AUTOMATIC SAMPLE CHANGING • windowless detection provides high efficiencies for H 3 , C14, P32, S35, Ca45 • c o n t i n u o u s p r e - f l u s h speeds counting
New R C L Automatic Sample Changer provides higher efficiency of windowless gas flow detection without contaminating the counting chamber—and a faster counting rate. New design features unique pre-flush chamber ahead of the counting chamber and a four-position precision geneva movement sample changer. Counting column holds 50 samples in pans up to 1J4" diameter. Samples automatically (or manually) advance to preflush chamber, where counting gas atmosphere flushes out normal air contamination. Samples then enter c o u n t i n g c h a m b e r under positive pressure which prevents contamination from the pre-flushing chamber. C o n t i n u o u s flow of c o u n t i n g gas over samples permits instantaneous reading. When changer is combined with R C L Printing Sealer-Timer, Model 20318, the count can be automatically recorded. Output can be routed to digital tape printer, x-y curve plotter, nixie display or almost any other readout or printout device.
RCL
RADIATION COUNTER LABORATORIES, INC.
5121 West Grove Street, Skokie, Illinois, U.S.A., Phone.-YOrktown 6-8700 Circle No. 181 tn Readers' Service Carl
3 2 A · ANALYTICAL CHEMISTRY
REPORT FOR ANALYTICAL CHEMISTS
is solar energy absorbed through the windows. The amount generated within the building from use of equipment is more difficult to estimate as different heat producing items may be used at different times or at one time. Jacketing of equipment and other factors may reduce the heat. The fume hood is the most commonly encountered exhaust equipment. Air requirements for hoods are supplied by the manufacturers. Special considerations, such as separate exhaust systems, are involved in cases of gross hazards such as encountered in radiochemical, bacteriological, and virological research. The ventilation requirements of a laboratory are further complicated when air conditioning is involved. In the case of non air-conditioned laboratories, consideration should be given in the design of the ventilation system so that air conditioning can be added later at a minimum cost. A wide variety of heating and air conditioning systems is available depending on needs involved. Ventilation exhaustsystems should be designed to handle exhaust hoods already installed or which may be installed at a later date. Special laboratories present additional design problems. Spectrographic and microscopic laboratories, for example, require temperature, humidity, and air filtration systems. In such cases, separate, self-contained refrigeration and air-handling equipment can be installed to avoid the need for complicating the larger central system. Other examples of special laboratories are fine tolerance measuring, animal, environmental study, radiochemical, and bacteriological. Materials used in constructing ventilation systems vary widely depending on the nature of the exhaust gases. The desirability of air conditioning is unquestioned. Other alternatives, however, must be considered because of economic conditions. In air conditioning the cooling and heating of outdoor air is the largest single item of installation and operating costs. An adequate
source of cold water (from wells) can reduce costs. External heat gains can be reduced by careful orientation of the building and by sunshielding devices (louvers at the windows). This chapter of the book describes in considerable detail the various facets of air conditioning including heat load tables. Electrical Services. The electrical requirements for laboratories are varied and complex. In this discussion, the author makes no attempt to recommend any specific system but only to outline various possibilities. Major factors involved are the systems which supply power to the facility, those which distribute power within the facility, and those needed to handle local power distribution. Other topics covered are grounding, lighting, auxiliary systems, and such special requirements as systems for refrigeration and electric heating, voltage and current regulation, high frequency power, variable frequency power, direct current, and high voltage. Each of these topics is developed in some detail. LABORATORY FURNITURE and EQUIPMENT
Practically speaking, choice of laboratory equipment is governed by money and space available and type of work to be done. More specifically, one major factor is the specific discipline within the field of science or technology being investigated. Within the field of chemistry, for example, there are such areas as organic, inorganic, physical, and analytical. Analytical includes instrumental analysis. There is so much crossing of lines between these disciplines that the result is use of chemical furniture in biological work, electronic equipment in chemical laboratories, etc. Another factor is the nature of the work, for example, research, development, quality control, engineering design, or teaching. The type of material being investigated and the type of personnel using the equipment are other factors. A high school student's needs, for example, differ from those of a professional chemist.
