Section 8.8: Compressed-Gas and Cryogenic Systems

Transcription

1 : Compressed-Gas and Cryogenic Systems Design Requirements: 1. Gas systems may consist of a cylinder or bulk supply system, each with a separate reserve supply as determined appropriate in consideration of anticipated demand. The reserve supply shall operate automatically to supply the pipeline if the primary supply becomes exhausted and shall consist of a minimum 3 days average consumption unless the local resupply situation dictates a greater secondary supply capacity. 2. Primary supply should typically provide not less than two weeks consumption for local systems, and at least 3 weeks consumption for bulk systems, after including the 20% overage. Point-of-use gas cylinder systems are sized in accordance with program requirements through consultation with the use group. Compressors are utilized for production of compressed air, except that cylinders may be utilized for very limited applications where provision of central compressed air would be impractical and is approved by the NIH Project Officer. (1 through 2) These requirements set forth the types of systems that shall be utilized to ensure adequate capacity and efficient operation. 3. Bulk supply systems shall include a telemetry system that is compatible with the various vendor suppliers as utilized by NIH. Telemetry systems are required for bulk gas supplies to ensure appropriate monitoring and refill of the supply system. 4. Gas manifold systems (with the exception of single-cylinder point of use gas cylinders) shall incorporate automatic or semi-automatic switchover manifolds, NFPA-99 approved as appropriate for the gas service to ensure continuous supply of gas. Alarms shall be provided to the program area and BAS to alert of gas supply status. A pressure gauge and isolation valve is required at each source supply for line pressure and to monitor status of each cylinder bank. Connectors shall be properly labeled and where providing a critical service gas, provided with distinct connections to preclude cross connections when changing out manifolds. Automatic or semi-automatic switchover is required to maintain continuous gas supply. Alert upon switchover to reserve bank and for low pressure condition is required to allow sufficient notification for replacement of manifold cylinders. 5. Laboratory and Animal Research Facility (ARF) gas supply and distribution systems shall be completely independent of gas systems serving clinical patients. Gas system components for medical or Animal Research Facility (ARF) or laboratory use shall, at a minimum be factory cleaned and packaged as for oxygen service. Prior to operation, all gas systems shall be verified free of cross connections, pressure tested to at least 150% design operating pressure using inert gas of cleanliness and purity Page 1

2 not less than the design process fluid, and verified of required cleanliness and purity throughout the entire system. Refer to ((Section xx Plumbing Requirements for Animal Research Facilities)) for specific requirements for animal clinical gas systems. Cleanliness of all bulk gas storage systems (including microbulk tanks and high pressure gas bulk tanks) and materials of construction shall be verified to be as specified for program requirements, but shall not be not less than USP/ NF/medical gas grade, verified prior to release of gas into the distribution system. Ensuring gas systems provide required purity and that system construction and joining methods are free of contaminants and cross connections is critical to research applications and preventing damage to equipment or contamination of pipelines. 6. The arrangement of reserve cylinder or back-up supply connections shall be made to preclude discharge of reserve cylinders during normal operation or loss of gas due to failure of the bulk tank or primary supply (such as due to a over pressure relief condition). The reserve capacity shall be maintained for use in the event of system failure or loss of primary supply to preclude disruptions to research. 7. Central gas supply manifolds shall be located in a secure and appropriately ventilated area, free of hazards of combustion or mechanical damage, and accordance with the requirements of NFPA standards (including NFPA-99) and as appropriate for the gas served and ambient environmental conditions. The location of gas supplies shall consider access and materials handling for replacement of cylinders and tanks, and should ideally be located outside of the program area. Cylinders shall not be placed in open corridors except where approved by NIH. Gas tanks and cylinders must not be subject to damage or tampering such as through materials corridors, high traffic areas, or subject to hazards associated with inadequate ventilation or fire. Sufficient controlled access is required to facilitate gas cylinder replacement, and ideally should not require entrance into actual lab areas or disruption of research activities. Cylinder placement in corridors can interfere with use of the space, and be subject to damage or tampering. Gas heaters, flame arrestors, piped safety relief devices and similar components shall be provided for each gas manifold as appropriate for the gas, in accordance with the recommendations of the gas purveyor, fire codes, and the guidelines of the Compressed Gas Association Sizing and Distribution: 1. In general and unless noted otherwise, maximum velocity in distribution systems shall not exceed 20 m/s (4000 fpm), and pressure drop shall not exceed 10% for systems operating above 380 kpa (55 psi), and shall not exceed 20 kpa (3 psi) for systems operating at or below 380 kpa (55 psi). Refer to Section 8.1 Plumbing General Requirements for additional criteria pertaining to pressurized piping systems. Page 2

