The P-Trap features solder cups. A major application of the fitting is on the suction line of a refrigeration compressor. The line is looped, by use of the P-Trap, to the floor prior to being run vertically upwards to prevent the drainage of oil back to the compressor during shut-down periods. Additional P-Traps are used for each 20 feet of riser pipe; this prevents high velocity build-up as the oil or liquid begins to return to the compressor during the shut-down period. Please refer to NIBCOmore technical data sheets and catalogs for engineering and installation information. In addition to its inherent qualities of beauty, durability and low maintenance, copper's reusability makes it an ideal application in sustainable projects. NIBCO® copper fittings are manufactured in an ISO 9001 certified facility, and backed by a 50-year limited warranty. Because of its longstanding reputation for innovation and precision in design and manufacturing, NIBCO is the preferred brand in the industry. less