A water supply must deliver the required volume of water at a residual pressure of what minimum psi at the highest sprinkler head?

In fire protection systems, particularly in sprinkler systems, it is crucial that the water supply can provide not just the required flow rate, but also maintain a sufficient pressure at the highest sprinkler head during operation. The minimum residual pressure is essential to ensure that the water can effectively reach the elevated sprinkler heads and adequately suppress a fire.

A residual pressure of 15 psi at the highest sprinkler head is typically recognized as the minimum standard in many fire codes and guidelines. This pressure ensures that enough force is available to both deliver the water and overcome potential friction losses within the piping system, which can occur due to the elevation of the sprinkler heads and other hydraulic factors.

Higher pressures may provide better performance, especially in large or complex installations where additional pressure losses may be encountered. However, maintaining a pressure of at least 15 psi is generally sufficient for proper sprinkler operation, ensuring the system can deliver the necessary volume at an effective pressure to provide adequate fire suppression.