Technical Assessment of Dry Ice Limits on Aircraft (2013)

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H A Z A R D O U S M A T E R I A L S C O O P E R A T I V E R E S E A R C H P R O G R A M HMCRP REPORT 11 Technical Assessment of Dry Ice Limits on Aircraft Michael J. Murphy Thomas I. McSweeney Battelle MeMorial institute Columbus, OH Subscriber Categories Aviation  •  Freight Transportation TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2013 www.TRB.org  Research sponsored by the Pipeline and Hazardous Materials Safety Administration

HAZARDOUS MATERIALS COOPERATIVE RESEARCH PROGRAM The safety, security, and environmental concerns associated with transportation of hazardous materials are growing in number and complexity. Hazardous materials are substances that are flammable, explosive, or toxic or that, if released, produce effects that would threaten human safety, health, the environment, or property. Hazardous materials are moved throughout the country by all modes of freight transportation, including ships, trucks, trains, airplanes, and pipelines. The private sector and a diverse mix of government agencies at all levels are responsible for controlling the transport of hazardous materials and for ensuring that hazardous cargoes move without incident. This shared goal has spurred the creation of several venues for organizations with related interests to work together in preventing and responding to hazardous materials incidents. The freight transportation and chemical industries; government regulatory and enforcement agencies at the federal and state levels; and local emergency planners and responders routinely share information, resources, and expertise. Nevertheless, there has been a long- standing gap in the system for conducting hazardous materials safety and security research. Industry organizations and government agencies have their own research programs to support their mission needs. Collaborative research to address shared problems takes place occasionally, but mostly occurs on an ad hoc basis. Acknowledging this gap in 2004, the U.S. DOT Office of Hazardous Materials Safety, the Federal Motor Carrier Safety Administration, the Federal Railroad Administration, and the U.S. Coast Guard pooled their resources for a study. Under the auspices of the Transportation Research Board (TRB), the National Research Council of the National Academies appointed a committee to examine the feasibility of creating a cooperative research program for hazardous materials transportation, similar in concept to the National Cooperative Highway Research Program (NCHRP) and the Transit Cooperative Research Program (TCRP). The committee concluded, in TRB Special Report 283: Cooperative Research for Hazardous Materials Transportation: Defining the Need, Converging on Solutions, that the need for cooperative research in this field is significant and growing, and the committee recommended establishing an ongoing program of cooperative research. In 2005, based in part on the findings of that report, the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) authorized the Pipeline and Hazardous Materials Safety Administration (PHMSA) to contract with the National Academy of Sciences to conduct the Hazardous Materials Cooperative Research Program (HMCRP). The HMCRP is intended to complement other U.S. DOT research programs as a stakeholder-driven, problem-solving program, researching real-world, day-to-day operational issues with near- to mid- term time frames. Published reports of the HAZARDOUS MATERIALS COOPERATIVE RESEARCH PROGRAM are available from: Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet at: http://www.national-academies.org/trb/bookstore Printed in the United States of America HMCRP REPORT 11 Project HM-09 ISSN 2150-4849 ISBN: 978-0-309-25883-8 Library of Congress Control Number 2013956247 © 2013 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, RITA, or PHMSA endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not- for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The project that is the subject of this report was a part of the Hazardous Materials Cooperative Research Program, conducted by the Transportation Research Board with the approval of the Governing Board of the National Research Council. The members of the technical panel selected to monitor this project and to review this report were chosen for their special competencies and with regard for appropriate balance. The report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the Governing Board of the National Research Council. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board, the National Research Council, or the program sponsors. The Transportation Research Board of the National Academies, the National Research Council, and the sponsors of the Hazardous Materials Cooperative Research Program do not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the object of the report.

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. On the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Charles M. Vest is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, on its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. Charles M. Vest are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is one of six major divisions of the National Research Council. The mission of the Transporta- tion Research Board is to provide leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Board’s varied activities annually engage about 7,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individu- als interested in the development of transportation. www.TRB.org www.national-academies.org

C O O P E R A T I V E R E S E A R C H P R O G R A M S CRP STAFF FOR HMCRP REPORT 11 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs Joseph D. Navarrete, Senior Program Officer Terri Baker, Senior Program Assistant Eileen P. Delaney, Director of Publications Doug English, Editor HMCRP PROJECT 09 PANEL David Brennan, International Air Transport Association, Geneva (Chair) Thomas Ferguson, Currie Associates, Inc., Queensbury, NY Bradley H. Hallmark, U.S. Department of Transportation, Oklahoma City, OK Robert McClelland, UPS Airlines, Louisville, KY Michel A. Wentz, American Airlines, Inc., Fort Worth, TX Duane Pfund, PHMSA Liaison James Simmons, PHMSA Liaison Bill Wilkening, FAA Liaison Christine Gerencher, TRB Liaison

