Api rp 505 1997 (2013) (american petroleum institute)

Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Zone 0, Zone 1, and Zone API RECOMMENDED PRACTICE 505 FIRST EDITION, NOVEMBER 1997 REAFFIRMED, AUGUST 2013 `,,```,,,,````-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,```,,,,````-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Zone 0, Zone 1, and Zone Manufacturing, Distribution and Marketing Department API RECOMMENDED PRACTICE 505 FIRST EDITION, NOVEMBER 1997 REAFFIRMED, AUGUST 2013 `,,```,,,,````-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale SPECIAL NOTES API publications necessarily address problems of a general nature With respect to particular circumstances, local, state, and federal laws and regulations should be reviewed API is not undertaking to meet the duties of employers, manufacturers, or suppliers to warn and properly train and equip their employees, and others exposed, concerning health and safety risks and precautions, nor undertaking their obligations under local, state, or federal laws Information concerning safety and health risks and proper precautions with respect to particular materials and conditions should be obtained from the employer, the manufacturer or supplier of that material, or the material safety data sheet Nothing contained in any API publication is to be construed as granting any right, by implication or otherwise, for the manufacture, sale, or use of any method, apparatus, or product covered by letters patent Neither should anything contained in the publication be construed as insuring anyone against liability for infringement of letters patent Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least every five years Sometimes a one-time extension of up to two years will be added to this review cycle This publication will no longer be in effect five years after its publication date as an operative API standard or, where an extension has been granted, upon republication Status of the publication can be ascertained from the API Manufacturing, Distribution and Marketing Department [telephone (202) 682-8000] A catalog of API publications and materials is published annually and updated quarterly by API, 1220 L Street, N.W., Washington, D.C 20005 This document was produced under API standardization procedures that ensure appropriate notification and participation in the developmental process and is designated as an API standard Questions concerning the interpretation of the content of this standard or comments and questions concerning the procedures under which this standard was developed should be directed in writing to the director of the Manufacturing, Distribution and Marketing Department, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C 20005 Requests for permission to reproduce or translate all or any part of the material published herein should also be addressed to the director API standards are published to facilitate the broad availability of proven, sound engineering and operating practices These standards are not intended to obviate the need for applying sound engineering judgment regarding when and where these standards should be utilized The formulation and publication of API standards is not intended in any way to inhibit anyone from using any other practices Any manufacturer marking equipment or materials in conformance with the marking requirements of an API standard is solely responsible for complying with all the applicable requirements of that standard API does not represent, warrant, or guarantee that such products in fact conform to the