What is the required turn adjustment for a PIV and O.S. and Y valve to prevent jamming?

The required turn adjustment for a post indicator valve (PIV) and an outside screw and yoke (O.S. and Y) valve to prevent jamming is a 1/4 turn. This adjustment is important for ensuring that the valve can operate smoothly without becoming stuck or jammed due to environmental factors such as corrosion or debris.

Adjusting the valve to a 1/4 turn allows it to have adequate clearance for movement while still maintaining a secure closure when in the closed position. This preventative measure aids in prolonging the lifespan of the valve and ensures that it can be readily operated during an emergency when functionality is critical. Ensuring valves are not too tightly closed prevents issues in operation that can arise from over-tightening or improper adjustment in the field.

Understanding the specifics of valve adjustments is crucial for maintaining compliance with NFPA 25 standards, which underscore the importance of regular inspection, maintenance, and testing of water-based fire protection systems.