F O R E W O R D By Joseph D. Navarrete Staff Officer Transportation Research Board HMCRP Report 11: Technical Assessment of Dry Ice Limits on Aircraft describes a technical approach to determining the maximum quantity of dry ice (solid carbon dioxide) that can be safely carried aboard aircraft. A key finding of this research is that dry ice transport limits would best be based on packaging surface area rather than on the current mass-based limits. As a result of this finding, guidelines are provided that could be used to provide safe limits for carriage of dry ice on commercial airplanes. In addition, a software tool is provided to allow users to input variables for specific aircraft and trip profiles to determine appropriate dry ice loadings. This tool is located on the CD-ROM that accompanies this report. Dry ice is widely used to keep perishable goods cold while in transit. Since dry ice subli- mates (i.e., passes directly from a solid state to a gaseous state) to produce carbon dioxide gas, there are specified limits on the amount of dry ice that can be transported on passenger and cargo aircraft. The current dry ice limits are based on the mass of dry ice carried. How- ever, there has been little experimental data on the sublimation rate of dry ice in packages, and much of the analysis was undertaken nearly 50 years ago. Thus, there is a need to review and update current recommendations. The research, led by Battelle Memorial Institute, initially reviewed current regulations and guidance for dry ice shipments, and also reviewed aircraft manufacturer and air carrier guidelines and procedures. All the guidance focuses on establishing a mass-based limit on the quantity of dry ice that can be shipped. A heat transfer and dimensional analysis showed that the sublimation rate of dry ice is determined by specifying the surface area and insula- tion properties of the packages, not by the quantity of dry ice present in the package, and laboratory tests were performed to confirm these findings. Using the heat transfer analysis and the results of the laboratory tests, the research team developed a model to predict the performance of dry ice during flight conditions and tested the model with data obtained in flight. Based on the research findings, the team developed guidelines that could be used to provide safe limits for carriage of dry ice on commercial airplanes. The guidelines have two key parts: (1) a packaging standard that specifies a minimum amount of insulation and (2) a total surface area limit for dry ice packages. The team then developed a tool that enables operators of passenger or cargo aircraft to first determine the total surface area of dry ice packages that can be safely loaded onto a particular flight and, using this information, con- firm that the dimensions of all the dry ice packages being shipped do not exceed these limits. The report is organized into 12 chapters. Chapter 1 provides an introduction to the research. Chapter 2 provides an overview of the properties and use of dry ice in commerce. Chapters 3, 4, and 5 present a review of guidelines and regulations for dry ice shipments, aircraft manufacturer guidelines and procedures, and air carrier procedures. A dimensional

analysis of dry ice sublimation is described in Chapter 6, while Chapter 7 provides a ratio- nale for basing dry ice limits on heat transfer analysis. Chapters 8, 9, and 10 describe the laboratory and field testing efforts undertaken as part of the research. The development of dry ice guidelines for aircraft is described in Chapter 11. Chapter 12 provides recommenda- tions for future research. The software tool, available on the CD-ROM that accompanies this report, illustrates how the surface area method can be used by airlines and shippers to estimate the total surface area of packages containing dry ice that can be loaded for specific aircraft and trip profiles. Prior to a flight, a carrier can verify that this surface area limit will not be exceeded using the dimensions of all the dry ice packages being shipped.

C O N T E N T S 1  Summary 4 Chapter 1  Introduction 4 Project Background 4 Project Objectives and Scope 4 Objectives 4 Scope 6 Chapter 2  Dry Ice 6 Properties of Dry Ice 6 Use of Dry Ice in Commerce 6 Forms of Dry Ice Used in Commerce 6 Types of Air Cargos that Use Dry Ice 6 Packaging for Dry Ice Shipments 7 Insulated Cardboard Cartons 7 ULDs 11 Chapter 3   Review of Guidelines and Regulations  for Dry Ice Shipments 11 Carbon Dioxide Exposure Limits 11 General Industrial Exposure Limits 11 Carbon Dioxide Exposure Limits for Aircraft 12 Dry Ice Packaging Requirements 12 ICAO and IATA Packaging Requirements 13 DOT Regulations for Dry Ice Packaging 13 FAA and NTSB Guidelines 14 Chapter 4   Review of Aircraft Manufacturer Guidelines  and Procedures 14 Information from Airbus 14 Information from Boeing 15 Information on Regional Jets 16 Chapter 5   Review of Air Carrier Procedures  for Shipments Containing Dry Ice 16 Packaging Requirements for Air Shipments Containing Dry Ice 16 Procedures for the Tender of Dry-Ice–Containing Packages 16 Packages Tendered by Companies and Shipping Agents 16 Packages Tendered by Individuals 17 Aircraft and Compartment Limits 17 Special Loading, Unloading, and Location Procedures 17 Considerations Related to Transport of Animals 18 Unloading 18 Location and Climate

