DESIGN OF LABORATORIES FOR CHEMICAL ENGINEERING INSTRUCTION' HAROLD C. WEBER Massachusetts Institute of Technology, Cambridge, Massachusetts
about 30 research associates. The building, completed just a t the outbreak of the late war, was used In the design of any unit there are fundamental concepts which must be kept clearly in mind if the final first by a Government agency for research and develophas been Octhe Past l4 construction is to fulfill completely the expectations of ment work, but the designers. A good chemical engineering laboratory cupied by the Chemical Engineering ~ e ~ a r t m e n t . utility, (2) great- The soundness of the design is proved by the relatively should be designed for (1) maximum est flexibility, (3) minimum cost,consistent with sound few minor changes which would be made if the building to what one might at first were to be rebuilt a t the present time with the advanconstmction. contrary gained the groups thought believe, these principles are not inconsistent tage of the have used it during the ~ a s five t vears. The fact that a building c ~ n s t r ~ t e d ~ ~ r i m afor r i l chemical y engineering instruction could serve so admirably for governmental research and development is additional indication of the firm,broad basis on which it was conceived. EUNDAMENTALS
GENERAL FEATURES
Figure 1.
Chemical Engineering Lmbo~atorie. et th. Mui..chusetta Institute of Technolopy
with good physical appearance. Construction of laboratories has too often followed the whims of some individual or has served merely to produce a monument in the form of a memorial, with but limited practical utility. The comments presented in the following paragraphs are based on experience with three groups of'chemical engineering laboratories used by the Massachusetts Institute of Technology during the past 35 years. The knowledge so gained was used in the design of the present chemical engineering laboratory group (Figure I). This is of such size as to accommodate approximately 150 graduate students and 90 to 100 senior undergraduates, together with the necessary staff and personnel. In addition, sufficient space is provided for Presented before theDivision of Chemical Education a t the 111th meeting of the American Chemical Society in Atlantic City, Anril 1418, 1947. 34
The optimum building height is probably two stories and the construction should certainly be fireproof throughout. The advantages of a flat roof should not be overlooked. It can serve as space on which to construct additional temporary units, particularly if they are of an obnoxious or dangerous nature, and if properly designed, it can serve to aid in cooling the building in localities where uncomfortably hot weather is experienced. Bulky or heavy objects are readily placed on or removed from such a structure by a portable crane. A raised, central penthouse section on the building makes ventilation easier, improves lighting, and gives additional height a t minimum expense for the few pieces of high apparatus which would not be accommodated in a height of two stories. Numerous, readily-
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removed, pitched skylights will be found useful for bringing services to and from temporary equipment located on the roof and, in addition, they offer a convenient place to exhaust hot or obnoxious gases to the atmosphere. Moreover, they can often serve as convenient openings for the installation or removal of heavy equipment. I t is surprising how readily such equipment can be moved in and out through the skylights, particularly with the aid of a simple lifting device. Any objection to skylights, based on the difficulty of keeping the room in which they are installed cool in hot weather, can be largely overcome by the proper use of shades. The optimum distance of floor to ceiling probably ranges between 11 and 14 feet, irrespective of whether or not the room is to be an office, a laboratory, or a classroom. Too many laboratories are built with excess headroom. Soundproof ceilings should be installed at least in offices and classrooms. In chemical engineering work, some space must be available with a 30 to 40foot headroom for installation of columns and similar tall equipment. The fraction of the total area devoted to such space need not be large. Possibly too much such space has been provided in the building a t Cambridge, but this can be readily corrected, if necessary, since provision was made in the original design for flooring over part of this space either temporarily or permanently. Concrete seems to be the most suitable material for floors. Linoleum in offices and conference rooms is desirable, while corridors had best be covered with one of the plastic-coated, asphalt-base materials which withstand heavy wear and are resistant to damage from burning cigarets. Interior laboratory walls constructed of hollow terra cotta tile, besides being inexpensive, can readily be removed or changed. Even inexperienced students find no difficulty in attachingequipment to such walls. The holes left when apparatus is removed can be quickly and inexpensively plugged with terra cotta colored cement or, if need be, whole blocks may be inexpensively replaced. When painted, such walls present a very pleasing appearance and, in addition, do not show dirt and stain as noticeably as do smoother surfaces. For
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3. Bas.".."*
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offices,classrooms, and conference rooms where objects are not often attached to or removed from permanent walls, plaster on magnesia block gives a more soundproof wall of somewhat better appearance but a t increased cost. A satisfactory ventilating system follows the conventional idea of supplying heated, filtered air under pressure to all laboratories from a central unit. Exhaust air should be removed a t several points, each provided with a separate fan and contiol. To satisfy individual desires, offices should probably be provided with manually-controlled radiators. There should be a t least two 110-volt outlets on opposite walls of each office, classroom, and conference room. All the necessary conduits for telephones and any other desired signal systems will be laid while the building is being constructed. Certainly, every at-
Figure 4.
