– Made up of high graded PVC
– Prevent water from flowing back down
– Allow the pump to pull water up
– Helps in keeping the pipe full of water while the pump is not running
– Used in a suction line of the pumping system in a well
– Prevent back flow thus it is useful at places where suction pipe is at lower than pump height
– Prevent the pump column from draining upon pump shutdown
– Provide a positive sealing action at both low and high pressures without slamming
15 mm to 100 mm