| 摘要 |
An automatic drain exhaust valve (1) for draining water and the like from a pressurized gas system includes a housing (1') defining an inlet orifice (5), an intermediary space (8), and an outlet orifice (6). Valve surfaces (30 and 40) respectively close the inlet and outlet orifices (5 and 6), said valve surfaces (30 and 40) being respectively moved to open positions by gas pressure from the pressurized gas system acting on surfaces of valve actuators such as pistons (3 and 4). One valve surface (30) is moved to a closed position by springs operating on the piston (3) while the other valve surface (40) is moved to a closed position by fluid pressure from the intermediary space (8) acting on a relatively large surface area (42) of the piston (4). When a liquid, such as water, is introduced into the intermediary space (8) through the inlet orifice (5) it exits from the outlet orifice (6) while maintaining a lower pressure in the intermediary space (8) than the gas pressure tending to hold the second valve surface (40) open. The valve surface (40) therefore remains open. However, when gas is introduced through the inlet orifice (5) gas flow through the outlet orifice (6) reaches a critical velocity at sonic speeds and therefore builds up pressure in the intermediary space (8) acting on the surface (42) to close the valve surface (40).
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