3 These sizing requirements are to ensure reasonable design velocities and adequate pressure within the systems. 2. Pressurized gases shall not be piped into a biosafety cabinet unless approved by DOHS. The use of compressed gases (such as lab air and fuel gas) has been shown to disturb intended airflow patterns within biosafety cabinets, and in the case of fuel gas, could also result in build-up of hazardous vapors in recirculated cabinets, disruption of sterile fields, and damage to HEPA filters. Pressurized gases should be piped to BSC s only where approved by DOHS, appropriate protocols incorporated to preclude aerosolization from compressed gasses, and inclusion of an emergency shut-off valve for immediate shut-off of gas supply in the event of a cabinet fire. 3. Pressurized gases including all general lab gasses, CO2, compressed air, and other gasses (but with the exception of fuel gas, vacuum, and general instrument air) shall utilize materials, handling, and installation procedures to maintain system cleanliness, at least equivalent to that required for medical oxygen service, and shall be designed and installed in conformance with the Compressed Gas Association (CGA) guidelines. The A/E shall specify the performance qualifications to maintain system cleanliness. Brazing criteria of general lab gases shall meet Section IX, ASME Boiler and Pressure Vessel Code or ANSI/AWS B2.2 Standard for Brazing Procedure & Performance Qualifications, both as modified by NFPA-99 or the Copper Development Association for medical gas application. Where high purity gases are required, additional specification criteria shall be provided to ensure product standards, joint quality, materials, and cleanliness are consistent with the required application. Where gas distribution systems are stainless steel, conform to equivalent medical gas (oxygen) requirements except where higher purity standards are otherwise required. Materials and joining operations can introduce substantial contaminants into compressed gas distribution systems, and contaminate downstream piping and equipment. A variety of expensive scientific equipment and research applications are dependent upon service from clean, dry uncontaminated gas streams. Qualifications of brazers and use of materials and joint procedures appropriately installed and handled consistent with oxygen and medical gas applications help to control of contamination from piping systems. 4. Stand-by power shall be provided for electrically operated compressed gas equipment, and critical gas manifold and alarm systems. The extent of criticality of each service shall be reviewed on a per program basis. Gas supplies often serve critical equipment such as HVAC controls, sterilizers and special process needs that must be maintained to preclude loss of research. Page 3

4 Each lab equipment item shall be provided with its own independent equipment isolation shut-off valve, and equipment stub-outs shall be coordinated with actual equipment layouts and utility connection points to minimize exposed piping. Connections to equipment shall be made up with appropriate threaded, flared, or double ferrule compression (swage-lock type) connections as suitable for the gas service, and without use of contaminating thread compounds or lubricants. Serrated outlets shall not be used for fixed equipment connections. Continued operation of equipment may be necessary while other equipment within the same lab is being serviced. For example, separate isolation valves are required for double stack incubators. Improper coordination of utility services can adversely affect lab spaces and equipment usage. Gas connections must be of a sufficiently durable type to preclude potential for leaks, disconnection or displacement. 6. Except as otherwise approved by NIH and in accordance with codes and standards, relief gas from all pressure relief valves and emergency devices shall be piped to the outside. This provision does not apply to LN2 freezers and dewars where the serving bulk system incorporates appropriate over-fill and pressure protection, and for portable devices not requiring connection to a piped relief system. Discharge shall occur at a safe location away from pedestrians and hazards, in accordance with NFPA standards and as appropriate for the specific gas. RATOINALE Safe disposal of relief gas is necessary to preclude hazardous conditions within the facility. Discharge locations must similarly be approved. 7. Stubouts for lab gas turrets shall be secured to structure to provide rigidity. Where acceptable to the research program, the A/E should provide a stainless steel plate for wall-mounted turrets. Drywall is easily damaged from minor displacement of wall turrets during usage and the application of a stainless steel plate, free of sharp edges, has been shown effective to protecting walls. This will assist in protecting walls from damage Bulk Gas and Cryogenic Systems: 1. Where sufficient demand exists, central bulk gas systems (including cryogenic tanks and vaporizers) shall be provided in lieu of numerous compressed gas cylinders. Typically, this applies to gases such as carbon dioxide and nitrogen, but may vary for each project. Bulk systems shall be located in a secured area and in full compliance with NFPA standards. The specific location of bulk tanks shall be subject to NIH approval (and to the extent possible the location of freezer farms shall consider locations of the bulk system). 2. For cases where a set contract is in place, the NIH project officer can advise as to the gas purveyor to be utilized for provision and service of the bulk cryogenic tank farm, as well as how systems are to be specified for purchase or (less common) rental. The selection of leased vs. owned bulk systems shall be made through Page 4

