F.1 Reference Design and Safety Guidelines for the HVAC Designer
F.2 Building Design Considerations
F.3 Noise and Vibration
F.4 Mechanical Equipment Location and Access
F.5 Systems Identification
F.6 Piping Systems
F.7 Insulation Systems
F.8 Testing and Balancing
F.9 Program Equipment
F.10 Motors and Drives
F.11 HVAC Systems
F.12 Fuel Supply
F.13 Steam Systems
F.14 Chilled-Water Systems
F.15 Hydronic Heating Systems
F.16 Fume Hoods and Biological Safety Cabinets

F.1 Reference Design and Safety Guidelines for the HVAC Designer

The NIH is a progressive and dynamic biomedical research institution where state-of-the-art medicine is the standard practice. To support state-of-the-art research and medical care, the facilities must also be state of the art. It is the NIH intent to build and maintain the physical plant and facilities in accordance with the latest standards. It has been the NIH experience that renovation and rehabilitation of existing facilities do not lend themselves to incorporating the “latest” standards of the industry, primarily because of outdated and inadequate mechanical systems or because the planned function is incompatible with the original criteria for the facility.

The architect and engineer (A/E) will be alerted to this type of situation and make an evaluation early in the design stage to determine the feasibility of implementing the latest standard. The A/E should document such findings, provide recommendations, and report them to the Project Officer for a decision on how to proceed.

The A/E design firm should use and comply with, as a minimum, the latest issue of the following design and safety guidelines. In addition, the A/E should use other safety guidelines received from the NIH Project Officer or as required by program. The A/E should utilize the latest versions of guidelines available at the time the project proceeds with schematic design.

The design and safety guidelines include, but are not limited to, the following:

• The International Building Code.
• The International Mechanical Code.
• The International Energy Conservation Code.
  
• International Code Council, Inc., and Building Officials and Code Administrators (BOCA) International, Inc.: 4051 W. Flossmoor Road, Country Club Hills, IL 60477-5795.
• American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), Inc.: 1791 Tullie Circle, NE, Atlanta, GA 30329.
• ASHRAE Handbooks and Standards.
• Industrial Ventilation: A Manual of Recommended Practice: American Conference of Governmental Industrial Hygienists, 6500 Glenway Avenue, Building D-7, Cincinnati, OH 45211.
• Occupational Safety and Health Standards, CFR 29, Part 1910:U.S. Department of Labor, Occupational Safety and Health Administration (OSHA).
• Guidelines for Research Involving Recombinant DNA Molecules: U.S. Department of Health and Human Services, U.S. Public Health Service, National Institutes of Health, Federal Register/Vol. 51, No. 88: 16957-16985, Bethesda, MD: National Institutes of Health.
• Standard 49 for Class II (Laminar Flow) Biohazard Cabinetry: National Sanitation Foundation Joint Committee on Biohazard Cabinetry, Ann Arbor, MI: National Sanitation Foundation.
• Ventilation Design Handbook on Animal Research Facilities Using Static Microisolators, Volumes I and II, September 1998, Farhad Memarzadeh, Ph.D., P.E. National Institutes of Health, Bethesda, MD: Office of Research Services.
• Methodology for Optimization of Laboratory Hood Containment, Volumes I and II, November 1996, Farhad Memarzadeh, Ph.D., P.E. National Institutes of Health, Bethesda, MD: Office of Research Services.
• Assessing the Efficacy of Ultraviolet Germicidal Irradiation (UVGI) and Ventilation in Removing Mycobacterium Tuberculosis, November 2001, Farhad Memarzadeh, Ph.D., P.E. National Institutes of Health, Bethesda, MD: Office of Research Services.
• Ventilation Design in Animal Research Facilities Using Static Microisolators, Farhad Memarzadeh, Ph.D., P.E., Gerald Riskowski, Ph.D., P.E., ASHRAE Transactions 2000, Volume 106, Part 1, 859-866.
• Investigation of Static Microisolators in Wind Tunnel Test and Validation of CFD Cage Model, Farhad Memarzadeh, Ph.D., P.E., Gerald Riskowski, Ph.D., P.E., ASHRAE Transactions 2000, Volume 106, Part 1, 867-876.
• Analysis of Air Supply Type and Exhaust Location in Laboratory Research Facilities Using CFD, Andrew Manning, Ph.D., Farhad Memarzadeh, Ph.D., P.E., Gerald Riskowski, Ph.D., P.E., ASHRAE Transactions 2000, Volume 106, Part 1, 877-883.
• Methodology for Minimizing Risk from Airborne Organisms in Hospital Isolation Rooms, Farhad Memarzadeh, Ph.D., P.E., Jane Jiang, Ph.D., ASHRAE Transactions 2000, Volume 106, Part 2, 731-747.
• Thermal Comfort, Uniformity, and Ventilation Effectiveness in Patient Rooms: Performance Assessment Using Ventilation Indices, Farhad Memarzadeh, Ph.D., P.E., Andrew Manning, Ph.D., ASHRAE Transactions 2000, Volume 106, Part 2, 748-761.
• Laboratory Safety Monograph: A Supplement to the NIH Guidelines for Recombinant DNA Research, U.S. Department of Health and Human Services, U.S. Public Health Service, National Institutes of Health, Bethesda, MD: National Institutes of Health.
• Guidelines for Laboratory Design: Health and Safety Considerations, 3rd Edition. DiBernardinis, L., and J.S. Baum, M.W. First, G.T. Gatewood, and A.K. Seth. September 2001. New York: John Wiley and Sons.
• Biosafety in Microbiological and Biomedical Laboratories: U.S. Department of Health and Human Services. Washington, DC: Public Health Service, Centers for Disease Control, and National Institutes of Health, HHS Pub. No. (NIH) 99-8395, IVth Edition, April 1999.
• NIH Guidelines for the Laboratory Use of Chemical Carcinogens: U.S. Department of Health and Human Services, Bethesda, MD: National Institutes of Health, NIH Pub. No. 81-2385.
• National Fire Codes, all volumes, National Fire Protection Association (NFPA), 1 Batterymarch Park, Quincy, MA 02269-9101.
• Guide for the Care and Use of Laboratory Animals, Institute of Laboratory Animal Resources, National Academy of Sciences. Washington, DC: National Academy Press.
• Guidelines for Design and Construction of Hospital and Health Care Facilities, American Institute of Architects Committee on Architecture for Health with assistance from the U.S. Department of Health and Human Services. American Institute of Architects Press, 1735 New York Avenue, NW, Washington, DC 20006.
• Medical Laboratory Planning and Design: College of American Pathologists, Skokie, IL.
• American Society for Healthcare Engineering, all volumes: American Hospital Association, One North Franklin, 28th Floor, Chicago, IL 60606.

