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.
A check valve is a type of valve that allows fluids to flow in one direction but closes automatically to prevent flow in the opposite direction (backflow). Check valves are used in a wide variety of locations, but the focus of the discussion in this tutorial will be the installation of check valves at the steam trap outlet side.