5 consultation with the NIH. Even where systems are leased, conformance with the requirements of this section is required. 3. The A/E shall provide an analysis of life cycle cost effectiveness where foam insulated bulk tanks are provided in lieu of vacuum jacketing. Reserve cryogenic tanks (typically micro-bulk tanks) shall be vacuum insulated. 4. Bulk systems shall be provided with appropriate anchorage for the seismic application of the project site. 5. Duplex vaporizers, refrigeration units, and related near tank equipment etc., shall be provided as necessary to ensure continuous service and preclude single point failures or disruptions of flow (such as during routine maintenance). 6. Bulk systems supplies and distribution shall be of materials, design, and cleanliness to provide not less than USP/NF grade product, except where greater purity is required by the program. Bulk system cleanliness/quality control documentation shall be reviewed and confirmed in accordance with this section. Prior to discharge of fluid into system, tank contents purity shall be verified. 7. Stand-off warning signage shall be provided for bulk tanks with regards to safety valve/rupture disc discharge. Systems shall be provided with appropriate pressure relief and over-fill protection designs that relieve over-pressure conditions at the bulk tank, and preclude risk of venting such conditions through building systems or cryogenic freezer relief valves. 8. Cryogenic systems shall be designed and installed in conformance with NFPA standards, ASME B31.3 Process Piping Code, Code of Federal Regulations (49 CFR), and Section III of the ASME Boiler and Pressure Vessel Code, 9. Telemetry systems are required. 10. Cryogenic systems shall be designed by qualified personnel experienced in cryogenic systems engineering. Distribution systems shall utilize static vacuum insulation and include appropriate flexibility analysis. The application of pressure relief devices, cryovents, phase separators, gas traps, heaters and other specialized controls shall be as required for proper and efficient system operation and safety, and such components shall be documented on drawings. 11. Cryogenic piping systems shall be vacuum jacketed with static (passive) vacuum jacket systems. 12. Flexible equipment connections shall be provided with an appropriate restraint or chain to preclude breakage. Flexible cryogenic supply connections shall be static vacuum flexible type where excessive lengths are required so as to maintain operating efficiency and avoid condensation. 13. A listing of all valves and openings which may discharge into the building shall be provided to NIH for review as part of design submittals prior to construction. An analysis shall be provided to demonstrate adequate sizing of pressure relief Page 5

6 arrangements under worst case failure scenarios. This analysis shall be included in the project O&M manuals. 14. A safety analysis shall be provided outlining all significant likely component failures and operator errors, and the method to safely detect and mitigate the issue. This document shall be included in the project O&M manuals. 15. O&M Manuals shall outline all required safety provisions and written documentation of all training material. 16. Dewar fill station locations are typically located outside the building (often near the loading dock) and the specific location shall be coordinated with the program and NIH DOHS for safety requirements through the NIH project officer. The location of the nitrogen dewar stations shall take due consideration of the safety and transport issues in transporting nitrogen dewars to and from use points. Nitrogen Dewar fill stations shall be of the fully automatic type. 17. Oxygen level monitors and visible/audible alarms shall be provided as appropriate to the cryogenic service, and shall be located in sufficient quantity and location for effective monitoring of O2 levels and interface with HVAC ventilation systems. Refer to Chapter 6, HVAC. Alarms and response sequence shall be connected to building stand-by power. 18. Confirmed low oxygen condition (not initial alert) shall provide automatic shut-off of the cryogenic supply. (13 and 14) This is to prevent an entire bulk tank from being emptied into a space in the event of a line break or significant malfunction. Nuisance tripping is prevented through proper location of sensors and activation of the shut-off at the appropriate point in the alert sequence. (1 through 14) These provisions outline basic standards for bulk tank and cryogenic systems to ensure the design provides for safe and efficient operation Compressed Air Systems: 1. Compressed Air Production: a. Air for building processes are produced at the central plant and distributed to each building. This air is delivered to buildings at a pressure of 650 kpa (95 psi) to 830 kpa (120 psi) and is distributed throughout the facility at the delivered central plant air pressure, considered nominal 690 kpa (100 psi). The incoming plant air service shall be sized to supply 100% of the compressed air peak demand including a 20% capacity allowance for future expansion. For new buildings, a dedicated compressed air production system shall be installed as a backup to the central system and shall be capable of supplying 100% of the system peak demand with the plant air system completely out of service. Air from the campus central plant shall intertie into the building system upstream of dryers and filtration, and an arrangement of Page 6

