What is the pressure in a dry sprinkler system?

• A. 0 to 5 psi above trip point
• B. 15 to 20 psi above trip point
• C. 5 to 10 psi above trip point
• D. 30 to 40 psi above trip point

Answer: (B)

In a dry sprinkler system, the piping is pressurized with air (not water) to hold back the water until a sprinkler head is activated. The air pressure must sit above the valve’s trip point so the dry-pipe valve stays closed during normal operation. The trip point is the pressure at which the valve will release water into the dry pipe. Keeping the system about 15–20 psi higher than that trip point provides a safety margin for friction losses, leakage, and temperature changes, ensuring the system remains dry yet responds quickly when a head is activated. That’s why the typical answer is 15 to 20 psi above the trip point.