UL 448B:2017 pdf download.Residential Fire Pumps Intended for One- andTwo-Family Dwellings and Manufactured Homes.
9.3 lf a pump utilizes the shaft bearings of the driver to carry the axial and radial forces of the impellers,compliance with the requirements in 9.1 and 9.2 is to be verified by a review of bearing life calculationsfor the driver based on the maximum loads applied by the pump.
9.3 effectiwe December 2a, 2010
9.4 The bearing assembly on one end of a split-case-pump shaft shall be arranged to float axially. Twobearing assemblies shall be provided for an end-suction pump; one that is free to float within the frame tocarry radial forces,and the other arranged to carry both radial and axial thrust. The bearings shall belubricated with grease.
9.4 effective December 23,2010
9.5 Bearings shall be constructed such that additional lubrication is not necessary.
9.5 effectiwe Decembar 23,2010
9.6 Bearings and their races shall be constructed of a case-hardened material or a material hardenedthroughout.
9.6 effective Decemlbar 23,2010
9.7 Means, such as water slingers and dust caps,shall be provided to limit the entrance of water orforeign matter to the bearings.
9.7 effactiwe Decemlber 2a,2010
10 Shaft Seals
10.1 The pump shall be provided with mechanical seals.
10.1 etfective December 23,2010
10.2 A mechanical seal shall be used within the seal manufacturer's specifications for pressure,peripheral velocity (based upon shaft rotational speed), shaft or sleeve finish， maximum shaft deflectionand alignment with shaft.
10.2 ellective December 23, 2010
10.3 As specified by the seal manufacturer,the seal shall be suitable for vacuum as well as positivepressure conditions.
10.3 effective December 23,2010
10.4 The seal faces shall be mechanically loaded,such as the use of a spring, to provide for leaktightness when the pump is not operating.
