Specialized Pieces of Equipment

Collection of Gas Chromatographic Effluents. The trapping and collection of gas chromatographic liquid fractions become particularly important exercises in microscale experiments. When yields of a liquid product are less than 100 xL conventional distillation, even using microscale equipment, is impractical. 

In this case, preparative gas chromatography replaces conventional distillation as the route of choice to product purification. A number of the reaction products in Chapters 6, 7, and lOW depend on this approach for successful purifi- H[www] cation and isolation. The ease and efficiency of carrying out this operation is greatly fadHtated by employing the 5/5 i collection tube and the 0.1-mL 5/5 I conical collection vial (Chapter 3W, Fig. 3.12W). 

An appliance found in almost all homes is a microwave oven. It is possible to heat food much more quickly and easily using a microwave as compared to the stove top. The observation that microwave energy can be used to heat food 

This section has been written by Dr. Nicholas E. Leadbeater from the Department of Chemistry at the University of Connecticut, and Dr. Cynthia B. McGowan from the Department of Chemistry at Merrimack College, MA. 

There are two ways that microwaves can heat a sample, both involving the interaction of molecules in the sample with the electric field of the microwave irradiation (Fig. 3.22). 

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Because the pellets are susceptible to sintering during heat-up, the annealing takes place in a special piece of equipment known as a roof-type preheater, shown in Figure 4.16. In the preheater, the pellets flow by gravity between the angular roofs. This promotes relative movement between the pellets and also reduces the overall product bulk pressure in the vessel, thereby suppressing the tendency of the pellets to sinter. 

The electron-beam guns may also be integral parts of several special pieces of equipment. Electron-beam evaporation and the related directed vapour deposition technology are relevant examples. 

A special piece of equipment, known as the holiday detector, is a hoop of metal placed around the pipe after it is coated and wrapped. A small electrical current flows through the hoop, If there is a holiday. i.e., a spot where there is no coating, the detector alerts tine operator. This is brought to the attention of a special crew that coats and waps bare spots in tile pipe. 

The achievement and utilization of low temperatures require the use of various specialized pieces of equipment including compressors, expanders, heat exchangers, pumps, transfer lines, and storage tanks. As a general rule,... 

The atomic mass is a number that is used to describe the average mass of an element. It represents the weighted average of the mass of all isotopes of an element. Calculating the atomic mass requires knowledge of the mass numbers of each isotope for an element as well as each isotope s relative abundance. This latter quantity is determined experimentally with the help of a special piece of equipment known as a mass spectrometer. This is not a required calculation on the AP test, but, for clarity, a sample calculation is shown below. 

Eventually, a canner will have a question which requires the use of one of the directories. Perhaps he will want to know who manufactures a special piece of equipment or who sells a particular type of sugar sirup. He may need to know the address of a processor, the owner of a particular label, or how many packers of tomato products there... 

Extraction can be done in a single stage, countercurrent cascades, and cross-flow cascades. Extraction columns may have distinct stages or packing, and many have highly specialized pieces of equipment to facilitate mixing. 

Computerized systems are specialized pieces of equipment which must meet all the requirements as other pieces of equipment. A logical application of the cGMPs should be applied in conjunction with special requirements such as 211 CFR Part 11. Validation is required, however, the depth and scope of the validation is dependent of the computerized application. The degree of validation may be dependent on the source of the computer system commercially available software requires little validation, while software developed for a specific manufacturing step will require extensive validation. Once validated, the computer system must be maintained in a state of control. After all, it is still a piece of equipment, albeit highly specialized. 

The variety of equipment used for extraction is much greater than for distillation, absorption, and stripping. Efficient contacting and separating of two liquid phases is considerably more difficult than contacting and separating a vapor and a liquid. In addition to plate and packed (random, structured and membrane) columns, many specialized pieces of equipment have been developed. Some of these are... 

Depalletizers. Depalletizers are highly specialized pieces of equipment which automatically depalletize cartons and cases. Automatic squaring mechanisms permit the handling of loose pallet loads. Depalletizers generally operate in the range of 3500 cases per hour and are seen primarily in beverage distribution. 

Ultrasonic cleaners are highly specialized pieces of equipment and generally correspond to a U.S. Environmental Protection Agency (EPA)—specified method. It is useful to look at specific cleaner models at this point. 

In order to be effective in imparting various chosen characteristics, all additives employed in a blend must be homogeneously dispersed throughout the blend. The two most commonly employed pieces of equipment for blending rubber and additives are rubber mills and a special type of mechanical mixer known as the Banbury mixer. A typical rubber mill consists of two rolls which rotate toward each... 

The computer could remind the user of any special hazards associated w ith this piece of equipment and its contents and the actions that should be taken. 

Special pieces of downhole equipment and special concerns must be considered during downhole air (or gas) drilling operations. 

One specific piece of equipment, which had to be mounted on a vehicle, was extensively sold for locust control in an underdeveloped country. The roads in this area were not passable to trucks and the machine was mounted on a jeep. The machine was too heavy for a jeep, so the net result was a broken-down jeep and a piece of specialized equipment shaken to pieces by travel over almost impassable terrain. Add to this the complete lack... 

If there is no special reason for elevating equipment, it should be placed on the ground level. The superstructure to support an elevated piece of equipment is expensive. It can also be a hazard should there be an earthquake, fire, or explosion. Then it might collapse and destroy the equipment it is supporting as well as that... 

The smallest pores that can be observed using this approach depend on the highest pressure to which the mercury can be subjected in a particular piece of equipment. Volumes corresponding to pore radii as small as 100 to 200 A can be measured with commercially available equipment. Beyond this point the pressures required to fill up the capillaries with smaller radii become impractical for routine use. Unfortunately, there are many catalysts of industrial significance where these very small capillaries contribute substantially to the specific surface area. Special research grade mercury porosi-meters capable of measurements down to 15 A radii have been developed but, for routine measurements, the desorption approach described below is more suitable. 

Special equipment is itemized in the materials list of each protocol. Listed below are standard pieces of equipment in the modem food science laboratory—i.e., items used extensively in this manual and thus not usually included in the individual materials lists. See suppliers appendix for contact information for commercial vendors of laboratory equipment. 

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