7 pressure transmitter and normally closed automatic control valves shall automatically activate the backup system upon pressure loss or drop below 620 kpa (90 psi). These requirements are to ensure continuous supply of adequate pressure compressed air to the facility. b. Air intakes shall be taken from the exterior of the facility, above the roof or at least 6.0 meters (20 ft) above grade, away from loading docks, generator exhaust etc., and at least 7.6 m (25 ft) from any powered exhaust or likely source of contamination. Air intakes shall be in conformance with the requirements of NFPA-99 as applicable to Medical Air systems. Compressors shall be adequately ventilated to address heat loads. Clean air intake is necessary to ensure air supplies are free of contaminants that can affect piping systems, equipment, controls, and research activities. c. Equipment capacity split shall be selected to appropriately match the demand profile of the building to minimize waste of compressed air, including the selection of a duplex, triplex, or quadraplex arrangement of smaller compressors, rather than a single large or duplex unit. The system shall be set to automatically supplement the incoming plant air supply via a normally closed valve, actuated by a pressure switch. All compressors shall include an automatic exerciser such that each compressor is activated for sufficient run time not less than once per week. Local control systems with system operating status and alarm condition readout shall be provided at the equipment. A remote signal-to-building automation system shall be limited to a general fault alarm for each system source. The need for standby power shall be evaluated on an individual program basis, but is not typically required for general lab air systems. Standby power is typically required where systems provide air as a primary supply or back-up for control or instrument air functions. Compressed air production utilizes substantial energy, and systems shall be designed to correspond with loads for optimal efficiency. Connections to BAS for monitoring and standby power are required to ensure continuous service to critical demands and preclude disruptions to research or scientific equipment. d. If the plant air is utilized as a backup supply to the building compressed air system rather than as the primary supply, the building compressed air system shall be designed to maintain peak capacity by itself with any one compressor out of service. The incoming plant air supply is connected to the building system upstream of duplex desiccant dryers and high-performance coalescing filtration equipment. Page 7

8 Provision of adequate compressed air shall not be subject to single point equipment failures. Locating the plant air supply upstream of building filters and treatment equipment is to ensure the building distribution system and delivered air quality are protected from any contamination that might occur during distribution from the central plant to the building, such as in the event of a break in a line, construction debris, or mechanical failure. e. Central compressed air serving laboratory and building control systems shall be oil-free, no oil permitted in the compression chamber of production compressors, and then filtered to remove hydrocarbons and particulates, and dried to a maximum pressure dew point of -12 C (10 F) through dryers capable of producing air down to -20 C (-4 F). In some cases, air will need to be dried to -40 C/F, and the need for widespread air at this level should be verified on a per-program basis before specifying dryers. While -12 C (10 F) is generally adequate for normal lab use, in no case shall the provided dewpoint be higher than 2.8 C (5 F) below the lowest temperature at which any portion of the system distribution will be exposed at any time of year. Where higher quality air is only sporadically required; additional dehumidification and filtering shall be provided at the necessary points of use rather than centrally. Refrigerated dryers are not accepted. f. Lab air shall be oil free and provided with duplex filtration (arranged in parallel) such that each filter passes the full design flow rate at a maximum pressure drop not to exceed 21 kpa (3 psi) as follows: i. Prefilters shall provide minimum of 98% efficiency at 3 micron. ii. High performance coalescing filters shall provide.03 micron absolute iii. Final particulate filters (after dryers) shall provide absolute filtration to 1 micron. These requirements provide standards of air quality appropriate for general applications in the facility, to preclude damage to scientific equipment and ensure satisfactory air supplies that may be readily conditioned at points of use to higher standards for specialized applications where required. g. All dryers, filters, regulators and components shall provide N+1 redundancy to allow continuous service. Desiccant dryers may be pressure swing (heatless regeneration) type, utilize heat of compression, or be externally heated; however internal bed dryers are not permitted. These requirements are intended to ensure continuous availability of air supply. Internally heated bed dryers are avoided due to potential fire hazards and air quality. h. The A/E shall coordinate heat loads of compressor equipment with adequate ventilation and cooling of compressors. The use of liquid-cooled compressors supplied by the central process cooling water closed loop system shall be considered. Page 8

