Automatic switchover valve.

摘要

An automatic switchover valve includes first and second regulator valves (20; 120) arranged to oppose each other axially in a single housing (10; 110) and ducted in a parallel configuration within the housing (10; 110). Each regulator valve (20; 120) includes an inlet port, a diaphragm poppet valve (30, 30', 130, 130'), and a common outlet port (33; 133). Each regulator valve (20; 120) includes structure for adjusting the pressure setting of the diaphragm poppet valve. During operation, the poppet valve (30; 130) of the first regulator valve (20; 120) is selectively adjustable between a first setting providing a first pressure P<5>, and a second setting providing a second pressure P<6> less than P<5> by an amount equal to 2 p. The poppet valve (30'; 130') of the second regulator valve (20; 120) is preset a reference pressure PR wherein P<5>>PR>P<6>, and P<5> - p = PR = P<6> + p, and wherein p is greater than or equal to the incremental pressure characteristic of the regulator poppet valves (30, 30'; 130, 130').