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A defrost timer taken out of a household refrigerator. The defrost mechanism in a refrigerator heats the cooling element (evaporator coil) for a short period of time and melts the frost that has formed on it. [1] The resulting water drains through a duct at the back of the unit. Defrosting is controlled by an electric or electronic timer.
Brass-bodied float valve. An automatic bleeding valve or air release valve (ARV) is a plumbing valve used to automatically release trapped air from a heating system. Air, or other gas, may collect within plumbing. For water delivery systems to taps and basins, particularly with good main supply pressure, this air is usually flushed through with ...
The solenoid/diaphragm timer uses more battery power throughout the "on" cycle because the solenoid must be actuated the entire time that the water flow is "on". The ball valve timer using the motor and gear actuator only uses more battery power during the few seconds that motor is used to turn the water flow on or off.
Isolation valves in a flare, relief or vent system must ensure that a flow path is always available to the flare or vent. These valves are secured in the open position (LO). Drain valves that connect a high pressure system to a low pressure drain system are locked in the closed position (LC) to prevent potential over-pressurisation of the drain ...
Choke valve, Butterfly valve used to limit air intake in internal combustion engine. (Not to be confused with choke valves used in industrial flow control, above.) Clapper valve: a type of check valve used in the Siamese fire appliance to allow only one hose to be connected instead of two (the clapper valve blocks the other side from leaking out)
Pneumatically-actuated globe valves and diaphragm valves are widely used for control purposes in many industries, although quarter-turn types such as (modified) ball and butterfly valves are also used. Control valves can also work with hydraulic actuators (also known as hydraulic pilots). These types of valves are also known as automatic ...
An automatic control valve consists of three main parts in which each part exist in several types and designs: Valve actuator – which moves the valve's modulating element, such as ball or butterfly. Valve positioner – which ensures the valve has reached the desired degree of opening. This overcomes the problems of friction and wear.
The blue valve body is visible in-line with the pipe. The valve actuator opens or closes the butterfly disc of the valve based on electrical signals sent to the actuator. Another valve actuator is visible in the background, with windows to indicate the valve position. A valve actuator is the mechanism for opening and closing a valve. Manually ...