applicable API standard All rights reserved No part of this work may be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission from the publisher Contact the Publisher, API Publishing Services, 1220 L Street, N.W., Washington, D.C 20005 Copyright © 1997 American Petroleum Institute `,,```,,,,````-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale FOREWORD This Recommended Practice is under the joint jurisdiction of the API Exploration and Production (E&P) Department Committee on Production Equipment Standards, the API Manufacturing Distribution and Marketing (MDM) Department, Committee on Refinery Equipment, and the Pipeline Operations Technical Committee It is based upon a level of knowledge gained through experience and through the successful application of this practice in the refining, drilling and producing, and pipeline segments of the petroleum industry Recommended Practice 505 was prepared as a supplement to the 1996 Edition of the National Electrical Code (NEC) Article 505, with a scope limited to those petroleum facility locations classified as Class I, Zone 0, Zone 1, and Zone Efforts were coordinated with the work of the ISA SP12 committee, which concurrently normalized the International Electrotechnical Commission (IEC) Standard 79-10 that addresses the zone area classification scheme in general RP 505 will serve the petroleum industry, essentially as an supplement to both ISA 12.24.01 (IEC 79-10 Mod) and NEC Article 505 RP 500 is presently referenced by Article 500 of the NEC; it is anticipated that the 1999 NEC will also reference RP505 in Article 505 API publications may be used by anyone desiring to so Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state or municipal regulation with which this publication may conflict Suggested revisions are invited and should be submitted to the director of the Manufacturing, Distribution and Marketing Department, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C 20005 iii `,,```,,,,````-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,```,,,,````-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale CONTENTS Page SCOPE 1.1 Purpose 1.2 Scope REFERENCES 2.1 Industry Codes, Guides and Standards 2.2 Government Codes, Rules, and Regulations 3 ACRONYMS AND ABBREVIATED DEFINITIONS 3.1 Acronyms 3.2 Definitions 4 BASIC CONDITIONS FOR A FIRE OR EXPLOSION FLAMMABLE AND COMBUSTIBLE LIQUIDS, GASES, AND VAPORS 5.1 General 5.2 Flammable and Combustible Liquids 5.3 Flammable Highly Volatile Liquids 5.4 Flammable Lighter-Than-Air Gases 5.5 National Electrical Code Grouping of Atmospheric Mixtures CLASSIFICATION CRITERIA 6.1 General 6.2 Sources of Release (IEC 79-10, Mod) 6.3 Zone Designation (IEC 79-10, Mod) 6.4 Extent of Zone (IEC 79-10, Mod) 6.5 National Electrical Code Criteria 6.6 Ventilation 6.7 Adjacent Areas 6.8 Use of Combustible Gas Detection Equipment 10 10 10 11 11 12 16 18 19 EXTENT OF A CLASSIFIED LOCATION 7.1 General 7.2 Outdoor Locations 7.3 Enclosed Locations 20 20 21 21 RECOMMENDATIONS FOR DETERMINING DEGREE AND EXTENT OF CLASSIFIED LOCATIONS—COMMON APPLICATIONS 21 8.1 General 21 8.2 Recommendations for Areas Surrounding Specific Equipment 21 RECOMMENDATIONS FOR DETERMINING DEGREE AND EXTENT OF CLASSIFIED LOCATIONS IN PETROLEUM REFINERIES 36 9.1 Introduction 36 9.2 Recommendations 36 8 9 10 RECOMMENDATIONS FOR DETERMINING DEGREE AND EXTENT OF CLASSIFIED LOCATIONS AT DRILLING RIGS AND PRODUCTION FACILITIES ON LAND AND ON MARINE FIXED PLATFORMS 44 v `,,```,,,,````-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale Page 