// Lifting, pushing, pulling

NIOSH Lifting Equation - 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.

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: Weight equals 10 kg H (Horizontal Distance)- 20 cm V (Vertical Distance) - 75 cm D (Lifting/ carrying Distance) - 0 cm F (Frequency) - 6 sec over 1 hour, standing A (Angle) - 90° C (Coupling/quality of grip) - fair, standing The revised NIOSH Lifting Equation is: 23 kg x HM x VM x DM x AM x FM x CM = RWL 23 kg x 1.00 x 0.93 x 1.00 x 0.71 x 0.13 x 1.00 = 1.97 kg * In this example, the vertical distance is 75 cm. From the tables, the vertical multiplier (VN) was greater than 70 cm (value of 0.99), so the value of 0.93 was selected (lifting distance of 70 cm) to be more protective. Conclusion The weight of the load is 10 kg, which is higher than the calculated recommended weight limit of 1.97 kg. Therefore, this task is likely to increase the risk of a lifting related injury.

requirement Determine the weight of the load.
requirement Assess the six components of the lifting task. Refer to Assessing Relevant Handling Factors for more information.
requirement Select the appropriate multiplier factors for each component of lifting from the tables in Assessing Relevant Handling Factors.
requirement Determine the Recommended Weight Limit for the task. Refer to Assessing Relevant Handling Factors and Calculating Recommended Weight Limit (RWL).
requirement Compare weight of the load against the calculated Recommended Weight Limit for the task. The weight of 10 kg is much larger than the recommended weight limit of 1.97 kg.

Recommendations

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

Evaluate the Redesigned Task:

The revised NIOSH Lifting Equation is: 23 kg x HM x VM x DM x AM x FM x CM = RWL 23 kg x 1.00 x 0.93 x 1.00 x 0.71 x 0.75 x 1.00 = 9.90 kg * In this example, the vertical distance is 75 cm. From the tables, the vertical multiplier (VN) was greater than 70 cm (value of 0.99), so the value of 0.93 was selected (lifting distance of 70 cm) to be more protective. The weight of the load at 10 kg is now similar to the calculated weight limit of 9.90 kg. Further improvement can be achieved by reducing the weight of the object. Therefore, while most workers can likely safely perform the task, the work should be monitored for the development of injuries.

context Assess the six components of the task in redesigned task.
context Determine new Weight Limit. Refer to Assessing Relevant Handling Factors and Calculating Recommended Weight Limit (RWL).
context Compare weight of the box against Recommended Weight Limit for redesigned task.