A coefficient and a flow in litres per minute are different entries in a pneumatic rating.
Keep the characteristic definition
SMC's flow-characteristic reference identifies sonic conductance C and critical pressure ratio b, alongside a pressure-ratio basis. Preserve those definitions with the rating. Primary reference: SMC pneumatic flow characteristics.
A capacity comparison should retain the component path, upstream and downstream conditions and relevant gas basis. Copying one coefficient into a field labelled machine air demand mixes different questions. The actual manufacturer's equation or applicable curve determines how its characteristic is used.
A hypothetical incomplete comparison
Imagine offer A supplies C and b with their units, while offer B lists a flow value but omits its pressure conditions. Neither row establishes which valve supports the proposed circuit at the required operating point. Ask for compatible condition-specific evidence rather than choosing whichever printed number is larger.
Create columns for characteristic type, units, selected path, pressure definitions, gas conditions and resulting capacity basis. Keep missing entries visibly unresolved. This comparison reports no HM air requirement and gives no universal conversion between an isolated C, Cv or litres-per-minute label.
Separate capacity from consumption
The system's demanded flow also depends on its actuators and operating schedule. A valve-capacity figure describes an identified component's flow behavior; it is not automatically the amount of plant air the machine consumes over a cycle.
Preserve the selected valve reference and calculation basis with the circuit. If an exhaust path or downstream condition changes, recheck the applicable capacity comparison. The guide helps a buyer collect complete evidence without reproducing an ISO test procedure, asserting that one coefficient proves every operating point or selecting a valve solely from a nominal connection size.
Customer Questions
Is a coefficient automatically a flow inL/min?
No. Retain its definition and application conditions.
Does valve capacity equal machine consumption?
No. They describe different quantities.
Can two flow labels be compared with missing pressures?
Resolve the applicable conditions first.
Primary References
These references support the technical principles discussed in this guide. The worked examples and review questions are educational.
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