![header thumbnail](/images/publishers\api_cover.gif)
API 4628 : 1996
Withdrawn
A Withdrawn Standard is one, which is removed from sale, and its unique number can no longer be used. The Standard can be withdrawn and not replaced, or it can be withdrawn and replaced by a Standard with a different number.
![header thumbnail](/images/publishers\api_cover.gif)
A GUIDANCE MANUAL FOR MODELING HYPOTHETICAL ACCIDENTAL RELEASES TO THE ATMOSPHERE
14-11-1996
01-11-1996
NOMENCLATURE
CHAPTER ONE: Introduction
Manual Organization
Quick References
Conventions
Terminology
Subject Indexes Development
CHAPTER TWO: Overview of Release/Dispersion Processes
and Demonstration Scenarios
The Overall Modeling Process
Near vs Far Field Modeling
Release-to-Dispersion Phenomena
Demonstration Scenarios
CHAPTER THREE: Source Modeling
Overview
Phase Equilibria
Fluid Properties
Thermodynamics of Fluid Depressurization
Flow Rate Estimation
Initial Jet Expansion
Example Calculations
Evaporation
CHAPTER FOUR: METEOROLOGY
Modeling Parameters
Release Duration
Plume Buoyancy Criteria
CHAPTER FIVE: Mitigation Countermeasure Modeling
Introduction
Review of Plume Mitigation Methods
Estimation of Plume Modification Parameters
CHAPTER SIX: Analysis and Simulation of Release Scenarios
Introduction
1: Hydrogen Sulfide from Unlit Flare Stack
2: Hydrogen Sulfide and Carbon Dioxide from a Safety
Relief Stack
3: Supercritical Propane Pipe Hole Release
4: Oil Well Blowout
5: Liquified Chlorine Tank Truck Accident
6: Ammonia Hose or Pipe Break
7: Hydrogen Chloride Pipe Break
8: Evaporating Pool of Liquid Benzene
REFERENCES
APPENDIX 1: Recommended Default/Starting Values for
Modeling Parameters
Appendix II: Overview of Scenario Modeling Programs
Submodels
Time Dependent Modeling
Thermodynamic and Physical Properties
Program Output
New Version of HGSYSTEM
APPENDIX III: HGSYSTEM File Listings for Scenario 7
INDEX
I. Figures
Chapter 2: Overview of Release/Dispersion Processes and
Demonstration Scenarios
1 Paths to Air Dispersion Near the Release Point
2 Release Paths for Scenarios 1, 2 and 3
3 Release Paths for Scenarios 4, 6 and 7
4 Release Paths for Scenario 5
5 Release Path for Scenario 8
Chapter 3: Source Modeling
1 Equilibrium Vapor Pressures
2 Binary VLE Diagram
3 Control Volume Example
4 Critical Pressure Ratio Definitions
5 Flashing Choked Flow Methods
6 High and Low Subcooling: Leung
7 Non-Flashing and Flashing Flow: Leung
8 Expanding Jet Force Balance
9 Evaporating Pool Mass and Energy Flows
10 Heat Conduction Model
Chapter 4: Meteorology
1 Incident Wind Profile Diagram
2 Roughness Length vs. Site Classification
3 Stability Class and Plume Height
4 Pressure and Temperature vs Height
5 Humidity Effect of Air Density
6 Concentration Time Series
Chapter 5: Mitigation Countermeasure Modeling
1 Dilution-only Mitigation by a Spray Barrier: Meroney
2 ICHMPA HF Water Spray Study
3 Spray Curtain Removal: Meroney
4 Spray Curtain Removal with Entrainment: Meroney
5 Steady-state Concentration Correction Factors for
Constant Rate, Finite Duration Releases
6 Overhead View of Intercepted Plume
Chapter 6: Scenario 1
1 Plume Centerline Paths
2 SLAB H2S Concentrations
Chapter 6: Scenario 2
1 Initial DEGADIS Distance
2 Search for Acceptable Stack Height
3 Final Centerline Ground Level Concentrations
4 Final Plume Centerline Elevations
Chapter 6: Scenario 3
