Element D Services Heating, Ventilating, and Air Conditioning

Transcription

1 PART 1 - GENERAL 1.01 OVERVIEW A. This section supplements Design Guideline Element D3042 on exhaust and ventilation with specific criteria for projects involving design of Laboratory Exhaust and Systems. B. Refer to Design Guideline Element D3042 for the following: 1. General design criteria related Exhaust and. 2. Special Contract Document Requirements and products applicable to the Project. PART 2 - DESIGN CRITERIA 2.01 GENERAL A. In general, laboratory exhaust systems shall comply with procedure and support room ventilation air requirements of NFPA 45, 90A, NIH, CDC, and OSHA. B. Special exhaust systems, noted below, are hazardous and shall not be housed in the same chase that houses environmental supply, return, and exhaust ducts. 1. Laboratory hood exhaust systems. 2. Biological laboratory exhaust. 3. Radioactive hot lab exhaust. 4. LN 2 freezer room exhaust system. C. All other ductwork carrying make-up air that is connected to special exhaust systems may be installed in the same chase that carries environmental supply and/or return ducts. D. Exhaust fans serving laboratory hoods shall be connected to an emergency power source LABORATORY HOOD EXHAUST FANS A. While the type of exhaust system would depend on the hood characteristics, the following features shall be incorporated into the design to avoid excessive noise levels and ensure accurate air balancing. 1. The system shall conform to OSHA Regulation 29 CFR, Part ODG OF 6

2 2. Exhaust shall be continuously monitored and an alarm system (local audible and visible alarm and an alarm at M. D. Anderson Cancer Center s central monitoring services, shall be provided for each hood and biological safety cabinet). 3. Exhaust fans shall be selected to operate at low tip speed (approximately at 50 percent of the maximum permissible tip speed) and maximum static efficiency. 4. Provide fan selection data on a performance curve and ensure that the fan discharge is directed vertically upward. 5. Design duct sizing to maintain velocity in the ductwork between 2000 and 2500 fpm. 6. Select fans with backward inclined fans. 7. Perform sound analysis for each exhaust fan and provide sound attenuation, if required. 8. To ensure design airflow is achieved on manifold and shared exhaust systems, pressure independent, factory-set, field-adjustable automatic airflow control shall be provided for each fume hood and biological safety cabinet. 9. An independent flow monitor shall be provided and alarm locally and to the building automation system (BAS). Provisions need to be incorporated in the design to allow access to the independent flow monitor. B. Each laboratory exhaust air system shall have a corresponding supply air system to comply with laboratory, hood exhaust air, and laboratory ventilation exhaust air change (AC/hr) requirements listed below: Room Description Occupied 3 AC/hr (minimum) Unoccupied AC/hr (minimum) Vacant 4 AC/hr (minimum) Fume Hood Rooms Radio Chemistry Laboratory Open Lab Traditional Lab Tissue and Culture Dark Room Storage Room Glass Wash Room Cold Room LN 2 freezer Room Notes: 1. Lab room has no fume hood. 2. Lab room has fume hood(s). Listed minimums are current. The minimums may be lowered future pending test results. 3. Occupied defined as space with personnel present during specific time. 4. Vacant defined as space that is not assigned to a lab user and that does not have equipment that generates chemicals. ODG OF 6

3 C. Actual air change rates may exceed the above stated rates to maintain temperatures in the laboratory or prevent a hazardous environment. BL3 s and Tissue Culture Rooms are exempt from the occupied and unoccupied air change rate. By definition, one AC/hr is the total of supply air and infiltration air from surrounding space provided in one hour divided by the total room volume. D. Laboratory exhaust fans and 30 percent filter banks shall be an N+1 redundant system capable of maintaining constant volume with the capacity to exhaust listed rooms at the required minimum ventilation design air change rates. E. Exhaust fans shall be direct drive and powered though the use of variable frequency drives that vary fan speeds to maintain the exhaust air requirement during exhaust air filter loading. Fan speed is determined by maintaining and airflow measurement setpoint (adjustable) from the BAS. F. The design exhaust rate through the fume hoods, radioisotope fume hoods and (BSCs) will be determined based on using restricted sash opening and maintaining a minimum face velocity of 100 fpm at any point at the open sash. 1. Laboratory chemical hood operation: Face velocities should be between 80 and 125 fpm at the working sash height with an optimum level of 100 fpm. G. Constant volume bypass type hoods will be utilized. If substantial Organic Chemistry area is included, variable volume type hoods with restricted bypasses will be utilized for those spaces. In addition to fume hoods, the BSCs, flammable storage cabinets, and acid storage cabinets will be served as follows: 1. A typical fume hood and Class II Type B1 cabinets should be included in laboratory exhaust system. 2. Class II Type B2 cabinets should have a dedicated exhaust system or they can be combined with an exhaust system that transports air from radioisotope hoods. 3. Radioisotope hoods should have a dedicated exhaust. 4. Organic chemistry hoods may also require a dedicated exhaust air system. 5. Flammable storage cabinets and acid storage cabinets will be ventilated utilizing a 2-inch galvanized pipe directly connected from the cabinet to the fume exhaust ductwork. An exhaust air valve will not be utilized for the cabinet. 6. Some of the Class II Type B2 BSCs will utilize bag-in/bag-out percent HEPA filters located on top of the BSC cabinet, and the supply air filters are within the BSCs. H. The type of filtration components that will be placed in the laboratory exhaust shall be evaluated based on the work being performed in each of the laboratories and exhaust hoods. ODG OF 6

