API MPMS CAP 19 Section 1 API 2518 - Cesar Delgado

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ADOPT I ON 
ADOPTION NOTICE 1 
24 January 1992 for 
API PUBL 2518 
Second Edition 
OCTOBER 1991 
SUPERSEDING 
API BULL 2518 
June 1962 
REAFFIRMED, AUG 1987 
1 
API Publication 2518 was adopted on 24 January 1992 and i8 approved for use by 
the Department of Defense (DoD). The Subcommittee on Evaporation Loss 
Measurement (CELM) of the Committee on Petroleum Measurement (COPM) prepared 
this: document for the American Petroleum Institute (API). Copie8 of this 
document are stocked by the DoD Single Stock Point (DODSSP), Documents Order 
Desk, BLDG 4D, 700:;Robbins Avenue, Philadelphia, PA 19111-5094, for issue to 
DoD activities qnly. All other requestors must obtain documents from: .: , 
API Headquarters 
1220 L Street, N.W. 
'*. Washington, D.C. 20005 
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Title of Document: Manual of Petroleum Measurement Standards Chapter 19- 
Evaporation Losa Measurement, Section 1- Evaporative Loss From Fixed-Roof 
Tanks 
Date of Specific Issue Adopted: October 1991, Second Edition 
Releasing Non-Government Standards Body: The American Petroleum Institute 
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COPYRIGHT American Petroleum Institute
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A P I MPMS+Lî=L 91 0732290 05L8715 597 
Manual of Petroleum 
Measurement Standards 
Chapter 19-Evaporative Loss 
Measurement 
Section 1 -Evaporative Loss from 
Fixed-Roof Tanks 
API PUBLICATION 251 8 
SECOND EDITION, OCTOBER 1991 
American Petroleum Institute 
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4) Washington, D.C. 20005 
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A P I MPMS*LS=L 91 0732290 05L87Lb 423 
Manual of Petroleum 
Measurement Standards 
Chapter 19-Evaporative Loss 
Measurement 
Section 1 -Evaporative Loss from 
Fixed-Roof Tanks 
Measurement Coordination Department 
API PUBLICATION 2518 
SECOND EDITION, OCTOBER 1991 
American 
Petroleum 
Institute 
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A P I MPMStLS-L 91 0732290 05LB717 3bT = 
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FOREWORD 
In 1952, the American Petroleum Institute sponsored the Symposium on Evapora- 
tion Loss at its 32nd Annual Meeting. Loss information was presented at that meeting 
which focused attention on the need to develop an industry accepted evaporative loss 
estimation procedure for fixed-roof tanks. 
The API Evaporation Loss Committee initiated an extensive effort to collect 
available petroleum industry data on evaporative losses from fixed-roof tanks. An 
intensive study was made of these data that resulted in correlations for estimating 
evaporative losses from fixed-roof tanks. These correlations were developed from 
evaporative-loss data for fixed-roof tanks that stored gasoline and crude oils with a 
true vapor pressure in the range from I .5 to 8.8 pounds per square inch absolute. The 
results were published in June 1962 as the First Edition of API Bulletin 2518. 
By the mid-l970s, as a result of the national energy crisis and increased concern for 
the environment, additional emphasis was placed on the need to estimate evaporative 
losses from petroleum storage tanks. Accordingly, in 1976 the API Committee on 
Evaporation Loss Measurement began a review and analysis of the prior API work and 
of more recent work performed by oil companies, manufacturers, industry groups and 
regulatory agencies. From this analysis, and in view of the fact that volatile liquid 
stocks were not typically stored in fixed-roof tanks with a true vapor pressure over 
1.5 pounds per square inch absolute, the Committee recommended that the evaporative- 
loss data be updated and combined with new data obtained from an extensive test 
program. API responded by sponsoring a program that included test-tank and 
field-tank studies, as well as the development of a computer model that simulated the 
standing storage loss process for fixed-roof tanks. From these intensive efforts, the 
mechanisms of evaporative loss were better understood, and the effects of the relevant 
variables were more precisely quantified. As a result, API Bulletin 2518 was updated 
with this information, and this Chapter 19.1 was published. 
a. The equations necessary for estimating the evaporative loss or the equivalent 
atmospheric hydrocarbon emissions from the general types of fixed-roof tanks 
currently available are included in 19.1.2. 
b. Current typical fixed-roof tanks, including types of roof fittings, are described 
in 19.1.3. 
c. The mechanisms of evaporative loss and the development of the loss equations are 
discussed in 19.1.4. 
The entire data base and the details of the data analysis are on file at API. This 
Chapter 19.1 supersedes all previous editions of API Bulletin 2518. 
Suggested revisions are invited and should be submitted to the Director of the 
Measurement Coordination Department, American Petroleum Institute, 1220 L Street, 
N.W., Washington, D.C. 20005. 
This edition contains the followinginformation: 
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A P I MPMS*19.L 91 0732290 0518719 132 
CONTENTS 
Page 
SECTION 1 -EVAPORATIVE LOSS FROM FIXED-ROOF TANKS 
19.1.1 General . . 1 
19.1.1.1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 
19.1.1.2 Referenced Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 
i 9. I .2 Procedures for Calculating Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 
19.1.2.1 Loss Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 
19.1.2.1.2 Standing Storage . . . . . . . . . . . . . . . . . . . . . . . 2 
19.1.2.1.3 WorkingLoss,Lw . . . . . . . . . . . . . . . . . . . . . . . . . . 7 
19.1.2.1.4 TotalLoss,LT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 
19.1.2.2 Discussion of Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 
19.1.2.2. I General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 
8 19.1.2.2.2 Standing Storage Loss Variables . . . . . . . . . . . . . . . . . . . . 
19.1.2.2.2.1 Vapor Space Outage, H, . . . . . . . . . . . . . . . . . . . 8 
19.1.2.2.2.2 Meteorological Data, T M , Tm, I . . . . . . . . . . . . . . . . . . . 10 
19.1.2.2.2.3 Tank Paint Solar Absorptance, (Y . . . . . . . . . . . . . . . . . . . . 14 
19.1.2.2.2.5 Daily Average Liquid Surface Temperature, Tu . . . . . . . . 14 
Temperatures, Tu, TLN . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 
19.1.2.2.2.8 Vapor Molecular Weight, M v . . . . . . . . . . . . . . . . . . . . . . 15 
Pressures, Pm, PvA, PvN . . . . . . . . . . . . . . . . . . . . . . . 16 
19.1.2.2.2.11 Breather Vent Pressure Setting Range, APB . . . . . . . . . . . . 2 1 
19.1.2.2.2.12 Vented Vapor Saturation Factor, Ks . . . . . . . . . . . . . . . . . . 24 
19.1.2.2.2.13 Condensed Vapor Density, Wvc . . . . . . . . . . . . . . . . . . . . . 24 
Working Loss Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 
19.1.2.2.3.1 Annual Net Throughput, Q . . . . . . . . . . . . . . . . . . . . . . . . . . 25 
19.1.2.2.3.3 Product Factor, K p . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 
19.1.2.3 Summary of Calculation Procedure . . . . . . . 
19.1.2.4 Sample Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 
19.1.2.4.1 Problem.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 
19.1.2.4.2 Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 
19.1.2.4.2.1 Standing Storage Loss, Ls . . . . . . . . . . . . . . . . . . . . . . . . . . 26 
19.1.2.4.2.2 Working Loss, Lw . . . . . . . . . . . . . . . . . . . . . . . 27 
19.1.3 Description of Fixed-Roof Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 
19.1.3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 
19.1.3.2 Fixed-Roof Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 
19.1.3.3 Roof Fittings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . 29 
19.1.3.3.1 Pressure-Vacuum Vents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 
19.1.3.3.2 Gauge-Hatch/Sample Wells. . . . . . . . . . . . . . . . . . . . . . . . . . 29 
19.1.3.3.3 Float Gauges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 
19.1.3.3.4 RoofManholes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 
19.1,3.4 Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 
19.1.3.5 Paint 30 
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 
2 19.1.2.1.1 General . . . . . . . . . . . . . . . . . . . . . . . . . 
14 19.1.2.2.2.4 
19.1.2.2.2.6 Daily Vapor Temperature Range, ATv . . . . . . . . . . . . . . . . 15 
19.1.2.2.2.7 
Liquid Bulk Temperature, TB . . . . . . . . . . . . . . . . . . 
Daily Maximum and Minimum Liquid Surface 
19.1 .2.2.2.9 Daily Maximum, Average, Minimum Vapor 
19.1.2.2.2.10 Daily VaporPressureRange, v . . . . . . . . . . . . . . . . . . . 21 
19.1.2.2.3 
19.1.2.2.3.2 TurnoverFactor,K, . . . . . . . . . . . . . . . . . . . . . . . 25 
. . . . . . 25 
19.1.2.4.2.3 TotalLoss,L, . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 
V 
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19.1.4 Details of Loss Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 
19.1.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 
19.1.4.2 Loss Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 
19.1.4.2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 
19.1.4.2.2 Evaporative Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 
19.1.4.2.2.1 StandingStorageLoss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 
19.1.4.2.2.2 Working Loss . . . . . . . . . . . . . . . . . . . . . . . . . . 31 
19.1.4.2.4 Working Loss Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 
19.1.4.2.4.1 Filling Loss Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 
19.1.4.3 Database for Loss Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 
19 . I .4. 3.2 Working Loss Data . . . . . . . . . . . . . . . . . . . . . . . . . 33 
19.1.4.4.2 Vapor Space Expansion Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 
19.1.4.4.3 Vented Vapor Saturation Factor . . . . . . . . . . . . . . . . . . . . . . . . . . 34 
19.1.4.4.4 Vapor Space Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . 35 
19.1.4.4.6 Liquid Surface Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 
19.1.4.5 Development of Working Loss Equation . . . . . . . . . . . . . . . . . . . . . . . 36 
19.1.4.5.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 
19.1.4.5.2 Turnover Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 
19 . I .4. 5.3 Product Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 
19.1.4.2.3 Standing Storage Loss Mech . . . . . . . . . . . . . . . . . . . 32 
19 . I .4.2. 4.2 Emptying Loss Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . 32 
19.1.4.3.1 Standing Storage Loss Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 
19.1.4.4 Development of Standing Storage Loss Equation . . . . . . . . . . . . . . . . 34 
19.1.4.4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 
19.1.4.4.5 Paint Solar Absorptance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 
APPENDIX A . CONTENTS OF DOCUMENTATION RECORDS . . . . . . . . . . . 37 
APPENDIX B . API COMMITTEE ON EVAPORATION LOSS 
MEASUREMENT (1991) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 
Figures 
1 -Fixed-Roof Tank Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 
3 -Vapor Pressure Function Coefficient (A) of Refined Petroleum 
Stocks with a Reid Vapor Pressure of 1 to 20 Pounds Per 
4-Vapor Pressure Function Coefficient (B) of Refined Petroleum 
Stocks with a Reid VaporPressure of 1 to 20 Pounds per 
9 
10 2-Dome Roof Outage (HRo) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 
Square Inch. Extrapolated to O . 1 Pounds Per Square Inch . . . . . . . . . . . . . . . . 
