// Lifting, pushing, pulling

NIOSH Lifting Equation - Vertical Distance Multiplier Factor

How can the vertical distance affect the weight limit? Example: A worker lifts a 13 kg load from loosely piled pieces of metal from the floor to the table five times an hour.

How can the vertical distance affect the weight limit?

Example: A worker lifts a 13 kg load from loosely piled pieces of metal from the floor to the table five times an hour. To calculate the recommended weight limit (RWL) for the task: Weight of the object equals 13 kg H (Horizontal Distance) - 30 cm V (Vertical Distance) - 0 cm D (Lifting/Carrying Distance) - 115 cm F (Frequency) - 12 min A (Angle) - 0° C (Coupling/quality of grip) - poor The revised NIOSH Lifting Equation is: 23 kg x HM x VM x DM x AM x FM x CM = RWL 23 Kg x 0.83 x 0.78 x 0.85 x 1.00 x 1.00 x 0.90 = 11.39 kg * In this example, the distance was 115 cm. From the tables, the distance factor (D) was greater than 100cm (value of 0.87), so the value of 0.85 was selected (lifting distance of 145 cm) to be more protective. NIOSH does allow for some extrapolation for values that do not match the figures presented in their tables. Conclusion The weight of the load is 13 kg, which is higher than the calculated recommended weight limit of 11.39 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.
requirement Select the numeric multiplier factors for each component of the task from the tables in Calculating Recommended Weight Limit (RWL).
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 determined Recommended Weight Limit for the task:

Recommendations

The components: V - starting height, D - lifting distance and H - horizontal distance and C - poor grasp contribute similarly to the risk.

requirement Assess which of components of the task contribute most to the risk. Refer to Assessing Relevant Handling Factors.
requirement Raise the metal collection area (starting height) off the floor. This change also decreases D, the lifting distance.

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 0.83 x 0.93* x 0.93 x 1.00 x 1.00 x 0.90 = 14.86 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 15 kg is similar to the recommended weight limit of 14.86 kg. Further improvement can be achieved by providing the working materials in containers with handles, or by reducing the weight of the lift. 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 layout.
context Determine the new Recommended Weight Limit. Refer to Assessing Relevant Handling Factors.
context Compare weight of the load with these adjustments against the Recommended Weight Limit.