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 10.10 10.11 10.12 10.13 10.14 10.15 10.16 General Drilling Areas Production Facilities Drilling Wells Producing Oil and Gas Wells Oil and Gas Processing and Storage Equipment Automatic Custody Transfer (ACT) Units Flammable Gas-Blanketed Equipment and Produced/Processed Water Handling Equipment Compressor or Pump Handling Flammable Liquids, Gases, or Vapors Drip Pans Instruments Sumps Drains Reserved for Future Use Screwed Connections, Flanges, Valves, and Valve Operators Control Panels Containing Instrumentation Utilizing or Measuring Flammable Liquids, Gases, or Vapors `,,```,,,,````-`-`,,`,,`,`,,` - 11 RECOMMENDATIONS FOR DETERMINING DEGREE AND EXTENT OF CLASSIFIED LOCATIONS ON MOBILE OFFSHORE DRILLING UNITS (MODUS) 11.1 General 11.2 Definitions Specific to MODUS 11.3 Reserved for Future Use 11.4 Classified Locations on Mobile Offshore Drilling Units (MODUS) 11.5 Basis for Area Classification 11.6 Classification of Hazardous (Classified) Locations 11.7 Drill Floor and Derrick Areas 11.8 Substructure or Moonpool Areas 11.9 Mud System Processing Equipment Overview 11.10 Mud Tanks (After Discharge of Final Degasser) 11.11 Mud Ditches or Troughs 11.12 Mud Pumps 11.13 Mud Processing Equipment (Between the Bell Nipple and Mud Discharge of Final Degasser) 11.14 Desander or Desilter (Between Mud Discharge of Final Degasser and the Mud Pit) 11.15 Vents 11.16 Diverter Line Outlet 11.17 Blowout Preventer (BOP) 11.18 Well Test Equipment Areas 11.19 Rooms Used to Store Paint (Paint Lockers) 11.20 Battery Rooms 11.21 Reserved for Future Use 11.22 Helicopter Fuel Storage Areas 11.23 Classification of Adjacent Spaces 44 44 44 44 51 56 57 58 58 59 59 62 63 65 65 66 67 67 68 68 68 69 70 71 71 78 78 80 80 82 82 83 84 84 84 84 84 84 84 84 12 RECOMMENDATIONS FOR DETERMINING DEGREE AND EXTENT OF CLASSIFIED LOCATIONS AT DRILLING RIGS AND PRODUCTION FACILITIES ON FLOATING PRODUCTION UNITS 85 12.1 General 85 vi Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale Page 12.2 12.3 12.4 12.5 Floating Production Storage and Offloading Units (FPSOS) Tension Leg Platforms (TLPS) Spars, Caissons, and Similar Units Classification of Adjacent Spaces 85 85 85 85 13 RESERVED FOR FUTURE USE 89 14 RECOMMENDATIONS FOR DETERMINING DEGREE AND EXTENT OF CLASSIFIED LOCATIONS AT PETROLEUM PIPELINE TRANSPORTATION FACILITIES 14.1 General 14.2 Use of Figures 14.3 Figures Figures 10 11 12 13 14 107 109 111 119 121 Increase in Flow Caused by Excess of One Opening Over Another Adequately Ventilated Nonenclosed Area Adjacent to a Classified Area Enclosed Area Adjacent to a Classified Area Enclosed Area Adjacent to a Classified Area Enclosed Area Adjacent to a Classified Area Fixed Roof Flammable Liquid Storage Tank in a Nonenclosed, Adequately Ventilated Area Open Top Floating Roof Flammable Liquid Storage Tank in a Nonenclosed, Adequately Ventilated Area Combustible Liquid Storage Tank in a Nonenclosed Adequately Ventilated Area Tank Car or Tank Truck Loading and Unloading Via Closed System Product Transfer Through Dome Only Tank Car or Tank Truck Loading and Unloading Via Closed System Product Transfer Through Dome Only Tank Car or Tank Truck Loading and Unloading Via Closed System Product Transfer Through Bottom Only Tank Car or Tank Truck Loading and Unloading Via Open System Product Transfer Through Top or Bottom Tank Car or Tank Truck Loading and Unloading Via Closed System Product Transfer Through Bottom Only Process Equipment Vent in a Nonenclosed Adequately Ventilated Area vii Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS 