公称通径 A系列 B系列 al Pipe Size D Series A Series B 15 21.3 18 1.6 2.1 2.6 --- --- --- --- 2.9 --- --- 3.6 --- --- --- 4.5 20 26.9 25 1.6 2.1 2.6 --- --- --- --- 2.9 --- --- 4 --- --- --- 5.6 25 33.7 32 1.6 2.8 3.2 --- --- --- --- 3.2 --- --- 4.5 --- --- --- 6.3 32 42.4 38 1.6 28 3.2 --- --- --- --- 3.6 --- --- 5 --- --- --- 6.3 40 48.3 45 1.6 2.8 3.2 --- --- --- --- 3.6 --- --- 5 --- --- --- 7.1 50 60.