From EA Basic and your own experience, you know that a construction drawing may be one of several different types, and more than one type may be used during the design and construction of a new structure. There are presentation drawings to “sell” an idea or concept, shop drawings to illustrate a material, product, or system and, of course, project (or working) drawings to describe to construction crews the construction of a complete facility or structure. This lesson centers on project drawings pertaining mostly to building construction and the organization of those drawings into their civil, architectural, structural, mechanical, electrical, and fire protection categories or divisions. Besides providing a brief review of these divisions, this lesson also recaps some of the EA Basic information on riser diagrams for plumbing and electrical wiring diagrams, and then expands on elements of heating, ventilating, and air-conditioning systems (HVAC) and drawings. Lastly, it provides you with information and tips you can use when checking and editing project drawings. For NAVFAC policy regarding drawing sizes, formats, and conventions, refer to UFC 1-300-09N Design Procedures and to the various Department of Defense (DOD), American Society for Testing and Materials (ASTM), Whole Building Design Guide (WBDG), and military standards referred to in UFC 1-300-09N.
When you have completed this lesson, you will be able to:
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1.0.0 Project Drawing Divisions
2.0.0 HVAC Systems and Drawings 3.0.0 Checking and Editing Construction Drawings Summary Review Quiz |
Although other divisions may be included when necessary or some excluded when unnecessary, project drawing divisions for a building typically includes civil, architectural, structural, mechanical, electrical, and fire protection. The following paragraphs briefly describe their contents.
The civil division describes a project’s existing conditions and its planned development (Figure 8-1). Figure 8-1 — Example of information provided in the “Civils.” As applicable to a particular project, the “Civils” typically, at a minimum, include drawings that describe the following information:
• Project location (shown on regional and vicinity maps)
• Soil boring logs and profiles
• Existing site conditions o Terrain contours o Buildings or structures o Utilities and drainage o Other physical features on or near the project site For small projects, you can show this information on the site (plot) plan. For large or complex construction projects, develop a separate existing conditions plan.
• Planned demolition as a part of the project o Existing buildings o Structures 8-4 o Utilities o Other physical features Like existing site conditions (above), for small projects show this information on the site plan, or develop a separate demolition plan for larger projects.
• Planned grading o Surface drainage by contours or a combination of contours and spot elevations o Grading and paving of driveways, access roads, and parking areas For grading and paving, show plans, profiles, cross sections, and paving details (curbs, gutters, sidewalks, and so forth) to describe fully the new construction. Depending on the complexity of the project, this can also be placed on the site plan for small projects or be a separate drawing.
• Proposed site plan o Property boundaries o Construction limits o Exact defined locations and finished floor elevations of new buildings or structures using a minimum of two location dimensions o Location and direction of all new utilities unless separate utility site plans are included in other divisions
1.2.0 Architectural Division The architectural division includes drawings affecting the general and specific appearance of a structure (Figure 8-2). Figure 8-2 — Example of information provided in the “Architecturals.” 8-5 Architectural drawings include the following:
• Floor and roof plans
• Interior and exterior elevations
• Millwork
• Door and window schedules
• Finish schedules
• Special architectural treatments
• Nonstructural sections and details Review Chapter 11 of EA Basic to refresh your knowledge of the “Architecturals.”
