Nozzles shall be within 15% of the nominal diameter.
To check for wear of a known to be 5/16" nozzle:
Check 5/16” nozzles with a .344” pin gage, if the pin gage does not enter the opening then nozzle passes. If the .344” pin gage does fit, check the same nozzle with a.360” pin gage. If the .360” pin gage goes in, the nozzle fails and a corrective action is required.