105 Not for Resale 17 18 19 19 19 22 23 24 25 26 27 28 29 30 `,,```,,,,````-`-`,,`,,`,`,,` - APPENDIX A—SAMPLE CALCULATION TO ACHIEVE ADEQUATE VENTILATION OF AN ENCLOSED AREA BY NATURAL MEANS USING EQUATIONS AND APPENDIX B—CALCULATION OF MINIMUM AIR INTRODUCTION RATE TO ACHIEVE ADEQUATE VENTILATION USING FUGITIVE EMISSIONS APPEMDIX C—PREFERRED SYMBOLS FOR DENOTING CLASS I, ZONE 0, ZONE 1, AND ZONE HAZARDOUS (CLASSIFIED) AREAS (IEC 79-10, MOD) APPRNDIX D—INFORMATIVE ANNEX—AN ALTERNATE METHOD FOR AREA CLASSIFICATION APPENDIX E—PROCEDURE FOR CLASSIFYING LOCATIONS ANNEX F—(INFORMATIVE) ALTERNATE VENTILATION CRITERIA (IEC 79-10, MOD) 89 89 89 90 Page 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 Instrument or Control Device Vent in a Nonenclosed Adequately Ventilated Area Atmospheric Vent From a Zone Area Atmospheric Vent From a Zone Area Relief Valve in a Nonenclosed Adequately Ventilated Area Marine Terminal Handling Flammable Liquids Adequately Ventilated Process Location With Heavier Than-Air-Gas or Vapor Source Located Near Grade Adequately Ventilated Process Location With Heavier-Than-Air Gas or Vapor Source Located Above Grade Inadequately Ventilated Process Location With Heavier-Than-Air Gas or Vapor Source Adequately Ventilated Compressor Shelter With Lighter-Than-Air Gas or Vapor Source Adequately Ventilated Process Location With Lighter-Than-Air Gas or Vapor Source Inadequately Ventilated Compressor Shelter With Lighter-Than-Air Gas or Vapor Source Inadequately Ventilated Process Location With Lighter-Than-Air Gas or Vapor Source Separators, Dissolved Air Flotation (DAF) Units, and Biological Oxidation (BIOX) Units Mechanical Draft Cooling Tower Handling Process Cooling Water Drilling Rig, Adequate Ventilation in Substructure, and Derrick is Not Enclosed, But is Equipped With a Windbreak, Open Top, and Open V-Door Drilling Rig, Adequate Ventilation in Enclosed Derrick (Open Top), and Inadequately Ventilated Substructure Platform Drilling Rig, Adequately Ventilated in Substructure and Inside Derrick, Several Producing Wells Beneath in an Adequately Ventilated Area Platform Drilling Rig, Adequate Ventilation in Substructure and Inside Derrick, Several Producing Wells Beneath in an Inadequately Ventilated Location Mud Tank in a Nonenclosed Adequately Ventilated Area Mud Tank in an Enclosed Inadequately Ventilated Area Shale Shaker in a Nonenclosed Adequately Ventilated Area Desander or Desilter in a Nonenclosed Adequately Ventilated Area Desander or Desilter in an Adequately Ventilated Enclosed Area Degasser Vent In Nonenclosed Adequately Ventilated Area Flowing Well in a Nonenclosed Adequately Ventilated Area and Without a Cellar or Below Grade Sump Flowing Well in a Nonenclosed Adequately Ventilated Area With an Inadequately Ventilated Cellar or Below Grade Sump Flowing Well in an Inadequately Ventilated Enclosed Area Nonenclosed Adequately Ventilated Well on Which Wireline Work is Being Performed Nonenclosed Beam Pumping Well in an Adequately Ventilated Area Without a Cellar Nonenclosed Beam Pumping Well in an Adequately Ventilated Area With an Inadequately Ventilated Cellar viii Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale 31 32 32 32 34 37 37 38 39 40 40 41 42 43 45 46 47 48 49 49 50 50 51 51 51 52 53 54 54 54 `,,```,,,,````-`-`,,`,,`,`,,` - 15 126 API RECOMMENDED PRACTICE 505 F.7 Calculations to Ascertain the Degree of Ventilation Calculation No Characteristics of release Flammable material Source of release Lower explosion limit (LEL) Grade of release Safety factor, k Release rate, (dG/dt)max