Laboratory Control and Safety Solutions Application Guide

Transcription

1 Laboratory Control and Safety Solutions Application Guide s

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3 Laboratory Control and Safety Solutions Application Guide Rev. 5, January, 2009

4 Rev.5, January, 2009 NOTICE The information contained within this document is subject to change without notice and should not be construed as a commitment by Siemens Building Technologies, Inc. Siemens Building Technologies, Inc. assumes no responsibility for any errors that may appear in this document. All software described in this document is furnished under a license and may be used or copied only in accordance with the terms of such license. WARNING This equipment generates, uses, and can radiate radio frequency energy and if not installed and used in accordance with the instructions manual, may cause interference to radio communications. It has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC rules. These limits are designed to provide reasonable protection against such interference when operated in a commercial environment. Operation of this equipment in a residential area is likely to cause interference in which case users at their own expense will be required to take whatever measures may be required to correct the interference. SERVICE STATEMENT Control devices are combined to make a system. Each control device is mechanical in nature and all mechanical components must be regularly serviced to optimize their operation. All Siemens Building Technologies, Inc.branch offices and authorized distributors offer Technical Support Programs that will ensure your continuous, trouble-free system performance. For further information, contact your nearest Siemens Building Technologies, Inc. representative. Copyright 2009 by Siemens Building Technologies, Inc. TO THE READER Your feedback is important to us. If you have comments about this manual, please submit them to: SBT_technical.editor.us.sbt@siemens.com APOGEE and Insight are registered trademarks of Siemens Building Technologies, Inc. Tracer Summit is a trademark of The Trane Company BACnet is a registered trademark of American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) Other product or company names mentioned herein may be the trademarks of their respective owners. Country of Origin: US

5 Table of Contents About this Application Guide... I Purpose of this Guide... I How this Guide is Organized... I Suggested Reference Materials... II Symbols...IV Getting Help...IV Where to Send Comments...IV Chapter 1 Introduction... 1 Laboratory Control and Safety Solutions... 1 Intended Audience... 1 Chapter 2 Goals of the Laboratory Environment... 3 Occupant Health and Safety... 3 Room Ventilation Rates... 4 Ventilation Air... 4 Air Changes Per Hour... 5 Dilution... 5 ACH Calculations... 6 Process Ambient Requirements... 7 Occupant Comfort Versus Occupant Safety... 7 Room Sound Level... 8 Emergency Provisions... 8 Chapter 3 Unique Ventilation Needs of a Laboratory Facility... 9 Microbiological/Biomedical Laboratory Rooms... 9 Biosafety Level Biosafety Level Biosafety Level Biosafety Level High Toxicity Laboratory Rooms Medical Laboratory Rooms Animal Rooms Vivariums General Chemical and Analytical Laboratory Rooms Siemens Building Technologies, Inc. i

6 Purpose of this Guide Chapter 4 Ventilation Systems Classification Types of Ventilation Systems CAV Systems Two-position CAV VAV Systems Choice of Ventilation System Chapter 5 Laboratory Facility Exhaust Systems Laboratory Exhaust Air Exhaust Systems Overview Configuration Individual Exhaust Systems Centralized Exhaust Systems Exhaust System Expansion Exhaust System Energy Recovery Cleaning Systems for Exhaust Air Proper Exhaust System Functionality Centralized Exhaust Systems with Constant Volume Fans One Position CAV System Applications Two Position CAV System Applications VAV Applications General System Applicability Centralized Exhaust Systems Using Variable Air Volume Fans Exhaust System Discharge Exhaust System Stacks - Height, Location and Exit Velocity Stack Diameters and Exit Velocity Exhaust Stack Airflow Velocity Calculations Laboratory Exhaust Systems - General Requirements Exhaust System Materials Stainless Steel Galvanized Steel PVC FRP (Fiberglass Reinforced Polyester) Epoxy and Teflon Coated Materials Exhaust System Configuration Transport Velocity Fire Dampers Maintenance Access Specialty Exhaust Systems Perchloric Acid Fume Hoods ii Siemens Building Technologies, Inc.

7 Purpose of this Guide Radioisotope Fume Hoods Chapter 6 Laboratory Containment Units - Ventilation Containment Units Containment Units and Ventilation Biological Safety Cabinets Chemical Fume Hoods Fume Hood Containment Fume Hood Face Velocity Ventilation for Chemical Fume Hoods Fume Hood Monitoring Chapter 7 Room Ventilation, Makeup Air, and Pressurization Control Systems Laboratory Ventilation - Room System Configuration Room Environmental Modeling Laboratory Room Pressurization Pressurization Concept Room Pressurization Control by Pressure Sensing Advantages and Disadvantages of Room Pressurization Control by Pressure Sensing Room Pressurization Control by Airflow Tracking Advantages and Disadvantages of Room Pressurization Control by Airflow Tracking Cascaded Static Pressure Control Dual Pressurization of Laboratories Chapter 8 Laboratory Temperature and Humidity Control Systems Room Temperature Control by Temperature Sensing Variable Air Volume Room Temperature Control Room Temperature Control by BTU Compensation Laboratory Room Humidity Control Humidification Systems Humidity Control for General Applications Individual Laboratory Room Humidity Control Humidity Sensor Location Dehumidification Chapter 9 Laboratory Emergencies - Ventilation System Response Ventilation Systems for Emergencies Fire Chemical or Biological Emergency Medical Emergency Other Emergencies Siemens Building Technologies, Inc. iii