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F.2 Building Design Considerations

The project engineer should include at the completion of the schematic design phase a Basis of Design report. The report should be a bound presentation with documentation sufficiently complete to justify the complete design concept of the A/E. Detailed building design criteria, computations, schematic system diagrams, commissioning plan criteria, economic analysis, and life-cycle costing comparisons shall be included as a part of the Basis of Design report.

F.2.1 Energy Conservation: The International Energy Conservation Code should be utilized to regulate the design and construction of the exterior envelopes and selection of HVAC, service water heating, electrical distribution and illuminating systems, and equipment required for the purpose of effective use of energy, and shall govern all buildings and structures erected for human occupancy. When requirements of the energy conservation code cannot be satisfied because of program requirements, the NIH Project Officer should be notified. Refer to General Design Guidelines, Section: Sustainable Design, for energy conservation guidelines to be followed for the design of NIH buildings.

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F.3 Noise and Vibration

These design guidelines are intended to provide general information about noise and vibration control to the A/Es charged with designing mechanical and electrical systems for the NIH. They cover situations that arise in the design process and significant items to check at design reviews. As a supplement to other sources of technical information, such as the Sound and Vibration Control section of the ASHRAE Applications Handbook and the advice of an acoustical consultant, they are intended to help the engineers achieve appropriate sound and vibration levels required by the program functions.

F.3.1 Background Noise: All rooms in all buildings, except special acoustical laboratories, are exposed to some level of audible and measurable ambient sound. It may be due to nearby street traffic but more often is governed by the building’s own mechanical and electrical systems. Ambient sound should be, and usually is, anonymous in character. This is an accepted acoustical condition to which we are almost always exposed. The ambient sound should never be so loud as to interfere with speech or telephone use in a space. Frequently, modest levels of ambient sound are needed to mask distracting extraneous sounds.
Noise is characterized by a certain spectrum indicating the sound pressure level at various frequencies. Very often, the spectrum of a noise is as important as its absolute level. Although speech and airplane takeoff may be perceived as being about the same loudness, it is much more difficult to attenuate the lower frequency noise. The level of such background sounds is commonly related to a series of noise criteria (NC) or room criteria
(RC) curves. These spectra have been developed to account for the approximate sensitivity of the human ear to high-frequency noise over low-frequency noise and also to the typical spectrum of human speech. The NC/RC value for a given spectrum is then determined by its highest point in relation to the NC curves. To determine the NC/RC value in the field, sound pressure levels should be measured with an octave-band sound-level meter.

For most spaces, recommended NC/RC levels have been established through many years of experience. In general, for areas where listening is critical and speech communication is important, the NC/RC level should be low. For areas where speech is at close distances (1.8-3.0 m), the NC/RC level may be higher. Table F.3.1 lists recommended NC levels for a variety of spaces. NC levels are based on rooms not being occupied and with all user equipment off.

Table F.3.1 Recommended NC Levels

Note. When evaluating the noise levels in research animal housing areas, it is necessary to consider both the people and the animals in these spaces. For reasonable speech communication in these spaces, a maximum noise level of NC-45 should be maintained. The acoustical consultant should determine specific requirements for animal research areas with the Project Officer and research staff.

The above NC values may be increased for unitary or user equipment installed within occupied spaces as approved by the Project Officer. The sound levels apply to these spaces in most common situations. If the users of the space are hearing impaired, then the tolerance for high background noise levels is greatly reduced. For situations involving audiological testing, there are very specific requirements. In either of the latter two cases, an acoustical consultant should be involved in the design at an early stage. Systems must be engineered and the use of sound attenuation provided as required to achieve specified sound levels.

Both the project engineer and the Government should be aware of the costs and benefits related to the choice of noise criteria or room criteria curves. Studies have shown RC curves to have a more desirable spectrum for background noise. However, RC curves may require more noise reduction in lower octave bands than would be required for an NC curve. This noise reduction may entail significant costs in equipment and operations. For spaces at about NC-30 or NC-40, the duct silencers will be 1.5 to 2.0 times longer and pressure drop will increase 10 to 20 percent. If architectural constructions are used for noise control, they will also be more massive and elaborate. In general, NC curves provide a more reasonable fit between costs and benefits and should be utilized for NIH buildings.

F.3.2 Scientific Equipment Noise: The design team should be aware that many noise sources in health care and research facilities are not related to the building mechanical system. NIH buildings are often equipped with refrigerators, centrifuges, and other scientific equipment that contribute significantly to the ambient noise level. In some cases, this equipment will be located in service corridors and adjacent to occupied spaces.

Most of this equipment operates intermittently and is often under the control of the user. Since the types of equipment vary greatly, it is not possible to prescribe a single means of noise control. We recommend that equipment that produces significant amounts of noise be considered during the design stage. Any equipment that either produces noise levels in excess of 50 dB (A) at a distance of 914 mm, or is simply known by the laboratory users to produce objectionable noises, should be considered a significant noise source.

For adequate speech intelligibility at a distance of 1.8 m, with normal voice effort, the background noise level should not exceed 50 dB (A) or NC-45. In addition, the background noise spectrum should not interfere with speech intelligibility. Since the bulk of speech intelligibility is in the 500 to 4 000 Hz octave bands, sound levels should be lower in that area. A goal of NC-45 is equal to 53 dB (A) and has been designed to account for the
frequency distribution of speech intelligibility. NC-45 should be used as a maximum design goal for occupied research areas in NIH buildings.

As noted previously, refrigerators and other scientific equipment are frequently removed from occupied areas and placed in corridors. In many cases, this alone can cause fairly high noise levels. Because of this, noise levels of NC-45 in corridors and support areas are recommended.

F.3.3 Background Noise for Open Offices: Most office workers have difficulty concentrating when distracted by conversations and intruding noises. In open-plan offices, voices and the sounds of other activities are easily transmitted between workstations because there are no full-height partitions or barriers. Even with the most effective acoustical treatment on the partial-height partitions and ceilings, the intruding sounds will be clearly audible unless they are masked by other sounds. For this reason, providing such masking sound is essential in the design of any open-plan office where speech privacy or the ability to concentrate is important. Even in buildings with conventional enclosed offices, full-height partitions may not provide adequate acoustical isolation for confidential speech privacy if the background sound levels are too low. Installation of a sound-masking system can be the least expensive, simplest way to achieve satisfactory privacy.
For satisfactory performance, a sound-masking system must provide an even blanket of sound throughout the office. The masking sound must be free of annoying spatial or temporal differences in loudness and must provide specific levels of sound at specific frequencies. At the same time, it must be unobtrusive in overall level and character so that it is not, in itself, an annoyance to the office occupants. Elevated background noise levels
can, however, cause problems for hearing-impaired employees. If it is known that one or more hearing-impaired employees will be working in an area, then the designer should endeavor to provide a space with low background noise levels and a significant amount of acoustical absorption. If a sound-masking system is provided, the use of adjustable levels in zones can be beneficial.

