Pressurized manhole

Why install a MANHOLE in a pressure zone?

I have not heard of such a term as pressurized manhole. As far as my experience The sewer comes to the manhole as a partial full pipe and leaves the manhole the same way and manhole is basically a check-up point. If you are looking for a sealed chamber with inlet and outlet pipe pressurized, the volume of the manhole can not be more than the area of the pipe X unit length. In the other word if you change the cross-section area of the pipe at manhole, you are changing the velocity. Based on increase or decrease in area you will have almost the same proportion change in velocity(NOT PRESSURE) because using Q1=A1 x V1 =Q2= A2 x V2 (since Q1=Q2 inlet and outlet flow should be equal), then A1xV1=A2xV2.

Please let me know if I could help you further more.

It does not matter if you are running a low pressure line with little grinder pumps feeding it or a forcemain from a lift station - use a saddle to connect another line to it. Of course you can always dump your pressure lines into another lift station, this is how you would add a gravity fed to the system.

Usually one would do a vacum test on a manhole and a pressure test on the pipes. This is done to insure that stormwater does not infiltrate the sewer system, because it takes as much effort ($$$$) to run storm water through the plant as it does sewer.

For a force main, only the pump and the pipes are pressurized. Could possibly be thinking of a waterproof manhole and lid?