The general causes where overheating and material of construction failure.In details, the following conclusions were made:1. The piston rod failed by fatigue initiated at the cross head end threads.2. No evidence was found of any individual error in assembly or operation which contributed directly to the initiation of this incident.3. Indications are that the vibration trip was however keyed out at the time of this piston rod failure, increasing the secondary damage at the motor and resulting in the provision of a possible ignition source for the escaping hydrogen.4. The damage to the compressor indicates that both the compressor and the driver motor, acting as a flywheel, may have been subjected to extreme impulsive forces, with possible damage being caused to frames or shafts but subsequent inspections have shown any distortions to be negligible and no cracks have been detected.5. There is some evidence that liquid passes into this compressor in sufficient quantities under some conditions to cause mechanical distress.