9 Compressors typically produce high heat loads which must be appropriately coordinated with building HVAC systems. Use of closed loop cooling systems as opposed to reliance on air handlers promotes cost effective operation i. A primary wet receiver shall be installed immediately downstream of the compressor aftercoolers and moisture separator, but prior to the primary air treatment. After the desiccant dryers and final filtration, a dry receiver shall be provided for the required system stored energy. A final pressure control station shall be provided downstream of the receiver to stabilize distribution pressures. Receivers shall be provided with internal corrosion resistant coatings or preferably be constructed of stainless steel. Provision of a wet receiver provides preliminary moisture removal, additional cooling, and to help minimize short cycling of compressors and reduce load on dryers and filters. This can reduce operating costs associated with producing suitable compressed air. The use of corrosion resistant receiver is to preclude contamination of the air system from eventual tank corrosion. j. Control air systems shall provide air of quality that is in no case less than the requirements of the ANSI ISA S Quality Standard for Instrument Air, typically ISO 8573 Class 2 or Class 3 as appropriate for the application. In some cases, -20 C (-4 F) air may be required for certain HVAC control applications, and final requirements including particulate and oil content shall be coordinated with the system. Process air serving door operators and similar devices are not required to be oil-free or clean for oxygen service, and should meet typical ISA standards for instrument air. Air systems shall provide sufficient capacity and flow to ensure adequate air supply to all devices at any time of operation. High quality control air is necessary to ensure reliable operation of controls and instrumentation. k. Control air systems shall be arranged to provide N+1 redundancy and preclude single point failure of air production equipment. Reliability can be accommodated by use of a redundant dedicated control air compressor that is intertied with the supply from the primary control air or building air system, interconnection with a secondary reliable air supply source (such as building lab or plant air of adequate pressure) and through use of dedicated adequately sized receiver arrangement provided with inlet check valves or other means to ensure required air supply is available for control system operations. Primary and redundant systems shall each be provided with stand-by power. Control air must be constantly available to serve critical applications within the facility. 2. Compressed Air Distribution, Gas Specific Requirements: Page 9

10 a. Risers for compressed air systems shall be provided as high pressure [nominal 690 kpa (100 psi) pressure systems], so that laboratories may utilize either high-pressure or low-pressure distribution via local pressure-reducing valves at the riser take-offs for each floor to deliver the necessary local or zone low pressure condition. Even where high pressure air is not initially required, valved and capped provisions shall be provided at the distribution space or riser take off for each floor, with forethought in system sizing to permit future connections. High pressure air is often required in laboratories for a number of applications, including autoclaves, pure gas generators, air tables, mass spec, and a variety of other scientific equipment, and shall be available to each floor at a point no farther than at the connection with risers. On individual floors, low pressure lab air (35 to 40 PSI) is utilized, and high pressure air may also be distributed as required, however combined high pressure distribution with seaperate PRV s to each lab is avoided due to maintenance and lack of pressure monitoring associated with numerous PRV s subject to unauthorized adjustment. b. High-pressure distribution piping systems shall be sized to limit pressure drop to 10% of the system operating pressure. Downstream of the PRV s, 275 kpa (40 psi) laboratory air is distributed to turrets and is sized to limit pressure drop to 21 kpa (3 psi) at design demands to the farthest outlet. Velocities shall not exceed 1220 m/min (4000 ft/min). Conventional lab turrets shall provide a flow of 0.5 L/s (1 cfm) at every outlet station. High pressure air is sized based on projected demand requirements, and detailed programming. Special attention should be applied to sizing of systems with regards to quantity and type of high purity gas generators, air tables, and similar equipment which may have high consumption rates and not allow significant application of diversity. Laboratory building diversity factors may be used for outlets if these can be properly assessed, and such diversity is typically provided for sizing of gas turrets. These requirements ensure reasonable sizing of distribution systems for control of pressure loss and velocity to ensure adequate air supply for program flexibility. Sterilizers, research equipment, and high demand items (such as gas generators) may be in simultaneous use, so application of diversity shall be carefully evaluated in consideration of quantity, duration, flow and throughput requirements so as not to pose undue limitations Carbon Dioxide Lab Gas: 1. The need for central distribution of carbon dioxide shall be verified with users on a per-project basis. The A/E shall consult with program requirements to determine demand loading, quantity, and door opening allowance for incubators, (typical baseline for sizing purposes should be to allow for at least 3 door openings per incubator per day). a. Where bulk systems are justified, a liquid carbon dioxide storage tank, vaporizer, and associated controls shall be located outside the building, sized Page 10

