The notes and legend section of a drawing provides explanations of special symbols or conventions used on the drawing and any additional information the designer or draftsman felt was necessary to understand the drawing. Categories of Drawings The previous chapter reviewed the non-drawing portions of a print. This chapter will introduce the five common categories of drawings. Examples are piping layout, flowpaths, pumps, valves, instruments, signal modifiers, and controllers, as illustrated in Figure 6.
Just because two pieces of equipment are drawn next to each other does not indicate that in the plant the equipment is even in the same building; it is just the next part or piece of the system. These drawings only present information on how a system functions, not the actual physical relationships.
Electrical Single Lines and Schematics Electrical single lines and schematics are designed to present functional information about the electrical design of a system or component. Examples of typical single lines are site or building power distribution, system power distribution, and motor control centers. Figure 7 is an example of an electrical single line. Electrical schematics provide a more detailed level of information about an electrical system or component than the single lines.
Electrical Figure 7 Example of a Single Line schematic drawings present information such as the individual relays, relay contacts, fuses, motors, lights, and instrument sensors. Examples of typical schematics are valve actuating circuits, motor start circuits, and breaker circuits. Electrical single lines and schematics provide the most concise format for depicting how electrical systems should function, and are used extensively in the operation, repair, and modification of the plant.
These drawings are usually used by circuit designers and electronics repair personnel. Figure 9 Example of an Electronic Diagram Rev. The most common use is to provide a simplified functional representation of an electrical circuit, as illustrated in Figure For example, it is easier and faster to figure out how a valve functions and responds to various inputs signals by representing a valve circuit using logic symbols, than by using the electrical schematic with its complex relays and contacts.
These drawings do not replace schematics, but they are easier to use for certain applications. Figure 10 Example of a Logic Print Fabrication, Construction, and Architectural Drawings Fabrication, construction, and architectural drawings are designed to present the detailed information required to construct or fabricate a part, system, or structure.
These three types of drawings differ only in their application as opposed to any real differences in the drawings themselves. Construction drawings, commonly referred to as "blueprint" drawings, present the detailed information required to assemble a structure on site. Architectural drawings present information about the conceptual design of the building or structure.
Examples are house plans, building elevations outside view of each side of a structure , equipment installation drawings, foundation drawings, and equipment assembly drawings. Fabrication drawings, as shown in Figure 11, are similar to construction and architectural drawing but are usually found in machine shops and provide the necessary detailed information for a craftsman to fabricate a part.
All three types of drawings, fabrication, construction, and architectural, are usually drawn to scale. PR Page 14 Rev. The standard formats are single line, pictorial or double line, and cutaway. Each format provides specific information about a component or system.
The single line format represents all piping, regardless of size, as single line. All system equipment is represented by simple standard symbols covered in later modules. By simplifying piping and equipment, single lines allow the system's equipment and instrumentation relationships to be clearly understood by the reader. Figure 13 provides an example illustration of a pictorial drawing.
This format is rarely used since it requires much more effort to produce than a single line drawing and does not present any more information as to how the system functions. Compare the pictorial illustration, Figure 13, to the single line of the same system shown in Figure Pictorial or double line drawings are often used in advertising and training material. PR Page 16 Rev. As seen in Figure 14, an assembly drawing is a pictorial view of the object with all the components shown as they go together.
This type pictorial is usually found in vendor manuals and is used for parts identification and general information relative to the assembly of the component. Figure 14 Example of an Assembly Drawing Rev. In a cutaway, as the name implies, the component or system has a portion cut away to reveal the internal parts of the component or system.
Figure 15 is an illustration of a cutaway. This type of drawing is extremely helpful in the maintenance and training areas where the way internal parts are assembled is important. The most commonly used are the orthographic projection and the isometric projection. Orthographic Projections Orthographic projection is widely used for fabrication and construction type drawings, as shown in Figure Orthographic projections present the component or system through the use of three views, These are a top view, a side view, and a front view.
Other views, such as a bottom view, are used to more fully depict the component or system when necessary. The orthographic projection is typically drawn to scale and shows all components in their proper relationships to each other. The three views, when provided with dimensions and a drawing scale, contain information that is necessary to fabricate or construct the component or system. This provides a more realistic three- dimensional view. As shown on Figure 18, this view makes it easier to see how the system looks and how its various portions or parts are related to one another.
