Piping for a remote air-cooled condenser should follow good refrigeration equipment installation practices. All manufacturer’s recommendations should be followed. Remote air-cooled condensers are usually mounted at a higher level than the compressors. Therefore, it is a good practice to provide an oil loop (vertical) at the compressor discharge. This protects the compressor from starting against a liquid column following an OFF cycle.The height of the loop should be 6 in. for every 10 ft of vertical discharge line.
Excerpt from the Technical Institute Manual #1 of the Refrigeration Service Engineers Society online store. For more comprehensive information visit the RSES.ORG online store.