8 Purpose of this Guide Chapter 10 Laboratory Ventilation System - Validation Integrated Laboratory Facility Monitoring and Control Facility Control and Monitoring Functions Alarm Reports Safety Analysis Reports Energy Usage Reports Graphical Displays Safety Analysis Reports Sorted By Fume Hood Number Time Shown As Hours:Minutes:Seconds Energy Usage Reports Sorted By Average Fume Hood Opening Graphical Displays Chapter 11 Laboratory Ventilation System - Commissioning Commissioning Process Commissioning Plan Glossary Index iv Siemens Building Technologies, Inc.

9 About this Application Guide This section discusses the following topics: Purpose of this guide. How this guide is organized. Conventions and symbols used It also provides information on how to access help and where to direct comments about this guide. Purpose of this Guide This guide provides information to assist in properly configuring laboratory ventilation and the associated control systems. It covers laboratory ventilation requirements beginning with quantity of ventilation air needed, desirable room airflow patterns to maximize system effectiveness, preventing cross contamination by room pressurization, and the unique ventilation needs of different types of laboratory rooms. It also addresses how to minimize the potentially high energy costs associated with these systems and how to ensure continued proper system functionality. This section covers manual organization, manual conventions and symbols used in the manual, how to access help, related publications, and any other information that will help you use this manual. How this Guide is Organized This application guide contains the following chapters: Chapter 1, Introduction, discusses laboratory control and safety solutions, and identifies the intended audience for this guide. Chapter 2, Goals of the Laboratory Environment, discusses the goals of the laboratory environment in terms of occupant health, comfort, and safety. It also discusses ventilation and room sound levels. Chapter 3, Unique Ventilation Needs of a Laboratory Facility, summarizes the types of individual laboratory rooms likely to be present in a large laboratory facility and their unique ventilation requirements; including vivariums. Chapter 4, Ventilation Systems Classification, discusses the various classes of ventilation systems. It includes a description of the types of ventilation systems and VAV systems as well as how to choose a ventilation system. Siemens Building Technologies, Inc. I

10 About this Application Guide Chapter 5, Laboratory Facility Exhaust Systems, addresses the configurations, components, materials, and control requirements of laboratory facility exhaust systems as an aid to selecting and designing the most appropriate exhaust system for a specific laboratory facility. Chapter 6, Laboratory Containment Units - Ventilation, discusses containment units specifically intended to allow laboratory occupants to work with and manipulate chemicals, biological specimens, and other potentially hazardous elements. Chapter 7, Room Ventilation, Makeup Air, and Pressurization Control Systems, discusses room ventilation, makeup air, and pressurization control systems in terms of room system configuration, environmental modeling, and pressurization. Chapter 8, Laboratory Temperature and Humidity Control Systems, discusses laboratory room control systems that maximize worker concentration and productivity. It includes room temperature control by temperature sensing, variable air volume room temperature control, and room temperature control by BTU compensation. Chapter 9, Laboratory Emergencies - Ventilation System Response, discusses ventilation systems for laboratories designed to address emergency situations. It includes ventilation systems for emergencies, fire, chemical or biological emergency, medical emergency, and other emergencies. Chapter 10, Laboratory Ventilation System - Validation, discusses validation of laboratory ventilation systems. It includes integrated laboratory facility monitoring and control, ventilation systems for emergencies, safety analysis reports, energy usage reports, and graphical displays. Chapter 11, Laboratory Ventilation System - Commissioning, discusses the commissioning process for laboratory ventilation systems. The Glossary describes the terms and acronyms used in this manual. The Index helps you locate information presented in this manual. Suggested Reference Materials In addition to this application guide, the following publications are recommended sources of detailed technical and regulatory information associated with laboratory ventilation systems, HVAC systems, and associated control systems: Ventilation Systems Manuals ASHRAE Handbook HVAC Applications, Chapter 13 - Laboratory Systems, American Society of Heating, Refrigeration, & Air Conditioning Engineers, Inc. ASHRAE Handbook Fundamentals, Chapter 15 - Airflow Around Buildings, Exhaust Stack Design, American Society of Heating, Refrigeration, & Air Conditioning Engineers, Inc. II Siemens Building Technologies, Inc.

