???? ??????? AWWA C504: ???? ????? ???? ??????

???? ??????? AWWA C504 ?????? ?? Shijiazhuang Deye Piping Idndustrys Co.,Ltd. ?? ???? ???? ?????? ?????? ???? ????????? ?? ????? ?????? ?????? ?????? ????? ????? ?????????? ???????? ??????. ????? ??? ?????? ?????? ???? ??? ???? ????? ????? ????? ?? ???????? ??????? ??? ????? ?????? ??????? ?????? ?????? ????? ????? ?????? ??? ????? ?? ???? ?????? ???? ??????? ??? ???? ??? ???? ????? ????? ?????? ?????? ??????? ???????. ? ?????? ?????? ?????????? ??? ????? ??????. ???? ?????? ????????? ????? ??????? ?????? ?? ?????? ????? ?????? ?? ?????? ?????? ??? ????? ?????? ?????? ?????? ?????? ?????? ???????? ?? ?????? ?? ??????? ???????? ????? ???????? ???? ??????? AWWA C504 ?? Shijiazhuang Deye Piping Idndustrys Co.,Ltd. ???? ??????? ?????? ??????? ??????? ???????. ???????? ??? ???? ???? ?????? ????? ????? ?????? ????? ?? ??? ????? ????? ??? ???????. ?? ?? ???? ????? ???? ??????? ??? ?????? ????????? ????????