1 Propane Choked Flow Rates
2 Turbulent Jet Centerline Concentrations
Chapter 6: Scenario 4
1 Downwind H2S Concentrations
2 SLAB Cloud Half-widths
3 Downwind H2S Concentrations
Chapter 6: Scenario 5
1 Centerline Concentrations, E Stability,3 m/s Wind,293 K
2 Centerline Concentrations, C Stability 4 m/s Wind,303 K
3 1 ppm Chlorine Isopleths, E Stability, 3 m/s Wind,293 K
4 1 ppm Chlorine Isopleths, C Stability, 4 m/s Wind,303 K
Chapter 6: Scenario 6
1 Vapor Pressure of Ammonia
2 Molal volume of Liquid Ammonia
3 Vapor Enthalpy of Saturated Ammonia
4 Enthalpy of Liquid Ammonia
5 Maximum Centerline Concentrations, Horizontel Jet, 10 s
Averagine Time
6 Times to Maximum Concentrations
7 Maximum Centerline Concentrations, Horizontal Jet, 60 s
Averaging Time
8 Vertical Jet Release
Chapter 6: Scenario 7
HCI Release Water Spray Mitigation
1 Steady State and Finite Duration Centerline
Concentrations
2 Time Dependent Simulations
3 Time Dependent and Steady State (corrected)
Simulations, instantaneous averaging
4 Time Dependent and Steady State (corrected)
Simulations, averaging time = 300 s
Chapter 6: Scenario 8
1 Downwind Centerline Concentrations, Evaporating Benzene
Pool
2 Concentration Isopleths, 1 ppm Benzene
3 Concentration Isopleths, 50 ppm Benzene
II. Tables
Chapter 2: Overview of Release/Dispersion Processes and
Demonstration Scenarios
1 Summary of Senario Attributes
Chapter 3: Source Modeling
1 STN Databases
2 Minimum rs, Ratios of Liquid Chlorine Heads, vs.
Stagnation Temperatures
3 Summary of Evaporation Model Features
4 Thermal Properties of Natural Materials
Chapter 4: Meteorology
1 Definition os Pasquill-Gifford Stability Classes
2 Typical Values of p in Equation 3
Chapter 6: Scenario 1
1 Stack Gas Composition
2 Summary of SLAB Results for Scenario 1
Chapter 6: Scenario 2
1 Stack Diameter Sizing Parameters
2 Source/Release Parameters
3 H2S Ground Level Centerline Concentrations
Chapter 6: Scenario 3
1 Propane Properties at 7.0 Mpa
2 Source Parameters and Modeling Results
Chapter 6: Scenario 4
1 Crude Oil Flash Results - Two-Phase Summary
2 Summary of Results for Scenario 4
Chapter 6: Scenario 6
1 Base Case Input for SLAB
Chapter 6: Scenario 7
1 Release Parameters
2 Development of Spray Curtain Plume Mitigation
Parameters
3 Parameter Symbols and Conversion Factors from PLUME
to HEADAGAS
4 Vapor Cloud Characterization Parameters for Spray
Curtain Barrier Mitigation Simulations
Chapter 6: Scenario 8
1 Benzene Properties
2 Storage Tank Parameters
Appendix II: Overview of Scenario Modeling Programs
1 Comparison of Modeling System Features
III Example Boxes
Chapter 3: Source Modeling
Phase Rule Examples
Heat of Vaporization Example
Multicomponent Vapor-Liquid Equilibrium Calculation
Examples
Example Calculation of Pseudo-Pure component Properties
Example for Instantaneous Flashing Release
Example Gas Flow Rate Calculations
Example: Expanded Jet Diameter for Chloring Vapor Choked
Flow
Example: Expanded Jet Diameter for Flashing Liquid
Chlorine Choked Flow
Example Rate Calculations for Evaporation
Access your standards online with a subscription
Features
-
Simple online access to standards, technical information and regulations.
-
Critical updates of standards and customisable alerts and notifications.
-
Multi-user online standards collection: secure, flexible and cost effective.