Work bench

A good indication of the student s technique will be apparent from the appearance of the working bench. 

Work benches A bench on which a process is carried out. 

Some experimenting nught be necessary if it turns out that quadratic terms such as improve the fit between the model and the data. However, the relevant point is that such a model is only a means to refine and speed up the process of finding optimal conditions. For this purpose it is counter-productive to try for a perfect fit, it might even be advantageous to keep the model simple and throw out all but the best five to 10 experiments, choose new conditions, and then return to the work bench. 

A typical laboratory that has been in operation for some time usually has run out of space for optimum operation. In some cases, the space may be there but cannot be utilized to full advantage. Work benches gradually get covered with permanent equipment set-ups, leaving little room for other work. Lack of storage space for supplies and samples becomes the rule rather than the exception. Adequate room for a desk, bookcase, or typewriter has often been overlooked. As more personnel is added, these problems become critical. Overcrowding also has a serious effect on safety. 

There is more to a laboratory than work benches and the instruments mounted on them. Free-standing equipment must also be considered. This includes refrigerators, safety storage cabinets for chemicals, safety shower, desk space, typewriter stand or computer terminal, or any other equipment that is not bench-mounted. File cabinets, which are real space-robbers, must not be forgotten. In one laboratory, much space was saved by placing two-drawer file cabinets beneath the large table used for sorting samples. 

Preparation Space. The stockroom should have space for preparation of solutions and other items, such as unknowns for courses in qualitative analysis. This requires a regular work bench with sink. There must also be room for prepared solutions to be dispensed to student laboratories in bench-sized bottles, which take up a good deal of space. 

The distance between work benches should not be less than four feet. In one laboratory an extra bench was fitted into a large room by decreasing this distance to three feet, but the result was serious congestion. In educational laboratories, five feet would be advisable because of heavier traffic. 

Educational laboratories often have island work benches, generally with a sink at one or both ends. Depending on room size, a peninsula arrangement could save considerable cost with no loss in efficiency. 

Laboratory storage cabinets and shelves are available in different widths and are usually 12 inches deep. A depth of more than this is not recommended unless large, bulky items are to be stored. Narrower shelves, six to nine inches deep, have been found more practical for reagents and other small items. If shelves and cabinets are to be mounted on walls above work benches, possible interference with work performed there must be considered. Three feet or more should be allowed for aisles. 

The laboratory workers office space should be as close as possible to work areas and to fi equently used files. There should also be room for a typewTiter, if required. The work may be done on a separate desk or a section of desk-height work bench. 

Gradually all things that are to go into the laboratory, such as work benches, refrigerators, safety storage cabinets, floor-mounted equipment, desks, file cabinets, balance tables, and a myriad of other items, are in place. Now is another good time to check on traffic patterns. Will a piece of equipment stick out too far Will a desk chair cause obstruction Will the refrigerator door cause problems when open These are just a few of the questions that should be asked again. 

Waste containers and stools are frequent occupants of laboratory aisles, where they may cause congestion. One answer to this is to provide a sufficient number of knee-holes in the work benches to hold them. 

Food in most cases should not be in the laboratory, not even candy bars. There is always a chance that food products could become contaminated by chemicals on the work bench or on unwashed hands. There should be designated areas where food can be consumed. 

In the laboratory, wastes are collected in suitable containers placed in convenient locations. Kneeholes in work benches are... 

Catalyzed paints, while quite expensive, do have superior coverage as well as excellent protective qualities. They can be used not only on walls but on work benches, equipment, or any other paintable surface. 

Colors in a laboratory should be coordinated, just as in a home. If pre-finished work benches are to be installed, they might set the color scheme. While they are available in several colors or combination of colors, the choice is not unlimited. In one case, the laboratory operator was color blind, so his wife took over the job as decorator. First, she selected a two-color scheme for the work benches. Color chips in hand, she then chose a floor covering from a number of samples submitted. For the wall paint, she found a standard color of the recommended quality that harmonized with the cabinets. A few appropriate charts and a colorful cloth wall-hanging of pipes and valves completed the decor. The result received many favorable comments from visitors to the facility. 

In another case, a wooden structure was built to hold equipment. A paint dealer matched the work bench color, which made the painted structure look like an expensive built-in. 

Work benches and fume hoods constitute a major cost factor in any laboratory. A careful study of available products and good planning, however, can bring about significant savings with no loss in serviceability. 

Distributors of general laboratory equipment also offer one or more lines of work benches and fume hoods, often shown in a separate catalog. In addition, there are several companies specializing in this field. The annual LabGuide issue of Analytical Chemistry, published by the American Chemical Society, has a good listing of suppliers. A laboratory planner should obtain catalogs from several sources and compare both features and prices. 

The general layout of work benches, including hoods, was described in Chapter 2. Now comes the decision about where there should be drawers, cupboards, or other features. Small, shallow drawers, for instance, are just right for storing hydrometers and similar pieces of equipment and should be close to where these are to be used. Burets also need shallow drawers, but they must be wide. Certain pieces of glassware need fairly deep drawers. Much equipment calls for cupboards of certain sizes. 

A work bench rarely consists of a solid bank of cabinets. So-called knee-holes are placed in appropriate locations for sit-down work. Stools can be stored in them when not in use. They are also good for keeping waste containers out of the traffic pattern. 

Bringing in the various utilities, such as water, gas, and electric power, has been discussed in Chapter 3. While the work benches are being installed, the utilities will be hooked up to suitable outlets, or inlets in case of the sewer. This is another area where good planning can produce significant savings with no loss in performance or durability. 

This problem can be avoided by mounting utility outlets above the work benches. This method also has the advantage of keeping the benches clear of obstructions and easy to clean. Of course, exposed water pipes and electrical conduit do not have much esthetic value, and they are dust catchers as well. A coat of paint, however, both improves their appearance and makes cleaning easier. An even better solution is to box them in and cover them with removable panels. 

In an educational laboratory such overhead mounting must be planned with care. The typical work benches here are either peninsulas or islands where the utility box would go down the center with a shelf on top. The total height must be such that the instructor is able to look over the shelf in order to supervise a class. To complicate matters, there may be a waste water trough along the center of the bench which requires some free space above it. These multiple requirements present a challenge to the designer. 

Drain troughs are often put along the center of the island or peninsula type work benches, sometimes with water outlets... 

Compressed air is often required in the laboratory. In some cases, it comes from a compressor beneath the work bench, while in others, the compressor may be at some remote location in the building. 

Electrical outlets can be installed in one of several ways. Small pedestals holding two or more outlets are often placed along the rear of wall-mounted work benches. They may also be put along the center of peninsulas or islands. Wiring is from below the countertop, which makes modifications difficult, just as with plumbing. While easy to reach, pedestals clutter the top and interfere with cleaning. 

Some laboratories have installed outlets on the front of work benches, just below the top. Dangling wires from such outlets are at best a nuisance and could also be hazardous. This method of installation is not recommended. 

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