F.3.4 Design Guidelines: The evaluation of mechanical system noise should take place in the early design phase of a project. This evaluation is as important as thermal load calculations. System noise calculations are the responsibility of the project engineers designing the system, unless an acoustical consultant is employed. It is not recommended that a project engineer without experience in acoustical matters attempt an acoustical analysis of a major project. It is the experience of the NIH that about two-thirds of these analyses are wrong in very elementary ways, and the monetary consequences to correct acoustical deficiencies can be substantial.

F.3.5 Noise Control: For most large buildings, there will be three types of mechanical rooms: central mechanical rooms, interstitial spaces, and individual floor mechanical rooms. To begin an analysis of the requirements for sound attenuation and vibration isolation of the mechanical room, two items must be identified. The first is requirements of adjacent rooms, both in plan and in section. The second is the type and size of equipment in the mechanical room. The selections need only to be general at this point. Reasonable sound-level estimates can be made without specific manufacturer’s model numbers for standard equipment.

The ASHRAE Applications Handbook Sound and Vibration Control section allows the project engineer to make general estimates of equipment noise levels. For significant equipment, manufacturers should be asked to provide laboratory-generated sound power levels. These should then be incorporated into the equipment requirements of the project specifications. In many cases, it may be possible to minimize expensive noise control measures if quieter equipment can be selected.
At this point, it is possible to estimate the noise reduction requirements for the mechanical room. If a mechanical room is to be located below or above a noise-sensitive space, this should be identified early in the design. If the floor slab above or below mechanical equipment is not sufficiently massive to provide adequate noise isolation, then it may be difficult to modify it after the structural system has been sized and set. At this point, two solutions are often used. One is a floating floor and the other is a resiliently suspended gypsum board ceiling in the mechanical room or in the noise-sensitive space below. The first is very expensive, and the second is very difficult to install properly in the equipment room below because of pipes, conduit, and equipment. Spaces underneath mechanical rooms face similar problems, but it is generally easier to install a suspended gypsum ceiling in a conference room or office than in a mechanical room.

If possible, the mechanical room should be located away from noise-sensitive spaces. Buffer spaces such as corridors, toilets, elevator shafts, electric closets, and other service spaces may eliminate the need to build special noise-isolating constructions such as floated floors or double-layer wall constructions. In all cases, central mechanical rooms in occupied buildings should have heavy walls of masonry or poured concrete. All penetrations of walls, floors, and ceilings by ducts, pipes, conduit, and so on should be resiliently sealed airtight. Particular attention should be paid to doors, as these often represent the “weak link” in sound isolation. A good-quality gasket system to minimize the maintenance problems may be used where required to seal air leaks. Mechanical and electrical equipment spaces located within NIH buildings should preferably be designed without additional sound treatments. When a mechanical room is near noise-sensitive areas, it shall have a soundabsorbing treatment installed on the walls and ceiling. At least 30 percent of the available wall surfaces and 50 percent of the ceiling surface should be covered with a soundabsorbing treatment. The preferred material is a glass fiberboard with a density in the range of 24 to 64 kg/cm. Other sound-absorbing materials can be used, except cellular plastic materials, and these should provide a minimum noise reduction coefficient (NRC) of 0.65 for a 25 mm thickness and a minimum NRC of 0.80 for 50 mm and 75 mm thicknesses as determined by American Society for Testing and Materials (ASTM) C423. They should also provide a minimum flame-spread rating of 25 and a minimum smoke-developed rating of 50 as determined by ASTM E84.

The minimum thickness of the sound-absorbing glass fiber material used in equipment spaces should be as follows:

Table F.3.5.a Minimum Thickness of Sound-Absorbing Treatment

Consideration should be given to the application of enclosures or jackets over generators to provide additional attenuation for equipment operators within the space. Sound-absorbing treatment also reduces the noise levels in mechanical equipment and other high noise-level spaces and helps reduce the possibility of hearing damage to maintenance personnel. Tabulated below are the maximum allowable noise exposure limitations for hearing conversation of individuals in high noise-level areas, as defined by the Occupational Safety and Health Administration (OSHA).

Table F.3.5.b OSHA Sound Level Limits

F.3.5.1 Airborne Noise Control: In designing a building HVAC system, it is most common to size ductwork on an equal-friction basis and consider velocities indirectly, as they relate to the volume flow and pressure drop in the ducts. For purposes of noise control, it is often necessary to consider duct velocity for its own ability to generate noise in a system. (Velocities in airflow generate turbulence and therefore noise.) The amount of noise generated is proportional to 50 x log (velocity). Because of the uncertainties involved in calculating exact velocities through elbows, dampers, and other fittings during the design process, it is often best to use general guidelines. The path of noise to any potential receiver should be examined. In most cases, the dominant path for noise is through the duct to a room outlet. In more severe cases, noise from turbulence may “break out” of the duct and enter a space directly. The final general area to consider is the acceptable noise level at the receiver location. Duct velocities serving auditoriums must be considerably less than those serving research laboratories.

The selection of quieter, initially more expensive equipment is generally more economical than a less expensive type, which requires considerably more noise and vibration control. Measured sound-power ratings should be supplied by the manufacturer and should be a factor in the selection of each major piece of mechanical equipment. Low- or medium-air velocity systems should be used. Low- velocity distribution requires less energy to move the air and also greatly reduces the generation and regeneration of noise produced by high velocities.

Table F.3.5.1 lists recommended velocities for ductwork serving spaces with a given NC rating. When measuring distance from the air terminal, it is important to measure from each terminal, not just the last one. In this case, the “terminal” is a bit different from what is used for static pressure calculations. These velocities may be increased if all paths to the receiver from the turbulence in the duct are considered. In general, this means installing a silencer along the duct. To prevent breakout noise, a duct enclosure or architectural construction must also be used.

Table F.3.5.1 Recommended Maximum Air Velocity in Duct System

Note: Velocities for exhaust systems should refer to recommended return velocities unless higher velocities are required by Industrial Ventilation Standards.