11 Suggested Reference Materials ASHRAE Handbook Fundamentals, Chapter 32 - Duct Design, American Society of Heating, Refrigeration, & Air Conditioning Engineers, Inc. Industrial Ventilation, American Conference of Governmental Industrial Hygienists Laboratory Ventilation Standards Fire Protection For Laboratories Using Chemicals, NFPA 45, 1996, National Fire Protection Association Smoke Control Systems, NFPA 92A, National Fire Protection Association Laboratory Ventilation Standard, ANSI No. Z9.5, American Industrial Hygiene Association Method of Testing Performance of Laboratory Fume Hoods, ANSI/ASHRAE 110, American Society of Heating, Refrigeration, & Air Conditioning Engineers, Inc. Laboratory Fume Hoods - Recommended Practices, SEFA, Scientific Equipment & Furniture Association Guide for the Care and Use of Laboratory Animals, U.S. Dept. of Health & Human Services, Public Health Service, National Institutes of Health, Publication: No , U.S. Government Printing Office Class II (Laminar Flow) Biohazard Cabinetry, NSF 49, NSF International Laboratory Ventilation Regulatory Publications Occupational Exposure to Hazardous Chemicals in Laboratories; Final Rule, 29 CFR Part 1910, Dept. of Labor, Occupational Safety & Health Administration, U.S. Government Printing Office Laboratory Biosafety Guidelines, Office of Biosafety Laboratory Centre for Disease Control, Health and Welfare Canada Uniform Building Code, International Conference of Building Officials Siemens Building Technologies, Inc. III

12 About this Application Guide Symbols The following table lists the symbols used in this guide to draw your attention to important information. Notation Symbol Meaning WARNING: Indicates that personal injury or loss of life may occur to the user if a procedure is not performed as specified. CAUTION: Indicates that equipment damage, or loss of data may occur if the user does not follow a procedure as specified. Note Tip Provides additional information or helpful hints that need to be brought to the reader's attention. Suggests alternative methods or shortcuts that may not be obvious, but can help the user better understand the capabilities of the product. Getting Help For more information about regulated facilities, contact your local Siemens representative. Where to Send Comments Your feedback is important to us. If you have comments about this guide, please submit them to: SBT_technical.editor@siemens.com IV Siemens Building Technologies, Inc.

13 Chapter 1 Introduction Chapter 1 introduces laboratory control and safety solutions. It includes the following topics: Laboratory control and safety solutions Intended Audience Laboratory Control and Safety Solutions Proper laboratory room ventilation is an absolute requirement for maintaining the health, safety and well being of laboratory facility occupants. Inadequate ventilation poses serious health and safety risks to the occupants of a laboratory room due to the wide range of hazardous airborne substances that may be present at times within the room. In addition, an inadequately designed or operating laboratory ventilation system can create a hazard beyond the laboratory rooms since it can spread potentially dangerous substances throughout an entire facility. The performance of laboratory ventilation systems is subject to a growing number of standards and regulatory requirements. Aside from not providing adequate occupant protection and incurring high operational costs, improperly designed and poorly operating laboratory ventilation systems can be a liability risk for both the designer and facility. Intended Audience This guide is intended to serve the needs of a wide range of interests: Persons with overall laboratory facility management or administrative responsibilities should find this guide a comprehensive source of information on laboratory ventilation requirements and proper system functionality. This will enable them to effectively communicate with their own safety professionals concerning ongoing facility operational issues. In addition, this guide will make the reader aware of the different types of systems available and the choices applicable to new facilities or renovations to existing ones. Facility safety professionals and senior laboratory staff members can refer to this guide for specific data to determine if existing ventilation systems and their operating conform to laboratory safety standards and regulations. HVAC system designers should find the descriptions of operation and associated control of the different laboratory ventilation systems informative and helpful for choosing one type of system over another, and as an aid in properly configuring a system to meet specific applications. Siemens Building Technologies, Inc. 1

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15 Chapter 2 Goals of the Laboratory Environment Chapter 2 discusses the goals of the laboratory environment. It includes the following topics: Occupant health and safety Room ventilation rates Ventilation air Air changes per hour Occupant comfort versus occupant safety Room sound level Emergency provisions Occupant Health and Safety The primary goal of a laboratory ventilation system is to maintain occupant health and safety. The secondary goal is to meet any room ambient conditions (temperature and humidity) required for the research activities that are taking place. Finally, the ventilation system must maintain occupant comfort. A very important function of the overall laboratory ventilation system is providing reliable laboratory facility exhaust to address many needs of the facility. In particular, chemical storage areas must be continually exhausted to prevent the buildup of hazardous and flammable fumes and vapors. With respect to laboratory room operations, the exhaust system must continuously remove an adequate amount of air from the laboratory room itself, known as the room ventilation rate, to ensure a safe working environment. In addition, the exhaust system must also serve equipment located within laboratory rooms that is intended to further isolate workers from potential hazards. Typically this includes containment units known as chemical fume hoods and biological safety cabinets. In addition, laboratory rooms often need additional exhaust specialty provisions such as canopy hoods and bench type snorkel exhausts to remove heat, moisture and annoying vapors given off by certain laboratory equipment. Aside from maintaining this all-important exhaust function, the laboratory ventilation system must simultaneously provide sufficient conditioned replacement air for the air that was removed by the exhaust provisions. In HVAC (Heating, Ventilation, and Air-Conditioning) terminology the replacement air is referred to as the room supply air or makeup air. The designer of a laboratory ventilation system must determine the exhaust and supply rates necessary for each individual laboratory room to ensure that all ventilation system requirements indicated above are met. Siemens Building Technologies, Inc. 3