Square Inch. Extrapolated to O . 1 Pounds Per Square Inch . . . . . . . . . . . . . . . . 
19 
19 
With a Reid Vapor Pressure of 1 to 20 Pounds Per Square Inch . . . . . . . . . . . . 20 
with a Reid Vapor Pressure of 2 to 15 Pounds Per Square Inch. 
5-Tme Vapor Pressure (Pv) of Refined Petroleum Stocks 
6-Vapor Pressure Function Coefficient (A) of Crude Oil Stocks 
Extrapolated to O . 1 Pounds Per Square Inch . . . . . . . . . . . . . . . . . . . . . . . . . . 22 
Extrapolated to O . 1 Pounds Per Square Inch . . . . . . . . . . . . . . . . . . . . . . . . . . 22 
Vapor Pressure of 2 to 15 Pounds Per Square Inch . . . . . . . . . . . . . . . . . . . . . . 23 
9-Vented Vapor Saturation Factor (K , ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 
10- Working Loss Turnover Factor ( K N ) 
1 1 -Typical Fixed-Roof Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 
7-Vapor Pressure Function Coefficient (B) of Crude Oil Stocks 
with a Reid Vapor Pressure of 2 to 15 Pounds Per Square Inch. 
8-True Vapor Pressure (Pv) of Crude Oil Stocks With a Reid 
24 
25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 
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A P I HPHS*LS*L 91 m 0732290 0514721 890 m 
Tables 
1 -Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 
2-Summary of Procedure for Calculating Standing Storage Loss (L. ) . . . . . . . 5 
7 
11 
5-Solar Absorptance (a) for Selected Tank Paints . . . . . . . . . . . . . . . . . . . . . . . . 14 
6-Properties (M". Wvc. Pv. A . B ) of Selected Petroleum Liquids . . . . . . . . . . . . 15 
17 
8-ASTM Distillation Slope ( S ) for Selected Refined Petroleum Stocks . . . . . . . 21 
9-Annual Stock Turnover Rate (N) for 123 Test Tanks . . . . . . . . . . . . . . . . . . . . . 33 
3 -Summary of Procedure for Calculating Working Loss (L. ) 
4-Meteorological Data (TM. Tm. I ) for Selected U.S. Locations . . . . . . . . . . . . 
7-Properties (M". W,. Pv. A . B ) of Selected Petrochemicals 
. . . . . . . . . . . . . . 
. . . . . . . . . . . . . . 
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Chapter 19- Evaporative Loss Measurement 
SECTION 1 -EVAPORATIVE LOSS FROM FIXED-ROOF TANKS 
19.1.1 GENERAL 
19.1.1.1 Scope 
This publication contains an improved method for 
estimating the total evaporative losses or the equivalent 
atmospheric hydrocarbon emissions from fixed-roof tanks 
that contain multicomponent hydrocarbon mixture stocks 
(such as petroleum liquid stocks like crude oils) or 
single-component hydrocarbon stocks (such as petro- 
chemical stocks like ethanol). The standing storage loss 
equation has been improved over that which appeared in 
the first edition of API Bulletin 2518, but the working 
loss equation is the same as that in the First Edition. 
This publication was developed by the API Committee 
on Evaporation Loss Measurement. The equations pre- 
sented are based on test-tank and field-tank data. The 
equations are intended to provide loss estimates for 
general equipment types, since it is not within the scope 
of this publication to address specific proprietary equip- 
ment designs. 
Types of fixed-roof tanks and roof fittings currently 
available are described for information only. This publi- 
cation is not intended to be used as a guide for equipment 
design, selection, or operation. 
The equations are intended to be used to estimate 
annual losses from uninsulated fixed-roof tanks for 
various liquid stocks, stock vapor pressures, tank sizes, 
meteorological conditions, and operating conditions. The 
equations are applicable to properly maintained equip- 
ment under normal working conditions. The equations 
were developed for nonboiling stocks, although volatile 
liquid stocks with a true vapor pressure over 1.5 pounds 
per square inch absolute are not now typically stored in 
the U.S. in fixed-roof tanks. Without detailed field 
information, the estimation techniques become more 
approximate when used to calculate losses for time 
periods shorter than one year. 
The equations are not intended to be used in the 
following applications: 
a. To estimate losses from unstable or boiling stocks or 
from petroleum liquids or petrochemicals for which the 
vapor pressure is not known or cannot readily be predicted. 
b. To estimate losses from fixed-roof tanks which have 
an internal floating roof. 
c. To estimate losses from fixed-roof tanks which have 
either roof or shell insulation. 
d. To estimate losses from horizontal cylindrical tanks. 
A complete guide for estimating evaporative stock loss 
or the equivalent total atmospheric emissions from vola- 
tile stocks stored in fixed-roof tanks is included in 
19.1.2. The calculated pounds per year of total hydrocar- 
bon losses may include both reactive and nonreactive 
compounds. To obtain reactive hydrocarbon emissions, 
the weight fraction of reactive hydrocarbons in the vapor 
must be applied. Detailed equations are given in 19.1.2.1, 
and a description of how to determine specific values for 
the variables included in the equations is given in 
19.1.2.2. References are made to tables and figures that 
include information about the most common (typical) 
values to use when specific information is not available. 
The loss-estimation procedures are summarized in 19.1.2 
(Tables 2 and 3), and a sample problem is presented in 
19.1.2.4. 
Typical fixed-roof tank construction is described in 
19.1.3. 
The bases and development of the loss-estimation 
procedures presented in 19.1.2 are described in 19.1.4. 
The estimation procedures were developed to provide 
estimates of typical losses from fixed-roof tanks that are 
properly maintained and in normal working condition. 
Losses from poorly maintained tanks may be greater. 
Because the loss equations are based on equipment 
conditions that represent a large population of tanks, a 
loss estimate for a group of fixed-roof tanks will be more 
accurate than a loss estimate for an individual tank. It is 
difficult to determine precise values of the loss-related 
parameters for any individual tank. 
Equipment should not be selected for use based solely 
on evaporative-loss considerations. Many other factors 
not addressed in this publication, such as tank operation, 
maintenance, and safety, are important in designing and 
selecting tank equipment for a given application. 
19.1.1.2 Referenced Publications 
[i] API, “Welded Steel Tanks for Oil Storage”, Stan- 
dard 650, Eighth Edition, Washington, D.C., November 
1988. 
[2] U.S. Department of Commerce, National Oceanic 
and Atmospheric Administration, “Comparative Cli- 
matic Data Through 1984”, National Climatic Data 
Center, Asheville, North Carolina, 1986. 
[3] Cinquemani, V., J.R. Owenby, Jr., and R.G. Baldwin, 
“Input for Solar Systems”, Prepared by the U.S. Depart- 
ment of Commerce, National Oceanic and Atmospheric 
1 
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A P I MPMS*LS.L 93 0732290 0538723 663 W 
2 CHAPTER 1 EVAPORATI TIVE Loss MEASUREMENT 
Administration, Environmental and Information Ser- 
vice, National Climatic Center, Asheville, North Caro- 
lina, Prepared for the U.S. Department of Energy, 
Division of Solar Technology, under Interagency Agree- 
ment No. E (49-26)-1041, November 1978 (Revised 
August 1979). 
[4]API, “Evaporation Loss from Internal Floating-Roof 
Tanks”, Publication 25 19, Third Edition, Washington, 
D.C., June 1983. 
[5] U.S. Environmental Protection Agency, “Compila- 
tion of Air Pollutant Emission Factors”, USEPA Report 
No. AP-42, Third Edition, Section 4.3, “Storage of 
Organic Liquids”, September 1985. 
[6] The Chemical Rubber Co., “Handbook of Chemis- 
try and Physics”, 51st Edition, R.C. Weast, Editor, 
Cleveland, Ohio, pp . D 146-D 165, 1970. 
[7] API, “Technical Data Book-Petroleum Refining”, 
Publication 999, Ninth Revision, Washington, D.C. 
1988. 
[8] “Perry’s Chemical Engineers’ Handbook”, Sixth 
Edition, R.H. Perry, D.W. Green, and J.O. Maloney, 
Editors, McGraw-Hill Book Co., Inc., New York, New 
York, 1984. 
[9] API, “Use of Pressure-Vacuum Vent Valves for 
Atmospheric Pressure Tanks to Reduce Evaporation Loss”, 
Bulletin 2521, First Edition, Washington, D.C., Septem- 
ber 1966. 
[lo] API, “Venting Atmospheric and Low-Pressure Stor- 
age Tanks (Nonrefrigerated and Refrigerated)”, Standard 
2000, Third Edition, Washington, D.C., January 1982. 
[ 1 i ] API, “Evaporation Loss from Fixed-Roof Tanks”, 
Bulletin 2518, First Edition, Washington, D.C., June 
1962. 
[ 121 Engineering-Science, Inc., “Hydrocarbon Emis- 
sions From Fixed-Roof Petroleum Tanks”, Prepared for 
the Western Oil and Gas Association, July 1977. 
[ 131 Engineering-Science, Inc., “Synthetic Organic Chem- 
ical Manufacturing Industry, Emission Test Report, Breath- 
ing Loss Emissions From Fixed-Roof Petrochemical 
Storage Tanks”, Prepared for the U. S. Environmental 
Protection Agency, EPA Report No. EMB-78-OCM-5, 
February 1979. 
