Answer: For bottom mounted springs it is mentioned to avoid large spring bending by frictional force and displacement. So that additional measures can be taken to lower frictional force by providing PTFE/graphite slide plate. For top mounted spring hangers horizontal displacement is mentioned to check angularity of 4 degree to reduce transmission of horizontal force to piping systems as spring hangers are designed to take the vertical load only. If angle becomes more than 4 degree due to large horizontal movement then install the spring hanger in a offset position so that after movement the angle becomes less than 4 degree.