F.3.5.2 Rooftop Equipment: For some buildings, packaged rooftop or commercial-grade unitary equipment may be used rather than having equipment located in central or individual mechanical rooms. Special care should be taken in the location, selection, and design of this type of equipment. The roof structure should be sufficiently stiff that it does not vibrate with the equipment. Most commonly used vibration isolation selection tables assume a reasonably stiff supporting structure. In the case of many lightweight roofs, that assumption is neither safe nor accurate. From an acoustical viewpoint, the preferred mounting arrangement is to place the unit above the roof by 610 mm or 915 mm on supplemental steel framing. Equipment manufacturers’ internal vibration isolation furnished as standard or optional equipment may not be adequate for controlling the transmission of noise and vibration. The required deflection should be maintained for either internal or external isolation. However, manufactured, spring-isolated roof curbs are available with integral isolation. These units can provide spring deflections ranging from 6 to 75 mm and can be used as an acceptable option. Curb isolation may be adequate, but proper isolator selection is important to compensate for each building construction condition. In addition to structural vibrations, the noise radiated from the unit casing and the supply and return ductwork must be considered. In most of these cases, there is a potential noise problem that would almost always be worst directly under the unit. In addition to these unique problems, normal duct-borne fan noise should also be considered. All of this is not a reason to eliminate the use of rooftop equipment, but it is necessary to review these points to properly evaluate all these potential problems. It is recommended that housed-type vibration isolation mounts not be used.

F.3.5.3 Noise Outside Equipment Rooms: Many noise problems with mechanical systems are associated with that part of the building just outside the equipment room. This type of noise is generated in two ways. The most common is noise generated by the fan that is propagated within the ducts to outlets. The second type is noise generated by air turbulence at fittings, vanes, and dampers. High-pressure, high-velocity systems will often have significant quantities of both types of noise and vibration. The noise generated by ducted systems will typically enter spaces in three ways. It may pass through the duct walls and into noise-sensitive spaces. It may travel within the ductwork and enter a space through supply or return grilles. Finally, vibrations in the duct may be transmitted into other surfaces or utility systems to either create noise or become perceived vibrations. This final type will be covered in the Vibration Isolation paragraph.

Noise that passes through duct walls is usually referred to as “breakout” or “breakin” noise. This noise may be either fan noise or velocity-generated fitting noise. This is often a problem closest to the fan. At this point, the ducts are large and therefore not very stiff. Near the mechanical room, noise from the fan has not been attenuated by long runs of ducts. This usually causes a low-frequency rumble in the vicinity of main ducts, especially if the duct is directly above a lay-in acoustical tile ceiling. Exposed duct, in itself, does not create a noise problem. In the case of exposed ducts, breakout noise would not be attenuated by a ceiling. However, the noise reduction provided by a lay-in ceiling is negligible at low frequencies. Calculations based on the ASHRAE Applications Handbook Sound and Vibration Control section should be performed to determine the likelihood of a problem. Should there be a problem, several methods can reduce the potential noise level. First, the duct may be rerouted over a noncritical area. Second, round duct or multiple round ducts may be used in lieu of rectangular duct if adequate space is available, since round duct is stiffer. Third, the duct may be externally wrapped or encased. The final two methods are difficult to do well.

Duct wrappings may encounter sufficient numbers of obstructions and penetrations to render them ineffective. Accessing valves and duct-mounted equipment becomes difficult. While wrapping can be effective, it should be employed only when absolutely necessary.

F.3.5.4 Duct-Borne Noise: The passage of noise from the fan along the inside of the duct and into a space is one of the most common noise problems associated with mechanical systems. The engineering procedures to deal with this problem are also well documented in the ASHRAE Applications Handbook Sound and Vibration Control section. It should be pointed out that this method can also be used to calculate the propagation of noise generated at fittings and dampers away from the fan. This is particularly relevant in the design of laboratory exhaust systems, where the velocities and pressures in the systems are often quite high. In these circumstances, high levels of noise may be generated at fittings and volume-regulating dampers. For laboratory systems in particular, this noise should be included in the acoustical analysis of the system. Within the duct system, several items provide some attenuation of noise. These are branch takeoffs, open-end reflections, fittings, and duct silencers. These are all discussed in detail in the ASHRAE Applications Handbook, so only some minor points will be discussed here. Branch takeoffs provide a division of sound energy proportional to the decibel ratio of the areas involved. For example, assume the room in question is served by a 508 x 254 mm (129 032 mm²) branch from a 1 219 x 1 219 mm (1 485 961 mm²) trunk. The attenuation provided is 10 x log (200/200 + 2,304) or 11 dB. This credit should be taken only where one of the branches does not enter the room in question. Where a fan serves many rooms, this can be a substantial help. Duct lining is one of the most efficient noise control measures available, but lining is not approved for use in NIH buildings.

Manufactured duct silencers are another commonly used means of noise control. These are commercially manufactured sound absorbers. They consist of a section of sheet metal with perforated interior skin and sound-absorbing in-fill and are available in many constructions, sizes, and shapes. In general, these factors can be matched to the requirements of the system under design. In the design of hospital, animal, and laboratory systems, it may not be appropriate to allow standard perforated, fiberglass-packed, galvanized silencers. Alternately, a requirement for high-grade stainless steel, packless washable silencers may be necessary. Silencer manufacturers can also provide thin plastic bags for the fill. They also provide a thin mesh screen between the bagged fill and the perforated metal baffles to ensure minimum degradation of acoustical performance. Insertion loss and spectrum level are also important characteristics when selecting duct silencers. Generally, the 125, 250, and 500 Hz octave-band center frequencies are most critical. Duct-borne sound-level calculations will provide the required insertion loss for a silencer. Sample calculations provided by some manufacturers will often show a very close match between the octaveband insertion loss requirements and the performance of the silencer that is chosen. This does not usually happen in real-world situations. The insertion loss requirement for the silencer will usually be dominated by one or two low-frequency octave-band center frequencies depending on fan type, blade passage frequency, and blade configuration, which affect the fan sound-power level. The other factors in silencer performance that should be considered are size and pressure drop. It is usually possible to meet the insertion loss requirements with several different-sized silencers. That choice is usually between a long, low-pressure drop silencer and a shorter, high-pressure drop silencer. At this point, the engineer must make a choice between system operating cost and first cost. Once a silencer is selected, it must be incorporated into the duct layout. The silencer should be located so that smooth airflow is maintained into and out of the silencer. Poor design in these areas can cause the actual pressure drop to be much more than that listed by the manufacturer and can also degrade acoustical performance. Proper specifications should require ratings in dynamic insertion loss (DIL), i.e., with air flowing through the silencer. All supply and return exhaust air (research laboratory and animal research facilities only) systems shall use packless type silencers. Silencers such as IAC type HS may be used for all supply boxes if they are clean flow boxes with Tedlar or other coverings conforming to NFPA 90 standard over perforated metal cover liner with an erosion-proof surface meeting ASTM C1071-91 test. The liner must have passed and shown no observed growth for the test for mold growth and humidity using UL 181, fungi resistance ASTM C1071, and ASTM G21 tests and bacteria growth using ASTM G22 test.

