Sprinkler System’s OS&Y Valves

One type of valve commonly used to control water flow to fire sprinkler systems is known as an OS&Y gate valve. OS&Y means “outside stem and yoke” or “outside screw and yoke”. OS&Y gate valves operate by opening and closing via a gate, which lowers into or rises out of the valve. Raising the gate allows water to flow through the valve while lowering the gate cuts off the water flowing through the valve. When fully open, the typical gate valve has no obstruction in the flow path, resulting in very low friction loss. Here is more on the workings of this type of valve…