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A check valve, non-return valve, reflux valve, retention valve, foot valve, or one-way valve is a valve that normally allows fluid (liquid or gas) to flow through it in only one direction. [1] Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to leave. There are various ...
Flutter (Heimlich) valve: a specific one-way valve used on the end of chest drain tubes to treat a pneumothorax; Foot valve: a check valve on the foot of a suction line to prevent backflow; Four-way valve: was used to control the flow of steam to the cylinder of early double-acting steam engines
One solution is the use of the valve's non-linear characteristic in the control algorithm to compensate for this. An asymmetric application, for example, is temperature control in HVAC systems using only active heating (via a heating element), where there is only passive cooling available.
As in Perl and Ruby, these control statements also have postfix versions; for example, if can also be written in consequent if condition form. Many unnecessary parentheses and braces can be omitted; for example, blocks of code can be denoted by indentation instead of braces, function calls are implicit, and object literals are often detected ...
Globe control valve with pneumatic diaphragm actuator. Such a valve can be designed to fail to safety using spring pressure if the actuating air is lost. Examples include: Roller-shutter fire doors that are activated by building alarm systems or local smoke detectors must close automatically when signaled regardless of power.
These valves often provide a simple on-off function. 3-way valves can be normally closed, normally open, and offer a universal function where gas can be diverted through a third opening to move the valve into the normally closed or normally open position. [1] [2] 3-way valves pressurize and exhaust one outlet port to control a single-acting ...
The hydraulic actuators respond to changes of pressure or flow and will open or close the valve. Automatic control valves do not require an external power source, meaning that the fluid pressure is enough to open and close them. Flow control valves, a type of automatic control valve, regulate fluid flow by maintaining a predetermined flow rate ...
The construction of the flutter valve enables it to function as a one-way valve allowing airflow, or the flow of a fluid, in only one direction along the drainage tube. The end of the drainage tube is placed inside the chest cavity of the patient — into the air mass or into the fluid mass to be drained from the thorax.