Laboratory for Work of a Chemical Rather than an Engineering Nature
tempt should be made to eliminate exposed wiring of any sort except in laboratories. Probably fluorescent lighting will be chosen for any new building. This is quite satisfactory in all rooms with the possible exception of offices. There still seems to be some discussion as to whether a combination of fluorescent and incandescent lighting may not be superior where close work must be performed. Adequate shipping and receiving facilities are a necessity. This is a feature often overlooked in an educational bhilding. There are decided advantages in having the lower floor of the building at ground level so that relatively heavy objects can be easily moved t o and from trucks. The large receiving and shipping entrance should be provided with some type of simple hoist and trolley to facilitate loading and unloading operations. Laboratories and classrooms need not be drab and colorless. Modern flat paints in pastel colors propcrly chosen can do much to make such rooms attractive, and there is considerable argument to substantiate the claim that properly-chosen colors do have a desirable
JULY, 1947
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psychological effect on people. Light-colored,chemicalproof, semi-gloss paints are attractive finishes for laboratory walls. ROOM TYPES
center of the floor, have been found particularly useful. I t is desirable to provide all laboratories with space far writing notes and operating delicate instruments (Figure 6). Writing shelf space along one wall of each laboratory has been provided for this purpose a t Technology. For advanced work involving specially constructed, large apparatus, large, open laboratories with conveniently arranged utilities are needed (Figure 7). Similar space should be available for a unit operations laboratory. Any equipment installed in these rooms should be considered of either a temporary or a t most a semipermanent type. Chemical engineering laboratories and sEhools throughout the country tend to become cluttered with large, heavy, obsolete, permanently installed equipment. No equipment in chemical engineering laboratories should be considered truly permanent except that connected with the supplying of the necessary utilities. Flexibility and the opportunity to change as new developments occur are prime essentials. Special Rooms: Rooms for storage of apparatus and for apparatus loan are necessary. A relatively small amount of storage space will be adequate if provision is made for efficient utilization of the space by providing suitable racks and shelves. A large amount of
Offices for staff, the executive head, and secretaries are, of course, necessary. Washrooms for men and wash and restrooms for women should be provided. At least .one and possibly two conference rooms will be found useful. These should be sufficiently large to accommodate 30 to 40 people and they should be provided with blackboard. snace. a rolled. ~, headed nroiection screen, and suitable electrical outlets. I t may also be advantageous to provide for telephone service in these rooms. They will be found especially useful for staff meetings, seminars, and for interviews between students and prospective -employers, particularly where other space is not specifically provided for this purpose. Classrooms should be of sufficient size to accommodate classes expected. In addition to blackboards, these should be provided with rolled, beaded screens and the proper electrical outlets for thebperation of projection equipment. At Cambridge four classrooms and two conference rooms are sufficient for the work in chemical engineering. One classroom with seats for 75 is used for lectures. The work can be handled in these few rooms only if class scheduling is efficiently carried out. Laboratories: Several types of laboratories are needed. For large undergraduate classes carrying on work of essentially a chemical nature, rooms with properly designed chemical laboratory benches are entirely satisfactory (Figure 4). Probably the space so furnished should not he over 20 to 25 per cent of the total laboratory space available. For much of the research and some of the instructional work, laboratories should he provided with apparatus racks rather than benches. A rack which has been found satisfactory and which can readily be constructed, preferably using arc-welded joints, is shown in Figure 5. Racks should occupy upwards of 30 to 35 per cent of the total laboratory space available. For advanced research, particularly for men studying for the doctorate, small rooms accommodating four to eight men. ~rovidedwith chemical bench space along the walls and racks in the ~s,,. s. spas.for writing, which .I ~
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JOURNAL OF CHEMICAL EDUCATION @inden One 2HP, snagginggrinder Two '/s HP, for offhand grinding HP, for tool grinding One automatic surface grinder equipped with permanent magnet chuck with working surface 6" X 18" Milling Machines One small, Universal-type, with ram head and hand-opereted feeds One large, Universal-type, with power-operated feeds One light duty, preeisioq-type, vertical miller with ram-type head Woodsaws