19 Chapter 6   Dimensional Analysis of Dry Ice Sublimation 19 Dimensional Analysis for Heat Transfer 20 Dimensional Analysis for Ventilation Flow 20 Discussion of Dimensional Analysis Results 21 Chapter 7   Heat Transfer and Carbon Dioxide Production 21 Rationale for Basing Dry Ice Limits on Heat Transfer Analysis 21 Review of Existing Information on Heat Transfer to Cold Cargo 21 Insulated Cardboard Cartons Containing Dry Ice 21 Insulated ULDs Containing Dry Ice 22 Other Cold Cargo 22 Heat Transfer Calculations 22 Heat Transfer to Packages 23 Heat Transfer to Insulated Unit Load Devices 23 Discussion of Heat Transfer Analysis Results 23 Uncertainties in the Heat Transfer Analysis 24 Steady-State Versus Transient Analysis 25 Summary of Dimensional Analysis and Heat Transfer Model Results 26 Chapter 8   Experimental Measurements  of Dry Ice Sublimation Rates 26 Laboratory Tests of Single Packages 26 Objective 26 Test Packages 26 Mass and Temperature Measurement 26 Procedure 26 Results 26 Laboratory Tests of Multiple Package Configuration 26 Objective 26 Test Configurations 27 Results 28 Package Shipment Tests 28 Procedure 28 Results 29 Discussion of Experimental Test Results 29 General Observations 29 Uncertainties in Experimental Measurements 29 Comparison of Single- and Multiple-Package Test Results 29 Comparison with Heat Transfer Analysis 29 Proposed Use of an Area-Normalized Dry Ice Loss Rate 31 Chapter 9   Factors Affecting Carbon Dioxide Concentrations  on Aircraft 31 Carbon Dioxide Sources 31 Carbon Dioxide in Ventilation Air 31 Carbon Dioxide Produced by Human Metabolism 32 Carbon Dioxide Produced by Animal Metabolism 32 Volume of Carbon Dioxide Produced by Sublimation of Dry Ice 32 Carbon Dioxide Removal: Ventilation Air Flows 32 Aircraft Ventilation Requirements

33 Understanding of Aircraft Ventilation Air Flows 33 Information on Ventilation Rates 34 Calculation of Expected Carbon Dioxide Concentrations 34 Examples of Carbon Dioxide Concentration Calculations 35 Chapter 10   Measurements of Carbon Dioxide Concentrations  on Aircraft 35 Review of Previous Measurements 35 Studies of Carbon Dioxide Concentrations in Aircraft Passenger Cabins 35 Studies of Carbon Dioxide Concentrations in Aircraft Cargo Compartments 35 Results of Previous Studies 35 Measurements Made for This Study 35 Experimental 37 Results of Measurements 37 General Observations 41 Analysis of the Relative Importance of Carbon Dioxide Sources 41 Carbon Dioxide from Passengers and Cabin Crew 41 Carbon Dioxide from Ventilation Air 42 Carbon Dioxide from Dry Ice Used for Food and Beverage Cooling 42 Carbon Dioxide from Sublimation of Dry Ice in Cargo Compartment 42 Ventilation Model for Onboard Test 42 Comments on Dry Ice Sublimation Rate 42 Importance of Various Sources 43 Chapter 11   Development of Dry Ice Limit Guidelines 43 Summary of Steps to Determine the Quantity of Dry Ice Packages Allowed in an Airplane 44 Development of Guidelines for Establishing Dry Ice Limits on Airplanes 44 Selection of Target Carbon Dioxide Concentration Limit 44 Estimation of Sublimation Rates 44 Consideration of Ventilation Air Flow 44 Calculation of Maximum Allowable Dimensional Area 45 Guidelines for Implementation of Dry Ice Limits 45 Packaging 46 Guidelines for Specific Locations and Situations 47 Summary of Implementation Steps 48 Chapter 12  Recommendations for Future Work 48 Administrative Steps 49 Recommended Future Technical Studies on Dry Ice Sublimation 49 Assessment of Sublimation Rates from Palletized Packages 49 Effect of Variation in Dry Ice Form 49 Obtaining Further Technical Data on Aircraft Ventilation 49 Aircraft Ventilation System Configuration 49 Aircraft Ventilation System Operation 49 Off-Normal Operation 49 Regional Jets 50 Obtaining Further Technical Data on Aircraft Operations 50 Dry Ice in Passenger Cabin from Carry-On Packages

50 Aircraft Loading and Unloading Procedures 50 Use of Dry Ice for Food and Beverage Cooling 50 Obtaining Further Technical Data on Carbon Dioxide Measurements on Board Aircraft 50 Onboard Measurements in Passenger Cabin 50 Onboard Measurements of Carbon Dioxide in Cargo Compartments 51 Improving Precision for the Decision Tool 52  References Note: Many of the photographs, figures, and tables in this report have been converted from color to grayscale for printing. The electronic version of the report (posted on the Web at www.trb.org) retains the color versions.