toluene vapor flange 0.046 kg/m3 (1.2% vol.) continuous 0.25 2.8 x 10-10 kg/s Ventilation characteristics Indoor situation Number of air changes, C Quality factor, f Ambient temperature, T Temperature coefficient, (T/293 K) 1/h, (2.8 x 10-4/s) 20°C (293 K) Minimum volumetric flow rate of fresh air: – 10 ( dG ⁄ dt ) max T 2.8 × 10 293 –8 - × - = × - = 2.4 × 10 m ⁄ s ( dV ⁄ dt ) = k × LEL 293 0.25 × 0.046 293 Evaluation of hypothetical volume Vz: –8 f × ( dV ⁄ dt ) × 2.4 × 10 –4 V z = - = - = 4.3 × 10 m –4 C 2.8 × 10 Time of persistence: Time of persistence is not applicable to a continuous release Conclusion: The hypothetical volume Vz, is reduced to a negligible value `,,```,,,,````-`-`,,`,,`,`,,` - The degree of ventilation is considered as high with regard to the source Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale CLASSIFICATION OF LOCATIONS FOR ELECTRICAL INSTALLATIONS AT PETROLEUM FACILITIES CLASSIFIED AS CLASS I, ZONES 0, 1, AND 127 Calculation No Characteristics of release Flammable material Source of release Lower explosion limit (LEL) Grade of release Safety factor, k Release rate, (dG/dt)max toluene vapor failure of flange 0.046 kg/m3 (1.2% vol.) secondary 0.5 2.8 x 10-6 kg/s Ventilation characteristics Indoor situation Number of air changes, C Quality factor, f Ambient temperature, T Temperature coefficient, (T/293 K) 1/h (2.8 x 10-4/s) 20°C (293 K) Minimum volumetric flow rate of fresh air: –6 ( dG ⁄ dt ) max T 2.8 × 10 293 –4 - × - = - × - = 1.2 × 10 m ⁄ s ( dV ⁄ dt ) = k × LEL 293 0.5 × 0.046 293 Evaluation of hypothetical volume Vz: –4 f × ( dV ⁄ dt ) × 1.2 × 10 - = - = 2.2m V z = –4 C 2.8 × 10 Time of persistence: – f LEL × k – 1.2 × 0.5 t = ln - = ln - = 25.6h C Xo 100 Conclusion: The hypothetical volume Vz is significant, but can be controlled The degree of ventilation is considered as medium with regard to the source on this basis However, any release would persist and the concept of Class I, Zone may not be met `,,```,,,,````-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale 128 API RECOMMENDED PRACTICE 505 Calculation No Characteristics of release Flammable material Source of release Lower explosion limit (LEL) Grade of release Safety factor, k Release rate, (dG/dt)max propane gas can-filling nozzle 0.039 kg/m3 (2.1% vol.) primary 0.25 0.005 kg/s Ventilation characteristics Indoor situation Number of air changes, C Quality factor, f Ambient temperature, T Temperature coefficient, (T/293 K) 20/h (45.6 x 10-3/s) 35°C (308 K) 1.05 Minimum volumetric flow rate of fresh air: ( dG ⁄ dt ) max T 0.005 308 - × - = × - = 0.6m ⁄ s ( dV ⁄ dt ) = k × LEL 293 0.25 × 0.039 293 `,,```,,,,````-`-`,,`,,`,`,,` - Evaluation of hypothetical volume Vz: f × ( dV ⁄ dt ) × 0.6 - = = 1.1 × 10 m V z = –3 C 5.6 × 10 Time of persistence: – f LEL × k – 2.1 × 0.25 t = ln - = ln = 0.26h C 20 Xo 100 Conclusion: The hypothetical volume Vz is significant, but can be controlled The degree of ventilation is considered as medium with regard to the source based on this criterion With a persistence time of 0.26 h, the concept of Class I, Zone may not be met if the operation is repeated frequently Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale CLASSIFICATION OF LOCATIONS FOR ELECTRICAL INSTALLATIONS AT PETROLEUM FACILITIES CLASSIFIED AS CLASS I, ZONES 0, 1, AND 129 Calculation No Characteristics of release Flammable material Source of release Lower explosion limit (LEL) Grade of release Safety factor, k Release rate, (dG/dt)max ammonia gas evaporator valve 0.105 kg/m3 (14.8% vol.) secondary 0.5 x 10-6 kg/s