Suppose you want to find the female population percentage for lifting tote pans. Your measurements include (see guidelines below):
- Tote pans weigh 29 pounds
- Hand distance away from body of 7 inches
- An initial hand height at start of 30 inches
- A hand height at end of task of 50 inches, and
- Tote pans are lifted once every 5 minutes
- Select the Lifting task from the Task dropdown menu.
- Enter the Object Weight of 29 lb.
- Select the Between Knuckle and Shoulder Height option from Lifting Task - Ending radio menu.
- Select the 7 inches option from the Hand Distance radio menu.
- Select the 20 inches option from the Lifting Distance radio menu.
- Select the 5 minutes option from the Frequency - One Lift Every radio menu.
- Click the Calculate button - the population percentage for both Male and Female is displayed in the calculation box on the right side of the page. This is the percentage of population that can perform this task without overexertion or fatigue.
Many times measurements will lie in-between those values in the radio menus e.g. Hand Distance, Frequency, Lifting, Lowering, Carrying Distance, and Hand Heights. If so, round off to the higher or lower value depending on whether the value is above or below the middle value of the measurements. For example, for Female - Lifting Task Ending Between Knuckle Height & Shoulder Height (≥28” and ≤53”) task; for a measured Lift Distance of 16 inches, then select 20 inches. For a measured Lift Distance of 14 inches then select 10 inches etc.
Liberty Mutual Tables is intended to be a flexible tool. If you would like to see the population percentage differences between a Lifting Distance of 20 inches and 10 inches then select one and then the other and calculate the population percentage each time. Compare population percentage results. Same would be true for entering Object Weights and any other measurements including Hand Distance. This is how What-If scenarios can be performed using Liberty Mutual Tables.
Hand Distance is the distance from the front of the body to the hands. (Note that this is a different measurement from the 1991 Revised NIOSH Lifting Guide). Hand Distance will normally be half the width of the object being handled, unless the object is purposely held away from the body.
For Pushing and Pulling Tasks you will need to obtain a force gauge or force measurement device and enter the initial force, in pounds, needed to start the object moving. Take several measurements and enter the highest value particularly when floor or wheel conditions are poor. For pushing tasks, you can measure the force by pulling. However, while the effect on the worker may be different between a push and pull, the measured force will be the same. Also obtain the sustained force measurement to keep the object moving. All measurements should be taken at an acceleration representative of the task as performed in the actual operating environment.