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Chemical Instrumentation
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Edited by GALEN W. EWING, Seton Hall University, So. Orange, N. J. 07079
These articles are intended to serve the readers of THIS JOURNAL by calling attention to new developments i n the themy, design, or availability of chemical laboratory instrumentation, or by presenting useful insivhts and explanations of topics that are of practical imporlance to those who use, or teach the use of, modern instrumentation and instlumenla1 techniques. The editor invites correspondence from pmspectiue contributors.
LIV. Inert Atmosphere Enclosures LEONARD F. DRUDING, Deportment of Chemistry, Rutgers University, Newark, N. J. 07102 Frequently when chemists are hnndling air-sensitive mnl,erisls, intricate m n n i p ulations or complexity of the %pparatus requires t,he rrsc of an enclosure containing an inert, atmosphere. Where ritdioective or eut.romely t,oxic materials are involved, such enrlosures are necessary to protect the experimenter. For the special precautions and design fcatwes of the latter type of enelosnre, the reader is referred to B a t o n ' s excellent disoussion (1). The inert atmosphere for handli~igairsensitive materials can take the form of a flexible plastic bag or a rigid glove box. With tho availability of a number of commercial models of each typo of enclosme, an experimenter no longer has t o construct his own.
GLOVE BAGS For simple operations with small xpparatos, transparent polyethylene bags can be quite useful. The apparatus is placed in t,he bag and the bag is either evacuated or flushed before i t is filled wit,h en inert atmosphere, and then sealed. The contents may be manipulnted from
Figure 1 . Glove bag b y lnrtrumentr for Rereorch and Industry.
the out,sidc. An improvcd version equipped wit,h int,egml gloves (see Fig. 1) is offered in several siacs by hmtruments for llesearch aud Indust,ry. Glove bags are inexpensive, almosl impervious to moisture, and may hc easily disposed of when contaminated. IIowever, they are not conveniot~tlot. large apPSI.R~USor for complex manipulations.
GLOVE BOXES Before designing or ehoosi~lgn commercially available glove box, n number of factors should be cowidored whieh will aRect the type of box chosen. These fnctars include the kinds of chemicals and types of operations to be performed, tho siae of apparatus to be ,wed in the cnelosure, and the frequency with which the box will be used. The cl~ernicalst o he used will determine the best material of carrstruction for tho box, while the siae of the apparatus will determine the proper siae of the entry lock or ports. The frequency of use is a factor in determining the kind of box. After initial attainment of an inert atmosphere ill a n enclosure, constant at. tention must he paid to maintain this at. mosphere. If the use of an enclosure is only intermittent, then a glove bag would represent a saving in cost as well a in time required t o prepare the inert atmosphere. There are some general considerations in the choice of a glove box. The maximum reach of a. pair of gloves is about 36 in. so that the working spnec reached from a single pair of gloves is about 6 it. Layout of the apparat,us and accessories in the box as well as in the lock should be planned with this limitation in mind. Some larger boxes have additional glove ports, but most boxes designed for general laboratory work have only a single pair of gloves. There are some designs of rigid glove boxes whieh may be completely evacuated, greatly reduoing the purging time; most manufacturers offer evacuable enbry looks. Materials used in the fabrication of com-
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