Event-driven Process Chain (EPC) Diagrams

Retract resistor check valve application: pneumatic cylinder, piston driven by Compressed air through 2 Retract resistor check valves.
"A check valve, clack valve, non-return valve or one-way valve is a valve that normally allows fluid (liquid or gas) to flow through it in only one direction.
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 types of check valves used in a wide variety of applications. Check valves are often part of common household items. Although they are available in a wide range of sizes and costs, check valves generally are very small, simple, or inexpensive. Check valves work automatically and most are not controlled by a person or any external control; accordingly, most do not have any valve handle or stem. The bodies (external shells) of most check valves are made of plastic or metal.
An important concept in check valves is the cracking pressure which is the minimum upstream pressure at which the valve will operate. Typically the check valve is designed for and can therefore be specified for a specific cracking pressure.
Heart valves are essentially inlet and outlet check valves for the heart ventricles, since the ventricles act as pumps." [Check valve. Wikipedia]
This hydraulic schematic example was redrawn using ConceptDraw PRO diagramming and vector drawing software from the Wikimedia Commons file: Retract resistor check valve application.png.
[commons.wikimedia.org/ wiki/ File:Retract_ resistor_ check_ valve_ application.png]
The hydraulic engineering drawing example "Retract resistor check valve application" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Mechanical Engineering solution from the Engineering area of ConceptDraw Solution Park.