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storage space is a distinct disadvantage as it fosters the hoarding of obsolete and worn-out equipment. A small room provided with grinding equipment, permanently installed, is extremely useful, as is also a glass-blowing room suitably equipped. Probably some will want a constant-temperature, constant-humidity room and where money is available, this will be found useful. A small low-temperature room is needed for some types of work. The one a t Technology is approximately 8 X 8 X 12 feet and is capable of being operated a t -40°F. continuously. At least one balance room with six to ten balances is needed and if much work on plastics or rubber is contemplated, laboratories of limited size equipped with the proper presses, mills, calenders, and similar machinery should be provided. The shop and the apparatus loan room are of su5cient importance to warrant discussion under separate headings. Shop: in chemical engineering research, there is the probability that practically every conceivable material of construction will have to be worked, and it would be highly impractical to equip a shop to do this. Machines should be available, however, for working all of the more common materials including the newer alloys. The following machine equipment has been found practical and adequate for the work a t Technology:
Sheet Metal Brakes One F'hnnd-opwntcrl,simplr lmke Onr O'hand-oprratcd, box-type brake Shears One 6', foot-operated, sheet metal squaring shear One small hand-operated shear to take bar stock up to approximately J/8" in diameter Sheet Metal Rolla One 4'set to handle stock up to 16-18 gage Welding Equipment Two 20C-amp. d.-c. arc welders One 400-amp. d.-c. arc welder Two sets of tanks and torches for oxyacetylene welding
It is, of course, understood that the above-mentioned equipment will be completely equipped with such accessories as the work to he done may dictate. These will certainly include the necessary vises, index heads, and rotary tables to be used on the milling and boring units. A very completely-equipped tool crib, properly supervised, is a necessity. Provision must be made in the shop td supply students, as well as professional workers, with the tools and stock needed for the work to be done. Certainly, in this day, all poweroperated tools should have individual motors. Apparatusfor Loan and Storage: The large amount of diverse equipment needed in chemical engineering.can best be handled from a central point. Here, all instruments and apparatus can be kept under orderly, safe conditions. Steel shelving is excellent for this purpose. At this point, provision should also he made for cleaning and minor overhauling of returned equipment to insure that it will be in proper working order when reloaned. To this end, space should be provided a t the apparatus loan center for a small metal working lathe, an electrical Lathes test bench, a small drill press, and a utility grinder. Three 14", serew cutting, completely equipped with collets, An 8- or lbinch circular saw will also be found useful. jaw chucks, taper attachment Three lo", screw cutting, completely equipped with collets and In addition to lending apparatus and overhauling it jaw chucks when it is returned, this center can well serve as the One 14", screw cutting, with gap bed to take diameters up to shipping and receiving point for the laboratory and nnn -as the place to mimeograph the very large number of One 12",wood turning sheets which must be prepared in connection with Planer chemical engineering educational work. The proper he6' handling and equipping of this center can do much to simplify and expedite the work carried on in the labs. Dtill Presses Four 14",light dity One 24",heavy duty, back-geared Hacksaws Tno standard reciprocating-type
There always seeks to he a tendency to distribute more types of service to laboratories where chemical
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JULY, 1947
work is done than are really needed. Such overequipping not only adds to the initial investment but is a constant source of expense for upkeep. Water: Water should certainly be provided in all laboratories, the glass-blowing room, the shop, and the apparatus storage room. Hot water should be available in all toilets and washrooms. However, a t other points where heated water is necessary, it is less expensive to install steam mixers on cold water faucets, thus eliminating the necessity for piping hot water throughout the huildiig and for installing a large hot water heatiig system. These steam mixers have worked entirely satisfactorily a t Cambridge. Distilled water should he availahle a t several points in the building, hut certainly not more than one or two outlets will be needed even in the largest laboratories. Gas: Gas is a necessity in all laboratories as well as in the glass-blowing room, the shop, and the apparatus storage and loan space. At least a three-inch main should he run in the laboratories where large-scale research equipment will he built. The tendency seems, however, to use less gas for heating and more electricity in research and experimental work. Although the meter in the laboratories a t Cambridge has a capacity of 5000 cubic feet per hour, the maximum demand which has ever been made on it is slightly over 1100 cubic feet per hour. Steam: Low pressure steam will he useful in all lahoratories and high pressure steam should he availahle a t a few locations in those laboratories where relatively large-scale research apparatus will be operated. It is doubtful whether compressed air should be distributed from a central point. Such a system is always inadequate and we have found it extremely convenient to use small, portable, motor-operated compressors wherever a source of air is needed. A permanently installed vacuum system will be of little utility. Most of them do not work satisfactorily and certainly from the point of convenience and cost, it is much better to have available small, motor-operated vacuum pumps or to use small steam or water ejectors. Electricity: The electrical distribution system is exceedingly important and every attempt should be made to install lines of sufficient capacity. Three-phase, 110volt circuits should be availahle in all laboratories and 220 volts should be distributed to any locations where considerable amounts of power will be used In addition, provision must be made for the operation of small, single-phase, 110-volt motors throughout the building. Where direct current is required, either small, dry plate rectifiers or small motor generators are recommended. The latter are exceedingly convenient, and by control of field resistance practically any voltage up to the maximum availahle from the machine can be had. Such a unit as this is ideal for supplying energy to electrical heating apparatus not only where smooth, stepless control is needed hut, in addition, where the use of alternating current would affect thermocouples. These motor generator units should be availahle in sizes from approximately 250 watts up to
