This chemical line describes what types of materials require the use of a glovebox to provide employee protection or isolation from highly toxic or radioactive materials.
When are glove boxes needed?
Glove boxes are used for handling high-hazard materials or when an inert atmosphere is required to control oxidation or fire. Gloves boxes should be used with high activity alpha or beta emitters and highly toxic chemicals and biological materials. Gloves boxes are also required to meet OSHA 29 CFR 1910.1003 Standard for handling the following carcinogens:
Methyl chloromethyl ether
3,3'-Dichlorobenzidine (and its salts)
Air Flow Requirements
A hazard evaluation must be made by Industrial Hygiene before flammable materials are used in a glove box. As a rule, these materials shall be avoided or the quantities kept to minimum practical amounts.
The pressure inside a glove box is kept negative with respect to room pressure so that any leakage or noncatastrophic failure of the enclosure will result in a substantial inflow of air through the opening into the glove box. For certain operations positive pressure boxes are designed to prevent intrusion of moisture or external contamination. Such boxes are not intended for highly hazardous operations and must be carefully evaluated for appropriateness. These installations must be readily identified and administratively controlled to prevent misuse.
An exhaust flow rate of from 35 to 50 CFM is usually sufficient from a glove box. The air locks used with a glovebox should be exhausted if they open directly into a room.
A HEPA filter shall filter exhaust air from glove boxes containing toxic or radioactive material that may generate airborne particulates. A second filter, in series, shall be used for radioactive materials. Filters that can handle the maximum required airflow must be chosen.
Because glove-box failures usually occur at the glove ports, these ports should be capped when not in use. The flexing of gloves, deterioration from corrosive chemicals, and radiation in the box reduce normal glove life. Experience based on previous glove failures usually dictates the useful safe life of gloves. It is mandatory, therefore, that a well-planned inspection and replacement schedule be observed.
A HEPA filter may be required in the supplied-air port to the box to prevent loss of material from the inside of the box to the room.
Glove boxes shall be equipped with vacuum gauges that indicate the box is under negative pressure. Before a box is used, this gauge shall be checked to ensure the box is in safe operating condition. If an inert gas environment is required in the box, care shall be exercised during all purging operations to ensure that the internal pressure in the box is maintained negative to room pressure. An airflow gauge (sharp-edged orifice) shall be installed to indicate whether exhaust is adequate for the box design and its current use.
Material is introduced or removed through airtight ports. These ports may be double-doored air locks in smaller glove boxes or large bag-covered ports in larger glove boxes. These ports shall be designed to prevent the loss of negative pressure within the box while the port is in use. Pass-in/ out ports shall be monitored for contamination after each use.
Glove boxes shall be well lighted from the outside. "Shadowless" illumination, like that provided by fluorescent tubes, is generally suitable.
Contact Environmental Health and Safety