[ 141 Environmental Monitoring & Services, Inc. (sub- 
sidiary of Combustion Engineering Co.), “Breathing 
Loss Emissions From Fixed-Roof Tanks”, Final Report, 
Prepared for the API, Committee on Evaporation Loss 
Measurement, June 1985. 
[ 151 Beckman, Duffie and Associates, “Evaporation 
Loss of Petroleum From Storage Tanks”, Final Report, 
Prepared for the API, Committee on Evaporation Loss 
Measurement, August 1, 1982. 
[16] Knodel, B.D. and Laverman, R.J., “Data Base 
Generation, Analysis, and Revision of API Bulletin 
25 18, Task 1 : Validate Computer Model”, Final Report 
for Task 1, Prepared by CBI Industries, Inc., Prepared 
for the API, Committee on Evaporation Loss Measure- 
ment, Task Group 2518, September 11, 1986. 
[17] Rinehart, J.K. and Laverman, R.J., “Data Base 
Generation, Analysis, and Revision of API Bulletin 
2518, Task 3: Correlate Data Base”, Final Report for 
Task 3, Prepared by CBI Industries, Inc., Prepared for 
the API, Committee on Evaporation Loss Measurement, 
Task Group 2518, August 26, 1988. 
[ 181 API, “Evaporation Loss in the Petroleum Industry - 
Causes and Control”, Publication 25 13, First Edition, 
Washington, D.C., February 1959. 
[19] Rinehart, J.K. and Laverman, R.J., “Data Base 
Generation, Analysis and Revision of API Bulletin 25 18, 
Task 2: Generate Computer Data Base”, Final Report for 
Task 2, Prepared by CBI Industries, Inc., Prepared for 
the API, Committee on Evaporation Loss Measurement, 
Task Group 2518, February 16, 1987. 
[20] API, “Symposium on Evaporation Loss of Petro- 
leum From Storage Tanks”, Papers Presented During the 
32nd Annual Meeting of the American Petroleum Insti- 
tute, Held in Chicago, Illinois, November 10, 1952, 
(Also Published in API Proceedings, Vol. 32, Part I, 
1952, pp. 212-281). 
19.1.2 PROCEDURES FOR CALCULATING 
LOSSES 
19.1.2.1 Loss Equations 
19.1.2.1.1 General 
Procedures for estimating the total annual evaporative 
stock loss, or the equivalent atmospheric hydrocarbon 
vapor emissions, from volatile stocks stored in fixed-roof 
tanks, are outlined in 19.1.2. The total loss, L,, is the 
sum of the standing storage loss, Ls, and the working 
loss, L W . 
For convenience, a description of each variable is given 
after each group of equations in the order in which they 
appear in the equations. In addition, a complete list of 
nomenclature is given in Table 1, A description of how to 
determine specific values for the variables is given in 
19.1.2.2. 
19.1.2.1.2 Standing Storage Loss, Ls 
calculate the standing storage loss, Ls: 
a. The tank diameter. 
b. The tank shell height. 
c. The tank roof type (cone roof or dome roof). 
d. The tank outside paint color. 
The following minimum information is needed to 
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API MPHS*39-3 93 = 0732290 0538724 5 T T 
SECTION 1 -EVAPORATIVE LOSS FROM FIXED-ROOF TANKS 3 
Table 1 -Nomenclature 
Reference Information 
Symbol Description Units Equations Tables Figures 
Constant in the vapor pressure equation Dimensionless 29, 32 6, 7 3, 6 
Constant in the vapor pressure equation "R 30, 33 6. 7 4, 7 . - 
Tank diameter 
Stock liquid height (or inage) 
Stock maximum liquid height 
Tank roof height 
Roof outage (or shell height equivalent to the volume 
contained under the roof) 
Tank shell height 
Vapor space outage (or height) 
Daily total solar insolation on a horizontal surface 
Vapor space expansion factor 
Working loss product factor 
Vented vapor saturation factor 
Working loss turnover factor 
Standing storage loss 
Total loss 
Working loss 
Stock vapor molecular weight 
Stock turnover rate 
Atmospheric pressure 
Breather vent pressure setting (always a positive value) 
Breather vent vacuum setting (always a negative value) 
Breather vent pressure setting range 
Stock vapor pressure at the liquid surface temperature, TL 
Stock vapor pressure at the daily average liquid 
Stock vapor pressure at the daily minimum liquid 
Stock vapor pressure at the daily maximum liquid 
Stock daily vapor pressure range 
Stock annual net throughput (associated with increasing 
Ideal gas constant (10.731) 
Tank dome roof radius 
Tank shell radius 
Stock Reid vapor pressure 
Stock ASTM-D86 distillation slope at 10 volume 
percent evaporated 
Tank cone roof slope 
Temperature at which 5 volume percent is evaporated 
Temperature at which 15 volume percent is evaporated 
Ambient temperature 
Daily average ambient temperature 
Daily minimum ambient temperature 
Daily maximum ambient temperature 
Daily ambient temperature range 
Liquid bulk temperature 
Liquid surface temperature 
Daily average liquid surface temperature 
Daily minimum liquid surface temperature 
Daily maximum liquid surface temperature 
Vapor temperature 
Daily vapor temperature range 
Tank maximum liquid volume (or tank liquid capacity) 
Tank vapor space volume 
Stock liquid density 
surface temperature 
surface temperature 
surface temperature 
the stock liquid level in the tank) 
ft 
ft 
ft 
ft 
ft 
ft 
ft 
Btu/ft2 day 
Dimensionless 
Dimensionless 
Dimensionless 
Dimensionless 
Ibíyr or bbüyr 
Ibíyr or bblíyr 
Ibíyr or bblíyr 
Ibílb-mole 
Turnoverslyr 
psia 
Psig 
Psi! 
PS' 
psia 
psia 
psia 
psia 
psi 
bblíyr 
psia ft3 
Ib-mole OR 
ft 
ft 
psi 
OF/vol. % 
fi/ft 
"F 
"F 
"R 
OR 
"R 
"R 
"R 
"R 
"R 
"R 
"R 
OR 
"R 
"R 
ft3 
ft' 
Ibígal 
- 
- 
- 
13, I5 
12, 14 
- 
11 
4 
43 
5 , 37 
39, 40 
1 , 6 
9, 10 
7, 8 
- 
- 
41 
- 
- 
- 
36 
27 
28 
26 
34 
- 
- 
- 
- 
- 
- 
31 
- 
31 
31 
18 
- 
- 
- 
19 
21 
22 
25 
24 
23 
42 
2 
- 
- 
- 
- - Stock vapor density Ibift3 3 
WV, Stock condensed vapor density at 60°F Ibígal 38 6, 7 - 
Greek Symbol Notation 
- a Tank paint solar absorptance Dimensionless 20 5 
C ~ R Tank roof paint solar absorptance Dimensionless - 5 
us Tank shell paint solar absorptance Dimensionless - 5 
T Constant (3.14159) Dimensionless - - - 
- 
- 
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A P I MPMS*l iS-L 91 0732290 051872.5 43b = 
4 CHAPTER 1 E EVAPORA TIVE Loss MEASUREMENT 
Table 1 -Continued. 
Symbol Description 
Function Notation 
exp( ) 
in() 
Exponential value of the quantity in parentheses 
Natural logarithm value of the quantity in parentheses 
Subscript Notation 
A Ambient, or atmospheric 
AA Ambient average 
AN Ambient minimum 
AX Ambient maximum 
B Breather, or liquid bulk 
BP Breather pressure 
BV Breather vacuum 
E Expansion 
L Liquid 
LA Liquid average 
UV Liquid minimum 
LX Liquid maximum 
N Turnover 
P Product 
R Roof 
RO Roof outage 
S 
T Total 
V Vapor 
VA Vapor average 
VC Vapor condensed 
VN Vapor minimum 
V û Vapor outage 
VX Vapor maximum 
W Workine 
Standing, or shell, or saturation 
Unit Notation 
Btu British thermal unit 
Ib Pound mass 
lb-mole Pound mole 
"R Degrees Rankine 
"F Degrees Fahrenheit 
Conversion Relationships 
"R = "F + 459.61 
psia = psig + 14.696 
e. The tank location. 
f. The stock type. 
g. The stock liquid bulk temperature. 
h. The stock vapor pressure (or the stock Reid vapor 
pressure). 
i. The stock liquid level. 
Improved estimates of the standing storage loss can be 
obtained through a knowledge of some or all of the 
following additional information: 
a. The tank cone roof slope or dome roof radius. 
b. The breather vent pressure and vacuum settings. 
c. The daily average ambient temperature. 
d. The daily ambient temperature range. 
e. The daily total solar insolation on a horizontal surface. 
f. The atmospheric pressure. 
g. The molecular weight of the stock vapor. 
h. The stock liquid surface temperature. 
The standing storage loss, Ls, pertains to evaporation 
of liquid stock which occurs as a result of tank vapor 
space breathing. The standing storage loss can be estimated 
from Equation '1: 
(1) Ls = 365 Vv Wv KE Ks 
Where Vv, Wv, KE, and Ks are calculated from Equations 
2 through 5 , respectively. 
Tank Vapor Space Volume, VV 
v - - D ~ H ~ ~ 
v - 4 
Stock Vapor Density, Wv 
Vapor Space Expansion Factor, KE 
( 3 ) 
(4) 
Vented Vapor Saturation Factor, Ks 
( 5 ) 
1 
K - 
- 1 + 0.053 PvA Hvo 
Where: 
Ls = standing storage loss, in pounds per year. 
Vv = tank vapor space volume, in cubic feet. 
Wv = stock vapor density, in pounds per cubic foot. 
KE = vapor space expansion factor (dimensionless). 
Ks = vented vapor saturation factor (dimensionless). 
D = tank diameter, in feet. 
Hvo = vapor space outage, in feet. 
Mv = stock vapor molecular weight, in pounds per 
pound-mole. 
P I / . = stock vapor pressure at the daily average liquid 
surface temperature, in pounds per square 
inch absolute. 
= ideal gas constant (10.731), in (pounds per 
square inch absolute) cubic feet per pound-mole 
degree Rankine. 