two kilowatts. For connecting apparatus requiring more than a few hundred watts, boxes containing 25ampere circuit breakers can be liberally distributed throughout the laboratories. These make convenient points from which research workers can take considerable amounts of electrical energy. Drainage: Floor drainage is needed in all rooms with the exception of offices, classrooms, and conference rooms. Such drains not only can carry off spilled water and solutions, but also provide a convenient point for discarding cooling water from apparatus.' In addition, they provide an outlet for the water from emergency showers which will of course he installed a t convenient points throughout the laboratory sections of the building. Utility Loops: Throughout the larger laboratories, especially those where research equipment of some size will be operated, it has been found convenient to distribute the various services in the form of loops running around the outer edges of the laboratories. It is. common practice to provide the electrical loops with many convenient outlet points. The same idea should be extended to the pipes carrying water, steam, and gas. About every 12 or 15 feet throughout these circuits, a tee should be inserted and the side outlet of the tee provided with a valve followed by a plug. This arrangement enables a research worker to gain access to any of the services'so equipped without the necessity of interfering with other equipment or obtaining the services of a skilled mechanic to make the required connection. Probably these service loops are most conveniently carried on the ceilings of the various laboratories where they are not only out of the way but immediately available for repair. Fume Hoods: Everyone seems to have his own ideas concerning hood design., Probably soapstone is still the most satisfactory material of construction. However, some of the newer plastic-bonded plywoods with a proper surface protection can be used to advantage with a very considerable saving in cost. All hoods should he provided with glazed sliding fronts. Open hoods have never proved successful in chemical engineering work a t Technology. Separate exhaust fans and ducts should be used for each small group of hoods, and preferably, for each individual hood. A large number of units connected through a single duct to a single exhaust fan is always unsatisfactory and in some instances may be hazardous due to the practical impossibility of keeping the flow through all balanced. It will be found advantageous to light hoods by fluorescent fixtures mounted outside the top section, the light being admitted through glazed areas. In this way corrosion of the lighting fixtures and the associated electrical circuits can be largely eliminated. EQUIPMENT
It: is seldom, indeed, that equipment of commercial size has any place in an educational laboratory. With the exception of air and water, there is practically never sufficientmaterial available in the ordinary edu-
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cational laboratory for processing in commercial-size equipment. Moreover, the upkeep and the cost ,of operating such units is excessive in comparison with the benefits derived. All the engineering principles and most of the design details can be illustrated and studied much more readily a t less expense, but just as effectively, on small or medinm-size equipment as on large units. Even where full-size equipment can be obtained a t no cost, the gift often turns out to be an expensive one. Moreover, once installed, it is exceedingly difficult to get rid of such apparatus even though it has become obsolete and has entirely outlived its original minor usefulness. Not only should the equipment be of small size, but wherever a t all practical, it should be skid-mounted and raised sufficiently so that a small hand-operated hydraulic truck can be slid under it to facilitate moving. None of the apparatus installed should he considered
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permanent. During periods of inactivity, apparatus should be removed to storage areas, and when apparatus has outlived its usefulness it should be discarded. CONCLUSIONS
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The fundamental ideas of utility, flexibility, and cost should be kept in mind not only in the construction but in the operation of any chemical engineering laboratory. Every'attempt should be made to prevent the laboratory from becoming static. To this end the design should include provision for periodic.modernization. All equipment should he considered of a temporary rather than a permanent nature. I t should .be so installed that it will be readily removable, thus making space for newer, more useful units. Close adherence to these principles will not only do much toward limiting the cost and the size of a laboratory, but will insure that it stays young with age.