Isometric projections may or may not be drawn to a scale. Figure 18 Example of an Isometric Rev. Figure 22 Symbols for Rotary Actuators. Globe valve g. Relief valve b. Gate valve h. Rupture disk c. Ball valve i. Three-way valve d. Check valve j. Four-way valve e.
Stop check valve k. Throttle needle valve f. Butterfly valve l. Pressure regulator 1. Diaphragm valve operator b. Motor valve operator c. Solenoid valve operator d. Piston hydraulic valve operator e.
Hand manual valve operator f. Reach-rod valve operator 1. Process b. Pneumatic c. Hydraulic d. Inert gas e. Instrument signal electrical f. Instrument capillary g. Electrical Rev. Differential pressure cell b. Temperature element c.
Venturi d. Orifice e. Rotometer f. Conductivity or salinity cell g. Radiation detector 1. Proportional b. Proportional-integral c. Proportional-integral-differential d.
Square root extractors 1. Centrifugal pumps b. Positive displacement pumps c. Heat exchangers d. Compressors e. Fans f. Tanks g. Open valve b. Closed valve c. Throttled valve d. Combination valves 3- or 4-way valve e. Locked-closed valve f. Locked-open valve g.
Fail-open valve h. Fail-closed valve i. Fail-as-is valve 1. Pump b. Compressor c. Reservoir d. Actuators e. Piping and piping junctions f. Valves 1. PR Page x Rev. B all valve i. Pressure regulator EO 1.
M otor valve operator c. Reach rod valve operator EO 1. Process e. Instrum ent signal electrical b. Pneum atic f. Instrum ent capillary c. Hydraulic g. Electrical d. Inert gas Rev. Differential pressure cell e. Rotom eter b. Tem perature element f. Conductivity or c. Venturi salinity cell d. Orifice g. Radiation detector EO 1. Square root extractors EO 1. Centrifugal pum ps e.
Fans b. Positive displacement pum ps f. Tanks c. Heat exchangers g. This chapter discusses the common symbols that are used to depict fluid system components. The reader should note that this chapter is only representative of fluid system symbology, rather than being all-inclusive. The reader may expand his or her knowledge by obtaining and studying the appropriate drafting standards used at his or her facility. Figure 1 shows the symbols that depict the major valve types. It shoud be noted that globe and gate valves will often be depicted by the same valve symbol.
In such cases, information concerning the valve type may be conveyed by the component identification number or by the notes and legend section of the drawing; however, in many instances even that may not hold true. Figure 1 Valve Symbols Rev. Figure 2 shows the symbols for the common valve actuators. Note that although each is shown attached to a gate valve, an actuator can be attached to any type of valve body. If no actuator is shown on a valve symbol, it may be assumed the valve is equipped only with a handwheel for manual operation.
Figure 2 Valve Actuator Symbols The combination of a valve and an actuator is commonly called a control valve. Control valves are symbolized by combining the appropriate valve symbol and actuator symbol, as illustrated in Figure 2. Control valves can be configured in many different ways. The most commonly found configurations are to manually control the actuator from a remote operating station, to automatically control the actuator from an instrument, or both.
In many cases, remote control of a valve is accomplished by using an intermediate, small control valve to operate the actuator of the process control valve.
The intermediate control valve is placed in the line supplying motive force to the process control valve, as shown in Figure 3. In this example, air to the process air-operated control valve is controlled by the solenoid-operated, 3-way valve in the air supply line. The 3-way valve may supply air to the control valve's diaphragm or vent the diaphragm to the atmosphere.
Further, Figure 3 is incomplete in that it does not show the electrical portion of the valve control system nor does it identify the source of the motive force compressed air. Although Figure 3 informs the reader of the types of mechanical components in the control system and how they interconnect, it does not provide enough information to determine how those components react to a control signal. Control valves operated by an instrument signal are symbolized in the same manner as those shown previously, except the output of the controlling instrument goes to the valve actuator.
Figure 4 shows a level instrument designated "LC" that controls the level in the tank by positioning an air-operated diaphragm control valve. Again, note that Figure 4 does not contain enough information to enable the reader to determine how the control valve responds to a change in level. Figure 4 Level Control Valve An additional aspect of some control valves is a valve positioner, which allows more precise control of the valve.
