发布时间:2025-02-06 13:24:35
DN适用于所有管材一般是钢管,是指管道的公称直径,注意:这既不是外径也不是内径,是指平均值。dn主要用作塑料管材,是指管道外径,一般采用dn标注的,均需要标注成外径X壁厚的形式,比如dn400X17.5表示外径400mm壁厚17.5mm
我有一款罗兰ac60有源吉他音响把它改成充电音响方便外出玩耍我试过用逆变器接电瓶但是逆变器的
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