The flow direction symbol for a check valve typically depicts an arrow pointing in the permitted direction of flow, with a barrier or check that prevents flow in the opposite direction. The specific graphical representation may vary slightly depending on the standard being used (e.g., ISO, ANSI).
Check valves, also known as non-return valves, are crucial components in many fluid systems because they allow flow in only one direction, preventing backflow and protecting equipment from damage. They rely on the pressure of the fluid to open the valve and a mechanism (gravity or a spring) to close it when the flow reverses or ceases.
While the exact symbol representation varies depending on the context (e.g., piping and instrumentation diagrams - P&IDs, hydraulic schematics), the core concept remains the same: illustrating the permissible flow path and the blockage against reverse flow. A common depiction involves a triangle pointing towards a line or seat. Fluid flow is permitted from the base of the triangle towards the line/seat, but reverse flow forces the triangle against the seat, preventing any backward movement of the fluid. The reference text describes a simple check valve symbol indicating permitted flow from the bottom to the top, prevented by a simple blocking mechanism rather than a spring-loaded one.