The structural division contains drawings describing the structural composition and integrity of a structure (Figure 8-3). 8-6 Figure 8-3 — Example of information provided in the “Structurals.” 8-7 Structural drawings include the following:
When applicable, the first sheet should include roof, floor, wind, seismic, and other loads, as well as allowable soil-bearing capacity and allowable stresses of all materials, such as concrete and reinforcing steel. Again, review Chapter 11 of EA Basic to refresh your knowledge of the “Structurals.” <p>14.0 Mechanical Division The mechanical division contains drawings that show the engineered airflow, plumbing features, and related equipment (Figure 8-4). Depending on the size and purpose of a project, you may need to look at the Civils, Mechanicals, and Fire Protections to find all piping requirements. Mechanical drawings include the following:
• Heating, Ventilating, and Air-Conditioning (HVAC)
• Plumbing plans o Water supply o Waste disposal piping o Riser diagrams and details o Fixture schedules Figure 8-4 — Example of information provided in the “Structurals.” 8-8 In the order of drawings in the mechanical division, if applicable, HVAC drawings always precede plumbing drawings. Furthermore, if the project is large enough with significant equipment of both, mechanical drawings may contain only HVAC, with the plumbing or “P” drawings organized as a separate division. Heating, Ventilating, and Air-Conditioning (HVAC) will be presented later in this lesson. A plumbing plan (or layout) is a plan view of the necessary lines, fittings, and fixtures. You can easily prepare a clear plumbing plan for users (planners and estimators, plumbers, inspectors) if the project is an uncomplicated structure with one water closet and one lavatory. A plumbing plan might be all you need for such a building; however, as a structure’s plumbing becomes increasingly complex, it diminishes your ability to describe the plumbing layout accurately and clearly using only a plumbing plan. This can lead to misinterpretations by the users, so for complicated plumbing, common practice is to supplement the layout with riser diagrams. Figure 8-4 is an example of the most common type of isometric riser diagram, a threedimensional representation of the plumbing system. Although not drawn to scale, it should be correctly proportioned, that is, a long or short run of piping in a plumbing plan should appear as a long or short run of piping in a riser diagram. Be sure you use proper symbols (found in ASME Y14.100, Engineering Drawing Practices) for the piping and fittings to make it easy for those familiar with the symbols to read and interpret the drawing. For example, a quick glance at Figure 8-4 shows the user that there are three gate valves and that all of the fittings are screw-type fittings. Properly label the pipe sizes, especially where changes in pipe size occur, and label all fixture connections to identify which fixture fastens to which pipe. Fixtures are spelled out in Figure 8-4, but another common practice is to label the fixtures with an alphanumeric coding keyed to a fixture schedule. Used less often is another type of riser diagram, an orthographic riser diagram showing the plumbing system in elevation. It is normally reserved for buildings that are two or more stories in height, and since you probably cannot clearly describe an entire plumbing system for a building in a single elevation, more than one orthographic riser diagram is necessary for the building. You can find examples of these diagrams in Architectural Graphic Standards, by Ramsey and Sleeper. Review Chapters 9 and 11 of EA Basic to refresh your knowledge of the “Mechanicals.” <p>1.5.0 Electrical Division The electrical division contains drawings that show the power and lighting features (Figure 8-5). 8-9 Electrical drawings include the following:
Electrical single-line block diagrams, as in Figure 8-5 A, identify electrical components and their related connections in a diagrammatic form. Seldom drawn to scale, the diagrams use standard symbols to represent individual pieces of electrical equipment, and lines to represent the wires connecting the equipment. In Figure 8-5 A, two electrical panels (L1 and L2) are planned for installation in a twostory building; notes identify each piece of equipment and indicate the number, size, and type of conductors in each conduit. For this example using electrical panels, there would also be panelboard schedules indicating the components (fuses or circuit breakers) that make up each panel. A schematic wiring diagram is similar but provides information in more detail, and shows the actual number of wires used in each circuit. Complete schematic wiring diagrams are usually used for unique and complicated systems, such as control circuits. Figure 8- 5 B is one example. Review Chapters 10 and 11 of EA Basic to refresh your knowledge of the “Electricals.”
The fire protection division includes the plans, details, and schedules describing the fire protection systems for the structure, including, as applicable, wet-pipe or dry-pipe sprinkler systems, monitoring equipment, and alarms. A presentation of these systems is beyond the scope of this course. Figure 8-5 — Example of information provided in the “Electricals.
| Test Your Knowledge 1. A construction drawing may be one of several different types, but only one type will be used during the design and construction of a new structure.
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An engineer is responsible for designing a heating, ventilating, and air-conditioning system, but it is usually a drafter who prepares the drawings for communication to the field installers (UTs). Consequently, drafters need to have a basic understanding of HVAC terminology and operating principles, some of which are presented in the following paragraphs. For more information in depth about heating principles (including theory, measurement of heat, and heat transfer), and the principles of refrigeration and air conditioning, refer to Utilitiesman Basic and Utilitiesman Advanced.
The purpose a heating system in a structure is obvious: to provide heat for occupants (residents or workers) or equipment in an enclosed space. However, the heat must be properly distributed to the various rooms or zones to be effective. This can be done by various types of heating systems depending on the configuration of the structure.