16 Chapter 2 Goals of the Laboratory Environment Room Ventilation Rates Standards, codes, and various regulatory agencies have established minimum requirements for most laboratory ventilation functions. The first one that we ll discuss is the minimum room ventilation rate that must be provided to attain an acceptable overall laboratory room environment. Virtually all regulatory agencies and standards address this issue and require that laboratory rooms have a room ventilation rate that substantially exceeds the rate required for non-laboratory occupancies. However, there is no way of reliably knowing specifically what chemical or airborne substances will be present and at what concentration in a given laboratory room. Further, laboratory rooms can be subjected to unpredictable combinations of airborne agents, thus resulting in a still more complex and indeterminate situation. For these reasons, no scientifically based process exists at this time to specifically determine the appropriate ventilation rate necessary for a given laboratory room. Therefore, there are variations between the requirements of different regulatory agencies and standards organizations. The American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE), a preeminent standards organization with regard to ventilation, has established and published minimum ventilation rate recommendations for an extensive list of different occupancies including various laboratory rooms. However, before reviewing these recommendations, it is important that the reader understand how a room s ventilation rate is determined. Ventilation Air The ventilation air that is provided to a room is sometimes called the room supply air or room makeup air. Regardless of what it s called, it is typically comprised of two components, the first being the fresh air or outside air. Ventilation rates for rooms that do not normally involve chemical fumes (for example, offices, auditoriums, libraries, classrooms, etc.) are primarily based on supplying a sufficient amount of fresh air per occupant. The basic intent is to ensure sufficient breathing air and thus prevent the carbon dioxide (CO 2 ) level from becoming too high. In most cases, a maximum occupancy is established based on the size, type and purpose of a room and the ventilation rate can therefore be determined based on providing a certain amount of cubic feet per minute (cfm) per person. The second component that must also be addressed when designing a ventilation system is determining the total amount of room supply air needed to maintain the required room ambient temperature and humidity. If a room has a relatively low occupancy, the low amount of fresh outside air required to satisfy the ventilation component might not be able to also maintain room ambient comfort. The common solution for non-laboratory room applications is to satisfy the total room supply air requirements by recirculating some of the air that is being exhausted from the room and combining it with the required amount of fresh air for ventilation. 4 Siemens Building Technologies, Inc.

17 Air Changes Per Hour Recirculated air is also known as return air. During much of the year the required fresh (outside) air must be substantially heated or cooled. However, the temperature and humidity of the return air is much closer to the required room supply air conditions. Thus the use of return air reduces the amount of energy required to provide the temperature and humidity level of the supply air necessary to maintain the required room temperature and humidity. Air Changes Per Hour The total amount of air that is supplied to a room normally exceeds the required fresh air component and is the room ventilation rate. The HVAC industry also uses expresses room ventilation rates in terms of number of air changes per hour (ACH) for the room. The amount of air necessary to achieve one air change for a room is equal to moving an amount of air into, and simultaneously out of, the room that equals the room s volume. Therefore, a room ventilation rate of one air change per hour is equivalent to moving a quantity of air through the room equal to the total volume of the room over the course of one hour. As was stated, of the total amount of air normally supplied to a room, a certain minimum amount must consist of fresh outside air. However, an occupant of a laboratory room is more likely to suffer the effects of harmful airborne substances than merely the discomfort of inadequate fresh outside air. Therefore, the room ventilation rates required for laboratory rooms are not based on a minimum cfm of fresh air per occupant since that would be quite low. Rather, laboratory rooms must maintain a relatively high room air change rate to ensure a safe room environment. Since air that is exhausted from a laboratory room is normally discharged outside and cannot be reused or recirculated 1, it follows that a laboratory facility needs to use nearly all outside air to maintain the required room ventilation rate of the individual laboratory rooms. Dilution Although the HVAC industry often uses the term air change per hour (ACH) with regard to quantifying the ventilation rate, the term can be misleading. The air being supplied to a room enters the room through a room air diffuser and then mostly mixes with the existing air in the room. This does not produce a true change out of the room air but rather a continual dilution and removal of any contaminants that are present in the room air. For example, consider a 1000 gallon water tank into which enough coloring dye is mixed to leave the water with a distinct dark coloration. Although clear water may be allowed to flow into the tank while an equal amount of water is being drained from the tank, the water in the tank will not be totally clear even after 1000 gallons of clear water is allowed to flow through the tank. Although this is the equivalent of one tank change, we know that the tank water will still possess some of the original coloration. If we continue to add clear water into the tank while draining an equivalent amount, we know that we ll be continually diluting and reducing the coloration but the last molecules of dye could be present for an indeterminate amount of time. 1 Although the reuse of air exhausted from a laboratory room is not always specifically prohibited, using such air for recirculation purposes requires ensuring removal of all hazardous substances which is technologically difficult and in the least very costly. Thus this option where available is not generally cost effective. Siemens Building Technologies, Inc. 5