11 such that bulk system refill is not required more frequently then every three weeks. Refer to cryogenic system requirements within this section. b. Manifold cylinder systems (for smaller or local applications) shall incorporate not less than 2-week demand and 3 day reserve. Carbon dioxide manifold rooms shall include oxygen level monitoring alarms. c. Carbon dioxide system distribution pressure shall be at 175 kpa (25 psi), and maximum pressure drop at peak demand shall not exceed 21 kpa (3 psi). For facilities with limited carbon dioxide requirements, the system may be fed from manifolded cylinders located in a central area or building cylinder closets. d. Central carbon dioxide systems shall have redundant components and reserve backup to ensure uninterrupted supply to incubators or bench mounted carbon dioxide regulators.. e. Carbon dioxide systems shall be of materials and construction suitable for oxygen service. Reliable carbon dioxide of adequate quantity and flow is critical for a number of research operations, including applications in labs and animal facilities. Provisions of oxygen level monitoring alarms are appropriate to ensure safety in the event of gas leakage. Construction suitable for oxygen service is to ensure gas purity for the range of typical applications Liquid and Gaseous Nitrogen Lab Service: 1. Nitrogen may be required in some lab facilities as a central system and shall be verified with users on a per project basis. Where large demands are required, a bulk liquid nitrogen storage tank, vaporizer, and associated controls shall be located outside the building. Refer to Bulk Gas and Cryogenic System requirements, this section. 2. For facilities with limited gaseous nitrogen requirements, the system may be supplied from manifolded cylinders located in a central area or building cylinder closets. Systems shall be designed to provide an uninterrupted gas supply. Medical gaseous nitrogen distribution systems shall be separate and independent of laboratory distribution systems. Nitrogen holding rooms shall include oxygen level monitoring alarms. 3. Piping and distribution systems serving laboratories and animal research facility areas, (with the exception of where used only as a driving/instrument gas) shall be designed and constructed for cleanliness provisions suitable for oxygen service. Gaseous systems shall be designed and installed in accordance with NFPA-99 and CGA guidelines. These requirements set forth basic criteria for nitrogen systems. Oxygen level monitoring alarms in manifold rooms will ensure safe conditions in the event of tank leakage Page 11

12 Special Laboratory Gases (Cylinder Gases): 1. Research at the NIH has requirements for many different specialty gases, including helium, argon, hydrogen, oxygen, nitrogen, carbon dioxide, and numerous gas mixtures of various purity. Planning shall allow for the proper storage of full and empty gas cylinders, including separate storage areas for flammable and oxidizing gases. Cylinder restraints shall be provided in storage areas and local distribution closets and at points of use in the laboratories. Cylinder restraints shall be secured to the building structure, toggle bolts and similar designs are not acceptable. Gas systems shall be designed in accordance with NFPA standards and fire codes, including provision of special gas storage cabinets, flame arrestors, and ventilation; as well as guidelines of the Compressed Gas Association (CGA). The arrangement of specialty gas systems shall be coordinated with NIH ORF, DOHS, and DFM. Ultra-high purity gases are typically located near to the point of use, and special system materials and procedures will be required to maintain system cleanliness and gas purity. Specialty gasses to meet pharmaceutical, clean room or similar ultra-high purity applications shall be designed and constructed in accordance with applicable standards, detailed on drawings, and arranged to ensure gas purity and reliability of the gas supply. These requirements set forth basic criteria for specialty gas systems supporting applications at the NIH. Page 12