Final answer:
A safety clamp must be installed if an air hose diameter exceeds 1/2 inch, to prevent accidental disconnection and potential safety hazards.
Step-by-step explanation:
If an air hose is greater than 1/2 inch in diameter, a safety clamp must be installed. This safety feature is designed to ensure that the coupling will not accidentally disconnect if the hose is snagged or pulled on, which could be dangerous due to the sudden release of high pressure air. The clamp provides an additional layer of security beyond a simple friction fit.