It is important in locating the silencer to keep in mind that any noise generated downstream or upstream in the case of exhaust systems from the silencer will not be attenuated. For a laboratory system, it is important to remember that constant-volume-regulating dampers will usually generate a substantial amount of noise, especially if there is a substantial pressure drop (more than about 25 mm) across the regulating damper. If the silencers are placed near the fan, then noise generated by these dampers will enter the laboratory unattenuated by the silencers. For spaces with critical listening requirements, such as auditoriums and large conference rooms, similar problems can be created by excessive velocities at supply
or return terminal devices. Since the amount of noise is velocity related, it is advisable to elect terminal devices with more free area for critical spaces.

F.3.6 Equipment Noise: In some cases, the engineer may be concerned with noise from relatively small pieces of equipment, particularly if they are located in an occupied space rather than in a remote mechanical room. These include “active” devices and “passive” devices. Active devices are most often items such as fan coil units, heat pumps, or air terminal units. Passive devices are most often diffusers, air-monitoring devices, grilles, and louvers. For the active devices, most manufacturers can provide octave-band sound-power levels. For passive devices, manufacturers’ ratings may also be provided. In general, these can be used if some attention is paid to the quantity of diffusers in a room. Hoods with velocities around 0.76 m/s will almost never be a direct cause of noise. System noise may come out of the hood, though. The same is true of louvers. Noise may often be heard coming out of these devices, but they are not often the actual cause of the noise.

F.3.7 Vibration Isolation: Structure-borne sound is produced by a noise source, such as a piece of vibrating machinery, that transmits energy directly into and through the structure, often to remote locations in a building, and is reradiated by wall and floor construction as airborne noise. All vibrating equipment in facilities must be resiliently mounted.

The purpose of vibration isolation is to reduce the vibrational energy produced by rotating equipment so that it is not passed into the structure and into larger “sounding boards” where it can be translated into audible noise. In the case of some sensitive scientific equipment, structural vibrations may be harmful to its operation. This is true even in some cases where the frequency and level of the vibration are so low that they cannot be felt but measured only with sophisticated instrumentation. When a project involves the use of vibrationsensitive equipment, such as electron microscopes, a vibration specialist should always be consulted. The ASHRAE Applications Handbook Sound and Vibration Control section contains guidelines and a table of vibration isolation selections for most common situations.

Space requirements for the isolation springs and equipment bases should be included in the equipment layout. At least 50 mm of horizontal and vertical clearance should be provided between all isolated equipment and the building structure. More space is usually preferred for proper access for installation and adjustment. If equipment can be located in an area that is as stiff as possible, then vibration isolation requirements will be minimized. Equipment that is located on grade is preferred; if that is not possible, then areas above stiff major beams are the second-best location. For standard mechanical equipment, the location is most important for large equipment with a slow rotational speed. For very lightweight mounting surfaces, particularly roof decks, it may be necessary to provide separate framing for the mechanical equipment.

Housekeeping pads are usually provided under all floor-supported equipment. The pads should be connected to the slab with steel dowels. The pad area may be sized to extend beyond the resilient mounts of isolated equipment. These pads are intended to provide local mass and stiffness below mechanical equipment and to keep resilient mounts off the floor, where they may be easily blocked by debris under the spring or equipment bases.

Four basic types of vibration isolators or resilient mounts are resilient pads, elastomeric mounts, steel springs, and pneumatic mounts. Each type has advantages over the others depending on the degree of isolation required, loadings, flexibility of the supporting structure, and driving frequency.

• Resilient Pad Mounts. Resilient isolators are the easiest and most commonly used material. Resilient pad mounts are available in a variety of materials such as ribbed or waffled neoprene and rubber, precompressed, load-bearing glass fiber, felt foam, and cork. For maximum life and durability, pads of rubber, neoprene, or glass fiber should be used. Care shall be taken, however, in the selection of the proper material type, density, thickness, and size to ensure that the appropriate loading of the material is achieved. Overloading a resilient pad material causes increased stiffness of the pad and thereby significantly reduces its isolating effectiveness.
• Elastomeric Mounts. General-purpose elastomeric mounts typically consist of a resilient material such as neoprene, which can be easily molded into special shapes. These mounts shall be bonded to metal plates and support members of the equipment.
• Steel Spring Isolators. The most effective vibration isolating devices available are steel-spring mounts, particularly where large pieces of equipment are involved.
• Pneumatic Mounts. Where low-natural-frequency mounts are required, pneumatic vibration isolators should be used. In this type of mount, an elastomer is combined with air to form a rubber/air spring. Pneumatic mounts provide both support and resilience for the equipment mounted on them. By proper sizing and distribution, a very stable, lowprofile and low-natural-frequency isolator mount can be obtained with built-in shock overload protection and built-in damping and, in certain cases, without the need for external lateral stability provisions.

F.3.8 Equipment Installation: Mechanical equipment with a high power-to-weight ratio should first be mounted on a concrete inertia base approximately 1 to 2 times the weight of the equipment, plus system fluids, if any. The inertia base and equipment should be resiliently isolated on freestanding, unhoused, stable steel springs and noise isolation pads. Typical pieces of equipment that require concrete inertia bases include fans and chillers over 18.6 kW and pumps and compressors over 3.7 kW. Fan equipment with motors smaller than 18.6 kW should be mounted on rigid structural-steel frames and the entire assembly mounted on vibration isolators plus noise isolation pads. When the building structural system cannot accommodate the added weight of concrete inertia bases, very high efficiency isolators such as pneumatic mounts should be used to isolate the equipment mounted on rigid steel frames.

Restraint for lateral and vertical seismic loadings should be achieved through the use of resilient snubbers, which are mounted outboard of the inertia base on the housekeeping pad. The snubbers shall consist of steel angles or brackets bolted to the structure with a layer of resilient material between the inertia base and steel angle. The steel angles and bolts should be sized by the structural engineer to accommodate the applicable G-force loadings (either static or dynamic) based on the design parameters of each project. Several vibration isolation manufacturers provide isolators that have integral seismic restraint elements built in. However, since inspection of the interior of the units is difficult, they are susceptible to flanking of vibrational energy due to metal-to-metal contact through misalignment.

