You ask, we answer
It’s the symbol which manufacturers of dairy equipment may place on their equipment when it meets the 3-A Sanitary Standards.
The 3-A sanitary standards are made up of groups representing processors, suppliers, and regulatory officials, with advice from federal government sanitation specialists. These standards are voluntarily met by manufacturers and fabricators. Local, State, Federal regulatory authorities generally accept equipment which conforms to the 3-A Sanitary Standards.
Only those manufacturers whose equipment meets the existing 3-A Sanitary Standards and who are authorized to do so by the 3-A Sanitary Standards Symbol Administrative Council. Since these standards may be amended, manufacturers must apply annually for the privilege of using the 3-A symbol, and annually indicate that their products conform in all respects to the published 3-A Sanitary Standards.
0.984″ O.D. is the same for 1/2″, 3/4″ I.D. styles.
1.984″ O.D. is the same for 1″ and 1-1/2″ I.D. styles.
Varying O.D. for the 2″, 2-1/2″ and 3″ I.D. styles.