Control drain venting and test connection valves must be provided with which of the following permanent markings?

Permanent markings for control drain venting and test connection valves are crucial for ensuring safety and compliance in fire protection systems. Having weatherproof metal or rigid plastic signs is imperative because these materials are durable and resistant to environmental factors such as moisture, UV rays, and physical wear. This durability ensures that the markings remain visible and legible over time, which is essential for effective communication and for maintaining safety standards.

Wooden signs, while potentially sturdy, could deteriorate or degrade when exposed to weather conditions, making them less reliable. Vinyl stickers and paper labels, while they may be easier to apply, typically lack the longevity and durability needed in outdoor or high-traffic environments. Therefore, the use of weatherproof metal or rigid plastic signs is the best choice for this purpose, as they maintain their integrity and visibility even in challenging conditions, supporting ongoing safety and compliance in fire inspection practices.