Rationale

Figure 2 of the current test method includes several errors on the type of thread used for the two different stones. Additionally, lead is referenced as sealing material between the air tube and stone. Ballot introduces a new modern image with corrections on thread used and a new safer sealing material for the washer. Stones are commercially available with only the 3/16 BSF thread, and to ensure consistency and compatibility with all suppliers, ballot removes metric threads and notation of their equivalency.