In pneumatic control systems, which protections apply to lines and control equipment?

• A. Lines shall be protected against crimping and mechanical damage.
• B. The lines must be color-coded and insulated.
• C. The lines shall be protected against crimping and mechanical damage, and control equipment shall be listed for the number and type of actuating devices utilized, and their compatibility shall be listed.
• D. Only lines in hazardous locations require protection.

Answer: (C)

Pneumatic control systems require both the physical protection of the supply lines and the proper qualification of the control hardware. Lines carrying compressed air must be protected against crimping and mechanical damage to prevent leaks, kinks, or rupture that could alter pressure and degrade system performance. At the same time, control equipment needs to be listed for the number and type of actuating devices used, and their compatibility must be listed. This listing ensures that the components have been tested and approved to work together in the specific system and environment, preventing mismatches that could lead to improper actuation or failure. While color-coding and insulation can aid identification, and hazardous-location protections may apply in some contexts, they do not provide the comprehensive protection and compatibility assurance required.