发布时间:2025-02-06 13:38:25
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
房屋装修贴壁纸后房子一股浓浓的刺鼻气味请问是壁纸的原因还是胶的原因
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