TM = daily average liquid surface temperature, in 
degrees Rankine. 
AT, = daily vapor temperature range, in degrees 
Rankine. 
APv = stock daily vapor pressure range, in pounds 
per square inch. 
APB = breather vent pressure setting range, in pounds 
per square inch. 
PA = atmospheric pressure, in pounds per square 
inch absolute. 
R 
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A P I MPMS*Lî.L 91 0732290 05L872b 372 
SECTION 1 -EVAPORATIVE Loss FROM FIXED-ROOF TANKS 5 
The constant, 365, in Equation 1 has units of (year)-'. 
The constant, 0.053, in Equation 5 has units of [(pounds 
Where: 
Wvc = stock condensed vapor density at 60"F, in 
per square inch absolute)feet] ~ I . pounds per gallon. 
The constant, 42, in Equation 6 has units of gallons per 
barrel. The standing storage loss is converted from pounds per year to barrels per year as follows: 
The procedures used to calculate the standing storage Ls (pounds per year) 
Ls (barrels per year) = (6) loss are summarized in Table 2. 
42 wvc 
Table 2-Summary of Procedure for Calculating Standing Storage Loss (Ls) 
Standing Storage Loss Equations 
Ls (Ib/yr) = 365 Vv Wv KE Ks 
15s (Iblyï) Ls (bbìlyr) = 
42 wvc 
Variable Descriotion Eauation Units Source 
~ ~~ ~ 
VV Tank vapor space volume ft3 Calculate from Equation 2 
= Z D ~ H ~ ~ 
4 
D Tank diameter 
HVO Vapor space outage 
= H s - H L + HRO 
Tank shell height 
Stock liquid height (or innage) 
e Hs H L 
HRO Roof outage 
2 
ft User specified 
ft Calculate from Equation 11 
11 
ft User specified 
ft User specified 
ft Calculate from Equation 12 for a cone roof 
Calculate from Equation 14 for a dome roof 
wv Stock vapor density Ibíft3 Calculate from Equation 3 
R Ideal gas constant (10.731) 
M V Stock vapor molecular weight 
3 
psia ft3 
lb-mole "R 
Ib/lb-mole User specified or 
Table 6 for selected petroleum liquid stocks 
Table 7 for selected petrochemical stocks 
64 for gasoline 
50 for U.S. midcontinent crude oil stocks 
VA Stock vapor pressure at the daily average psia Calculate from Equation 27 or 
liquid surface temperature Figure 5 for refined petroleum stocks 
Figure 8 for crude oil stocks 
= exp[A - (B/Tu)] 27 
A Constant in the vapor pressure equation 
B Constant in the vapor pressure equation 
TLA Daily average liquid surface temperature 
= 0.44Taa + 0.56Ta + 0.0079~~1 22 
/". " 
Daily average ambient temperature e Liquid bulk temperature 
Dimensionless Table 6 for selected petroleum liquid stocks 
Table 7 for selected petrochemical stocks 
Equation 29 or Figure 3 for refined petroleum stocks 
Equation 32 or Figure 6 for crude oil stocks 
Table 6 for selected petroleum liquid stocks 
Table 7 for selected petrochemical stocks 
Equation 30 or Figure 4 for refined petroleum stocks 
Equation 33 or Figure 7 for crude oil stocks 
"R 
"R Calculate from Equation 22 
"R 
"R User specified or 
User specified or Table 4 and Equation IS 
Calculate from Equation 21 
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A P I MPMS*LS.L 91 = 0732290 0538727 207 = 
6 CHAPTER 1 EVAPORATI TIVE Loss MEASUREMENT 
Table 2-Continued. 
Standing Storage Loss Equations 
Ls (Iblyr) = 365 V v W v KE Ks 
Ls (Iblyr) 
L, (bbllyr) = 
42 wvc 
Variable Description Equation Units Source 
Tank paint solar absorptance 
Daily total solar insolation on a horizontal 
Vapor space expansion factor 
surface 
- ATv + APV - *PB 
- 
Daily vapor temperature range 
= 0 . 7 2 A T ~ + 0 . 0 2 8 ~ Z 
Daily ambient temperature range 
Tank paint solar absorptance 
Daily total solar insolation on a horizontal 
Daily average liquid surface temperature 
Stock daily vapor pressure range 
surface 
= Pm - PVN 
Stock vapor pressure at the daily maximum 
Stock vapor pressure at the daily minumum 
Breather vent pressure setting range 
= - pBV 
Breather vent pressure setting 
Breather vent vacuum setting 
Atmospheric pressure 
Stock vapor pressure at the daily average 
liquid surface temperature 
liquid surface temperature 
liquid surface temperature 
Dimensionless User specified or Table 5 
Calculate from Equation 20 for different color roof and shell 
Btu/ft2 day User specified or Table 4 
Dimensionless Calculate from Equation 4 
4 
"R Calculate from Equation 23 
23 
"R User specified or Table 4 and Equation 19 
Dimensionless User specified or Table 4 and Equation 19 
Btuift' day User specified or Table 4 and Equation 19 
"R 
psi 
User specified or Table 4 and Equation 19 
Calculate from Equation 34 or 35 
34 
psia Calculate from Equation 26 for Tu from Equation 24 
psia Calculate from Equation 28 for TLN from Equation 25 
psi Calculate from Equation 36 
36 
psig 
pslg 
psia 
psia 
User specified or typically 0.03 
User specified or typically -0.03 
User specified or typically 14.7 
User specified or typically 14.7 
KS Vented vapor saturation factor Dimensionless Calculate from Equation 5 
1 - - 
1 f 0 . 0 5 3 P v ~ H v ~ 5 
liquid surface temperature 5 
VA Stock vapor pressure at the daily average psia Calculate from Equation 5 
Vapor space outage 5 ft Calculate from Equation 5 
Stock condensed vapor density at 60°F Ib/gal User specified orH v o 
wvc 
Table 6 for selected petroleum liquid stocks 
Table 7 selected petrochemical stocks 
Calculate from Equation 38 for refined petroleum stocks and 
crude oil stocks 
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A P I f lPf lS+LS-L 91 0732290 0538728 II45 
SECTION 1 -EVAPORATIVE Loss FROM FIXED-ROOF TANKS 7 a 19.1.2.1.3 Working Loss, Lw 
The working loss, Lw, can be calculated from the 
following information: 
a. The stock vapor molecular weight. 
b. The stock vapor pressure (or the stock Reid vapor 
pressure). 
c. The stock annual net throughput (associated with 
increasing the stock liquid level). 
d. The stock turnover rate. 
e. The stock type. 
The working loss, Lw, pertains to evaporation of liquid 
stock which occurs as a result of tank filling or emptying 
operations. The working loss can be estimated from 
Equation 7: 
(7) Lw = 0.0010 M v Pli, Q K N K p 
Where: 
Lw = working loss, in pounds per year. 
Mv = stock vapor molecular weight, in pounds per 
pound-mole. 
P , = stock vapor pressure at the daily average liquid 
surface temperature, in pounds per square inch 
absolute. 
Q = stock annual net throughput (associated with 
increasing the stock liquid level in the tank), 
in barrels per year. 
= working loss turnover factor (dimensionless). 
= working loss product factor (dimensionless). 
The constant, 0,0010, in Equation 7 has units of pound- 
moles per (pounds per square inch absolute) barrel. 
The working loss is converted from pounds per year to 
barrels per year as follows: 
KN 
K p 
Lw (pounds per year) Lw (barrels per year) = (8) 42 WVC 
Where: 
W,, = stock condensed vapor density at 60"E in 
The constant, 42, in Equation 8 has units of gallons per 
barrel. 
The procedures used to calculate the working loss are 
summarized in Table 3. 
19.1.2.1.4 Total Loss, LT 
year, can be calculated as follows: 
pounds per gallon. 
The total loss, LT, in pounds per year and barrels per 
Table 3- Summary of Procedure for Calculating Working Loss (Lw) 
L , (Ibiyr) = 0.0010 Mv PvA Q KN K p 
Working Loss Equations 
(7) 
Variable 
~ ~~ 
Descrimion Eciuation Units Source 
~ 
M V Stock vapor molecular weight Ibilb-mole User specified or 
Table 6 for selected petroleum liquid stocks 
Table 7 for selected petrochemical stocks 
64 for gasoline 
50 for U.S. midcontinent crude oil stocks 
pVA Stock vapor pressure at the daily average 
liquid surface temperature 
= exp[A - (+Y] 
psia Calculate from Equation 27 or 
Figure 5 for refined petroleum stocks 
Figure 8 for crude oil stocks 
A Constant in the vapor pressure equation Dimensionless Table 6 for selected petroleum liquid stocks 
Table 7 for selected petrochemical stocks 
Equation 29 or Figure 3 for refined petroleum stocks 
Equation 32 or Figure 6 for crude oil stocks 
B Constant in the vapor pressure equation "R Table 6 for selected petroleum liquid stocks 
Table 7 for selected petrochemical stocks 
Equation 30 or Figure 4 for refined petroleum stocks 
Equation 33 or Figure 7 for crude oil stocks 
T u Daily average liquid surface temperature "R Calculate from Equation 22 
Q = Stock annual net throughput bbl/yr User specified 
Q 
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8 CHAPTER 1 EVAPORATI TIVE Loss MEASUREMENT 
Table 3-Continued. 
Working Loss Equations 
Lw (Ibiyr) = 0.0010 M I / PVA Q K N K p (7) 
42 wvc (8) 
Lw(bbl/y) = 
Variable DescriDtion Eauation Units Source 
KN Working loss turnover factor Dimensionless Calculate from Equation 39 or 40 
(''O + N, (for N > 36) (39) - - 6N 
= 1 (for N s 36) (40) 
N Stock turnover rate turnoveriyr Calculate from Equation 41 
Q 
"Lx (41) 
Tank maximum liquid volume ft3 Calculate from Equation 42 
(42) 
= 5.614- 
", 
71 
= 4 ~ 2 H , 
H u Stock maximum liquid height ft User specified 
KP Working loss product factor Dimensionless 0.75 for crude oil stocks 
i .O0 for refined petroleum stocks 
1 .O0 for single-component petrochemical stocks 
wvc Stock condensed vapor density at 60°F Ibigal User specified or 
Table 6 for selected petroleum liquid stocks 
Table 7 for selected petrochemical stocks 
Calculated from Equation 38 for refined petroleum stocks and 
crude oil stocks 
(9) 
LT (pounds per year) = Ls (pounds per year) 
+ Lw (pounds per year) 
(10) 
L, (barrels per year) = Ls (barrels per year) 
+ Lw (barrels per year) 
Where: 
LT = total loss, in pounds per year or barrels per year. 
