Plast-O-Matic Valves Inc., of Cedar Grove, N.J., has introduced a 1/2” size air operated shut-off valve with no wetted metals or external fasteners for high-purity or corrosive environments. These “balanced,” compact valves are designed for liquid service ranging from full vacuum to pressures up to 150 psi. The balanced aspect means that the valve outlet pressure, commonly known as backpressure, can be as high as the inlet pressure without affecting performance.