20% is absolute low on surge margin for this unit.   IF IT GOES BELOW 20% RAISE THE SUCTION SET POINT!!!   The unit will lock into minimum RPM when surge margin hits 15% and will not unlock until surge margin gets above 20%.   Recommended to change set point in 10#  increments when lowering set point so surge margin can be better monitored.   Alarm limits have changed.

                                                                                                                  LO - 25

                                                                                                             LO LO - 20
                                                                           
                                                                                                    Thanks
                                                                                                       Bart