Ls = standing storage loss, in pounds per year or 
Lw = working loss, in pounds per year or barrels per 
barrels per year. 
year. 
19.1.2.2 Discussion of Variables 
19.1.2.2.1 General 
Information is summarized in 19.1.2.2.2 and 19.1.2.2.3 
on how to determine specific values for the variables in 
the loss equations given in 19.1.2.1. Tables, graphs, and 
the range of values of the variables for which the loss 
equations are applicable are cited for reference. 
To obtain the most accurate estimate, detailed informa- 
tion pertinent to the specific tank or tanks under consider- 
ation should be used. The typical values included in 
19.1.2.2 and the cited tables and figures should be used 
only when actual detailed information is not available. 
More detailed discussion of the definition, development, 
and effects of the variables is given in 19.1.4. 
19.1.2.2.2 Standing Storage Loss Variables 
to the following variables: 
a. Tank vapor space volume, Vv. 
b. Stock vapor density, W,. 
c. Vapor space expansion factor, KE. 
d. Vented vapor saturation factor, Ks. 
These variables can be calculated using Equations 2 
through 5 . Data sources and proper usage for each of the 
variables in Equations 2 through 5 are described in 
19.1.2.2.2.1 through 19.1.2.2.2.13. These subsections 
are arranged in the order in which the calculations are 
normally performed. 
The standing storage loss, Ls, is related in Equation 1 
19.1.2.2.2.1 Vapor Space Outage, HvO 
The vapor space outage, Hvo, is the height of a 
cylinder of tank diameter, D, whose volume is equivalent 
to the vapor space volume of a fixed-roof tank, including 
the volume under the cone or dome roof. Figure 1 
illustrates the geometry of a fixed-roof tank with either a 
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A P L MPMS*3S.3 93 0732290 0538730 8T3 
SECTION 1 -EVAPORATIVE Loss FROM FIXED-ROOF TANKS 9 
Cone roof slope, S, 
D I 
Cone roof 
s” 
1 
1 
I / 
1 
Dome roof 
Figure 1 -Fixed-Roof Tank Geometry 
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10 
A P I MPMStLS=L 91 0732290 05LB73L 7 3 T 
CHAPTER 1 E EVAPORA TIVE Loss MEASUREMENT 
cone roof or dome roof. The vapor space outage may be 
determined from Equation 1 1 : 
(11) Hvo = Hs - HL + H R O 
Where: 
Hvo = vapor space outage, in feet. 
Hs = tank shell height, in feet. 
HL = stock liquid height, in feet. 
H R O = roof outage (or shell height equivalent to the 
volume contained under the roof), in feet. 
19.1.2.2.2.1.1 Cone Roof 
For a cone roof, the roof outage (or shell height 
equivalent to the volume contained under the roof), 
H R O , can be calculated from Equation 12: 
(12) 
HR = S R Rs (13) 
1 
HRO 3 HR 
Where: 
Where: 
H R O = roof outage (or shell height equivalent to the 
HR 
SR 
Rs 
volume contained under the roof), in feet. 
= tank roof height, in feet. 
= tank cone roof slope, in feet per foot. 
= tank shell radius, in feet. 
If the tank cone roof slope, SR, is not known, a typical 
value of 0.0625 feet per foot may be assumed. 
0.70 
0.68 
0.66 
0.64 
0.62 
0.60 
0.58 
0.56 : : : : I l 1 
0.50O 0.2 0.4 0.6 0.8 1 .o 
Dome roof heighffshell radius, HdRs 
(dimensionless) 
Figure 2-Dorne Roof Outage (HRo) 
19.1.2.2.2.1.2 Dome Roof 
For a dome roof, the roof outage (or shell height 
equivalent to the volume contained under the roof), 
H R O , may be determined from Figure 2 or calculated 
from Equation 14: 
Where: 
HR = R R - (RR2 - R,2)0.5 (15) 
Where: 
HRo = roof outage (or shell height equivalent to the 
HR 
Rs 
RR 
Figure 2 shows for a dome roof that the ratio HR0:HR 
varies from 0.500 to 0.666. This may be compared to the 
same ratio for a cone roof which, from Equation 12, is a 
constant value of 0.333. 
Section 3.10.6 of API Standard 650 [ 1 J indicates that 
the tank dome roof radius, RR, varies between a mini- 
mum of 0.8 D and a maximum of 1.2 D. If the tank dome 
roof radius is not known, a typical value of 1 .O D may be 
assumed. In this case, Equations 14 and 15 simplify to 
Equations 16 and 17: 
volume contained under the roof), in feet. 
= tank roof height, in feet. 
= tank shell radius, in feet. 
= tank dome roof radius, in feet. 
HRo = 0.137 Rs (16) 
HR = 0.268 Rs (17) 
19.1.2.2.2.2 Meteorological Data, TM, TAN, I 
ing storage loss, L,, consists of: 
a. Daily maximum ambient temperature, TM; 
b. Daily minimum ambient temperature, TAN; 
c. Daily total solar insolation on a horizontal surface, I . 
The term insolation refers to incident-solar-radiation. 
When possible, meteorological data for the tank site 
should be used. If this data is not available, meteorolog- 
ical data from the nearest local weather station may be 
used. Data for selected U.S. locations is listed in Table 4. 
Data for other U.S. locations may be found in weather 
station records [2,3]. 
The daily average ambient temperature, Tu, and the 
daily ambient temperature range, ATA, may be calcu- 
lated from Equations 18 and 19, respectively: 
The meteorological data needed to estimate the stand- 
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A P I MPMS*17~1 7 1 = 0732270 0538732 676 = 
SECTION 1 -EVAPORATIVE LOSS FROM FIXED-ROOF TANKS 1 1 
Table 4-Meteorological Data (TAX, TAN, I ) for Selected U. S. Locations 
Annual Property Monthly Averages 
Location Symbol Units Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Average 
Birmingham Airport, AL 
Montgomery, AL 
Homer, AK 
Phoenix. AZ 
Tucson, AZ 
Fort Smith, AR 
Little Rock, AR 
Bakersfield, CA 
Long Beach, CA - a Los Angeles Airport, CA 
Sacramento, CA 
San Francisco Airport, CA 
Santa Mana, CA 
Denver, CO 
Grand Junction, CO 
Wilmington, DE 
Atlanta. GA 
Savannah. GA 
Honolulu. HI 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TM 
TAN 
I 
I 
I 
I 
I 
I 
I 
I 
I 
I 
I 
1 
I 
I 
I 
I 
I 
I 
I 
OF 
"F 
Btu/ft2 day 
"F 
"F 
Btu/ft2 day 
"F 
OF 
Btu/ft2 day 
"F 
"F 
Btu/ft2 day 
OF 
"F 
Btdft' day 
"F 
"F 
Btulft2 day 
"F 
"F 
Btu/ft2 day 
"F 
"F 
Btu/ft2 day 
"F 
"F 
Btu/ft2 day 
OF 
"F 
Btu/ft2 day 
T 
T 
Btulft2 day 
"F 
"F 
Btu/ft2 day 
OF 
"F 
Btu/ft' day 
"F 
"F 
Btulft' day 
OF 
"F 
Btu/ft2 day 
OF 
"F 
Btu/ft2 day 
"F 
O F 
Btu/ftz day 
"F 
"F 
Btu/ft2 day 
"F 
OF 
Btulft2 day 
52.7 57.3 65.2 75.2 
33.0 35.2 42.1 50.4 
707 967 1296 1674 
57.0 60.9 68.1 77.0 
36.4 38.8 45.5 53.3 
752 1013 1341 1729 
27.0 31.2 34.4 42.1 
14.4 17.4 19.3 28.1 
122 334 759 1248 
65.2 69.7 74.5 83.1 
39.4 42.5 46.7 53.0 
1021 1374 1814 2355 
64.1 67.4 71.8 80.1 
38.1 40.0 43.8 49.7 
1099 1432 1864 2363 