4 I. Instruments that control air valves shall be capable of changing the state of room pressurization, which will be dependant on current and future use of the laboratory. J. Storage rooms that contain laboratory specialty gases or liquid nitrogen stored in dewars shall be ventilated and shall have the appropriate gas detection monitoring and alarm systems per OSHA requirements to protect personnel from accidental asphyxiation. K. LN 2 freezer rooms shall have air change rate as listed in this sections air change rate table. Exhaust duct shall be galvanized and routed to the general lab exhaust air energy recovery system. The bottom of exhaust air grilles shall be placed low to the floor where nitrogen gas if present in the room can be readily exhausted from the room. Supply air grilles shall be placed at ceiling heights LABORATORY EXHAUST DUCTWORK A. Specify welded stainless steel Type 316L ductwork (18 gage minimum) for exhaust air ductwork from the BSCs, laboratory glassware washer, and chemical fume hoods where corrosive chemicals may be used, and hoods that use radioactive isotopes use a Type 316 polished at weld, stainless steel. Exhaust duct from synthesis labs should be Type 316L stainless or other suitably rugged/ inert material due to the corrosive and toxic exhaust. B. Galvanized steel can be used as the construction duct material on general exhaust systems. C. Exhaust ducts used to transport air from Biological Safety Cabinets where radioisotopes are used must be labeled with the standard Caution Radiation Symbol magenta on yellow background at 20 foot intervals. Equip Biological Safety Cabinets with proper filtration components to capture potential contaminates. D. Route the exhaust duct through the building roof at a distance of 25 feet and downwind from any outside air ventilation air intake. The final location and orientation of the laboratory exhaust or outside air intake is determined from wind tunnel results. E. The allowable exhaust air stack height shall be minimum 12 feet above centerline height of air intake or roofline. The stack discharge air velocity shall be equal to or greater than 3000 fpm (3600 fpm for NIH funded project). F. Locate exhaust discharge stack where it cannot be easily reintroduced into the building outside air intakes. Research prefers to locate outside ventilation air intakes on the side of the building and not on the roof. Refer to Design Guideline Element D3041 for additional criteria on outside air intakes. G. When high plume exhaust fans are being considered in the design of a laboratory exhaust system, the A/E needs to place the plume heights, design airflow rates, static pressure requirement, and maximum brake horsepower requirements on the equipment schedule. 1. A/E shall consider wind velocities and prevailing wind direction as listed in Chapter 26 in Tables 1A, 2A and 3A of ASHRAE Handbook of Fundamentals or airport weather data. ODG OF 6

5 2.04 AIR DEVICES A. Refer to Sound Criteria in Design Guideline Element D3002. B. Exhaust square panel face Titus Omni directional diffusers with round necks shall be provided in open areas. Increase neck sizes for the diffuser since they are being used for exhaust air purposes. C. Air valves shall be used to control the exhaust airflow rates from rooms, hoods, and BSCs via feed back signals from stand alone controllers and setpoints (adjustable) from the BAS. PART 3 - SPECIAL CONTRACT DOCUMENT REQUIREMENTS 3.01 GENERAL A. Include a single line riser drawing of the general exhaust ventilation exhaust systems in the Contract Documents. This shall be initially provided in the Schematic Design Submittal. PART 4 - PRODUCTS 4.01 GENERAL A. Refer to Master Construction Specifications. B. Evaluate energy recovery units as appropriate to the application in accordance with the latest edition of ANSI/ASHRAE/IESNA C. Evaluate the use of proximity occupant sensors on each hood to reduce the open sash face velocity to 60 fpm when the workspace in front of the fume hood is not occupied. D. The preferred direct drive exhaust fans are high plume dilution mixed flow fans, where feasible. E. Evaluate and provide test data for other laboratory HVAC airflow tracking equipment Phoenix (Accel II) or Tek-Air Valves that control the temperatures and exhaust airflow rates from the individual room or spaces. These systems should be operating with BACnet open protocol and also be compatible system with the existing BAS. F. Evaluate an exhaust duct material that is capable of withstanding the corrosion products from a synthesis laboratory. G. Evaluate recirculation of air in non-laboratory areas. H. Evaluate sensible cooling in low hazard, high heat load areas. ODG OF 6

6 PART 5 - DOCUMENT REVISION HISTORY Issue Date Revision Description Revisor Initial Adoption of Element Rev Part 2 Laboratory Exhaust Hoods added Titus; Part 2.1 revised Table for Tissue Culture Room AC rate from 8 to 12 for unoccupied mode; revised to exception on AC rates lab temp, and prevent hazardous environment; revised 150 to 125 fpm; deleted B3 and Class III BSCs; revised 10 ft to12 ft on exhaust stacks; revised Air Devices; added criteria that A/E to evaluate use of duct material serving synthesis labs; deleted additional exhaust requirement for RI room. Rev Revised AC/hr values in the table of 2.02 B. including the additions of notes and editorial format changes. PDN PDN / CC Rev Added 2.01B.4., added AC/hr value in the table of 2.02 B. for LN 2 Freezer Room, revised J. and added 2.02 K.. Rev. 4 Rev. 5 PDN END OF ELEMENT D ODG OF 6