Equipment Metering

Each problem will have its own solution or solutions (Fig. 2-17). Simplified guides to troubleshooting granulators, conveying equipment, metering/pro-portioning equipment, chillers, and dehumidifiers are available (1-3, 6-8, 33-35). 

Implants Lighting Medical appliances Memory back-up Meteorological equipment Meters, test equipment, and instrumentation Signals and alarms Telephones Tools Toys Watches, clocks Uninterruptible power systems ... 

The GAMMASCAN 1500 HR is a combined system for two-dimensional (2D-CT) and three-dimensional (3D-CT) computed tomography, as well as digital radiography (DR). The system is equipped with two separate detector systems for the fan-beam and cone-beam CT. The sire of the objects is limited to a height of four meters, maximum diameters of 1.5 meters and a weight of up to 15 tons. The turntable which carries the test samples can be moved along and across the beam direction ( X- and Y- direction). The radiation source and the detector systems can be moved in Z- direction, both, simultaneously and independently. 

The use of more complex or more costly articles of equipment, such as catalytic hydrogenation apparatus, autoclaves, polari-meters, ultraviolet absorption spectrometers, etc., has not been described, because the type of such apparatus employed indifferent laboratories varies considerably, and students must be taught the use of their own laboratory equipment. 

A pH electrode is normally standardized using two buffers one near a pH of 7 and one that is more acidic or basic depending on the sample s expected pH. The pH electrode is immersed in the first buffer, and the standardize or calibrate control is adjusted until the meter reads the correct pH. The electrode is placed in the second buffer, and the slope or temperature control is adjusted to the-buffer s pH. Some pH meters are equipped with a temperature compensation feature, allowing the pH meter to correct the measured pH for any change in temperature. In this case a thermistor is placed in the sample and connected to the pH meter. The temperature control is set to the solution s temperature, and the pH meter is calibrated using the calibrate and slope controls. If a change in the sample s temperature is indicated by the thermistor, the pH meter adjusts the slope of the calibration based on an assumed Nerstian response of 2.303RT/F. 

Economic Considerations. The principal economic consideration is, of course, total installed system cost, including the initial cost of the flow primary, flow secondary, and related ancillary equipment as well as material and labor required for installation. Other typical considerations are operating costs and the requirements for scheduled maintenance. An economic factor of increasing importance is the cost of disposal at the end of normal flow meter service life. This may involve meter decontamination if hazardous fluids have been measured. 

Flow measuring equipment must generally be wet caHbrated to attain maximum accuracy, and principal flow meter manufacturers maintain extensive facihties for this purpose. In addition, a number of governments, universities, and large flow meter users maintain flow laboratories. 

Process and Equipment. Rigid polyurethane foam processes use the same high or low pressure pumping, metering, and mixing equipment as earher described for flexible foams. Subsequent handling of the mixture is deterrnined by the end product desired. 

X 10 m (l.9x lO " /t ) of heHum in each cubic meter (35 ft ) of air entering the air separation process, the small quantities of cmde coUected in even a large air separation unit may be easily appreciated. It is sometimes desirable, therefore, to combine cmdes coUected from several air plants and to process them at a centralized location in specialized equipment. 

Specialized equipment for industrial measurements and automatic control have been developed (18) (see Process control). In general, the pH of an industrial process need not be controlled with great accuracy. Consequendy, frequent standardization of the cell assembly may be uimecessary. On the other hand, the ambient conditions, eg, temperature and humidity, under which the industrial control measurements are made, may be such that the pH meter must be much more robust than those intended for laboratory use. To avoid costiy downtime for repairs, pH instmments may be constmcted of modular units, permitting rapid removal and replacement of a defective subssembly. 

Industrial and Control Instruments. Mercury is used in many industrial and medical instmments to measure or control reactions and equipment functions, including thermometers, manometers (flow meters), barometers and other pressure-sensing devices, gauges, valves, seals, and navigational devices (see Pressure measurements Process control Temperature measurement). Whereas mercury fever thermometers are being replaced by... 

Batch processes for most phenoHc resins employ the equipment shown in Figure 2. Liquid reactants are metered into the stirred reaction vessel through weigh tanks, whereas soHd reactants such as bisphenol A and Ba(OH)2 present handling problems. FaciHties are provided to carry out the reaction under a vacuum or an inert gas. 

The location of exchangers is the key to maintenance. Usually the back head is kept at a distance of about three meters from the piperack support columns. Access equipment must be able to get in and remove the sheU cover and flange head. Access area must also be provided to handle and remove the sheU cover usually located under the piperack. The tube-pulling or rodding-out area must be kept clear to allow access to the channel end. This space should be at least equal to the tube length and about two meters from the tube sheet location. Tube removal space should be allowed for but is not mandatory if grade-mounted heat exchangers are used and mobile maintenance equipment employed to pick up the entire unit and transfer it to the repair shop. 

Fig. 14. Outside battery limit (OSBL) equipment spacing. Minimum spacing for off-site equipment is in meters. Classifications of tankage are Class 1 high ha2ard, flash point below 38°C Class 2 low ha2ard, flash point above 38°C. NFPA = National Fine Protection Association. Safety standards are calculated...

Urethanes are processed as mbber-like elastomers, cast systems, or thermoplastic elastomers. The elastomer form is mixed and processed on conventional mbber mills and internal mixers, and can be compression, transfer, or injection molded. The Hquid prepolymers are cast using automatic metered casting machines, and the thermoplastic peUets are processed like aU thermoplastic materials on traditional plastic equipment. The unique property of the urethanes is ultrahigh abrasion resistance in moderately high Shore A (75—95) durometers. In addition, tear, tensUe, and resistance to many oUs is very high. The main deficiencies of the urethanes are their resistance to heat over 100°C and that shear and sliding abrasion tend to make the polymers soft and gummy. 

Techniques for handling sodium in commercial-scale appHcations have improved (5,23,98,101,102). Contamination by sodium oxide is kept at a minimum by completely welded constmction and inert gas-pressured transfers. Residual oxide is removed by cold traps or micrometallic filters. Special mechanical pumps or leak-free electromagnetic pumps and meters work well with clean Hquid sodium. Corrosion of stainless or carbon steel equipment is minimi2ed by keeping the oxide content low. The 8-h TWA PEL and ceiling TLV for sodium or sodium oxide or hydroxide smoke exposure is 2 mg/m. There is no defined AID for pure sodium, as even the smallest quantity ingested could potentially cause fatal injury. 

Saline Water for Municipal Distribution. Only a very small amount of potable water is actually taken by people or animals internally, and it is quite uneconomical to desalinate all municipally piped water, although all distributed water must be clear and free of harmful bacteria. Most of the water piped to cities and industry is used for Htfle more than to carry off small amounts of waste materials or waste heat. In many locations, seawater can be used for most of this service. If chlorination is requited, it can be accompHshed by direct electrolysis of the dissolved salt (21). Arrayed against the obvious advantage of economy, there are several disadvantages use of seawater requites different detergents sewage treatment plants must be modified the usual metal pipes, pumps, condensers, coolers, meters, and other equipment corrode more readily chlorination could cause environmental poUution and dual water systems must be built and maintained. 

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