48.4 53.8 62.5 73.7 
26.6 30.9 38.5 49.1 
744 999 1312 1616 
49.8 54.5 63.2 73.8 
29.9 33.6 41.2 50.9 
731 1003 1313 1611 
57.4 63.7 68.6 75.1 
38.9 42.6 45.5 50.1 
766 1102 1595 2095 
66.0 67.3 68.0 70.9 
44.3 45.9 47.7 50.8 
928 1215 1610 1938 
64.6 65.5 65.1 66.7 
47.3 48.6 49.7 52.2 
926 1214 1619 1951 
52.6 59.4 64.1 71.0 
37.9 41.2 42.4 45.3 
597 939 1458 2004 
55.5 59.0 60.6 63.0 
41.5 44.1 44.9 46.6 
708 1009 1455 1920 
62.8 64.2 63.9 65.6 
38.8 40.3 40.9 42.7 
854 1141 1582 1921 
43.1 46.9 51.2 61.0 
15.9 20.2 24.7 33.7 
840 1127 1530 1879 
35.7 44.5 54.1 65.2 
15.2 22.4 29.7 38.2 
791 1119 1554 1986 
39.2 41.8 50.9 63.0 
23.2 24.6 32.6 41.8 
571 827 1149 1480 
51.2 55.3 63.2 73.2 
32.6 34.5 41.7 50.4 
718 969 1304 1686 
60.3 63.1 69.9 77.8 
37.9 40.0 46.8 54.1 
795 1044 1399 1761 
79.9 80.4 81.4 82.7 
65.3 65.3 67.3 68.7 
1180 1396 1622 1796 
81.6 
58.3 
1857 
83.6 
61.1 
1897 
49.8 
34.6 
1583 
92.4 
61.5 
2677 
88.8 
57.5 
267 1 
81.0 
58.2 
1912 
81.7 
59.2 
1929 
83.9 
57.2 
2509 
73.4 
55.2 
2065 
69.1 
55.7 
2060 
79.7 
50.1 
2435 
66.3 
49.3 
2226 
67.3 
46.2 
2141 
70.7 
43.6 
2135 
76.2 
48.0 
2380 
72.7 
51.7 
1710 
79.8 
58.7 
1854 
84.2 
62.3 
1852 
84.8 
70.2 
1949 
87.9 90.3 
65.9 69.8 
1919 1810 
89.8 91.5 
68.4 71.8 
1972 1841 
56.3 60.5 
41.2 45.1 
1751 1598 
102.3 105.0 
70.6 79.5 
2739 2487 
98.5 98.5 
67.4 73.8 
2730 2341 
88.5 93.6 
66.3 70.5 
2089 2065 
89.5 92.7 
67.5 71.4 
2107 2032 
92.2 98.8 
64 .3 70.1 
2149 2684 
77.4 83.0 
58.9 62.6 
2140 2300 
72.0 75.3 
59.1 62.6 
2119 2308 
87.4 93.3 
55.1 57.9 
2684 2688 
69.6 71.0 
52.0 53.3 
2317 2392 
69.9 72.1 
49.6 52.4 
2349 2341 
81.6 88.0 
52.4 58.7 
2351 2273 
87.9 94.0 
56.6 63.8 
2599 2465 
81.2 85,6 
61.2 66.3 
1883 1823 
85.6 87.9 
65.9 69.2 
1914 1812 
88.6 90.8 
68.5 71.5 
1844 1784 
86.2 87.1 
71.9 73.1 
2004 2002 
89.7 84.6 
69.1 63.6 
1724 1455 
91.2 86.9 
71.1 66.4 
1746 1468 
60.3 54.8 
45.2 39.7 
1189 791 
102.3 98.2 
77.5 70.9 
2293 2015 
95.9 93.5 
72.0 67.3 
2183 1979 
92.9 85.7 
68.9 62.1 
1877 1502 
92.3 85.6 
69.6 63.0 
1861 1518 
96.4 90.8 
68.5 63.8 
2421 1992 
83.8 82.5 
64.0 61.6 
2100 1701 
76.5 76.4 
64.0 62.5 
2080 1681 
91.7 87.6 
57.6 55.8 
2368 1907 
71.8 73.4 
54.2 54.3 
2117 1742 
72.8 74.2 
53.2 51.8 
2106 1730 
85.8 77.5 
57.0 47.7 
2044 1727 
90.3 81.9 
61.5 52.2 
2182 1834 
84.1 77.8 
65.4 58.0 
1615 1318 
87.6 82.3 
68.7 63.6 
1709 1422 
90.1 85.6 
71.4 67.6 
1621 1364 
88.3 88.2 
73.6 72.9 
1967 1810 
74.8 63.7 
50.4 40.5 
1211 858 
77.5 67.0 
53.1 43.0 
1262 915 
44.0 34.9 
30.6 22.8 
437 175 
87.7 74.3 
59.1 46.9 
1577 1151 
84.1 72.2 
56.7 45.2 
1602 1208 
75.9 61.9 
49.0 37.7 
1201 851 
75.8 62.4 
50.4 40.0 
1228 847 
81.0 67.4 
54.9 44.9 
1458 942 
78.4 72.1 
56.6 49.6 
1326 1004 
74.0 70.3 
58.5 52.1 
1317 1004 
77.7 63.2 
50.0 42.8 
1315 782 
70.0 62.7 
51.2 46.3 
1226 821 
73.3 68.9 
47.6 42.1 
1353 974 
66.8 52.4 
36.9 25.1 
1301 884 
68.7 51.0 
41.1 28.2 
1345 918 
66.7 54.8 
45.9 36.4 
984 645 
72.9 62.6 
51.4 41.3 
1200 883 
77.8 69.5 
55.9 45.5 
1217 941 
86.7 83.9 
72.2 69.2 
1540 1266 
55.9 73.2 
35.2 51.1 
661 1345 
59.8 75.9 
37.9 53.9 
719 1388 
27.7 43.6 
15.8 29.5 
64 838 
66.4 85.1 
40.2 57.3 
932 1869 
65.0 81.7 
39.0 54.2 
996 1872 
52.1 72.5 
30.2 49.0 
682 1404 
53.2 72.9 
33.2 50.8 
674 1404 
57.6 77.7 
38.7 53.3 
677 1749 
67.4 74.2 
44.7 53.5 
847 1598 
66.1 70.1 
47.8 55.0 
849 1594 
53.2 73.4 
37.9 47.8 
538 1643 
56.3 64.9 
42.2 48.3 
642 1553 
64.6 68.3 
38.3 45.3 
804 1608 
46.1 64.3 
18.9 36.2 
732 1568 
38.7 65.7 
17.9 39.6 
731 1659 
43.6 63.5 
27.3 44.5 
489 1208 
54.1 71.3 
34.8 51.1 
674 1345 
62.5 76.7 
39.4 55.1 
754 1365 
81.4 84.2 
66.5 69.7 
1133 1639 
COPYRIGHT American Petroleum Institute
Licensed by Information Handling Services
COPYRIGHT American Petroleum Institute
Licensed by Information Handling Services
12 
API rlPrlsriq.i 91 m o n z z q o 0 5 1 ~ ~ 3 3 502 rn 
CHAPTER 1 EVAPORATI TIVE Loss MEASUREMENT 
Table 4-Continued. 
Annual 
Location Symbol Units Jan. Feb. Mar. Apr. May Jun. Jul. AUE. Sep. Oct. Nov. Dec. Average 
Property Monthly Averages 
Chicago, IL 
Springfield, IL 
Indianapolis, IN 
Wichita,KS 
Louisville, KY 
Baton Rouge, LA 
Lake Charles, LA 
New Orleans. LA 
Detroit, MI 
Grand Rapids, MI 
Minneapolis-St. Paul, MN 
Jackson, MS 
Billings, MT 
Las Vegas, NV 
Newark, NJ 
Roswell, NM 
Buffalo, NY 
New York, NY 
(LaGuardia Airport) 
Cleveiand. OH 
TAX "F 
TAN "F 
TAX OF 
TAN "F 
TAX "F 
TAN "F 
TAX "F 
TAN "F 
TAX OF 
TAN "F 
TAX "F 
TAN "F 
TAX "F 
TAN "F 
TAX "F 
TAN "F 
TAN "F 
TAX "F 
TAN OF 
TAX "F 
TAN "F 
T4x "F 
TAN "F 
TAX "F 
TAN OF 
T4x T 
TAN OF 
TAX "F 
TAN "F 
TAX T 
TAN "F 
TAX T 
TAN "F 
TAX OF 
TAN "F 
TAX "F 
TAN "F 
I Btuift' day 
I Btu/ft' day 
I Btu/ft2 day 
I Btuift' day 
I Btuift? day 
I Btuift' day 
I Btuift' day 
I Btuift' day 
TM OF 
I Btuift' day 
I Btuift' day 
I Btuift' day 
I Btuift' day 
I Btu/ft' day 
I Btu/ft' day 
I Btu/ft* day 
I Btu/ft* day 
I Btu/ft* day 
I Btuift' day 
I Btu/ft2 day 
29.2 
13.6 
507 
32.8 
16.3 
585 
34.2 
17.8 
496 
39.8 
19.4 
784 
40.8 
24.1 
546 
61.1 
40.5 
785 
60.8 
42.2 
728 
61.8 
43.0 
835 
30.6 
16.1 
417 
29.0 
14.9 
3 70 
19.9 
2.4 
464 
56.5 
34.9 
754 
29.9 
11.8 
486 
56.0 
33.0 
978 
38.2 
24.2 
552 
55.4 
27.4 
1047 
30.0 
17.0 
349 
37.4 
26.1 
548 
32.5 
18.5 
388 
33.9 44.3 58.8 70.0 79.4 
18.1 27.6 38.8 48.1 57.7 
760 1107 1459 1789 2007 
38.0 48.9 64.0 74.6 84.1 
20.9 30.3 42.6 52.5 62.0 
861 i143 i515 1866 2097 
38.5 49.3 63.1 73.4 82.3 
21.1 30.7 41.7 51.5 60.9 
747 1037 1398 1638 1868 
46.1 55.8 68.1 77.1 87.4 
24.1 32.4 44.5 54.6 64.7 
1058 1406 1783 2036 2264 
45.0 54.9 67.5 76.2 84.0 
26.8 35.2 45.6 54.6 63.3 
789 1102 1467 1720 1904 
64.5 71.6 79.2 85.2 90.6 
42.7 49.4 57.5 64.3 70.0 
1054 1379 1681 1871 1926 
64.0 70.5 77.8 84.1 89.4 
44.5 50.8 58.9 65.6 71.4 
1010 1313 1570 1849 1970 
64.6 71.2 78.6 84.5 89.5 
44.8 51.6 58.8 65.3 70.9 
1112 1415 1780 1968 2004 
33.5 43.4 57.7 69.4 79.0 
18.0 26.5 36.9 46.7 56.3 
680 1000 1399 1716 1866 
31.7 41.6 56.9 69.4 78.9 
15.6 24.5 35.6 45.5 55.3 
648 1014 1412 1755 1957 
26.4 37.5 56.0 69.4 78.5 
8.5 20.8 36.0 47.6 57.7 
764 1104 1442 1737 1928 
60.9 68.4 77.3 84.1 90.5 
37.2 44.2 52.9 60.8 67.9 
1026 1369 1708 1941 2024 
37.9 44.0 55.9 66.4 76.3 
18.8 23.6 33.2 43.3 51.6 
763 1190 1526 1913 2174 
62.4 68.3 77.2 87.4 98.6 
37.7 42.3 49.8 59.0 68.6 
1340 1824 2319 2646 2778 
40.3 49.1 61.3 71.6 80.6 
25.3 33.3 42.9 53.0 62.4 
