Automatic-locking shut-off valve for liquid suction systems

In a rotatory-plug shut-off valve for liquid suction systems which includes a multi-port valve body forming a valve chamber and having an outlet and first and second inlets, a rotary plug in the valve chamber, and an actuator to turn the plug, the improvement comprising:

• an actuator housing affixed to the valve body adjacent to the plug and forming an actuator chamber communicating with the valve chamber;
• a base member attached to the actuator housing in fixed axial position and forming (a) an end of the actuator chamber, (b) a sleeve, (c) a guide, and (d) a first spring-abutment;
• a vacuum-reactive member within the actuator chamber, movable toward and away from the base member, and supported by spring pressure at a position away from the base member such that it is movable toward the base member by sufficient vacuum force on the vacuum-reactive member;
• a piston attached to the vacuum-reactive member, rotationally aligned with the plug, and having a (a) shaft extending through the sleeve and (b) an anti-rotation structure which is (1) slidably engaged with the guide in one rotational alignment therewith in a normal operating range of axial positions with respect thereto and (2) out of sliding engagement with the guide beyond such normal operating range;
• and
• a spring in rotational tension positioned and secured to rotate at least the piston and thereby rotate the plug from one inlet to the other inlet to close the other inlet, such rotation being by release of rotational tension in the spring when the piston anti-rotation structure moves out of sliding engagement with the guide.

In a rotary-plug shut-off valve for liquid suction systems which includes a multi-port valve body forming a valve chamber and having an outlet and first and second inlets from first and second inlet lines, respectively, a rotary plug in the valve chamber, and an actuator to turn the plug, the improvement comprising:

• an actuator housing affixed to the valve body adjacent to the plug;
• a vacuum-sensing-and-reacting device secured with respect to the actuator housing and in communication with the valve chamber;
• an actuator in the actuator housing, engageable with the rotary plug, and linked for control to the vacuum-sensing-and-reacting device hereby to rotate the plug from one inlet to the other inlet to close the other inlet when the vacuum-sensing-and-reacting device senses excessive vacuum;
• a vacuum-relief line extending from the first inlet line to atmosphere;
• and
• a vacuum-relief valve in the vacuum-relief line;
• whereby vacuum in the closed inlet line is relieved upon operation of the vacuum-relief valve.