3.17 Coupling: Seller shall provide an all metal, flexible disk or diaphragm, non-lubricated spacer type coupling to suit operating speed, horsepower, and service requirements with a service factor of no less than 1.5 times the maximum torque. The flexible coupling, mounted on a cylindrical pump shaft extension, shall facilitate removal of the inboard bearinghousing assembly and cartridge mounted seal assembly for easy maintenance. Exposed coupling