valve to ensure a secure connection. Oxygen cylinders have a unique pin arrangement that matches only with yokes or valves that are specifically designed for oxygen service. When an oxygen cylinder is connected to the correct yoke or valve, the pins align, allowing the cylinder to be securely attached. This prevents the use of oxygen cylinders with equipment intended for other gases, such as nitrous oxide or air.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the safety pin index system is specific to oxygen cylinders and cannot be used to determine the compatibility of other gas cylinders.
* **Option B:** This option is incorrect because the color of the cylinder is not a reliable indicator of the safety pin index system.
* **Option C:** This option is incorrect because the safety pin index system is a mechanical locking system, not a color-coding system.
**Clinical Pearl / High-Yield Fact**
Remember the mnemonic "O2 Only" to recall that oxygen cylinders have a unique safety pin index system that prevents them from being connected to equipment intended for other gases.
**Correct Answer: D.**