Equipment symbols Instruments

Ejectors, steam/water requirements, 371 Electrical charge on tanks, 537 Electrical precipaiaiors, 280 Applications, 280, 282 Concept of operation, 281 Emergency relief, 450 Engineering, plant development, 46 Equipment symbols, 19—2 L Abbreviations, 25 Instruments, 21, 26. 29 Piping, 22 Valve codes, 26 Equivalent feel (flow), 86 Estimated design calculation time,... 

The symbols used to show the equipment, valves, instruments and control loops will depend on the practice of the particular design office. The equipment symbols are usually more detailed than those used for the process flow-sheet. A typical example of a P and I diagram is shown in Figure 5.25. 

Useful equipment symbols are shown in Fig. 3-7. Other types of symbols are illustrated in Fig. 3-2. Drawing templates for some of these symbols are available. As mentioned previously, flow-sheet symbols are not as yet standardized within the industry. Hence, symbols should Compass Instrument and Optical Co., New York. 

Teacher desk/table is located at the front of the room Laboratory organization (equipment on teacher desk or table) Symbols of teaching (ABC s, chalkboard, bulletin boards, etc.) Symbols of science knowledge (science equipment, lab instruments, wall charts, etc.)... 

Distillation is a process that separates the components in a mixture by boiling point. At the heart of a distillation system is the column. Distillation columns come in two basic designs plate and packed. Flow arrangements vary from process to process. The symbols allow the technician to identify primary and secondary flow paths. The two standard symbols for distillation columns are shown in Figure 7-13. A distillation system is a complex arrangement of equipment and instruments. In most cases, all of the equipment covered in this text could be found in service within a distillation system. 

Data on spare and parallel equipment are often omitted. Valving is also generally omitted. A alve is shown only where its specification can aid in understanding intermittent or alternate flows. Instrumentation is indicated to show the location of variables being controlled and the location of the actuating device, usually a control valve. To help the reader better understand the process flow sheet, a list of commonly used symbols is presented in Fig. 5.9.1. 

Rather less freedom is allowed in the construction of mechanical flowsheets. The relative elevations and sizes of equipment are preserved as much as possible, but all pumps usually arc shown at the same level near the bottom of the drawing. Tabulations of instrumentation symbols or of control valve sizes or of relief valve sizes also often appear on P I diagrams. Engineering offices have elaborate checklists of information that should be included on the flowsheet, but such information is beyond the scope here. 

Many chemical and petroleum companies are now using Process Industry Practices (PIP) criteria for the development of P IDs. These criteria include symbols and nomenclature for typical equipment, instrumentation, and piping. They are compatible with industry codes of the American National Standards Institute (ANSI), American Society of Mechanical Engineers (ASME), Instrument Society of America (ISA), and Tubular Exchanger Manufacturers Association (TEMA). The PIP criteria can be applied irrespective of whatever Computer Assisted Design (CAD) system is used to develop P IDs. Process Industries Practice (1998) may be obtained from the Construction Industry Institute mentioned in the References. 

The nomenclature used for instrumentation is more complex than for equipment and process lines. Walker (2009) provides a list of commonly used instrument symbols. Typically an instrument balloon on a P ID contains two or three letters followed by five digits. So PI-30012, for example, identifies a pressure indicator number 12 in Section 30. 

Figure 8.18 Driven right leg (RL) circuit for reduced common mode voltage. Differential preamplifier. Input equipped with three-wire connections for two PU electrodes and one RL drive wire. The purpose is to equipotentialize human body and instrument and to reduce the common voltage between electrodes. Note power line ground symbol. See text.

Using STPF conditions, the instrumental response is reasonably stable, both between atomizers of the same type and on a day-to-day basis. As a measure of the response the term characteristic mass , symbolized by nto (pg), has been introduced. This is defined as the absolute mass of analyte yielding an integrated absorbance of 0.0044 s. Characteristic mass values are provided by the instrument manufacturers to specify the performance of the ET-AAS equipment, and can be used to check that certain vital parts of the system (atomizer, light source) are functioning... 

Symbols and diagrams have been developed for most pieces of industrial equipment, process flows, and instrumentation. The symbols covered in this chapter include those typically used with valves, piping, tanks, pumps, compressors, steam turbines, motors, heat exchangers, cooling towers, furnaces, boilers, distillation columns, and reactors. Figure 7-6 shows many of the basic symbols for valves. 

Modern piping and instrumentation drawings show the motor symbol connected to the driven equipment. This equipment may be a pump, compressor, mixer, fan, conveyor, or generator. Figure 7-9 illustrates the standardized symbols for compressors, steam turbines, and motors. 

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