Control Valve

The internal elements of a valve are collectively referred to as a valve's .
The manually operated handwheel, manual lever, motor operator, solenoid operator, pneumatic operator, or hydraulic ram are all examples of
Which one of the following valve parts is NOT usually considered to be a part of the pressure boundary.
Most valves use___________to prevent leakage from the space between the stem and the bonnet.
Which of the following types of valve uses a flow control element that involves sliding a flat, cylindrical, or spherical surface across an orifice?