793 1109 1449 1687 1795 
60.4 67.7 76.9 85.0 93.1 
31.4 37.9 46.8 55.6 64.8 
1373 1807 2218 2459 2610 
31.4 40.4 54.4 65.9 75.6 
17.5 25.6 36.3 46.3 56.4 
546 889 1315 1597 1804 
39.2 47.3 59.6 69.7 78.7 
27.3 34.6 44.2 53.7 63.2 
795 1118 1457 1690 1802 
34.8 44.8 57.9 68.5 78.0 
19.9 28.4 38.3 47.9 57.2 
601 922 1350 1681 1843 
83.3 
62.7 
1944 
87.1 
65.9 
2058 
85.2 
64.9 
1806 
92.9 
69.8 
2239 
87.6 
67.5 
1838 
91.4 
72.8 
I746 
91 .O 
73.5 
1788 
90.7 
73.5 
1814 
83.1 
60.7 
1835 
83.0 
59.8 
1914 
83.4 
62.7 
I970 
92.5 
71.3 
1909 
86.6 
58.0 
2384 
104.5 
75.9 
2588 
85.6 
67.9 
1760 
93.7 
69.0 
2441 
80.2 
61.2 
1776 
83.9 
68.9 
1784 
81.7 
61.4 
1828 
82.1 75.5 64.1 48.2 35.0 58.7 
61.7 53.9 42.9 31.4 20.3 39.7 
1719 1354 969 566 402 1215 
84.7 79.3 67.5 51.2 38.4 62.6 
63.7 55.8 44.4 32.9 23.0 42.5 
1806 1454 1068 677 490 1302 
83.7 77.9 66.1 50.8 39.2 62.0 
62.7 55.3 43.4 32.8 23.7 42.2 
1644 1324 977 579 417 1165 
91.5 82.0 71.2 55.1 44.6 67.6 
67.9 59.2 46.9 33.5 24.2 45.1 
2032 1616 1250 871 690 1502 
86.7 80.6 69.2 55.5 45.4 66.1 
66.1 59.1 46.2 36.6 28.9 46.2 
1680 1361 1042 653 488 1216 
90.8 87.4 80.1 70.1 63.8 78.0 
72.0 68.3 56.3 47.2 42.3 57.0 
1677 1464 1301 920 737 1379 
90.8 87.5 80.8 70.5 64.0 77.6 
72.8 68.9 57.7 48.9 43.8 58.3 
1657 1485 1381 917 706 1365 
90.2 86.8 79.4 70.1 64.4 77.7 
73.1 70.1 59.0 49.9 44.8 58.7 
1717 1514 1335 973 779 1437 
81.5 74.4 62.5 47.6 35.4 58.2 
59.4 52.2 41.2 31.4 21.6 38.9 
1576 1253 876 478 344 1120 
81.1 73.4 61.4 46.0 33.8 57.2 
58.1 50.8 40.4 30.9 20.7 37.7 
1676 1262 858 446 311 1135 
80.9 71.0 59.7 41.1 26.7 54.2 
60.3 50.2 39.4 25.3 11.7 35.2 
1687 1255 860 480 353 1170 
92.1 87.6 78.6 67.5 60.0 76.3 
70.2 65.1 51.4 42.3 37.1 52.9 
1781 1509 1271 902 709 1409 
84.3 72.3 61.0 44.4 36.0 57.9 
56.2 46.5 37.5 25.5 18.2 35.4 
2022 1470 987 561 421 1325 
101.9 94.7 81.5 66.0 57.1 79.6 
73.9 65.6 53.5 41.2 33.6 52.8 
2355 2037 1540 1086 881 1864 
84.0 76.9 66.0 54.0 42.3 62.5 
67.0 59.4 48.3 39.0 28.6 45.9 
1565 1273 951 596 454 1165 
91.3 84.9 75.8 63.1 56.7 75.3 
67.0 59.6 47.5 35.0 28.2 47.5 
2242 1913 1527 1131 952 1810 
78.2 71.4 60.2 47.0 35.0 55.8 
59.6 52.7 42.7 33.6 22.5 39.3 
1513 1152 784 403 283 1034 
82.3 75.2 64.5 52.9 41.5 61.0 
68.2 61.2 50.5 41.2 30.8 47.5 
1583 1280 951 593 457 1171 
80.3 74.2 62.7 49.3 37.5 58.5 
60.5 54.0 43.6 34.3 24.6 40.7 
1583 1240 867 466 318 1091 
COPYRIGHT American Petroleum Institute
Licensed by Information Handling Services
COPYRIGHT American Petroleum Institute
Licensed by Information Handling Services
A P I NPMS*LS.L 91 D 0732290 0518734 449 
SECTION i -EVAPORATIVE Loss FROM FIXED-ROOF TANKS 13 
Table 4-Continued. 
Annual Property Monthly Averages 
Location Symbol Units Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Average 
T A Y "F 34.7 38.1 49.3 62.3 72.6 81.3 84.4 83.0 76.9 65.0 50.7 39.4 61.5 Columbus, OH 
Toledo. OH 
Oklahoma City, OK 
Tulsa, OK 
Astoria, OR 
Portland, OR 
Philadelphia, PA 
Pittsburgh, PA 
Providence, RI 
a Columbia, SC 
Sioux Falls. SD 
Memphis, TN 
Amarillo. TX 
Corpus Christi, TX 
Dallas, TX 
Houston, TX 
Midland-Odessa, TX 
Salt Lake City, UT 
Richmond, VA 
, ". 
TAN 
T M 
TAN 
TAX 
TAN 
I 
I 
I 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
TAX 
TAN 
T4x 
TAN 
TAX 
TAN 
I 
I 
I 
I 
I 
I 
I 
I 
I 
I 
TAX 
TAN 
TAX 
T4N 
TAX 
TAN 
Teu 
TAN 
TAX 
TAN 
T M 
TAN 
I 
I 
I 
I 
I 
I 
"F 
Btuift' day 
"F 
"F 
Btuift' day 
"F 
"F 
Btuift' day 
"F 
"F 
Btuift? day 
"F 
"F 
Btuift' day 
"F 
"F 
Btu/ft2 day 
"F 
"F 
Btuift' day 
OF 
"F 
Btuift' day 
O F 
"F 
Btuift' day 
"F 
"F 
Btuift' day 
"F 
"F 
Btuift' day 
OF 
"F 
Btuift' day 
"F 
"F 
Btdft' day 
"F 
"F 
Btuift' day 
"F 
OF 
Btu/ft' day 
"F 
O F 
Btuift' day 
"F 
"F 
Btuift' day 
"F 
"F 
Btuift' day 
"F 
"F 
Btuift' day 
19.4 21.5 30.6 
459 677 980 
30.7 34.0 44.6 
15.5 17.5 26.1 
435 680 997 
46.6 52.2 61.0 
25.2 29.4 37.1 
801 1055 1400 
45.6 51.9 60.8 
24.8 29.5 37.7 
732 978 1306 
46.8 50.6 51.9 
35.4 37.1 36.9 
315 545 866 
44.3 50.4 54.5 
33.5 36.0 37.4 
310 554 895 
38.6 41.1 50.5 
23.8 25.0 33.1 
555 795 1108 
34.1 36.8 47.6 
19.2 20.7 29.4 
424 625 943 
36.4 37.7 45.5 
20.0 20.9 29.2 
506 739 1032 
56.2 59.5 67.1 
33.2 34.6 41.9 
762 1021 1355 
22.9 29.3 40.1 
1.9 8.9 20.6 
533 802 1152 
48.3 53.0 61.4 
30.9 34.1 41.9 
683 945 1278 
49.1 53.1 60.8 
21.7 26.1 32.0 
960 1244 1631 
66.5 69.9 76.1 
46.1 48.7 55.7 
898 1147 1430 
54.0 59.1 67.2 
33.9 37.8 44.9 
822 1071 1422 
61.9 65.7 72.1 
40.8 43.2 49.8 
772 1034 1297 
57.6 62.1 69.8 
29.7 33.3 40.2 
1081 1383 1839 
37.4 43.7 51.5 
19.7 24.4 29.9 
639 989 1454 
46.7 49.6 58.5 
26.5 28.1 35.8 
632 877 1210 
40.5 
1353 
59.1 
36.5 
1384 
71.7 
48.6 
1725 
72.4 
49.5 
1603 
55.5 
39.7 
1253 
60.2 
40.6 
1308 
63.2 
42.6 
1434 
60.7 
39.4 
1317 
57.5 
38.3 
1374 
77.0 
50.5 
1747 
58.1 
34.6 
1543 
72.9 
52.2 
1639 
71.0 
42.0 
2019 
82.1 
63.9 
1642 
76.8 
55.0 
I627 
79.0 
58.3 
1522 
78.8 
49.4 
2192 
61.1 
37.2 
1894 
70.6 
45.1 
1566 
50.2 
1647 
70.5 
46.6 
1717 
79.0 
57.7 
1918 
79.7 
58.5 
1822 
60.2 
44.1 
1608 
66.9 
46.4 
1663 
73.0 
52.5 
1660 
70.8 
48.5 
1602 
67.6 
47.6 
1655 
83.8 
59.1 
1895 
70.5 
45.7 
1894 
81 .O 
60.9 
1885 
79.1 
51.9 
2212 
86.7 
69.5 
1866 
84.4 
62.9 
1889 
85.1 
64.7 
1775 
86.0 
58.2 
2430 
72.4 
45.2 
2362 
77.9 
54.2 
1762 
59.0 
1813 
79.9 
56.0 
1878 
87.6 
66.3 
2144 
87.9 
67.5 
202 1 
63.9 
49.2 
1626 
72.7 
52.2 
177381.7 
61.5 
1811 
79.1 
57.1 
1762 
76.6 
57.0 
1776 
89.2 
66.1 
1947 
80.3 
56.3 
2100 
88.4 
68.9 
2045 
88.2 
61.5 
2393 
91.2 
74.1 
2094 
93.2 
70.8 
2135 
90.9 
70.2 
1898 
93.0 
66.6 
2562 
83.3 
53.3 
256 1 
84.8 
62.2 
1872 
63.2 
1755 
83.4 
60.2 
i 849 
93.5 
70.6 
2128 
93.9 
72.4 
203 1 
67.9 
52.2 
1746 
79.5 
55.8 
2037 
86.1 
66.8 
1758 
82.7 
61.3 
1689 
81.7 
63.3 
1695 
91.9 
70.1 
1842 
86.2 
61.8 
2150 
91.5 
72.6 
I972 
91.4 
66.2 
2281 
94.2 
75.6 
2186 
97.8 
74.7 
2122 
93.6 
72.5 
1828 
94.2 
69.2 
2389 
93.2 
61.8 
2590 
88.4 
67.2 
1774 
61.7 
1641 
81.8 
58.4 
1616 
92.8 
69.4 
1950 
93 .O 
70.3 
I865 
68.6 
52.6 
1499 
78.6 
55.8 
1674 
84.6 
66.0 
1575 
81.1 
60.1 
1510 
80.3 
61.9 
1499 
91 .O 
69.4 
I703 
83.9 
59.7 
1845 
90.3 
70.8 
1824 
89.6 
64.5 
2103 
94.1 
75.8 
1991 
97.3 
73.7 
1950 
93.1 
72. I 
1686 
93.1 
68.0 
22 IO 
90.0 
59.7 
2254 
87.1 
66.4 
1601 
54.6 
1282 
75. I 
51.2 
1276 
84.7 
61.9 
1554 
85 .O 
62.5 
1473 
67.8 
49.2 
1 I83 
74.2 
51.1 
1217 
77.8 
58.6 
1281 
74.8 
53.3 
1209 
73.1 
53.8 
