Stimuli are signals that trigger the senses. Receptors detect the stimuli and neurons send the signals to the brain where they're interpreted. Each sense organ includes receptors that capture relevant stimuli for transmission to the brain. The receptors in the skin are mechanoreceptors and thermoreceptors.
AWWA Butterfly valves are quick opening valves that consist of a metal circular disc or vane with its pivot axes at right angles to the direction of flow in the pipe, which when rotated on a shaft, seals against seats in the valve body. They are normally used as throttling valves to control flow.
The following sections deal first with the basic types of stop valves and check valves, then with some of the more complicated special valves. Stop Valves. Stop valves are used to shut off or, in some cases, partially shut off the flow of fluid. Stop valves are controlled by the movement of the valve stem.