Ventilation characteristics Indoor situation Number of air changes, C Quality factor, f Ambient temperature, T Temperature coefficient, (T/293 K) 15/h, (4.2 x 10-3/s) 20°C (293 K) Minimum volumetric flow rate of fresh air: –6 ( dG ⁄ dt ) max T × 10 293 –5 - × - = - × - = 9.5 × 10 m ⁄ s ( dV ⁄ dt ) = k × LEL 293 0.5 × 0.105 293 Estimation of hypothetical volume Vz: –5 f × ( dV ⁄ dt ) × 9.5 × 10 - = - = 0.02m V z = –3 C 4.2 × 10 Time of persistence: – f LEL × k – 14.8 × 0.5 t = ln - = ln = 0.17h ( 10min ) C 15 Xo 100 Conclusion: The hypothetical volume Vz is reduced to a negligible value The degree of ventilation is considered as high with regard to the source However any equipment located adjacent to the valve should be suitable for Class I, Zone (See Table F-1) `,,```,,,,````-`-`,,`,,`,`,, Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale 130 API RECOMMENDED PRACTICE 505 Calculation No propane gas compressor seal 0.039 kg/m3 (2.1% vol.) secondary 0.5 0.02 kg/s Ventilation characteristics Indoor situation Number of air changes, C Quality factor, f Ambient temperature, T Temperature coefficient, (T/293 K) 2/h, (5.6 x 10-4/s) 20°C (293 K) `,,```,,,,````-`-`,,`,,`,`,,` - Characteristics of release Flammable material Source of release Lower explosion limit (LEL) Grade of release Safety factor, k Release rate, (dG/dt)max Minimum volumetric flow rate of fresh air: ( dG ⁄ dt ) max T 0.02 293 - × - = - × - = 1.02m ⁄ s ( dV ⁄ dt ) = k × LEL 293 0.5 × 0.039 293 Estimation of hypothetical volume Vz: f × ( dV ⁄ dt ) × 1.02 - = = 9, 200m V z = –4 C 5.6 × 10 Time of persistence: – f LEL × k – 2.1 × 0.5 t = ln - = ln - = 11.4h C Xo 100 Conclusion: In a room of 10 m x 15 m x m, for example, the hypothetical volume Vz would extend beyond the physical boundaries and would persist The degree of ventilation is considered as low with regard to the source Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale CLASSIFICATION OF LOCATIONS FOR ELECTRICAL INSTALLATIONS AT PETROLEUM FACILITIES CLASSIFIED AS CLASS I, ZONES 0, 1, AND Calculation No Characteristics of release Flammable material Source of release Lower explosion limit (LEL) Grade of release Safety factor, k Release rate, (dG/dt)max methane gas pipe fitting 0.033 kg/m3 (5% Vol) secondary 0.5 kg/s Ventilation characteristics Outdoor situation Minimum wind speed Resulting in an air exchange, C Quality factor, f Ambient temperature, T Temperature coefficient, (T/293 K) 0.5 ms >3 x 10-2/s 15°C (288 K) 0.98 Minimum volumetric flow rate of fresh air: ( dG ⁄ dt ) max T - × - = - = 59.3m ⁄ s ( dV ⁄ dt ) = k × LEL 293 0.5 × 0.033 Estimation of hypothetical volume Vz: f × ( dV ⁄ dt ) × 59.3 V z = - = = 5930 m –2 C × 10 Time of persistence: – f LEL × k – × 0.5 t = ln - = ln = 370s ( maximum ) C 0.03 Xo 100 Conclusion: The hypothetical volume Vz is significant, but can be controlled, and would not persist The degree of ventilation is considered as medium with regard to the source `,,```,,,,````-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale 131 132 API RECOMMENDED PRACTICE 505 Calculation No Characteristics of release Flammable material Source of release Lower explosion limit (LEL) Grade of release Safety factor, k Release rate, (dG/dt)max toluene vapor failure of flange 0.046 kg/m3 (1.2% vol.) secondary 0.5 x 10-4 kg/s Ventilation characteristics Indoor situation Number of air changes, C Quality factor, f Ambient temperature, T Temperature coefficient, (T/293 K) 12/h (3.33 x 10-3/s) 20°C (293 K) Minimum volumetric flow rate of fresh air: –4 ( dG ⁄ dt ) max T × 10 293 –3 - × - = - × - = 