This is especially useful when instrument signals are used to control the valve. An example of a valve positioner is a set of limit switches operated by the motion of the valve. A positioner is symbolized by a square box on the stem of the control valve actuator.
The positioner may have lines attached for motive force, instrument signals, or both. Figure 5 shows two examples of valves equipped with positioners. Note that, although these examples are more detailed than those of Figure 3 and Figure 4, the reader still does not have sufficient information to fully determine response of the control valve to a change in control signal. However, the reader cannot ascertain whether it opens or closes the control valve.
Also, the reader cannot determine in which direction the valve moves in response to a change in the control parameter. In Example B of Figure 5, the reader can make the same general assumptions as in Example A, except the control signal is unknown. Without additional information, the reader can only assume the air supply provides both the control signal and motive force for positioning the control valve.
Even when valves are equipped with positioners, the positioner symbol may appear only on detailed system diagrams. Larger, overall system diagrams usually do not show this much detail and may only show the examples of Figure 5 as air-operated valves with no special features.
Control Valve Designations A control valve may serve any number of functions within a fluid system. To differentiate between valve uses, a balloon labeling system is used to identify the function of a control valve, as shown in Figure 6. The common convention is that the first letter used in the valve designator indicates the parameter to be controlled by the valve. The third letter is a "V" to indicate that the piece of equipment is a valve. For example, although the main process flow line may carry water, the associated auxiliary piping may carry compressed air, inert gas, or hydraulic fluid.
Also, a fluid system diagram may also depict instrument signals and electrical wires as well as piping. Figure 7 shows commonly used symbols for indicating the medium carried by the piping and for differentiating between piping, instrumentation signals, and electrical wires.
Note that, although the auxiliary piping symbols identify their mediums, the symbol for the process flow line does not identify its medium. Figure 7 Piping Symbols Rev.
Figure 8 shows symbols used to depict pipe fittings. The symbols used to represent instruments and their loops can Figure 8 More Piping Symbols be divided into four categories. Generally each of these four categories uses the component identifying labeling scheme identified in Table 1. The first column of Table 1 lists the letters used to identify the parameter being sensed or monitored by the loop or instrument.
The second column lists the letters used to indicate the type of indicator or controller. The third column lists the letters used to indicate the type of component. The fourth column lists the letters used to indicate the type of signals that are being modified by a modifier.
PR Page 8 Rev. The fourth column is used only in the case of an instrument modifier and is used to indicate the types of signals being modified. The following is a list of example instrument identifiers constructed from Table 1. To create a usable signal, a device must be inserted into the system to detect the desired parameter.
In some cases, a device is used to create special conditions so that another device can supply the necessary measurement. Figure 9 shows the symbols used for the various sensors and detectors. The exceptions are certain types of local instrumentation having mechanical readouts, such as bourdon tube pressure gages and bimetallic thermometers.
Figure 10 illustrates various examples of modifiers and transmitters. Figure 10 also illustrates the common notations used to indicate the location of an instrument, i. Transmitters are used to convert the signal from a sensor or detector to a form that can be sent to a remote point for processing, controlling, or monitoring. The output can be electronic voltage or current , pneumatic, or hydraulic. Figure 10 illustrates symbols for several specific types of transmitters.
Figure 10 Transmitters and Instruments Rev. The indicator or recorder may be locally or board mounted, and like modifiers and transmitters this information is indicated by the type of symbol used. Figure 11 provides examples of the symbols used for indicators and recorders and how their location is denoted. Controllers Controllers process the signal from an instrument loop and use it to position or manipulate some other system component. Generally they are denoted by placing a "C" in the balloon after the controlling parameter as shown in Figure There are controllers that serve to process a signal and create a new signal.
These include proportional Figure 11 Indicators and Recorders controllers, proportional-integral controllers, and proportional-integral-differential controllers. The symbols for these controllers are illustrated in Figure Note that these types of controllers are also called signal conditioners.
Figure 14 A shows a temperature transmitter TT , which generates two electrical signals. One signal goes to a board- mounted temperature recorder TR for display. The function of the complete loop is to modify flow based on process fluid temperature. Knowing the setpoint and purpose of the system will usually be sufficient to allow the operation of the instrument loop to be determined.