A warm-air furnace can be any type of heating device that circulates warmed air to locations where needed. A wall heater is one type; it draws in cold air near the floor, passes the air over a heating unit, and then exhausts the warmed air to heat the immediate surrounding area (Figure 8-6). Figure 8-6 — Example of a typical gas or electric wall heater. 8-11 A gravity warm-air furnace is another type (Figure 8-7). This is a direct-fired furnace that transfers heat by convection, that is, the furnacewarmed air rises through ductwork to the areas to be heated, and then as the air cools, it descends to the furnace for reheating. This system requires a basement and the installation of large, unsightly ductwork; it is seldom used in new construction. A forced-air furnace is a third and more commonly used type of warm-air furnace (Figure 8-8). Figure 8-7 — Typical gravity warm-air heating system (individual duct). 8-12 Figure 8-8 — Typical forced-air heating system. In a forced-air system, a burner, usually oil or gas, heats the fins of a heat exchanger, which in turn warms cool air passing over it. A fan forces the warmed air to the various areas or zones through relatively small supply ducts. The air returns to the furnace for reheating through a separate set of return ducts. The return ducts may draw on outside air for a continuous supply of fresh air. Two thermostats control forced-air furnaces: one to control the burner and another to control the blower. Most have filters to eliminate solid particles from the air before it reaches the heat exchanger, and frequently they have humidifiers to replace moisture removed from the air during heating. Forced-air furnace systems can use round, square, or rectangular ducts from tin-plated steel, fiberglass, or more commonly, galvanized sheet metal. Refer to Steelworker Basic for more information on ductwork fabrication. Ductwork insulation is typically achieved by wrapping the ducts with ½-inch to 2-inch-thick fiberglass or rockwool blankets. Supply and return outlets may be located in walls, ceilings, or floors. Supply outlets are covered by a grill (may be decorative) to cover the end of the duct. These grills may include a diffuser function to redirect the airflow, and/or a register function to adjust the amount of airflow. Supply outlets that provide hot air only are best located in or near the floor in order to introduce heat to the coolest part of the room. Cold air is then recycled through return outlets located near or in the ceiling. 8-13 For supply outlets that provide both hot and cooled air, the best arrangement is just the opposite. Small buildings, such as a residence, may have a single return air grill located in a central hallway, and if so, doors leading to the hall are usually undercut by about 1 or 2 inches to promote continuous circulation. Refer to Utilitiesman Basic for more information on warm-air heating systems and equipment.
Steam-heating systems consist of a boiler (fired by oil, gas, coal, or electricity), a piping system, and radiators or convectors. There are many variations and combinations of steam-heating systems, but essentially they are all either one-pipe or two-pipe systems. The one-pipe system uses a single pipe to both convey the steam to the radiator and return the condensate to the boils (Figure 8-9). Figure 8-9 — Example of a gravity one-pipe air-vent system. When the unit is fired, steam expansion forces the air out of the system at the radiators through their thermostatically controlled air valves. When the air has been expelled and steam reaches the valve, the valve closes automatically. As the steam gives up heat through the radiators, it condenses back to water and returns to the boiler through the bottom of the supply piping. In the one-pipe system, the mains must be large and sloped to allow the condensate to flow back to the boiler without interfering with the flow of steam moving forward. In a two-pipe system, the steam flows into one end of the radiator and out the opposite through a thermostatically controlled drip trap set to open automatically when the temperature drops below 180°F (Figure 8-10). 8-14 Figure 8-10 — Example of a two-pipe vapor system with a return trap. When enough condensate has collected in the radiator to cool it, the drip trap opens, allowing the condensate to flow into return lines where it is carried to a collecting tank. A radiator used in a steam (or hot water) heating system usually consists of a series of interconnected vertical cast-iron sections. As well as being available in both a one-pipe and two-pipe system, they are also available in multiple sizes and in a variety of configurations to meet supply and space considerations (Figure 8-11). Figure 8-11 — Example of one-pipe and two-pipe radiators in optional supply configurations. As the steam flows through the radiator, the surface of the sections radiates heat to the surrounding air, walls, and other objects. As the surrounding air heats, it rises towards the ceiling, setting convection current in motion, which transfers heat throughout the room. Convectors consist of pipes (usually iron or copper) surrounded by metal fins (Figure 8- 12). 8-15 At the top and bottom, openings in the shields allow air to circulate over the fins. That air movement over the fins transfers heat to the surrounding area. Small convectors placed around the base of the wall are commonly called baseboard heaters. Refer to Utilitiesman Basic for more information on steam-air heating systems and equipment.
