Most glove boxes are purchased from outside vendors. Two types are generally available: a low-profile glove box with a vertical glove port panel below the glass viewing panel (Figure IIA-10), and a high-profile glove box with glove ports set into the sloping glass front. The latter design offers advantages in visually demanding tasks. Glove ports are usually about 20 cm (8 in.) in diameter and 38 to 48 cm (15 to 19 in.) apart, center to center.
Chemical hoods include screens to prevent splashes to the face or eyes The design of the screen can vary according to the tasks performed in the hood. Two-handed tasks require access to the hood either through glove ports or around both sides of the screen. If glove ports are not provided, the screen should be no more than 46 cm (18 in.) wide so that constant static loading of the shoulder muscles is not required during the job.
Selection of a sitting or standing workplace for glove boxes and hoods is determined by the nature of the task to be done. The same general principles that apply for other workplaces apply here. Reaches should be kept within 15-41 cm (6-16 in.) of the front of the work surface for seated operations and within 51 cm (20 in.) for standing operations (W. J. Nielsen, 1981, Eastman Kodak Company). Since chemical hoods are often manufactured with cabinets below the work surface, and with plumbing, gas lines, and other built-in services at extended reaches from the front surface, most are used as standing workplaces. Hoods meeting the guidelines for standing arm reach and working surface height given earlier in this section should be selected wherever possible.