ASME A112-6-3 pdf download ASME STANDARDS COMMITTEE A112 Standardization of Plumbing Materials and Equipment 4.2 Open Area Requirements for Various Classifications of Drains Opening area requirements for drains shall be as shown in Table 4. 4.3 Openings in Top Grates Openings shall be any geometric shape. Openings shall be sized to exclude debris and accommodate the anticipated traffic. When drainage...