Sequencing valve Sequence valves control the sequence of operation between two branches of a circuit. They enable one unit to automatically set another unit into motion.
Fig. Sequence valve
Shows how to obtain the operation of a sequencing pressure by adjusting a spring’s compression, which holds piston in closed position. Liquid enters the valve at inlet port, flow freely past piston and enters the primary circuit through outlet port 0. When pressure of, the liquid flowing through the valve is below the valve’s setting, the force acting on piston is less than the downward force of the spring. The piston is held down and the valve is in the closed position.
When resistance in the primary circuit causes the pressure to rise so it overcomes the force of spring, piston rises. The valve is then opened for secondary port. Liquid entering the valve can now flow through secondary port.