Acetylene manifold should not exceed 15 psi. True or False?

• A. True
• B. False
• C. Depends on regulator
• D. Only for storage

Answer: (A)

Acetylene must be kept at a very low maximum pressure in welding manifolds because it becomes unstable when compressed to higher pressures. If the pressure in the acetylene line climbs beyond about 15 psi, acetylene can decompose explosively, especially if there’s heat, impurities, or a catalyst present. To prevent that, the acetylene side of the system is designed to operate at or below 15 psi, with regulators and manifold hardware arranged to maintain that limit. Keeping the pressure within this safe range reduces the risk of rapid gas decomposition, heat buildup, and potential ignition or explosion in fault conditions. That’s why the statement is true: the recommended maximum pressure on the acetylene manifold is 15 psi. The limit is a safety rule for operation, not just a matter of regulator type or storage conditions.