Pneumatic fluid power – Components using compressible fluids – Determination of flow-rate characteristics [Related standards: ANSI/(NFPA)T3.21.3-1990 (R1997), ISO 6358:1989], 14 pgs.
This International Standard specifies a method for testing pneumatic fluid power components which use compressible fluids, I.e. gases, to enable their flow-rate characteristics under steady-state conditions to be compared.
It specifies requirements for the test installation, the test procedure and the presentation of the results.
Accuracy of measurement is divided into two classes (A and B) which are explained in annex A.
General background information is give in annex B and the basic theoretical equations are given in annex C. Guidance as to the use of practical units for the presentation of results is given in annex D.
This International Standard generally applies to those fluid power components up to and including 20 mm nominal bore used with compressed fluids (gases), the internal flow passages of which remain constant during testing. Examples of such components are: a) directional control valves, flow control valves, quick exhaust valves, etc.
b) moving part logic devices.
It may also apply to components larger than 20 mm nominal bore but this may require the provision of exceptionally large flow generating equipment.
Two test methods are described according to the type of component. These are also two sets of characteristic constants: C and b
and A and s, respectively (as defined in 3.2 to 3.5). These may be calculated from the results.
The first set of characteristics (C and b) applies to cases where comparison of similar components is required, or when calculations of pressure and flow involve a single component only.
The second set of characteristics (A and s) is necessary when the flow behavior of several components which are connected in series is to be estimated. This set may also be used as an optional alternative to the first set for simple flow calculations and for comparison of components.
This International Standard does not apply to components which exchange energy with the fluid (gas), for example cylinders, accumulators, etc.