18 Chapter 2 Goals of the Laboratory Environment In the same way, one air change per hour will not remove all of the airborne contaminants in a room but will produce a dilution effect. As the rate of air changes per hour is increased, we ll reduce the concentration of hazardous airborne substances faster; but the time to remove every last trace of such substances could be quite long and just like in the tank example cannot really be determined. ACH Calculations TYPE OF ROOM To determine the airflow rate that is necessary to achieve one air change per hour (ACH), for a given room, the room volume in cubic feet must first be determined. Then, the room volume is divided by 60 (minutes per hour). This simple calculation yields the airflow rate in cubic feet per minute necessary to achieve one air change per hour (ACH). Thus, a room having dimensions of 12 feet in width, 20 feet in length and 10 feet in height will have an internal volume of 2,400 cubic feet. Next, the 2400 cubic feet is divided by 60 minutes per hour which yields 40 cubic feet per minute (cfm). Therefore, one ACH for the room will require a continuous air supply of 40 cfm. It follows also that 10 ACH would require cfm or 400 cfm. It is equally important to remember that an amount of exhaust equal to the supply airflow must simultaneously be removed from the room as part of the ventilation process. Note that air change rates are based upon the total internal volume of a room. In actuality rooms will have furniture, equipment and of course, people. Although the actual net air space left within the room therefore is less than the volume calculated using the room dimensions, the procedure to determine the airflow cfm for a specific ACH rate in order to comply with regulatory requirements or conform to HVAC standards is to always base the ACH on the overall room volume. Thus, it is not permissible to deduct the volume of furniture or equipment in a room when calculating the airflow required to attain a specific ACH ventilation rate. The ASHRAE organization provides the most comprehensive guide to the recommended amount of outside fresh air and the minimum room ventilation rates that should be supplied to various types of rooms. Table 1 is adapted from information following the ASHRAE recommended outdoor fresh air rates and the minimum ventilation (ACH) rates for the types of rooms that would normally be associated with a laboratory facility. In addition to ASHRAE, other organizations that address laboratory safety have established recommended ventilation rates for various types of rooms. The 1990 OSHA requirement (29 CFR Part 1910) for laboratories recommends a ventilation rate of 4 to 10 ACH for laboratories with fume hoods. Research facilities that have instituted their own minimum standards for laboratory ventilation rates most often maintain a minimum of 10 ACH. Experienced laboratory HVAC designers favor the use of minimum ACH rates between 10 and 12 ACH. Table 1. Minimum ACH and Outside Air Rates (From ASHRAE HVAC Applications 1995 & ANSI/ASHRAE Std ). General Office Classroom Corridor Auditorium Cafeteria ACH RATE 4 to 10 6 to 20 4 to15 12 to 15 OUTSIDE AIR 20 cfm 15 cfm 0.10 cfm per sq ft 15 cfm 12 cfm 6 Siemens Building Technologies, Inc.

19 Occupant Comfort Versus Occupant Safety TYPE OF ROOM Hospita l Patient Room Protective Isolation Rooms Infectious Isolation Rooms Biochemistry Lab Animal Lab Autopsy Lab Chemical Storage Room ACH RATE to to OUTSIDE AIR TO ACH RATE 1/3 1/3 1/3 1/3 100% 1/6 1/3 Process Ambient Requirements An experiment or process may require specific room ambient conditions that must be maintained. If so, then this also becomes a required goal of the laboratory ventilation system. Most laboratory room procedures and processes do not pose requirements that are unacceptable in terms of human comfort. For instance, although animal laboratories generally require maintaining specific relative humidities and temperatures along with higher air movement rates, these requirements generally do not pose an unacceptable comfort level for humans who must spend some time in these rooms. However, if the required ambient conditions (for example, very low temperatures) pose a significant discomfort level to persons who need to be present, it may become necessary to isolate and condition the process environment apart from the overall laboratory room. All requirements for specific process ambient requirements must be made known to the designers and planners as soon as possible and certainly well before a project design is finalized. HVAC system designs that are only required to maintain human comfort may not be able to maintain ambient conditions that are significantly different from that normally provided for human comfort. To ensure the HVAC systems can provide special ambient conditions, the HVAC designers and planners may need to incorporate specialized equipment or special design approaches to ensure such requirements will be met. Circumstances where process ambient requirements present a substantial conflict with personnel comfort will also need to be addressed, possibly by incorporating special physical partitioning in the laboratory room or other measures in conjunction with the room design. Occupant Comfort Versus Occupant Safety A laboratory environment should provide a high level of occupant comfort to maximize their productivity and concentration. A room environment that is not comfortable will entice the occupants to institute various measures of their own that could significantly compromise the health and safety of the environment. For instance, using a portable fan in a laboratory room that is too warm would likely upset ventilation air patterns that are specifically intended to keep airborne contaminants away from occupants. Similarly, adding portable heating appliances could create a dangerous situation if flammable or explosive substances are present in the room. Likewise, a room with too low of a relative humidity level would pose a hazard since static electricity discharges might occur in proximity to flammable liquids or gasses. Siemens Building Technologies, Inc. 7

