Pentair Union Connectors

My 13 year old Hayward Filter Assy blew up (my fault) and now I have a new Pentair Clean and Clear CC150. I have never dealt with the union connectors and I feel pretty stupid. I have looked it up and I have been told that you can use PVC in these connectors but are you supposed to use cement. I have all of the PVC cut to proper-lengths. I have it lined up where I think everything should be and it looks square on the angles and straight enough. It reminds me of a compression fitting I don't think it actually compresses so if I don't use cement will the PVC just blow at at full power. I just don't know if pressing the PVC in all the way is correct or is there something I am not getting.

Any help would be great Thanks......

Pretty sure those are PVC slip joints, and if so, they have to be glued.

If you've never done a PVC glued connection, it would be best if you could get a friend to help you. But here's a Youtube that looks OK:
http://www.youtube.com/watch?v=kXhZWgQb22k

However, there are definitely some gotchas waiting for you, so if help is available, get some. If not, I'll mention two:

#1) When gluing the union, take it apart and hold the fitting up, and the pipe down when you glue them together. If you get glue into the union, it can ruin the union's ability to seal. Also be very careful NOT to get glue on the either the male threads or the union nut. Again, glue there can ruin the union.

#2) When you dry-fit PVC it will not usually go in all the way. When you prime and glue properly, it will. If you've measured dry fitted joints, you're likely to find things out of alignment pretty quickly if you haven't allowed for this difference.