A water-heating system includes a boiler, a piping system, radiators or convectors, and a water-circulating pump to force the flow through the radiators or convectors and back to the boiler. There are three types of piping systems for water heating. The one-pipe system, shown in Figure 8-13, consists of a single supply main that carries hot water to each radiator in succession. In this system, the cooled water from each radiator returns to the flow before reaching the next. To overcome a loss of water temperature at each successive radiator, you must balance the size of the piping or the orifice at the radiator. The two-pipe system supplies hot water directly to each radiator with the cooled water returning to the boiler through a separate return pipe. The return piping system may be either a direct return as shown in View A, or a reverse return as shown in View B of Figure 8-14. Figure 8-12 — Typical baseboard convector function. Figure 8-13 — Example of a one-pipe water-heating system. 8-16 Figure 8-14 — Examples of two-pipe water-heating return systems. Refer to Utilitiesman Basic for more information on hot-water heating systems and equipment. 2.1.4 Unit Heaters Unit heaters may be gas-fired units (the more common type) or may consist of coils of tubing that circulate hot water or steam. A built-in fan behind the gas burner unit or tubing coils blows the heated air throughout the area. Unit heaters are commonly used for large open spaces such as garages, shops, warehouses, big box stores, and similar facilities, and are usually suspended from ceilings or mounted high on walls, as shown in Figure 8-15. Figure 8-15 — Typical unit heater placement. 8-17
When you feel chilled in a room, that sensation is due more to losing body heat to the surrounding surfaces than to the temperature of the air. A radiant-heating system compensates for this sensation by warming the surrounding surfaces so you are more comfortable at a lower air temperature. This type of heating system consists of hotair pipes, hot-water pipes, or electric coils embedded in walls, ceilings, or more commonly, the floors (Figure 8-16).
A natural ventilating system uses the forces of wind and the differences in interior-exterior temperatures to cause circulation and maintain a continuous freshening of the internal air. Air enters through openings at or near floor level and escapes through openings high on the walls or in ceilings and roofs. Opening windows or doors on two or more levels is one example. In mechanical ventilation, air circulation is induced by mechanical means-usually by fans-that may be combined with supply and exhaust duct systems (Figure 8-17). Figure 8-17 — Example of a typical ventilation system.
Air conditioning is a term used to describe the process of controlling a structure’s interior elements for complete “comfort conditioning.” Figure 8-16 — Typical radiant heating system in a floor. 8-18 Air conditioning involves the following:
• Temperature control
• Balanced humidity
• Fresh air
• Clean air (without odors, dirt, dust, lint, etc.)
• Air movement Winter and summer air conditioning (warming and cooling the air) is done by installing both heating and cooling equipment in the same air-conditioning system.
Of course, individual units for heating and cooling may also be used separately. Heating equipment for winter air conditioning is most often automatic. Heating, usually built into the air-conditioning unit, comes from water or steam tubing, a gas burner, or electric coils, but regardless of the type of heat used, the goal is to heat the air. Cooling equipment must be a type that will satisfactorily cool the air for a particular space that is being air conditioned. One method used to cool the air in airconditioning units is to evaporate water. One simple example of an evaporative cooling system is commonly known as a “Swamp Cooler,” which consists of two basic elements, water and a fan (Figure 8-18). Another method, and one of the most important, is mechanical refrigeration, which cools and dehumidifies the air. In mechanical refrigeration, air is cooled by blowing it across coils that have been cooled through the continuous recirculation of a refrigerant through an evaporationcompression-condensation-evaporation process (Figure 8-19). Refer to Utilitiesman Advanced for more information on mechanical refrigeration. Figure 8-18 — Example of a typical evaporative cooling system. 8-19 Figure 8-19 — Example of basic mechanical refrigeration. There are various types of air-conditioning units and systems. The following sections present information on a few of the more common types.
