water trap with oiler ?

I have a used water trap with oiler attached. It uses 2 plastic containers to hold the liqued which is screwed onto the mount with in and out 3/8 ports. Im wondering if these plastic containers will be able to handle the 150 PSI that i use in my setup. I am also wondering if it would be right to install this between the compressor and the tank or between the tank and the valves. Thanks for your help guys