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Frequency Factor

How can the frequency factor affect the weight limit?

Example: A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours.

Example of a worker lifting

To calculate the recommended weight limit (RWL) for the task:

  • Determine the weight of the load.

Weight - 10 kg

H (Horizontal Distance - 20 cm
V (Vertical Distance) - 75 cm
D (Lifting/ carrying Distance) - 0 cm
F (Frequency) - 6 sec
A (Angle) - 90°
C (Coupling/quality of grip) - fair

23 kg x 1.00 x .99 x 1.00 x 0.13 x 0.71 x 1.00 = 2 .1 kg

  • Compare weight of the load against determined Weight Limit for the task.

The weight of the load at 10 kg is higher than the calculated recommended weight limit of 2 .1 kg.

Therefore, TASK IS DANGEROUS.

Recommendations

  • Assess which of components most contribute to the risk. Refer to Assessing Relevant Handling Factors.
    • the critical factor is FM for the frequency of lifting and duration of task.
  • Shorten the frequency of lifting by:
    • reducing the frequency of incoming boxes in half, or
    • assigning additional workers to the task, or
    • shorten the time of the task to 1 hour.
Shorten the frequency of lifting

Evaluate the Redesigned Task:

23 kg x 1.00 x .99 x 1.00 x 0.75 x 0.71 x 1.0 = 12.1 kg

  • Compare weight of the box against Recommended Weight Limit for redesigned task.

The weight of the load at 10 kg is now lower than the weight limit calculated to be 12.1 kg.

Therefore, MOST WORKERS CAN SAFELY PERFORM THE TASK.

Document last updated on October 10, 2013

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