Demystifying Classifications: FEM vs. HST Hoist Duties
Hoist Duty Classifications Standards Comparison: US vs. EU
This is the fourth and final blog post in a series related to hoist and crane classifications. In our first post we discussed CMAA Crane Classifications. Our second post discussed the United States HMI/ASME hoist duty standards for hoist duty. The third blog post on demystifying classifications covered the European FEM standard for hoist duty rating. In this last blog posting on duty classifications we will compare the European and United States hoist duty rating standards and highlight the key differences.
Like many of our customers, Hoosier Crane increasingly operates in a global market. When working in the global market, it is helpful to be knowledgeable of the equivalent US vs EU standards. It is not uncommon to receive a bid specification from a European based customer for a hoist to be built in the US with an American hoist. Or conversely, customers may request a European hoist in a US crane project.
Please note, this comparison only applies to wire rope hoists. Due to a lack of any United States specifications that express a standard for electric chain hoist life, the comparison doesn't apply to electric chain hoists. The following comparisons are based on the American standards as maintained by ANSI (American National Standards Institute) and ASME (American Society of Mechanical Engineers) and the European standard FEM (Federation Europeenne de la Manutention).
From the United States: ANSI/ASME HST-4 Performance Standard for Electric Wire Rope Hoists From Europe: FEM 9.511-1986 (E) Rules for the Classification of Mechanisms FEM 9.683-1995 (E) Selection of Lifting and Travel Motors FEM 9.755-1993 (E) Measures for achieving safe working periods for Motorized serial hoist units.
Several hoist application parameters must be taken into account to compare and calculate the hoist duty ratings. We will start by defining these terms.
Average operating time per day - The average hoist operating time for each day.
Load spectrum – The load magnitude, as a percent of hoist rated capacity, expressed over the duration of hoist operation. For more detailed classification of a hoisting application the load calculation can be calculated as percentage of the max capacity. FEM design standards assume a mean effective load of .63 while ANSI/ASME HT-4 uses .65
Starts per Hour – The number of hoist motor starts per hour. This the number of times the motor is powered on per hour, not the number of lifts.
Operating periods – The hoist operating time in minutes per hour as expressed over a work period.
Equipment life – The projected hoist life based on a number of given factors including those previously defined.
There are two main differences between US and EU standards and how they calculate hoist duty ratings. The first big difference is the method used to calculate the hoist lifetime. The rules of the FEM 9.755 the hoist equipment working life to be 10 years of 250 working days per year. The ANSI/ASME HST-4 does not specify a hoist lifetime, but rather it specifies a required bearing life in hours based on the specified hoist service class. The methods used to calculate the mean effective load factor also differ, although the results are similar with ANSI/ASME HST-4 using .63 and FEM 9.511 specifying .65. For further more technical comparison of the standards please read the attached PDF from the Hoist Manufacturing Institute (HMI) titled Comparison of Hoist Duty Service Classifications.
The above table from Comparison of Hoist Duty Service Classifications breaks down each of the attributes by the duty rating. Based on the above table we can see that the requirements of the ANSI/ASME HST-4 hoist duty classifications H4 and H5 are greater than or equal to those of the FEM rule for a mean effective load of .65. Therefore, equipment meeting these classifications could be used for 2m and 3m applications. The class H3 product could be applied to a FEM class 1Am application if it was capable of 180 starts per hour instead of the standard HST-4 requirement of 150 starts.
The most important takeaway from this comparison should be a knowledge of the factors that go into classifying hoist duties. It is important to take into account more than just the capacity when selecting a hoist. Not taking into account the above factors can result in a number of problems. Buying a hoist duty that is too low can result in accelerated wear and shortened life span, as well as potential safety hazards. Buying a hoist duty class that is too high will result in excess costs. If you have any questions regarding hoist duty classifications or design standards, please contact us or call us at (800) 509-6131.