F.3.9 Steel Spring Isolator Specifications: The most effective vibration isolation system for mechanical equipment involves mounting the equipment plus inertia base or steel frame on freestanding, unhoused, stable-steel springs, with additional travel between solid (fully compressed) height and design height equal to 50 percent of the static deflection of the spring. Housed-spring units with multiple, small-diameter coils or units with rubber or neoprene cups must not be used. The horizontal stiffness of the spring isolators shall be specified to be between 0.9 and 1.2 times the vertical stiffness, and the outside diameter of the springs shall be between 0.85 and 1.25 times the operating height of the spring. Each spring should be equipped with a resilient noise isolation pad between the structure and spring foot. The noise isolation pad shall be precompressed, molded, neoprene-jacketed, load-bearing glass fiber or multiple layers of ribbed or waffled neoprene. For mechanical equipment located on grade, the noise isolation pad shall be a minimum of 13 mm thick. At all locations above the grade level, the noise isolation pad should be at least 25 mm thick.

F.3.10 Static Deflections: The static deflections required for vibration isolators are determined by the speed and horsepower of the equipment mounted on them, as well as by the location of the equipment within the building. For this reason, it is best to locate as much of the vibrating equipment at grade level as is practicable. All mechanical equipment above grade level should be located as close as possible to or over a column, load-bearing wall, or other stiff structural member. At above-grade locations, the minimum static deflection of any steel spring used to vibration-isolate a piece of equipment shall be 25 mm. Fractional horsepower equipment should be mounted on rubber-in-shear or glass fiber isolators providing at least 13 mm static deflection.

F.3.11 Flanking Transmission: Flanking transmission of vibrational energy from mechanical equipment should be minimized. All connections to vibrating equipment shall be through flexible connectors, conduits, piping, or hose. Resilient ceiling hangers or floormounted resilient supports should support all piping in mechanical equipment spaces connected to vibrating equipment. Penetrations through equipment room walls and ceilings should be oversized, packed with a resilient material such as glass fiber or mineral fiber, caulked airtight, and covered with escutcheon plates where required for fire ratings. Piping should be supported on both sides of the penetrations and should not rest on the structure.

F.3.12 Piping Systems: One of the most common acoustical problems found in buildings is noise generated by the piping systems. Because of its easily identifiable nature, piping noise is one of the most disturbing and offensive types of noises encountered in buildings even though the levels are seldom excessively high. Most of the noise from piping systems is structure-borne, being transmitted along the piping throughout the building where the noise is reradiated as airborne noise.

Piping runs should be resiliently isolated from the surrounding structure, particularly when the piping runs are adjacent to acoustically sensitive areas such as conference rooms. Isolating materials should consist of rubber, neoprene, or spring mounts and felt- or glass fiber-lined sheet metal straps or clamps. At all wall and floor penetration and anchorage points, water piping runs should be free from the structure and the opening packed with a resilient insulation material and fully caulked. Pipes larger than 50 mm in diameter should be suspended from the structure on neoprene-in-shear hangers or floor-mounted on resilient supports. Riser piping near critical areas shall be kept free of the structure, and vertical alignment should be achieved through the use of resilient guides rather than solid anchorage to the structure. Flexible pipe connectors should be used to connect the supply and drain pipes to vibrating units such as garbage disposals, pot and pan washers, and dishwashers.

High-pressure steam and water systems are inherently noisy because of turbulence in the fluid flow. To prevent the generation of excessive flow noise cause by turbulent flow in piping systems adjacent to sensitive areas, fluid pressure should be in the range of 276 to 345 kPa. In larger facilities where high-pressure main supply lines are required, pressure regulators should be used in the supply branches at each floor to maintain the fluid pressure within the above limits. High-velocity flow in the piping system also produces turbulent flow and high noise levels. In piping runs adjacent to acoustically critical areas, such as conference rooms and patient rooms, the maximum flow velocities should not be exceeded.

The use of short air-filled branch pipes or stubs to control water hammer is not effective since the entrapped air in the stubs gradually dissolves into the water. The most efficient means of preventing water hammer is to install one of the mechanical devices manufactured for this purpose, which employs a gas-filled stainless steel bellows to absorb the shock of the hydraulic waves by mechanical compression of the bellows. These devices are available in a variety of sizes to accommodate most fixture sizes used in buildings. Another method for preventing water hammer in piping systems is to install spring-actuated or relief valves that prevent the instantaneous closure of the valve.

Steam pressure-reducing stations and other major pressure control devices can generate significant noise within mechanical rooms. Design documents should require valve manufacturers to meet a specified noise criterion with the possible use of noise suppressors. Steam pressure-reducing valves should be selected for reduced noise generation to meet design criteria. Noise suppressors should be installed when required. Acoustical attenuation adjacent to the reducing station should also be considered.

Electrical conduit connections to all isolated equipment should be made so they do not short-circuit the resilient connections. Conduits less than 25 mm in diameter should be made using flexible conduit sections forming a grossly slack connection. Larger sized connections should be made with manufactured flexible fittings.

Cooling towers on top of buildings should be placed above the roof on an independently supported steel framework. Cooling towers with large, slow propeller fans require vibration isolators with much larger, higher deflection springs than comparably sized towers with centrifugal fans. For multiple- or variable-speed equipment, the isolator critical frequency should be one-half of the slowest equipment frequency (60 rad/s). For example, a cooling tower may have a maximum speed of 12 rad/s and a minimum speed of 4 rad/s, or 40 Hz. The isolator critical frequency for that cooling tower should be less than 20 Hz.

F.3.13 Noise Control for Electrical Equipment:

• Elevators. Both hydraulic and traction elevators may be the cause of disturbing noise and vibration problems and should be evaluated during design. Hydraulic elevators should have the motor/tank/pump assemblies mounted on neoprene isolators that achieve at least 9 mm deflection. Hydraulic piping should be resiliently isolated from the building. Neoprene pad isolators should be used at pipe sleeves, pipe supports, and pipe hangers. For traction elevators, the motor/winch lifting assemblies and motor/generator sets should be isolated from the structure with constrained neoprene isolators that achieve a minimum deflection of 9 mm. Electrical connections to the isolated equipment should not short-circuit the isolation and should employ flexible conduits or fittings previously noted.
• Electric Transformers and Dimmer Banks. Transformers and dimmer banks may be sources for both noise and vibrations. Large utility distribution transformers may be a noise problem in the surrounding community because of the pure tone noise or “hum” associated with them. Smaller distribution transformers inside a building should be isolated from noise-sensitive spaces. Neoprene pads or hangers should be used to attenuate structure-borne vibrations.
• Variable-Speed Drives (VSDs). Three basic types of variable-frequency drives can be used with HVAC equipment:
  • Current-source inverter type
  • Voltage-source inverter type
  • Pulse-width modulation (PWM) typ

The current-source type is usually the quietest. With voltage-source inverter types, generally the driver units themselves represent the noisiest source. PWM types generally make the motors on the equipment served most noisy while the drive units themselves may be very quiet. For the PWM type, drive units and motors should be compatibly matched.