Self-contained refrigerative air-conditioning units can be small window units, large floorstanding units, or units that are larger still (Figure 8-20). Each unit contains a complete system of refrigeration components. Figure 8-20 — Typical window and floor-mounted air-conditioning units. Window units are not limited to installation in windows; they also can be installed in transoms or framed into outside walls. However, using the windows or outside walls to access exterior air is important for optimum performance. 8-20 Refer to Figure 8-21 and compare its systems drawing to Figures 8-19 and 8-20. Note the continuous flow of the evaporation-compression-condensation-evaporation process. The following functions occur when the unit is operating:
• The compressor forces a high-pressure (high-temp) refrigerant gas to the condenser.
• The condenser fan draws in and blows outside air over the condenser coils.
• The movement of cooler outside air over hot condenser coils changes the gas to liquid, giving off heat exhausted to the outside.
• The liquid passes through the control device, regulating the flow of liquid to evaporator.
• The liquid changes to a low-pressure (low-temp) gas which is circulated through the evaporator coils.
• An evaporator fan circulates inside/room air over cold evaporator coils, removes heat from the air, and returns cooled air to the room. A heat pump is a variation of this type of unit. In a heat pump, the roles of the condenser and the evaporator are reversible with a valve so that the unit draws in and heats outside air, and expels cold inside air. In this way, the unit can function as a heating unit, rather than a cooling unit (Figure 8-22). Heat pump systems often have auxiliary heating capabilities that can initiate when the exterior temperature drops to a level at which the unit cannot draw on heat to extract from the outside air. Figure 8-21 — Typical refrigeration cycle of a self-contained unit. 8-21 Figure 8-22 — Example of the functions of a heat pump self-contained unit.
Most forced-air furnaces are designed to accommodate cooling coils for placement on the output side of the furnace, and then use the forced-air furnace blower to circulate air over the cooling coils. Placed outside the building, a cooling unit produces chilled water for circulation through the cooling coils near the air-conditioned space. The furnace fan blows the air over the cooling coils, which cools the air with the chilled water. This process warms the water and it is then returned to the cooling unit (Figure 8-23). The addition of a dehumidifier reduces moisture in the air.
You may have seen fan-coil units in a school or in temporary lodgings. Figure 8-23 — Typical function of cooling coils. 8-22 They contain a fan, coil, filter, condensate drain, and sometimes, an outside-air inlet. A central unit furnishes air to the unit, and duct coils heat or cool the air. The amount of air moving over the coils and the temperature of the coils can be controlled manually or thermostatically. A piping system provides hot or cold water to each unit (Figure 8- 24).
Refer to Figure 8-25 often for the next segment on layout. It is an example of a project drawing; this particular one is for a steam heating and air-conditioning layout for a hospital. Note the following features:
• The air-conditioning plant consists of four separate self-contained units, three in the mechanical equipment room and one on the porch of the ward.
• Two cooling towers support the units. o In a water-cooled air-conditioning system, cold water (rather than air) runs over the coils of the condenser to cool the piped water. Water is sprayed at the top of the tower, and is cooled by the air as it falls through the redwood louvers. Sometimes, large blowers force air through the water, making the cooling tower more efficient.
• The lines of air-conditioning ducts are shown running from each of the airconditioning units. o The dimensions for each section length are noted as a specified size on the drawing. Observe that the duct dimensions decrease as distance from the unit increases. o The dimensions for each section length are noted as a specified size on the drawing. Observe that the duct dimensions decrease as distance from the unit increases. Figure 8-24 — Typical fan coil unit without cover. 8-23
• Some spaces are heated by radiators rather than by the air-conditioning system. o These spaces (toilets, kitchen, and sterilizing room, for example) may contain odors or gases that would make it inadvisable to connect them with the airconditioning duct system.
• The heating capacity of each radiator is shown in British thermal units (BTUs).
• Each space (except the gear locker) not connected to the air-conditioning system shows an exhaust fan for ventilation.
• The air capacity for each exhaust fan is shown in cubic feet per minute (CFM).
• A circle (or more than one circle) on the duct in each air-conditioned room indicates an outlet for the conditioned air. o The outlets are diffusers (in this case) with the capacity of each diffuser inscribed CFM. Observe that CFM capacity varies directly with the size of the space serviced.
• Steam lines from the boiler in the mechanical equipment room to the airconditioning units and radiators are shown as solid lines. o Small diagonal lines on the steam lines indicate they are low-pressure lines.