20 Chapter 2 Goals of the Laboratory Environment Research by ASHRAE has established the range of ambient conditions over which the largest percentage of persons feel comfortable when involved in the type of activity generally associated with laboratory work. These conditions range from 71.6 F throughout the winter months to 72.7 F during the summer months. Relative humidity should be maintained within the limits of 30% (winter minimum) to 70% (summer maximum). Adequate room air movement is essential for comfort, but air movement should not exceed 50 feet per minute as most persons perceive a draft with rates higher than that. Room Sound Level Finally, designers must be aware of that the ambient sound level of a laboratory room is a very important component of overall occupant comfort. Since laboratory rooms must be ventilated at higher rates than typical office spaces, the potential problem of excessive ventilation system sound exists. Therefore, HVAC designers must configure the ventilation system design so as to achieve an acceptable sound level. For most laboratories this means the ambient sound level is best if it is in the range of 35 to 45 db based upon standard acoustical room criteria (RC) curves. Where chemical fume hoods are present, it is generally acceptable to allow an ambient sound level of 65dB at the fume hood with the fume hood sash fully open. In particular, it is very important to ensure that low frequency sound does not exceed the maximums permitted by the RC curves. Research indicates that low frequency sound has a very adverse affect on one s ability to maintain concentration. In addition, low frequency sound has a tendency to induce a feeling of general discomfort and sometimes even irritability. Emergency Provisions Aside from achieving a ventilation system design that provides the required ventilation rate, occupant comfort and other necessary qualities, a conscientious laboratory planner or HVAC designer must address laboratory room emergencies. At some time, it is inevitable that emergency situations will occur in a laboratory. This may consist of a hazardous or toxic chemical spill, possible release of noxious gasses, escape of harmful airborne biological pathogens, fire and of course various injuries or medical emergencies. The design of a laboratory ventilation system must include provisions to enable the ventilation system to specifically respond to such emergencies. For instance, room ventilation rates may need to be increased in response to a toxic spill. The room supply and exhaust airflow rates may need to be changed to create larger static pressure differences to prevent smoke spread during a fire. Various standards and practices exist that specifically address the proper use and operation of ventilation systems in response to emergency situations and these will be discussed in detail later in this guide. 8 Siemens Building Technologies, Inc.

21 Chapter 3 Unique Ventilation Needs of a Laboratory Facility Chapter 3 summarizes the types of individual laboratory rooms likely to be present in a large laboratory facility and their unique ventilation requirements. This is not a complete listing of all possible types of laboratory rooms or of every possible condition that may be encountered. Rather it is intended to enable you to attain an awareness of requirements that will be imposed on the ventilation system for such types of rooms. This chapter includes the following topics: Microbiological/Biomedical laboratory rooms High toxicity laboratory rooms Medical laboratory rooms Animal rooms vivariums General chemical and analytical laboratory rooms Microbiological/Biomedical Laboratory Rooms As expected, this category usually applies to the largest portion of laboratory rooms in a biological laboratory facility. These types of laboratory rooms cover a very wide variety of activities involving working with biological substances of varying degrees of risk depending on the nature of the infectious and/or toxic agents present. The ventilation rates, previously listed in Table 1, apply along with a requirement that the ventilation system be designed to prevent room air from migrating to other parts of the facility. The following listing focuses on the specific ventilation system requirements of each type of biological laboratory. The classifications represent the standards of the Centers for Disease Control (CDC) in the U.S. and also coincide with the biosafety containment levels of the Laboratory Centre for Disease Control of Canada. Biosafety Level 1 The biological safety levels or containment levels of a laboratory (Biosafety Levels 1 through 4) should not be confused or used interchangeably with the classification of Biological Safety Cabinets (Class I through III). This is the lowest biosafety classification and applies to biological laboratory activities that need no special ventilation requirements apart from an adequate ventilation rate as indicated in Table 1. Biosafety Level 1 activities may also be conducted within a general chemical laboratory in which case the room ventilation must meet the requirements for a general chemistry laboratory. Siemens Building Technologies, Inc. 9

22 Chapter 3 Unique Ventilation Needs of a Laboratory Facility Biosafety Level 2 This classification usually applies to the largest number of microbiological/biomedical laboratories. Although some of the substances present may be infectious, they may be worked on open benches provided that the potential for aerosol release is very low. Apart from providing an adequate minimum ventilation rate, the room supply airflow rate must be sufficient to replace the amount of air being exhausted from the room and any biological safety cabinets that are present. Note that adequately filtered air that flows through the Class IIA type of biological safety cabinets (very often used in a Biosafety Level 2 laboratory) may be returned to the room and thus does not increase the amount of air exhausted from the room. (See the Laboratory containment units - ventilation section for specific details on biological safety cabinets.) The Biosafety Level 2 lab room must be designed for thorough cleaning and provisions must be made in the facility for sterilization of apparatus and decontaminating biological waste from the room. Therefore, room ventilation components such as supply air diffusers and exhaust air grills must be suitable for periodic decontamination and washdown. Biosafety Level 3 Since this classification applies to laboratory rooms that work with infectious agents that are transmissible as aerosols, the requirements are quite stringent. Biosafety Level 3 rooms must have all of the provisions of Biosafety Level 2, plus they must utilize biological safety cabinets for all work being done in the room. The lab must also be separated from other building areas and a Biosafety Level 3 room requires a double door entry arrangement. Ventilation system provisions for Biosafety Level 3 requires single pass conditioned airflow. In addition, the room static pressure must be negative to ensure against outward airflow. Occasionally, there will be a need to filter all biological safety cabinet exhaust from the room with a high efficiency particulate air (HEPA) filter. The need to maintain an effective room barrier without penetrations makes it advantageous to use a dedicated room HVAC system located within the laboratory unit itself. Biosafety Level 4 Biosafety Level 4 are seldom present in most laboratory facilities. It is referenced here mainly to complete the description of the different biosafety laboratory classifications. Biosafety Level 4 activities require all of the Biosafety Level 3 provisions, plus utilization of the highest classification (Class 3) of biological safety cabinet. Laboratory entry and exit precautions are extensive and it is desirable to physically isolate the room from other parts of the overall laboratory facility. The room construction is more stringent and the ventilation system must be dedicated only such laboratory rooms. All intake air and all air exhausted from the lab or any containment unit must be HEPA filtered. The temperature and humidity of these laboratories is typically required to be closely controlled as required by the nature of the substances present. 10 Siemens Building Technologies, Inc.

