This page contains an uploaded file:
From the article: "Pressures in fire-protection systems that exceed the maximum allowed by NFPA standards must be reduced to acceptable levels for sprinkler systems and fire department hose valves. High-rise buildings, for example, often require pressure-reducing valves. A pump that is capable of supplying the minimum acceptable pressure to the top floor will deliver excessive pressure to lower floors. Pressure reduction should be provided to the lower floors when a building exceeds 15 to 20 floors. The most-common approach to pressure control is the use of direct acting pressure-reducing valves on each floor. These valves reduce the excess pressure from single zone supply risers and are either adjustable or the fixed reduction type. There are also less common and usually more-costly approaches to high-rise pressure control. One such approach is to use multiple supply zones with separate pump systems for each zone. Another method is to employ a single pump system that supplies multiple risers (zones) with the pressure on each riser controlled by a large pilot operated pressure-reducing valve. This article will concentrate on direct acting pressure-reducing valves."