• Return lines to the boiler appear as dashed lines.
• This indicates a two-pipe system for the radiators. Figure 8-25 — Example of heating and air-conditioning layout. 8-24 Figure 8-26 — Schematic of Figure 8-25’s lines to/from air-conditioning units. Now refer to Figure 8-26 for a detail showing the valve arrangement on the steam and condensate return lines to each of the air conditioners. NOTE MIL-STD-17/1B NOTICE 1 of 30 Jan 1998 Military Standard, Mechanical Symbols (Other than Aeronautical, Aerospacecraft and Spacecraft Use) MIL-STD-17/1B, dated 16 September 1977, is cancelled and replaced by ASTM F1000, Standard Practice for Piping Systems Drawing Symbols, ASTM F856, Standard Practice for Symbols-Heating, Ventilation, and Air Conditioning (HVAC), or ASME Y32.2.6, Graphic Symbols for Heat-Power Apparatus, as applicable. Following the mechanical symbols in ASTM F1000, Standard Practice for Piping Systems Drawing Symbols and ASTM F856, Standard Practice for Symbols-Heating, Ventilation, and Air Conditioning (HVAC) the schematic indicates the following:
• The steam headed for the A/C unit passes: 1. a gate valve 2. a strainer 3. an electrically operated modulating valve o This reduces the pressure to the coils’ designed level. 8-25
• The steam condensate leaving the A/C unit passes: 1. a gate valve 2. a strainer 3. a union 4. a steam trap o This trap device performs two functions: (a) provides a receptacle in which steam condenses into water (b) contains an automatic valve system that periodically releases this water into the rest of the return lines 5. another union 6. a check valve 7. a gate valve The check valve, of course, is a one-way valve permitting passage in one direction and preventing backup in the opposite direction.
| Test Your Knowledge 2. Who may be assigned the responsibility of designing a heating, ventilating, and air-conditioning system?
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Every drawing prepared in the drafting room must be checked and edited. As a senior EA, you may be tasked with the job. When you check a drawing, you are inspecting it to ensure it accurately conveys the information provided by the data sources. The information sources may be survey field notes, sketches, written data, another drawing, or any combination of these. Any error or omission of information will result in inaccuracies in the drawing. Therefore, the first check is to make sure the sources accurately provide everything needed to make the drawing. “Editing” means you are inspecting the drawing to make sure it follows the procedures and conventions prescribed in relevant NAVFAC publications and military standards. In a properly functioning drafting room, editing actually begins as soon as a drawing begins, that is, you must constantly edit drawings to ensure proper procedures and conventions are followed while the drawings are developing. ALWAYS use a print of a drawing when checking and editing rather than the original. That way, any needed corrections can be marked with a colored pencil or pen on the print without disturbing or destroying the original. The drafter can then use the marked-up print to make corrections to the original drawing, and after completion the checker can compare a follow-up print of the (now revised) original drawing with the marked-up print. 8-26 For a thorough job of checking and editing, first make an overall check with the following questions in mind:
• Does the drawing reproduce well? Any poorly defined or weak line work and lettering must be corrected. (Note: You can look for any weak lines by holding the print to a light and reviewing it from the back surface.)
• Do the size and format of the drawing and specifications conform to UFC 1-300- 09N requirements? o Is it prepared on flat C-, D-, or F-size paper? o Does the title block format meet the mandatory requirements (vertical for Dsize drawings and optional for F-size drawings)?
• For a set of drawings, does each sheet have a different assigned number, and are all the drawing numbers correct?
• Is the set of drawings arranged in the correct order as specified in UFC 1-300- 09N? That is, are they arranged as follows:: A. Title sheet and index of drawings (only for projects containing 60 or more drawings) B. Plot and vicinity plans (including civil and utility plans). This sheet should include an index for small projects C. Landscape and irrigation D. Architectural E. Structural F. Mechanical (HVAC —heating, ventilating, and air conditioning) G. Plumbing H. Electrical I. Fire protection If the overall check is satisfactory, proceed with detailed questions, such as these:
• Is the method of projection appropriate?
• Are the drawn views the minimum number required to show all the data?
• Are sectional views constructed correctly, and is the section lining correct?
