20mm=4 in charge
25mm=6 in charge
32mm=8 in charge
PR pipe is a general term for water pipe materials.
The so-called several inches of tubes all refer to the size of the nominal diameter, and one inch of tube is the nominal diameter of 25.4mm. For steel pipes, one inch of pipe is expressed as DN25; for PPR pipes, one inch of pipe is expressed as DN32, because the mark DN of PPR pipe indicates the nominal outer diameter, and one inch of pipe indicates the nominal diameter. Therefore, for PPR pipes, DN32 is a 1-inch pipe, DN25 is in charge of 6, and DN20 is in charge of 4.