Standard refrigeration suction lines are sized for long piping runs (100 ft). You may want to reduce line diameter one size for shorter runs.
Overall, keep the suction line as short and straight as possible and use as few elbows as possible, using long radius elbows where space permits. This will minimize pressure drop and enhance performance. Suction lines should always be insulated.
Oil traps: P-traps are made up with copper elbows and ells to help keep the oil mixed with the refrigerant as it travels to the compressor. Traps may not be necessary when the compressor is mounted below or level with the evaporator, unless you do not have a pumpdown control. In that case, you should have an inverted trap to prevent oil from draining into the compressor during the off cycle.
Simply pitching the suction line towards the compressor should be adequate when the compressor and evaporator are mounted at the same level.
A p-trap should be installed at the base of any suction line with a vertical rise. In long runs, a p-trap should be installed for every 20 ft of vertical rise and every 30 ft of horizontal run.
Suction accumulators: P-traps will not prevent large amounts of oil or liquid refrigerant from slugging the compressor. Systems that are prone to liquid damage, such as commercial and low-temperature systems, should use a suction accumulator. This will prevent floodback and slugging, and enhance oil return.
The accumulator should be installed at the same level as the compressor.
Suction line heat exchangers: These use suction gas to subcool the liquid refrigerant, boil off any liquid in the suction line, and add superheat. This increases system performance and adds a measure of protection for the compressor.
Wipe the joints clean with a wet rag when you are done brazing. Always pressure test with nitrogen when brazing is completed; 150 psig is recommended for testing.
Note: Ensure that all of the system’s components and relief valves are rated for at least that pressure.