F.3.14 Community Noise: During design, it is important to realize that noise created by the mechanical systems propagates outside the building, as well as inside. When the site is chosen, the location of nearby noise-sensitive neighbors should be considered. Most often these are residences, but churches, hotels, schools, and dormitories should not be neglected. There may be noise codes that apply and provide specific criteria that may not be exceeded. However, it may be desirable to use a “good-neighbor” policy and keep the noise level at or below the existing ambient condition. That level may be quite low at night, so some judgment must be used in establishing what will be considered satisfactory levels.

Several types of equipment may cause noise problems outside a building, as well as inside. The most common are emergency generators, cooling towers, roof fans, rooftop condensing units, and so on, which, if located outside, can be a problem if they are numerous or large enough. An area that is often overlooked is the exterior connection of a laboratory’s supply and exhaust fans. These fans are usually quite noisy, and the connections to the outside are generally quite short. It is important to identify significant sources early in design. These noises are most commonly treated with duct silencers or acoustical barriers.

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F.4 Mechanical Equipment Location and Access

The project engineer should ensure that all mechanical equipment room layouts are designed to facilitate easy, quick, and safe maintenance access and replacement of system components and housekeeping. Equipment room layouts should be designed using the largest physical dimensions possible for all specified equipment. All manufacturer’s specified items should fit within the allocated space. When spacial restrictions and weight restrictions exist in equipment areas, maximum equipment dimensions and weights should be indicated on the contract documents. The NIH requires a high level of reliability from its equipment and rapid repairs when it is out of service because of operational failure. Installation of the equipment on the rooftops exposed to weather compromises the long-term reliability and can make repairs of the equipment dependent on the weather. Where possible, all equipment should be installed in mechanical rooms of adequate size to service the equipment.

Placement of equipment outside mechanical rooms must permit access from non-restricted, uncontaminated areas. Systems must be accessible for maintenance 24 hours per day, 7 days per week. Equipment requiring frequent service should not be installed in occupied rooms or above ceilings in working areas unless it is unavoidable because of space configuration, and efforts should be made to locate it in the traffic areas of the occupied space.

System plenums and casings should be designed to permit maintenance, cleaning, and replacement of all system components without disassembly of the casing. Fan replacements may be accommodated through removable casing sections. Where possible, motors, drives, lubrication devices, valves, traps, and so on should be located exterior to the plenums and casings for ease of maintenance. In no case shall motors and drives or other components requiring regular service be located within an exhaust airstream.

Easy, quick, and safe access to building utilities such as piping, valves, electrical switches, and circuit breaker panels should be provided. All valves and switches should be properly identified in accordance with the governing codes and standards. Operation and maintenance (O&M) manuals for all mechanical supplied equipment on the project are required and should be called for in the specifications. A meeting shall be specified to turn over the equipment inventory and O&M manuals to the Office of Research Facilities (ORF).

Systems should be designed in accordance with the following principles:

• Systems should be selected with minimal mechanical components requiring service and maintenance.
• System components requiring frequent service and maintenance should be located in equipment rooms or service areas and not above suspended ceilings or in occupied spaces.
• Clear and safe access should be provided for servicing, removing, and replacing equipment.
• Sufficient instrumentation should be specified for measuring, indicating, monitoring, and operating at part load as well as full load.
• Equipment should be selected for long-term durability, reliability, maintainability, and serviceability.
• Equipment should not be located in confined, or with an access through, secured spaces.
• Main service isolation valves should not be located close to the mechanical room entrance so that mains may be secured safely in the event of a system failure.
• The building design should define installation zones for piping, ductwork, conduits, cable trays, and lighting so that access to all serviceable components is clearly defined and shown on the zoning diagrams as part of the construction documents.
• All environmental room air-conditioning components must be located to accommodate service from outside the plan area of the room. Temperature and humidity sensors may be located within the rooms. Condensing units must not be located directly above the room.

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F.5 Systems Identification

A complete identification system shall be provided for all mechanical and electrical systems/equipment that conforms with the requirements published in ANSI Standard 13.1. In existing buildings, coordinate with the existing system of identifications that may be in compliance with NFPA and NIH Specification 15011. Equipment and valves identification and numbering shall be coordinated with the ORF.

All control devices, i.e., panels, switches, starters, pushbutton stations, relays, temperature controls, and so on, should be clearly identified as to their function and the equipment controlled. All equipment such as pumps, fans, heaters, and so on should be marked to clearly identify the equipment and space or duty they serve. Equipment shall be identified using engraved, laminated black-and-white phenolic legend plates. Letters should be white on surrounding black at least 19 mm high.

Piping shall be identified with colored, prerolled, semi-rigid plastic labels set around pipes with a field-installed high-strength cement compound applied along their longitudinal edge. Labels shall be placed around the piping or insulation every 9 m and with one label on each pipe in rooms smaller than 4.5 m and on each side of penetrated wall/floor. A label shall be placed at every major valve at least 1.8 m from exit or entrance to an item of equipment and at each story traversed by the piping system. Exposed piping in mechanical rooms shall have full-color coding. Fire protection piping shall have full-color coding in all locations.

Labels shall have at least 19 mm-high black letters for pipes 25 mm and larger, and 13 mm letters for smaller pipes. All labels shall have flow arrows. Color-coding and stencil designations shall be in accordance with ANSI Standard 13.1. Where items requiring routine service are concealed above ceilings or behind access doors, a suitable and visible label should be attached to the surface to identify the location of such items. In no case shall piping be identified with generic terms, i.e., “cold water,” “hot water,” and so on. Instead, identification should be system specific, i.e., “potable or domestic cold water,” “Industrial or Laboratory Cold Water,” “Plant Air,” and so on. Each lab water outlet should be provided with a laminated identification sign that reads “Laboratory Water—Do Not Drink.” Similar signage should be provided for use at ice machines in laboratories and water faucets on nonpotable water systems.

