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埋地排水用聚氯乙烯双壁波纹管,管道安装完毕检查合格后,做闭水检验时,向管道内充水并保持()。

发布日期:2020-12-11

埋地排水用聚氯乙烯双壁波纹管,管道安装完毕检查合格后,做闭水检验时,向管道内充水并保持()。
A

下游管内顶以上2m水头压力

B

上游管内顶以上2m水头压力

C

本管段管内2m以上水头压力

D

上游管外顶以上1m水头压力

试题解析

聚氯乙烯

聚氯乙烯(Polyvinyl chloride),英文简称PVC,是氯乙烯单体(VCM)在过氧化物、偶氮化合物等引发剂或在光、热作用下按自由基聚合反应机理聚合而成的聚合物。氯乙烯均聚物和氯乙烯共聚物统称之为氯乙烯树脂。PVC为无定形结构的白色粉末,支化度较小,玻璃化温度77~90℃,170℃左右开始分解,对光和热的稳定性差,在100℃以上或经长时间阳光曝晒,就会分解而产生氯化氢,并进一步自动催化分解,引起变色,物理机械性能也迅速下降,在实际应用中必须加入稳定剂以提高对热和光的稳定性。工业生产的PVC分子量一般在5万~11万范围内,具有较大的多分散性,分子量随聚合温度的降低而增加,无固定熔点,80~85℃开始软化,130℃变为粘弹态,160~180℃开始转变为粘流态;有较好的机械性能,抗张强度60MPa左右,冲击强度5~10kJ/m2;有优异的介电性能。PVC曾是世界上产量最大的通用塑料,应

中文名
聚氯乙烯
颜色
微黄色
结构
-(CH
化学式
(C
密度
1.38 g/cm
外文名
Polyvinyl chloride
其他属性
半透明状 有光泽
缩写
PVC
CAS登录号
9002-86-2

地排水

地排水是比较传统的住宅排水方式,一般建筑毛坯房已经预留好了面盆、坐便、排水的位置

中文名
地排水
释义
地板下排水的方式
外文名
Ground drainage

检查

检查的英文名称为Check, 定义为为验证航空器其功能是否符合经批准的标准而进行的工作。 所属学科为航空科技(一级学科) ;航空器维修工程(二级学科)。

中文名
检查
拼音
jiǎnchá
作用
查找问题和缺陷
同义词
检验,
外文名
Check
意义
为了发现问题而用心查看
难度
难以自我发现

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此试题出现在

建筑继续教育

二级建造师继续教育

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