• How can the frequency factor affect the weight limit?

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.

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

• Determine the weight of the load.

Weight - 10 kg

• Assess the six components of the lifting task. Refer to Assessing Relevant Handling Factors for more information.

H (Horizontal Distance - 20 cm
V (Vertical Distance) - 75 cm
D (Lifting/ carrying Distance) - 0 cm
F (Frequency) - 5 sec
A (Angle) - 90°
C (Coupling/quality of grip) - fair

• Select the appropriate multiplier factors for each component of lifting from the tables in Assessing Relevant Handling Factors.
• Determine the Recommended Weight Limit for the task. Refer to Assessing Relevant Handling Factors and Calculating Recommended Weight Limit (RWL).

23 kg x 1.00 x 1.00 x 1.00 x 0.13 x 0.70 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.

Evaluate the Redesigned Task:

• Assess the six components of the task in redesigned task.
• Determine new Weight Limit. Refer to Assessing Relevant Handling Factors and Calculating Recommended Weight Limit (RWL).

23 kg x 1.00 x 1.00 x 1.00 x 0.80 x 0.70 x 1.0 = 12.9 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 12.9 kg.

Therefore, MOST WORKERS CAN SAFELY PERFORM THE TASK.

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Document last updated on November 21, 2002

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