26 × 10 m ⁄ s ( dV ⁄ dt ) = k × LEL 293 0.5 × 0.046 293 Estimation of hypothetical volume Vz: f × ( dV ⁄ dt ) × 26 × 10 –3 - = -= 23.4 m V z = –3 C 3.33 × 10 Time of persistence: – f LEL × k – 1.2 × 0.5 t = ln - = ln - = 0.85h ( 51min ) C 12 Xo 100 Conclusion: The hypothetical volume Vz is significant, but can be controlled The degree of ventilation is considered as medium with regard to the source Based on this persistence time, the concept of Class I, Zone would be met `,,```,,,,````-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale ❏ API Member (Check if Yes) API Related Publications Order Form Date: (Month, Day, Year) Invoice To – ❏ Check here if same as “Ship To” Ship To – (UPS will not deliver to a P.O Box) Company Company Name/Dept Name/Dept Address Address City State/Province City State/Province Zip Country Zip Country Customer Daytime Telephone No Customer Daytime Telephone No Fax No Fax No (Essential for Foreign Orders) (Essential for Foreign Orders) PREPAID AND CREDIT CARD ORDERS ARE NOT CHARGED FOR SHIPPING AND HANDLING TO U.S AND CANADIAN DESTINATIONS ❏ Payment Enclosed $ ❏ Payment By Charge Account: ❏ MasterCard ❏ Visa ❏ Please Bill Me P.O No ❏ American Express Customer Account No Account No State Sales Tax – The American Petroleum Institute is required to collect sales tax on publications mailed to the following states: AL, AR, CT, DC, FL, GA, IL, IN, IA, KS, KY, ME, MD, MA, MI, MN, MO, NE, NJ, NY, NC, ND, OH, PA, RI, SC, TN, TX, VT, VA, WV, and WI Prepayment of orders shipped to these states should include applicable sales tax unless a purchaser is exempt If exempt, please print your state exemption number and enclose a copy of the current exemption certificate Name (As it appears on Card) Expiration Date Exemption Number Signature State Title Unit Price C50002 RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Divison and Division $ 120.00 C54000 RP 540, Electrical Installations in Petroleum Processing Plants $ 85.00 G07190 RP 14F, Design and Installation of Electrical Systems for Offshore Production Platforms $ 85.00 Quantity Order No `,,```,,,,````-`-`,,`,,`,`,,` - 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Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,```,,,,````-`-`,,`,,`,`,,` - PG-01400—11/97—2.5C ( ) Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,```,,,,````-`-`,,`,,`,`,,` - Additional copies available from API Publications and Distribution: (202) 682-8375 Information about API Publications, Programs and Services is available on the World Wide Web at: http://www.api.org Order No C50501 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale Date of Issue: August 17, 1998 Affected Publication: API Recommended Practice 505, Recommended Practice for ClassiÞcation of Locations for Electrical Installations at Petroleum Facilities ClassiÞed as Class I, Zone 0, Zone 1, and Zone 2, 1st Edition, November 1997 ERRATA The following Þgures are replaced by the next three pages: Page 86, Figure 90 Page 87, Figure 91 and Page 88, Figure 92 `,,```,,,,````-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,```,,,,````-`-`,,`,,`,`,,` - Figure 90—Typical Floating Production Storage and Offloading Unit (FPSO) (See Section 12.2.1) Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,```,,,,````-`-`,,`,,`,`,,` - Figure 91—Typical Tension Leg Platform (TLP) (See Section 12.3.1) Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,```,,,,````-`-`,,`,,`,`,,` - Figure 92—Typical Spar, Caisson, or Similar Unit (See Section 12.4.1) Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale