I need to add a new refrigeration circuit to an existing rack. The suction and liquid manifolds are made of 10 cm and 7 cm OD copper pipe. I feel confident at doing all the isolation, shutting off and recovery job prior to the actual openning of the manifolds. What I´m not too secure about is on how to perform the actual punching of the copper pipes, without having too much debris entering the system. Any word of advice?