Questions on sink traps

The first picture is my kitchen sink P trap.  Second is bathroom sink trap.

I have some questions.  先多謝大家賜教.

1. What are those traps made of?

2. Are they better than the PVC/plastic ones?

3.  Are these pipes safe for liquid plumber gel?

4. What is a good way to prevent backflow?  My kitchen sink had a backflow several times in the same day, but obviously my drain does not seem to have any problem.  Two handymen told me that if my neighbors have problems with their drain, then my sink can be affected.  The only solution is for the building to hire a plumber to check which neighbor has that problem.  

Thank you so much for any input.

 

所有跟帖： 

• 住楼的的没办法。 -人生不止眼前的苟且- ♂ (0 bytes) () 07/30/2016 postreply 16:55:14

• Do you know if upstairs neighbors affect the people downstairs? -joeyli- ♀ (121 bytes) () 07/30/2016 postreply 17:01:19

• 水管不通畅有时候就是安装的问题，安装的下水道不够宽，然后邻居用水量大。看看这个视频 -人生不止眼前的苟且- ♂ (211 bytes) () 07/30/2016 postreply 17:11:50

• Thank you. Could you tell me what are my traps made of? Better -joeyli- ♀ (148 bytes) () 07/30/2016 postreply 17:25:24

• copper. -花椒- ♀ (0 bytes) () 07/30/2016 postreply 17:39:11

• 1, BRASS; 2, THE SAME; 3. SAFE; 4, DRAIN PIPE NOT GOOD ENOUGH. -聊聊看- ♂ (0 bytes) () 07/30/2016 postreply 18:01:20

• 我以前住老公寓洗很多油腻烤羊肉的盆，流下去羊油脂凝固，楼下的就backflow地都湿了 -姜小鱼- ♂ (0 bytes) () 07/30/2016 postreply 19:20:24