A glove box is a device for working with chemical, biological,
or radioactive materials. Typically, these materials are hazardous,
toxic or both, although there are other reasons for choosing operation
in a glove box. Following are some typical applications for glove boxes:
- In Biochemistry, a glove box is typically used for working with cell cultures and viruses that may be harmful to human
health. Also, the glove box allows for a controlled environment
(humidity, air pressure, temperature).
Pharmaceuticals may have (yet) unknown effects on
health, or may be toxic in high doses. These drugs are often handled in a
glove box.
- Radioactive materials are also often handled in a glove box, because
they can cause harm upon direct contact, or fine radioactive dust could
contaminate the air and work area. Glove boxes for radioactive
applications typically require extra shielding (lead glass, special
gloves).
- Chemicals are sometimes too toxic, even in low
concentrations to safely work with them in a fume hood.
Chemicals can also react with oxygen or water vapor from the air,
and decompose. In some cases, this reaction poses a hazard as well
(pyrophoric materials that spontaneously combust in air). Materials
can also be hygroscopic; by adsorbing water, they could become
useless for a desired application. The glove box is a suitable
environment for working with these materials.
- In the semiconductor industries, a clean, dust-free environment
is crucial to avoid damage of the silicon wafers. For
some applications, a full scale clean room isn't practical,
or too expensive to operate, and a glove box may be used.
A typical setup of a glove box can be seen in the following figure. Note
that this figure represents a glove box for chemical applications. Other
applications may require slightly different setups.
Vacuum Inert
line flush
Inert || Valve 1 ||
purge ||___._____||
|___/ ______|
|| ||
||__________________________________ ||
|____ | _ ## Valve 2
| | |P| ||
| |____|___||_______
| # Vestibule #
| Gloves Door 2 # # Door 1
| _ _ # Tray #
| / \ / \ # |____________| #
| \_/| \_/| #_|__|___|__|__|_#
| \ |_ \ |_ |
| \___E \___E |___
|_________________________________ |
||
||
Inert
inlet
The glove box is a sealed rectangular case with a transparent (glass
or plastic) front window. The side and back walls may be transparent as
well. The glass has at least two glove ports, with thick
rubber gloves attached (Viton or some other specialty rubber,
depending on the application).
Usually, the glove box has an inlet and purge for gases. For chemical
applications this is usually an inert. The choice of the purge gas
depends on the application and price; helium is more expensive than
nitrogen. The purge stream requires proper handling; it may be sent
directly into a fume hood, or through a gas scrubber.
The vestibule is an isolation chamber for inserting and removing
materials to and from the glove box. Its design is such that the
environment inside the glove box is not affected by a
transfer.
Materials can be transferred into the glove box as follows:
- Make sure door 2 is closed; this door should always be
closed immediately after a transfer. Make sure valve 2 is closed
- Open door 1, and insert material to be transferred. This
material must be dry, and compatible with the environment inside the
glove box. Close door 1
- Switch valve 1 to its vacuum position. Open
valve 2, and evacuate the vestibule. Monitor the pressure gauge. Close valve 2
- Switch valve 1 to its flush position. Open
valve 2 and flush the vestibule with inert gas. Monitor the
pressure gauge. Close valve 2.
- Repeat steps 3-4 one or several times. For most
applications, a total of three flushes is sufficient.
- Using the gloves, open door 2 and transfer materials in or out of the glove box. Close door 2
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