We have Dresser Rand make 2 stage 4 cylinder double acting Reciprocating compressor. It runs on 0%,25%,50%,75% and 100% load. It is equipped with plate type valve 4 suction and 4 discharge in each cylinder. Variation of load done by diaphragm type unloader on suction valve.
When we start compressor from 0% load and step wise increase to 100% load everything runs smoothly. when we decrease the load from 100% to 25% (Stepwise)everything runs smoothly. But when we further decrease the load from 25% to 0% heavy abnormal sound comes from one of HP cylinder.
On opening the end cover and removing the piston it has been observed that both the rider ring has been damaged in corner.
we have replaced the rider ring and after trial this thing again happened.
Today we have taken trial third times and problem still exists.
Please send us your information regarding this problem.