In refrigeration repairs, a pinch-off tool is used to seal off copper tubing up to three-eighth inch in diameter.
Figure 45g shows a typical pinch-off tool. To use it, put the tubing through the opening to the point where it is to be sealed. As the shaft is turned by the T-handle, the tubing is compressed between a ball bearing at the end of the shaft and the die at the base of the tool. A permanently pinched line is made by turning the handle slowly and not overtightening.
This too becomes necessary when there is a need to test the compressor efficiency or in an emergency, such as a severe leak, when a section of the sealed system must be isolated for repair. For example, in commercial units where there are multiple evaporators, the one with a leak can be isolated while allowing the rest of the system to operate during the repair work. Thus, the contents of the unit can stay cold and be saved.