Linear indicator for a valve

An apparatus for visually and electronically indicating a state of a valve, the valve having a stem being movable in closing and opening directions between closed and open valve positions, the apparatus comprising:

• a first cam system comprising:
• a first adjustable member engaging the stem when the stem is adjacent to the closed valve position, the first cam system being movable by the stem in a closing direction once engaged, and
• a first biasing member forcing the first cam system in the opening direction;
• a first switch capable of being actuated by the first cam system when the stem is at the closed valve position;
• a second cam system being integral to or separate from the first cam system and comprising:
• a second adjustable member engaging the stem when the stem is adjacent to the open valve position, the second cam system being movable by the stem in the opening direction once engaged, and
• a second biasing member forcing the second cam system in the closing direction;
• a second switch capable of being actuated by the second cam system when the stem is at the valve open position;
• and
• an indicator moveable by the first and the second cam systems and capable of indicating at least open, intermediate, and closed states of the valve.

A method for indicating states of a valve having a stem, the stem being movable in closing and opening directions between closed and open valve positions, the method comprising the steps of:

• a) adjusting a first cam system to engage the stem adjacent the closed valve position;
• b) adjusting a second cam system to engage the stem adjacent the opened valve position;
• c) indicating a closed-valve state by displacing the first cam system in the closing direction with the stem to the closed valve position;
• d) indicating an open-valve state by displacing the second cam system in the opening direction with the stem to the opened valve position;
• and
• e) indicating an intermediate-valve state in the absence of engagement of the stem with the first and second cam system by biasing the first cam system in the opening direction and biasing the second cam system in the closing direction.