This spin pit is used to overspeed gas compressor impellers at speeds to 40,000 rpm with a 75 kW electric drive system. Balancing capability is built into the 1000 mm spin chamber. Impeller balance is checked prior to spin. If the rotors are OK as manufactured, the spin test is subsequently performed. If not, the appropriate balance corrections are specified so that the appropriate balance level can be achieved without removing the test article from the spin pit.