23 High Toxicity Laboratory Rooms High Toxicity Laboratory Rooms This type of laboratory is so designated because of the higher level of hazard posed by the substances and chemicals often used. Federal (U.S. OSHA) and state regulatory agencies have established a list of what substances and chemicals pose, or are suspected of posing, a high risk due to their potential for causing cancer (carcinogens), birth defects, or other potentially very serious adverse affects if exposed. Maintaining environmental goals in a high toxicity laboratory is done by designing the lab with adequate access restriction, tight sealing doors, and ensuring an adequate overall ventilation rate. Work with highly toxic substances is preferably done in a glove box to prevent physical contact with the substance and ensure that air from the box is directly exhausted and prevented from flowing back into the laboratory room. Exhaust from glove boxes and the high toxicity laboratory itself must also be filtered by a high efficiency particulate air (HEPA) filter prior to discharge outdoors. The temperature and humidity of these laboratories is typically controlled for occupant comfort; however additional ambient control requirements may exit in specific instances. Medical Laboratory Rooms Laboratories associated with health care and patient treatment vary considerably with respect to their purpose, size and level of risk posed to the workers. Some of the activities include pathology (examining tissue specimens for structural and functional evidence of disease), urinalysis and cytology (analysis and examination of body fluids), virology and microbiology (analysis for determining the presence of viruses and other infectious disease pathogens), and nuclear medicine. The health risk posed to laboratory workers ranges from relatively small to quite substantial. In addition, odor control is a very often necessary for most of these activities. Laboratory room ventilation systems range from that required for a general chemistry laboratory way up to a Biosafety Level 3 laboratory, as appropriate to the activity. Where multiple laboratory functions are combined in a single room, the laboratory ventilation system design must address the most stringent health and safety requirements of any single activity. Animal Rooms Vivariums A wide variety of activities are associated with laboratory animals and extensive support activities are necessary. Some of the most intensive support activities include animal feeding and cage cleaning and the disposal of infected animal tissue and the carcasses of dead animals. In all activities associated with animal labs, the need to protect against biological hazards, transmission of allergens, and the ever present need for odor control imposes a multitude of requirements on the ventilation system and requires a higher ventilation rate than for chemical or biological labs. Air that is exhausted from an animal laboratory room cannot be recirculated or allowed to migrate to other parts of the facility. Siemens Building Technologies, Inc. 11

24 Chapter 3 Unique Ventilation Needs of a Laboratory Facility Stringent ambient controls appropriate for the species of animals present are necessary to ensure maintaining accreditation and thus validation of the research. Certain room arrangements may also require supplying highly purified air directly to cage racks or having a dedicated HEPA filtered exhaust. Exhaust air from these rooms should first be rough filtered to prevent animal hair and other airborne residue from accumulating in the laboratory exhaust system. General Chemical and Analytical Laboratory Rooms These are very common types of laboratory rooms using a wide variety of chemicals for experimentation and analysis work. This type of laboratory room is not intended for handling extremely hazardous substances such as highly explosive, highly toxic, carcinogenic, or any other that are considered very dangerous. In addition, these laboratories should not contain apparatus which requires very high voltage or high power including higher power lasers, high-pressure gasses or liquids, and all but minimal amounts of radioactive materials. Operations and procedures involving chemicals in these laboratory rooms are typically done in chemical fume hoods. Maintaining environmental goals in a general chemistry laboratory is normally done by providing a minimum overall ventilation rate, maintaining adequate fume hood face velocity and minimum fume hood exhaust rate, and ensuring that no room air is recirculated or migrates to other parts of the facility. The temperature and humidity of these laboratories is typically controlled for occupant comfort. 12 Siemens Building Technologies, Inc.

25 Chapter 4 Ventilation Systems Classification Chapter 4 discusses the various classes of ventilation systems. It includes the following topics: Types of ventilation systems VAV systems Choice of ventilation system Types of Ventilation Systems Ventilation systems for virtually any application can be classified into two general categories: constant air volume (CAV) or variable air volume (VAV). The constant air volume type of ventilation system is by far the most prevalent type of system in use today. However, the variable air volume type of system is becoming popular, particularly in new facility applications because it offers the advantages of greater operational flexibility and the opportunity for the greatest reduction in energy usage. CAV Systems As the name implies, a constant air volume type of ventilation system always provides a relatively constant amount of ventilation airflow or cfm. The amount of airflow is selected during the ventilation system design and is based upon satisfying a room s minimum ventilation requirements and whatever additional airflow might be necessary to handle worst case room comfort conditioning and any other special requirements. From the time this type of system is placed in operation, the airflow rate is typically never changed unless a major facility renovation takes place. While basically simple in function, the CAV system s major drawback is that it consumes a high amount of energy since it has no provision to allow reducing the ventilation rate when permissible as during unoccupied times. Figure 1 illustrates a typical CAV ventilation system applied to a laboratory room having chemical fume hoods. With reference to Figure 1, a constant volume of outside air is drawn into the primary air handling unit where it is filtered and conditioned (heated or cooled and humidified) in accord with the needs of the facility for at a given time of the year. A constant volume of conditioned air (normally at a cooler temperature than room air) is supplied throughout an entire facility or a portion of a larger facility. The temperature of the air that is supplied to an individual laboratory room is raised by a room terminal unit reheat coil as may be necessary to meet occupant comfort and other needs of the specific room. Siemens Building Technologies, Inc. 13

