How much psi is the clapper held closed by in automatic dry sprinkler systems?

In automatic dry sprinkler systems, the clapper is held closed by a pressure range of 30 to 40 psi. This pressure is important because it ensures that the clapper will remain sealed until there is sufficient water pressure to open it when a fire is detected. The function of the clapper is critical in preventing the accidental discharge of water, as these systems are designed to operate only when necessary.

When the system is in standby mode, it relies on this psi range to maintain the clapper in a closed position, ensuring that only the sprinklers activated by heat will release water. Knowing the correct psi range helps in understanding the operational characteristics of dry sprinkler systems, which are commonly used in environments where piping could be subject to freezing temperatures.