What should the system air pressure be maintained at in relation to the calculated trip pressure of the dry pipe valve?

The system air pressure for a dry pipe valve should be maintained at a specific level above the calculated trip pressure to ensure proper operation of the system. In the case of a dry pipe sprinkler system, it is critical to maintain the air pressure at 20 PSI higher than the trip pressure of the valve. This ensures that when the system detects a drop in air pressure due to a sprinkler activation, the dry pipe valve opens reliably in a timely manner to allow water flow into the system.

Maintaining the air pressure at this appropriate level minimizes the risk of inadvertent activation of the sprinkler system while ensuring that any actual discharge event can happen quickly and effectively. If the air pressure is not maintained at this level, it could lead to a delay in valve operation, potentially resulting in insufficient water distribution at the fire during an emergency. Thus, setting the air pressure at 20 PSI above the calculated trip pressure is key to ensuring the reliable performance of the dry pipe system in response to a fire event.