UL 448B:2017 pdf free download – STANDARD FOR SAFETY Residential Fire Pumps Intended for One- and Two-Family Dwellings and Manufactured Homes.
9.3 If 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 calculations for the driver based on the maximum loads applied by the pump.
9.3 effective December 23, 2010
9.4 The bearing assembly on one end of a split-case-pump shaft shall be arranged to float axially. Two bearing assemblies shall be provided for an end-suction pump; one that is free to float within the frame to carry radial forces, and the other arranged to carry both radial and axial thrust. The bearings shall be lubricated with grease.
9.4 effective December 23, 2010
9.5 Bearings shall be constructed such that additional lubrication is not necessary.
9.5 effective December 23, 2010
9.6 Bearings and their races shall be constructed of a case-hardened material or a material hardened throughout.
9.6 effective December 23, 2010
9.7 Means, such as water slingers and dust caps, shall be provided to limit the entrance of water or foreign matter to the bearings.
9.7 effective December 23, 2010
10 Shaft Seals
10.1 The pump shall be provided with mechanical seals.
10.1 effective 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 deflection and alignment with shaft.
10.2 effective December 23, 2010
10.3 As specified by the seal manufacturer, the seal shall be suitable for vacuum as well as positive pressure 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 leak tightness when the pump is not operating.
10.4 effective December 23, 2010
10.5 Glands, drive holders, and parts in contact with the liquid shall be corrosion resistant.
10.5 effective December 23, 2010
10.6 The seal mating surfaces shall be one of the following material combinations or a mating surface combination that provides seal performance at least equivalent to one of these material combinations:
a) Silicone carbide to silicone carbide;
b) Carbon to silicone carbide; or
c) Carbon to tungsten carbide.
10.6 effective December 23, 2010
PERFORMANCE
11 Operation Test
11.1 A pump shall have a rated capacity as specified in 6.2 and shall have rated net pressures of 20 psi (138 kPa) or higher. More than one capacity-pressure rating may be developed for any pump. For each rated capacity, a pump shall develop not less than the rated total head.
11.1 effective December 23, 2010
11.2 A pump shall develop not less than 65 percent of rated total head when discharging at 1-1/2 times rated capacity.
11.2 effective December 23, 2010
11.3 The maximum net pressure for a fire pump shall not exceed 140 percent of rated head.
11.3 effective December 23, 2010
11.4 The operation tests are to be conducted at rated speed or at a speed within ±10 percent of the rated speed, and the performance curves for the exact rated speed determined by means of the affinity relationships.
11.4 effective December 23, 2010
11.5 For the tests described in 11.6 — 11.9 the applicable Level 1 U test tolerances as specified in the American National Standard for Rotodynamic Pumps for Hydraulic Performance Acceptance Tests, ANSI/HI 14.6-2011 are to be utilized.
11.5 revised August 28, 2013
11.6 The pump is to be subjected to an operation test at rated speed. Performance curves are to be plotted showing the efficiency, brake-horsepower (kW), and total head developed at shutoff, at rated capacity, at 150 percent of rated capacity, and at selected intermediate capacities between shutoff and maximum capacities exceeding 150 percent of rated capacity.