What is the difference between PVC conduit, A conduit, and B conduit?
两者区别如下：
1、A管相对B管用料要好些，强度高点，厚度也厚一点。
2、A管相对B管，价格更高一些。
3、A管通常用作排水，B管通常用作通风。
The differences between the two are as follows:
1. The material used for pipe A is better than that for pipe B, with a higher strength and a thicker thickness.
2. Tube A is more expensive than tube B.
3. Pipe A is usually used for drainage and pipe B for ventilation.
PVC-U型管优点：
1、具有较好的抗拉、抗压强度：但其柔性不如其他塑料管。
2、流体阻力小：PVC-U管材的管壁非常光滑，对流体的阻力很小，其粗糙系数仅为0.009，其输水能力可比同等管径的铸铁管提高20%，比混凝土管提高40%。
3、耐腐蚀性、耐药品性优良：PVC-U管材具有优异的耐酸，耐碱，耐腐蚀，不受潮湿水份和土壤酸碱度的影响，管道铺设时不需任何防腐处理。
4、具有良好的水密性：PVC-U管材的安装，不论采用粘接还是橡胶圈连接，均具有良好的水密性。
Advantages of PVC-U pipe:
1. It has good tensile and compressive strength, but its flexibility is not as good as other plastic pipes.
2. Low fluid resistance: PVC-U pipes have very smooth pipe walls and low resistance to fluid, with a roughness coefficient of only 0.009. Their water delivery capacity can be increased by 20% compared to cast iron pipes of the same pipe diameter and 40% compared to concrete pipes.
3. Excellent corrosion resistance and drug resistance: PVC-U pipes have excellent acid, alkali, and corrosion resistance, and are not affected by moisture and soil acidity and alkalinity. No anti-corrosion treatment is required during pipeline laying.
4. Good water tightness: PVC-U pipes are installed with good water tightness regardless of whether they are connected by adhesive or rubber rings.