• Are line conventions and symbols consistent with the requirements of appropriate and current standards?
• Are all symbols (especially nonstandard ones) explained in a legend?
• Are proper scales used for the drawing and are the scales shown? Appropriate scales for construction drawings are as follows: o Floor plans and elevations: 1/4 inch, 3/16 inch, 1/8 inch, or 1/16 inch = 1 foot — 0 inches o Architectural details: 3/4", 1 1/2", or 3" = 1´—0″ o Molding sections and similar details: full scale or half scale o Mechanical and electrical details: 3/8", 1/2", 3/4", or 1" = 1´—0″ 8-27 o Structural details: 3/8", 1/2", 3/4", or 1" = 1´—0″ o Structural erection drawings (such as structural floor and roof framing plans): 1/8" or 1/16" = 1´—0″ o Site (plot) plans: 1" = 10´, 20´, 30´, 40´, 50´, 60´, 100´, or 200´ o Utility plans: 1" = 20´, 30´, 40´, or 50´
• Are graphic scales shown as required by UFC 1-300-09N?
• Do dimensions agree with those shown in the data source?
• Does the sum of partial dimensions equal the overall dimensions?
• Are all required dimensions shown?
• Are there superfluous dimensions (ones that are not needed)?
• Are all necessary explanatory notes given?
• Are all general notes in their proper location?
• Are terms and abbreviations consistent with military standards?
• Are abbreviations (especially unusual ones) explained in a legend? In addition, be constantly alert for misspellings and improper use of phrases. Phrases used in common practice are not always acceptable for use in project drawings. The following are some of the most common phrase errors found in project drawings, followed by a corrected phrase.
• Incorrect: “As instructed by the architect.” o Correct: “As directed.” (Note: avoid using this type of language; it indicates uncertainty as to what the requirements are.)
• Incorrect: “As approved by the architect.” o Correct: “As approved.”
• Incorrect: “By the Navy.” “By others.” o Correct: “By the Government.”
• Incorrect: “By the electrical contractor.” “By the plumber.” “By the plumbing contractor.” o Correct: Usually no such phrase is necessary since the government recognizes only the prime contractor.
• Incorrect: “12 gauge zinc-coated steel flashing.” “Copper flashing.” o Correct: “Metal flashing.” (Metals are referred to only as metal and not as a particular kind or gauge. Type and weight should be covered in the project specifications.)
• Incorrect: “Formica.” o Correct: “Laminated plastic.” (Proprietary or brand names are not permitted.)
As a senior Engineering Aid, if (or more likely when) you are assigned to the drafting room, your responsibilities will include the quality as well as the quantity of work produced by the division staff. Your oversight of the staff-produced drawings or oversight of an assigned editor can provide the final quality control that allows informational data to be presented in drawing format for ease of communication with the other members of a project. This lesson provided a brief recap of project drawing divisions, a more in-depth presentation on HVAC systems in the Mechanical Division, and offered specific guidance on checking and editing construction drawings. The more familiar and confident you are with the elements of this lesson, the easier it will be for you to project your knowledge to the junior EAs in the division, and to produce the quality work that all field personnel are expecting and hoping to find.
