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Demystifying Classifications: HMI/ASME Hoist Duty Classifications

Today we are going to discuss the HMI and ASME hoist duty classifications and how to choose the best hoist for your application.  This is the second blog post in our Demystifying Classifications series.  We will be covering each type of classification in a biweekly post.  We will also be doing a comparison of these classifications as a separate post so you can determine which overhead crane and hoist best suits your application.  If you have any questions throughout the series, please feel free to contact us.
 
The Hoist Manufacturer’s Institute (HMI) and American Society of Engineers (ASME) have published safety and performance standards for hoists, including hoist duty service classifications.  These classifications are based on a number of factors, including: 
 
  • Number of lifts being performed per hour
  • Maximum number of starts and stops per hour
  • Average distance the load is raised and lowered
  • Average and maximum weight to be lifted
  • Frequency at which the maximum weight is lifted
 
Hoosier Crane Street Hoist
When choosing which hoist is the best fit for your application, always keep in mind that the hoist rating should meet or exceed your operational needs.  Duty cycle is one of the most important factors for choosing an electric hoist for your application.  A duty cycle for a hoist is basically the amount of work the hoist can perform in an hour.  Choosing the incorrect hoist can cause safety issues, reduced productivity and more downtime.  All of these can translate into negative financial impact to the bottom line.
 
Hoist Classifications are below.  Note that uniformly distributed usage is evenly spaced and predictable over an hour long period.  Infrequent usage occurs at irregular intervals.
 
H1 (infrequent handling or standby use) – used in maintenance applications, powerhouses and utilities. Primarily used to install and service heavy equipment, loads frequently approach capacity and hoist is idle for long periods between use.  
 
Maximum on time for uniformly distributed usage is 7.5 minutes per hour with 75 starts an hour.  For infrequent usage, maximum on time from cold start is 15 minutes with 100 starts an hour.
 
H2 (light use) – primarily used in light machine shop fabricating, service and maintenance; loads and use are randomly distributed.  Rated loads are infrequently handled.  Mostly average sized loads, only occasional max load lifting. Total running time not over 12.5% of the work period.  
 
Maximum on time for uniformly distributed usage is 7.5 minutes per hour with 75 starts an hour.  For infrequent usage, maximum on time from cold start is 15 minutes with 100 starts an hour.
 
H3 (standard use) – general machine shop fabricating, assembly, storage and warehousing.  Loads and use are randomly distributed.  Occasional max load lifting.  Total running time not over 25% of work period. 
 
Maximum on time for uniformly distributed usage is 15 minutes per hour with 150 starts an hour.  For infrequent usage, maximum on time from cold start is 30 minutes with 200 starts an hour.
 
H4 (heavy use) – High volume of heavy loads, frequently near rated load in steel warehousing, machine and fabricating shops, mills, and foundries.  Total running time not over 50% of the work period. Manual or automatic cycling operations of lighter loads with capacity loads handled infrequently such as in heat treating and plating operations, with total running time frequently at 50% of the work period.  
 
Maximum on time for uniformly distributed usage is 30 minutes per hour with 300 starts an hour.  For infrequent usage, maximum on time from cold start is 30 minutes with 300 starts an hour.
 
H5 (severe use) – Bulk handling of material in combination with buckets, magnets, or other heavy attachments.  Equipment is often cab operated.  Duty cycles approaching continuous operation are frequently necessary.  Regular lifting of heavy loads.  Exact details of operation are necessary, including the weight of attachments.
 
Maximum on time for uniformly distributed usage is 60 minutes per hour with 600 starts an hour.  Not applicable for infrequent work periods since there are none in class H5.
 
Hoosier Crane Hoists
 
To find out how hoist classifications relate to CMAA service classifications, look for our future blog posts in the series. If you missed our first post discussing CMAA classifications, be sure to check it out.
 
All information here is for reference.  Request a quote or contact us for assistance in making duty cycle application decisions for your facility.