ASME HST-5:2020 pdf download.Performance Standard for Air Chain Hoists.
SECTION 5-1.1: GENERAL
All equipment selected in accordance with this Standard is designed to perform satisfactorily when used in accordance with ASME B30.16, Chapters 16-2 through 16-4, and within the rated load and hoist duty service classifIcation. All equipment shall provide speeds, lifts, and headroom in accordance with the manufacturer’s specifications or to specifications agreed upon by the manufacturer and user.
SECTION 5-1.2: HOIST DUTY SERVICE CLASSIFICATION
5-1.2.1 GeneraL Considerations
Service conditions have an important influence on the performance of wearing parts of a hoist such as gears, bearings, load chain, sprockets, brake linings, load and lift limit devices, wheels, and pneumatic components. Careful consideration of the hoist duty service classifications described in this Section will enable the user to evaluate the application and to obtain a hoist designed for optimum performance and minimum maintenance. If doubt exists regarding hoist selection, the hoist supplier should be consulted. Many factors enter into the selection of the proper hoist to perform a given function. Hoisting equipment consists of both mechanical and pneumatic components and both must be considered when analyzing the service the hoist must perform. The factors that influence the performance of any hoist include
(a) Load Distribution. The actual distribution or proportion of full and partial loads to be handled by the equipment, including lifting devices, has an important effect on the life of power transmission components. For example, ball hearing life varies according to the cube of the load. A 2-ton (1814.4-kg) hoist operated at a mean effective load of 1 ton (907.2 kg) will have a ball bearing life of eight times that of the same hoist used steadily at its rated load.
(b) Operational Time. Operational time is the total running time of the hoist per hour or per work period.
(c) Repetitive Long Lowering Operations. Such operations generate heat in mechanical load brake.
(d) Environmental Conditions. Examples are high or low ambient temperatures, dust, moisture, corrosive fumes, etc.
5-1.2.2 Hazardous Locations
When hoists are used in hazardous locations as defined by ANSI/NFPA 70 or other special codes, modifications or additional precautions not covered by this Standard may be required. In these locations, only hoists designed in a manner suitable for the conditions encountered shall be used.
5-1.2.3 Duty CLassification
While all the factors listed in para. 5-1.2.1 must be considered in selecting the proper class of hoist, most industrial applications can be generalized according to the percentage of rated load normally handled and the running time. Listed in Table 5-1.2.3-1 are the two duty classes that have been established for air-powered chain hoists. The majority of hoist applications will fall into the A4 category.ASME HST-5 pdf download.