尺寸单位:
1/4” = 2分 = 8mm =DN8
3/8” = 3分 =10mm =DN10
1/2” = 4分 =15mm =DN15
3/4” = 6分 =20mm =DN20
1” = 8分 =25mm =DN25
1-1/4” =32mm =DN32
1-1/2” =40mm =DN40
2” =50mm =DN50
2-1/2” =65mm =DN65
3” =65mm =DN80
4” =100mm =DN100
1”wc =25.4mm
如12”wc=12×25.4=304.8mmwc
