scope:

This NFPA Recommended Practice describes methods of calibrating pneumatic flowmeters used in laboratories and in production testing for pneumatic fluid power components. It describes how a reference device is prepared, calibrated and then used as the means to calibrate pneumatic flowmeters on-site. It further describes how flowmeters should be used in service and how they should be maintained.

This practice is intended for use with only two classes of reference devices: sonic (critical flow) and subsonic flow reference devices.