The output of the level transmitter is pneumatic and is routed to a board-mounted level modifier LM. The level modifier conditions the signal possibly boosts or mathematically modifies the signal and uses the modified signal for two purposes. The modifier drives a board-mounted recorder LR for indication, and it sends a modified pneumatic signal to the diaphragm-operated level control valve. Notice that insufficient information exists to determine the relationship between sensed tank level and valve operation.
Components Within every fluid system there are major components such as pumps, tanks, heat exchangers, and fans. Figure 15 shows the engineering symbols for the most common major components. Figure 16 lists and explains four of the more common miscellaneous symbols.
Figure 16 Miscellaneous Symbols Summary The important information in this chapter is summarized below. To accurately interpret a drawing, these standards and conventions must be understood. Open valve e. Locked-closed valve b. Closed valve f. Locked-open valve c. Throttled valve g. Fail-open valves d. Com bination valves h. Fail-closed valve 3- or 4- way valve i.
The reader must be able to determine the valve position, know if this position is normal, know how the valve will fail, and in some cases know if the valve is normally locked in that position.
Figure 17 illustrates the symbols used to indicate valve status. This is usually interpreted as the normal or primary flowpath for the system. An exception is safety systems, which are normally shown in their Figure 17 Valve Status Symbols standby or non-accident condition. This will either be defined as the standard by the system of drawings or noted in some manner on the individual drawings.
Exa mple At this point, all the symbols for valves and major components have been presented, as have the conventions for identifying the condition of a system. Refer to Figure 18 as necessary to answer the following questions. The answers are provided in the back of this section so that you may judge your own knowledge level.
PR Page 18 Rev. Identify the following components by letter or number. Centrifugal pump b. Heat exchanger c. Tank d. Venturi e. Rupture disc f. Relief valve g. Motor-operated valve h. Air-operated valve i. Throttle valve j. Conductivity cell k. Air line l. Current-to-pneumatic converter m. Check valve n. A locked-closed valve o. A closed valve p. A locked-open valve q. A solenoid valve 2. What is the controlling parameter for Valves 10 and 21? Which valves would need to change position in order for Pump B to supply flow to only points G and H?
Which valves will fail open? Fail closed? Fail as is? PR Page 20 Rev. Temperature as sensed by the temperature elements TE 3. PR Page 22 Rev. Pum p d. Actuators b. Com pressor e. Piping and piping junctions c. Reservoir f. Valves EO 1.
Fluid Power Diagra ms and Schematics Different symbology is used when dealing with systems that operate with fluid power.
Fluid power includes either gas such as air or hydraulic such as water or oil motive media. Some of the symbols used in fluid power systems are the same or similar to those already discussed, but many are entirely different. Fluid power systems are divided into five basic parts: pumps, reservoirs, actuators, valves, and lines. Pumps In the broad area of fluid power, two categories of pump symbols are used, depending on the motive media being used i. The basic symbol for the pump is a circle containing one or more arrow heads indicating the direction s of flow with the points of the arrows in contact with the circle.
Hydraulic pumps are shown by solid arrow heads. Pneumatic compressors are represented by hollow arrow heads. Figure 19 provides common Figure 19 Fluid Power Pump and symbols used for pumps hydraulic and compressors Compressor Symbols pneumatic in fluid power diagrams. Although the symbols used to represent reservoirs vary widely, certain conventions are used to indicate how a reservoir handles the fluid. Pneumatic reservoirs are usually simple tanks and their symbology is usually some variation of the cylinder shown in Figure Hydraulic reservoirs can be much more complex in terms of how the fluid is admitted to and removed from the tank.
To convey this information, symbology conventions have been developed. These symbols are in Figure Figure 20 Fluid Power Reservoir Symbols Actuator An actuator in a fluid power system is any device that converts the hydraulic or pneumatic pressure into mechanical work. Actuators are classified as linear actuators and rotary actuators. Linear actuators have some form of piston device. Figure 21 illustrates several types of linear actuators and their drawing symbols. PR Page 24 Rev.
Several of the more common rotary symbols are shown in Figure Note the similarity between rotary motor symbols in Figure 22 and the pump symbols shown in Figure The difference between them is that the point of the arrow touches the circle in a pump and the tail of the arrow touches the circle in a motor. Full Record Other Related Research. Abstract The Mathematics Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of mathematics and its application to facility operation.
Publication Date: Research Org. United States: N. Copy to clipboard. United States. Other availability. Please see Document Availability for additional information on obtaining the full-text document.
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