pvc-U is equivalent to UPVC, which is a general term for rigid PVC pipes. PVC-P pipe is the representative symbol of soft PVC.
PVC-M improves toughness through modification, and develops a variety of modified polyvinyl chloride piping systems that have good impact and crack resistance while maintaining high strength, usually called PVC-M.
PVC-O is biaxially stretched during the processing of the pipe to orient the molecules to achieve a substantial increase in strength and toughness at the same time. Usually called PVC-O.
PVC-C is a chlorinated polyvinyl chloride pipe.
PVC-UH has more H in its name than PVC-U, which means High performance pipe, representative manufacturer Quanen.
The functionality of HPVC is basically the same as that of PVC-UH.