In dry pipe valves, the term differential refers to the ratio of what?

In dry pipe valves, the term "differential" specifically refers to the surface area on the air side of the clapper compared to the surface area on the water side of the clapper. This differential is crucial because it dictates how the valve operates during a fire condition.

When the system is pressurized with air in the dry pipe system, the air pressure acts against the clapper to keep it closed. Upon activation, when water flows into the system, the pressure differential created by the varying surface areas on either side of the clapper determines whether the clapper remains closed or opens to allow water to flow into the sprinkler piping network.

A larger surface area on the water side compared to the air side ensures that the force exerted by the water pressure will overcome the air pressure holding the clapper in place. This relationship is essential for the proper functioning of the system, helping it to effectively release water when needed while remaining sealed during normal conditions. Therefore, understanding this ratio is critical for those involved in the design, installation, and maintenance of dry pipe systems.