26 Chapter 4 Ventilation Systems Classification As the air passes through the laboratory room it provides the required room ventilation (ACH) rate. In cases where the room has chemical fume hoods, biological safety cabinets that are exhausted outdoors, or other types of exhaust needs, the supply air also provides the makeup air for the amount exhausted from these containment units. After passing through the room and/or the containment units, the air is exhausted out of the laboratory facility by the exhaust system. Most codes do not permit the recirculation of any laboratory exhaust air as return air for ventilation purposes. Those codes that do permit this require removal of all contaminants from the exhaust air. Because of the difficulty of ensuring all contaminants are removed and the potential high costs likely to be involved, air exhausted from laboratory rooms is not normally reused or re-introduced into the ventilation system. PRIMARY AIR HANDLING UNIT SUPPLY COOLING HUMIDIFICATION FAN HEATING FILTERING OUTSIDE AIR EXHAUST SYSTEM ROOM TERMINAL UNIT REHEAT GENERAL EXHAUST LABORATORY ROOM CAV FUME HOODS Figure 1. CAV Ventilation System Applied to Ventilate a Chemical Laboratory Room. In the case of a laboratory room with CAV fume hoods, (see Figure 1), some air leaves by means of the general exhaust provision in the room ceiling; however, most of the room air actually leaves by through the fume hoods since CAV fume hoods exhaust a relatively large amount of air. The amount of makeup air brought into the room that is necessary to replace the air exhausted by the fume hoods often exceeds the amount of air necessary to provide the required number of room air changes per hour. Therefore, ventilation system designers must be sure to determine the makeup air requirements for the fume hoods as well as any other containment units or specialized exhausts that will be in the laboratory room. The amount of ventilation air to be supplied to the room must be sufficient to makeup air for the totalized exhaust of the room and not just meet the required room ventilation rate. 14 Siemens Building Technologies, Inc.

27 Types of Ventilation Systems Two-position CAV A two-position CAV type of ventilation system is essentially the same as the one position CAV system shown in Figure 1. The difference is that the two-position system has a means to provide two separate levels of ventilation airflow. As was indicated previously, standards and codes typically allow a lesser ventilation rate when a laboratory is unoccupied as opposed to when the laboratory is occupied and in use. In order to take advantage of this and save considerable air conditioning energy, a two position CAV system may be utilized. The best way of attaining two separate levels of airflow in a two-position CAV system is by adding a control device, typically a variable speed drive, on the fan motor power circuit. This enables the fan to be run at a lower speed and thus deliver less air through the primary air handling unit when less ventilation air is required. It must also be noted that along with reducing the air supplied to the laboratory rooms, the exhaust system must also reduce the exhaust air removed by a similar amount. In fact the actual amount by which the supply can be reduced during the unoccupied time is mostly dependent upon the extent that the exhaust air can be reduced. Chemical fume hoods should maintain a minimum airflow even with their sash fully closed 2 and a minimum laboratory room ventilation rate must also be maintained. Therefore, the room supply air during the unoccupied period must still be sufficient to make up for the total amount of room exhaust that must be maintained. VAV Systems The variable air volume (VAV) ventilation system s major characteristic is that it has the ability to vary the amount of supply and exhaust air to closely match actual facility needs at any given time. This enables achieving a substantial reduction in the amount of energy necessary to transport and condition the ventilation air. Applying a VAV system to a facility with chemical fume hoods also requires that the fume hoods be equipped with VAV exhaust controls wherever possible 3. Thus, a VAV ventilation system with the appropriate control system can ensure that only the required amount of air is conditioned, supplied and then exhausted from the laboratory rooms. The specific amount of air supplied and exhausted will likely vary throughout the occupied time as the needs and activities in a laboratory room vary. The specific airflow needs of each room may be governed by such factors as meeting the required room ventilation (ACH) rate, providing sufficient replacement air for air being exhausted by the fume hoods, and the necessary amount of supply air to maintain the required room ambient conditions. Any of these requirements can establish the specific airflow rate that the VAV system must provide for each individual room at a given time. 2 3 Current standard recommend maintaining a minimum exhaust airflow of approximately 20% of the normal maximum fume hood airflow even with the sash fully closed. Perchloric acid fume hoods and radioisotope fume hoods are not normally suitable for the addition of VAV controls. Adding VAV control devices in the exhaust of such hoods would likely interfere with effective perchloric acid hood washdown and might also become contaminated with radioactive material making servicing difficult. Siemens Building Technologies, Inc. 15