All valves shall be provided with colored plastic, brass, or aluminum valve tags with stamped-in numbers. Tags shall be secured to the valve with a metal chain. Stop valves on individual fixtures or equipment where their function is obvious, or where the fixture or equipment is immediately adjacent, need not be so equipped. Care should be exercised in scheduling and selecting valve numbers. The number sequence should be specific and continuous with individual piping services; that is, domestic water system valves are always identified as 1.1, 1.2, 1.3, and so on, and other distinctly different piping systems should have another number series. Schematic drawings of each floor should show the approximate locations, identity, and function of all tagged service and control valves. One copy of each drawing and schedule should be mounted under glass where directed. A copy of each drawing and schedule should also be included as a part of the operations and maintenance manuals. Valve tags shall be at least 40 mm round tags with white characters describing the system and valve designation. Fire protection and fire alarm systems shall be identified as required by NFPA standards and NIH Standard Specifications. Medical/lab gas piping systems should be readily identifiable by appropriate labeling with metal tags, stenciling, stamping, or adhesive markers. Color coding should be used in accordance with NIH Standard Specifications.

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F.6 Piping Systems

This section is intended to define the general installation requirements for the numerous piping systems installed at the NIH. Many codes govern the actual sizing and installation of piping and should be used during the design process. Welding shall conform to current standards and recommendations of the National Certified Pipe Welding Bureau and all Occupational Safety and Health Administration, State fire protection, and NFPA Standard 241 requirements. Pipe and fittings shall be specified to meet one of the numerous industry standards such as ANSI, ASTM, AWWA, and so on and should be suitable for the operating temperatures and pressures to be encountered on the project. The project engineer, when deemed necessary, shall provide pipe stress analysis to the NIH.

Piping and conduits, except electrical conduits run in floor construction, shall be designed to run parallel with the lines of the building. Electrical conduits shall not be hung on hangers with any other service pipes. The different service pipes, valves, and fittings should be installed so that, after the covering is applied, there will not be less than 13 mm clear space between the finished covering and other work and between the finished covering and parallel adjacent pipes. Hangers on different service lines, running parallel with each other and nearly together, should be in line with each other and parallel to the lines of the building. The minimum pipe size shall be 19 mm for plumbing systems and HVAC systems, and 32 mm for fire protection systems. Size reductions may occur only immediately adjacent to equipment connections. Valves and specialties serving equipment should be full pipe size, not the reduced equipment connection size except where engineering calculations necessitate a different size. Hangers should be spaced to prevent sag and permit proper drainage of piping. Hangers should be spaced not more than 2.4 m apart, unless a greater spacing is specifically designed. A hanger should be placed within 300 mm of each horizontal elbow.

Materials and application of pipe hangers and supports shall conform to the latest requirements of ANSI/ASME B31.1 or ANSI/ASME B31.9 and MSS Standard Practice SP- 58, SP-69, and SP-89, and appropriate Federal specifications where applicable. All materials and anchorage methods for installations in Seismic Zones 3 and 4 shall comply with local building code requirements and shall utilize materials and methods as approved by the local body governing the jurisdiction.

Vertical runs of pipe and conduit less than 4.6 m long should be supported by hangers placed 300 mm or less from the elbows on the connecting horizontal runs. Vertical runs of pipe and conduit over 4.6 m long, but not over 18.3 m long, and not over 150 mm in size, shall be supported by heavy steel clamps. Clamps should be bolted tightly around the pipes and conduits and should rest securely on the building structure without blocking. Clamps may be welded to the pipes and placed below coupling. In lieu of individual hangers, multiple (trapeze) hangers for accessible piping should be considered for water pipes having the same elevation and slope and for electrical conduits. Each multiple hanger should be designed to support a load equal to the sum of the weights of the pipes, conduits, wire, and water and the weight of the hanger itself, plus 90 kg. The structural engineer must approve the structural loads caused by installation of large-diameter piping (200 mm and larger). Safety factors shall be in accordance with ANSI/ASME B31.1. Loading on anchors shall not exceed 25 percent of the proof load test. The size of the hanger rods should be such that the stress at the root of the thread will not be over 68 950 kPa at the design load. No rod should be smaller than 9 mm. The size of the horizontal members should be such that the maximum stress will not be over 103 425 kPa design load. Where vertical piping is specified to extend through sleeves, the riser clamp or pipe support shall transverse the sleeve directly to structure. Allow for differing rates of expansion and contraction of piping systems. Do not anchor piping of substantial operating temperature differences to the same hanger. Trapeze hangers supporting large-diameter piping (200 mm and larger) shall be placed to load joists at top panel points only.

Plastic piping shall be installed to permit proper movement and prevent stresses from expansion and contraction, as well as to protect from damage to piping from abrasion.

Fireproofing shall not be damaged by installation of any hanger or attachment. Where existing fireproofing is disturbed, it shall be restored as approved by the NIH Fire and Safety Officer.
Steam, condensate, and other hot service piping should be designed with loops, bends, and offsets to allow for thermal expansion and keep stresses within the allowable limits of the piping material. Expansion joints or ball joints should be avoided if possible. Rollertype pipe supports should be specified where significant horizontal pipe movement will occur as a result of thermal expansion, and spring-type supports shall be specified where significant vertical movement will occur and where vibration isolation is critical.

Piping should be designed and installed without due stress or strain and run parallel to the lines of the building, except to grade them as specified in a neat and workmanlike manner using a minimum of fittings. Specify provision of thrust restraints to prevent pipe blowout or joint separation due to test procedures or system thrust loads. Such fittings, valves, and accessories should be designed as may be required to meet the conditions of installation and accommodate service. All piping systems, materials, valves, joining methods, and components shall be suitable for the application, location, size, and working pressure of the system at the design operating pressure. Piping should be designed to suit the necessities of clearance with ducts, conduits, and other work and so as not to interfere with any passages or doorways and allow sufficient headroom at all places. No piping should penetrate ductwork.

Gas-piping systems and other hazardous services should be designed in strict compliance with applicable codes and standards. Gas vents, relief valves, rupture disc, and so on shall be piped safely outdoors. Overflow pipes, system drains, and relief devices should be piped to suitable drainage facilities and indirectly connected. Certain pieces of equipment may have high discharge rates that can quickly result in flooding. Drains, sumps, or other receiving devices must have the storage volume required.

Unions or flanges on each side of all pieces of equipment and other similar items should be designed in such a manner that they can be readily disconnected. Union flanges shall be placed in a location that will be accessible after completion of the project.

The project engineer should specify testing procedures in the commissioning guide/plan developed for all components installed on the project. Test procedures should include all items required by code and be sufficient to prove all systems tight at conditions that exceed the maximum design conditions. Water sampling to establish a treatment plan, pipeline sterilization, positive pressure, and vacuum testing may be included as part of the procedures.

Pipe and fittings for NIH buildings shall be as defined in Table F.6.

Table F.6 Pipe Assembly