Pneumatic valve and American standard gb pneumatic valves have to differ

pneumatic valve American standard at present more popular is API and ASME standard, not what 'hundred degrees' ASTM, ASTM material standard, not the standard of pneumatic valve itself.
pneumatic valve American standard: according to the standard design, manufacture, production, testing the pneumatic valve is called the American standard pneumatic valve.
pneumatic valve American standard and national standard of pneumatic valve is the main difference between:
pneumatic valve nominal diameter of the unit is mm, gb, American standard pneumatic valve nominal diameter of the unit is in ( Inches.
, flange standard American standard and national standard is not the same.
length, structure is different.
and inspection requirements, American standard pneumatic valve inspection requirements than the elevation.