1. Which of the following information should you provide in the civil division of project drawings? A. Direction and distance for all property boundaries B. Planned grading C. Existing site conditions D. All of the above 2. Which of the following drawings is/are NOT part of the architectural division? A. Millwork B. Landscaping C. Door and window schedules D. Interior and exterior elevations 3. Which of the following drawings is/are NOT part of the structural division? A. Foundation plan and details B. Beam and column details C. Demolition plan and details D. Reinforcing plans and details 4. In what division(s) of a project drawing is the size of water piping specified? A. Civil B. Mechanical C. Fire protection D. All of the above, depending upon the usage of the piping 5. When needed, in a set of drawings you should show seismic design data on the first sheet of what drawings? A. Project B. Civil C. Structural D. Electrical 6. Why is an isometric riser diagram is the most commonly used diagram? A. It is a three-dimensional representation of an entire piping system. B. It uses standard symbols to represent pipe fittings and connections. C. It can be drawn with less regard to exact dimensions. D. All of the above 8-30 7. In a forced-air heating system, what component(s) is/are used to distribute the heated air? A. Ducts B. Fans C. Pumps D. Heat exchanger 8. What component(s) of a warm-air heating system is/are used to circulate the heated air? A. Ducts B. Fans C. Pumps D. Heat exchanger 9. For which of the following reasons must a gravity warm-air heating system be installed in a basement? A. To hide unsightly ductwork B. To allow warm air to be blown upward by fans C. To provide the necessary floor space for the large-size furnace D. To allow heated air to rise through the ductwork into the areas requiring heat 10. What type of heating system is most often used for heating large industrial shops? A. Forced-air furnace B. Unit heaters C. Steam D. Hot water 11. What type of heating system is designed to compensate for the loss of body heat to surrounding surfaces? A. Steam B. Hot water C. Radiant D. Forced-air furnace 12. Which of the following conditions applies/apply to the term “comfort conditioning”? A. Controlled room temperature B. Controlled humidity C. Controlled air quality and motion D. All of the above 8-31 13. In addition to cooling, a secondary effect achieved with mechanical refrigeration is higher humidity. A. True B. False 14. What part of a window air-conditioning unit changes the liquid refrigerant to a low-pressure gas? A. Condenser B. Condenser coils C. Evaporator D. Evaporator coils 15. Which of the following descriptions best describes a heat pump? A. A self-contained air-conditioning unit with a reversible valve that you can use for both cooling and heating B. A device that is built into a window air conditioner that pumps the hightemperature refrigerant gas to the condenser C. A pump that blows heated air into a room from a self-contained airconditioning unit D. A control device that regulates the flow of liquid refrigerant to the evaporator coils 16. What publication provides information on the standard mechanical symbols used for preparing HVAC drawings? A. UFC 1-300-09N B. ASTM F856 C. MIL-STD-14A D. ASME-Y14.100 17. What action are you primarily performing when checking a drawing? A. Inspecting the drawing to ensure that all information shown is in compliance with the various data sources B. Making editorial changes to the drawing C. Making sure that all appropriate conventions and practices are followed D. Ensuring that the red-line drawings reflect all changes that occurred during construction 18. What action are you primarily performing when editing a drawing? A. Inspecting the drawing to ensure that all information shown is in compliance with the various data sources B. Making editorial changes to the drawing C. Making sure that all appropriate conventions and practices are followed D. Ensuring that the red-line drawings reflect all changes that occurred during construction 8-32 19. At what point in the development process do you begin to edit a construction drawing? A. When the drawing is approximately 30 percent complete B. When the drawing is completed and ready for review C. As soon as the red-line data is ready to be recorded D. As soon as the drawing first begins 20. What are you checking when you look at the reverse side of a drawing as it is held against a bright light? A. Translucency of the tracing paper or vellum B. Reproducibility of the drawing C. Opaqueness of the tracing paper or vellum D. Authenticity of the drawing 21. To save time and copy materials, you should make your editing corrections on the original drawing. A. True B. False 22. Which of the following groups of drawings is arranged in the proper order? A. Architectural, civil, structural, electrical, mechanical, plumbing, fire protection B. Civil, landscaping, architectural, structural, mechanical, plumbing, electrical C. Index, civil, architectural, structural, electrical, mechanical, plumbing D. Title sheet, civil, landscaping, architectural, structural, mechanical, fire protection, plumbing 23. When checking a site plan, you should expect to find how many dimensions (at a minimum) used to locate a building or structure? A. One B. Two C. Three D. Four 24. When you are checking a drawing that includes a cross-sectional detail of a chair rail, what is the minimum scale to which a detail should be drawn? A. 3/4 inch equals 1 foot B. 3/4 inch equals 1 inch C. 1 1/2 inches equals 1 foot D. Half scale 8-33 25. What title-block format should you use for a flat, D-size project drawing? A. Horizontal only B. Vertical only C. Horizontal or vertical, depending upon your preference or the direction given by your supervisor 26. When reviewing a set of A-E prepared project drawings, you find the incorrect phase “By the plumber.” What correct phrase, if any, should have been used? A. “By the Government” B. “By others” C. “By the UT” D. None 27. What publication provides basic guidance and NAVFAC policy for the preparation of project drawings and specifications? A. UFC 1-300-09N B. DOD-STD-100E C. MIL-STD-100E D. NAVFAC DM-6