Clarke - Fire Pump Torsional Coupling

For drive systems with a right angle gear drive, there is the possibility of damage, due to natural frequency, when a torsional coupling is not installed. In reference to NFPA 20, vertical turbine pumps using angle gear drives, driven by a diesel engine, a torsional vibration damping type coupling shall be used and mounted on the engine side of the driver shaft (7.5.1.6.4). The torsional vibration damping type coupling shall be permitted to be omitted when a mass elastic system torsional analysis is provided and accepted by the AHJ (7.5.1.6.4.1).