For glove box operations, seated workplaces are preferred, and an easily adjusted chair, such as a pneumatic chair, should be provided. Leg clearances of at least 66 cm (26 in.) are recommended. Some means should be provided to enable the operator to adjust the chair to a comfortable height for the arms and shoulders without having to remove his or her hands from the gloves Some tasks are easier to do with the chair adjusted to its highest level, while others are best done with the chair at its lowest level. An example of the former is a task in which the force is exerted downward; an example of the latter is a task involving extended reaches. Providing height adjustment by foot pedal, forearm switch, or a similar method allows the operator to move the chair to suit the task. Time is not lost in manual adjustments, then, and muscle fatigue from awkward working postures is less probable. Chair adjustability should be in a range of 15 cm (6 in.), and there should be adequate clearance to permit these adjustments to be made without wedging the thighs between the underside of the glove box floor and the seat pan of the chair.
If a standing glove box or a plastic screen in a hood is needed, the center of the arm ports should be 132 cm (52 in.) above the floor. This height should be comfortable for taller people, shorter operators will need a retractable step stool or platform with standing levels at 8 and 15 cm (3 and 6 in.) above the floor (W. J. Nielsen, 1981, Eastman Kodak Company). Since there is less flexibility in adjusting these platforms, every effort should be made to adapt the work to a seated operation, especially if the glove box is used regularly and for a majority of the shift.
The biomechanical problems of working through arm ports come from the restriction of body posture options; it is often not possible to utilize the most powerful muscle groups during lifting and force-exerting tasks. The shoulder and elbow ranges of motion are restricted, putting more stress on the hands and wrists. The options for moving objects to the side are reduced since the body cannot pivot with the arms in glove ports ; thus passing an object through a side pass-through port can be very awkward. Consequently, techniques that reduce the need to handle objects in the box are desirable Equipment to accomplish this reduction includes the following :
- Conveyors to supply and remove product (use of conveyors may be not possible if contamination is a problem). Leg clearance should not be compromised by the conveyor mechanism.
- Air pumps to remove liquids from stock bottles so that the liquids need not be poured manually.
-Trays or containers to permit parts or product to be moved into, out of , and around the inside of the box conveniently (especially if small part are involved).
- Small platforms of different heights inside the box. The platforms should be movable so that the operator can adjust the height of an operation to a comfortable working posture.