1209 
85.5 
63.9 
1439 
73.5 
48.5 
1410 
84.3 
64.1 
1471 
82.4 
56.9 
1761 
90.1 
72.8 
1687 
89.7 
67.5 
1587 
88.7 
68.1 
1471 
86.4 
61.9 
1844 
80.0 
50.0 
1843 
81 .O 
59.3 
I348 
42.8 
945 
63.3 
40.1 
91 1 
74.3 
50.2 
1233 
74.9 
50.3 
I164 
61.4 
44.3 
713 
63.9 
44.6 
724 
66.5 
46.5 
959 
62.9 
42. I 
895 
63.2 
43.1 
907 
76.5 
50.3 
121 1 
62.1 
36.7 
1005 
74.5 
51.3 
1205 
72.7 
45.5 
I404 
83.9 
64.1 
i416 
79.5 
56.3 
1276 
81.9 
57.5 
1276 
77.7 
51.1 
1522 
66.7 
39.3 
1293 
70.5 
46.7 
1033 
33.5 
538 
47.9 
30.6 
498 
59.9 
37.6 
901 
60.2 
38.1 
827 
53.5 
39.7 
387 
52.3 
38.6 
388 
54.5 
37. I 
619 
49.8 
33.3 
505 
51.9 
34.8 
538 
67.1 
40.6 
92 1 
43.7 
22.3 
608 
61.4 
41.1 
817 
58.7 
32.1 
1033 
75.1 
54.9 
1043 
66.2 
44.9 
936 
71.6 
48.6 
924 
65.5 
39.0 
1176 
50.2 
29.2 
788 
60.5 
37.3 
733 
24.7 41.8 
387 1123 
35.5 58.8 
20.6 38.3 
355 1133 
50.7 71.2 
29.1 48.6 
725 1461 
50.3 71.3 
29.3 49.2 
659 1373 
48.8 58.1 
37.3 43.1 
261 1000 
46.4 62.0 
35.4 44.0 
260 1067 
43.0 63.4 
28.0 45.1 
470 1169 
38.4 59.9 
24.3 40.7 
347 1069 
40.5 59.3 
24.1 41.2 
419 1112 
58.8 75.3 
34.7 51.2 
722 1380 
29.3 56.7 
10.1 33.9 
441 1290 
52.3 71.6 
34.3 51.9 
629 1366 
51.8 70.7 
24.8 43.8 
872 1659 
69.3 81.6 
48.8 62.5 
845 1521 
58.1 76.9 
37.4 55.0 
780 1468 
65.2 79.1 
42.7 57.4 
730 1351 
59.7 77.0 
32.2 49.9 
1000 1802 
38.9 64.0 
21.6 39.3 
570 1603 
50.2 68.8 
29.6 46.5 
567 1248 
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B P I M P M S * 1 9 ~ 1 91 m 0732290 0518735 385 m 
14 CHAPTER 1 EVAPORATI TIVE Loss MEASUREMENT 
Table 4-Continued. 
Annual 
Location Symbol Units Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Average 
Property Monthly Averages 
Seattle, WA TAX “F 43.9 48.8 51.1 56.8 64.0 69.2 75.2 73.9 68.7 59.5 50.3 45.6 58.9 
(Sea-Tac Airport) TAN “F 34.3 36.8 37.2 40.5 46.0 51.1 54.3 54.3 51.2 45.3 39.3 36.3 43.9 
I Btdft’day 262 495 849 1294 1714 1802 2248 1616 1148 656 337 211 1053 
Charleston, WV TAX “F 41.8 45.4 55.4 67.3 76.0 82.5 85.2 84.2 78.7 67.7 55.6 45.9 65.5 
TAN “F 23.9 25.8 34.1 43.3 51.8 59.4 63.8 63.1 56.4 44.0 35.0 27.8 44.0 
I Btuift’day 498 707 1010 1356 1639 1776 1683 1514 1272 972 613 440 1123 
Huntington, WV TAX “F 41.1 45.0 55.2 67.2 75.7 82.6 85.6 84.4 78.7 67.6 55.2 45.2 65.3 
TAN O F 24.5 26.6 35.0 44.4 52.8 60.7 65.1 64.0 57.2 44.9 35.9 28.5 45.0 
I Btuift’day 526 757 1067 1448 1710 1844 1769 1580 1306 1004 638 467 1176 
Cheyenne, WY TAX “F 37.3 40.7 43.6 54.0 64.6 75.4 83.1 80.8 72.1 61.0 46.5 40.4 58.3 
TAN “F 14.8 17.9 20.6 29.6 39.7 48.5 54.6 52.8 43.7 34.0 23.1 18.2 33.1 
I Btdft’day 766 1068 1433 1771 1995 2258 2230 1966 1667 1242 823 671 1491 
Source: TAX and TAN taken from Reference [2], Section 19.1.1.2; I taken from Reference [3], Section 19.1.1.2. 
Where: 
Tu = daily average ambient temperature, in degrees 
TM = daily maximum ambient temperature, in degrees 
TAN = daily minimum ambient temperature, in degrees 
AT, = daily ambient temperature range, in degrees 
Rankine. 
Rankine. 
Rankine. 
Rankine. 
19.1.2.2.2.3 Tank Paint Solar Absorptance, CY 
The tank outside surface paint solar absorptance, a, is 
a function of the tank paint color, paint shade or type, 
and paint condition. Table 5 lists the solar absorptance 
for selected tank paints. Section E of the Documentation 
File contains additional solar absorptance values for a 
variety of paint colors. 
If specific information is not available on the tank 
paint color and paint condition, a white shell and roof, 
with the paint in good condition, can be assumed to 
represent the most common or typical tank paint in use. 
If the tank roof and shell are painted a different color, 
Table 5-Solar Absorptance (CY) for 
Selected Tank Paints 
Paint Color 
Aluminum 
Aluminum 
Gray 
Gray 
Red 
White 
Paint Shade 
Or 5 p e 
Specular 
Diffuse 
Light 
Medium 
Primer 
- 
~ 
Solar Absorptance, (a) (dimensionless) 
Paint Condition 
Good Poor 
0.39 0.49 
0.60 0.68 
0.54 0.63 
0.68 0.74 
0.89 0.91 
O. i7 0.34 
Note: If specific information is not available, a white shell and roof, with 
the paint in good condition, can be assumed to represent the most common 
or typical tank paint in use. 
Equation 20 may be used to determine the tank paint 
solar absorptance, cy. 
&R -b (YS 
2 
a = 
Where: 
a 
aR 
cys 
= tank paint solar absorptance (dimensionless). 
= tank roof paint solar absorptance (dimension- 
= tank shell paint solar absorptance (dimension- 
less). 
less). 
19.1.2.2.2.4 Liquid Bulk Temperature, TB 
The liquid bulk temperature, TB, is the average tem- 
perature of the liquid stock in the storage tank. This 
information is usually available from tank gaging records 
or other tank operating records. The liquid bulk tempera- 
ture is used to estimate the daily average liquid surface 
temperature, Tu (see 19.1.2.2.2.5). 
If the liquid bulk temperature is not available, it may 
be estimated from Equation 2 1 : 
(21) TB = TM + 6a - 1 
Where: 
TB = liquid bulk temperature, in degrees Rankine. 
TM = daily average ambient temperature, in degrees 
a = tank paint solar absorptance (dimensionless). 
Rankine. 
19.1.2.2.2.5 Daily Average Liquid Surface 
Temperature, Tu 
The daily average liquid surface temperature, Tu, is 
used to calculate the stock vapor pressure at the daily 
average liquid surface temperature, PvA. 
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A P I MPNS*LS.L 71 W 0732270 05Lô736 2LL 
SECTION 1 -EVAPORATIVE Loss FROM FIXED-ROOF TANKS 15 
If actual daily average liquid surface temperature data 
for the tank is not available, this temperature can be 
estimated from Equation 22: 
TU = 0.44TM + 0.56TB + 0.0079aZ (22) 
Where: 
Tu = daily average liquid surface temperature, in 
TM = daily average ambient temperature, in degrees 
TB = liquid bulk temperature, in degrees Rankine. 
(Y = tank paint solar absorptance (dimensionless). 
I = daily total solar insolation on a horizontal 
surface, in British thermal units per square 
foot day. 
19.1.2.2.2.6 Daily Vapor Temperature Range, ATv 
The daily vapor temperature range, ATv, may be 
estimated from Equation 23: 
degrees Rankine. 
Rankine. 
AT" = 0.72 ATA + 0.028d (23) 
Where: 
ATv = daily vapor temperature range, in degrees 
Rankine. 
ATA = daily ambient temperature range, in degrees 
Rankine. 
I = daily total solar insolation on a horizontal 
surface, in British thermal units per square 
foot day. 
= tank paint solar absorptance (dimensionless). 
19.1.2.2.2.7 Daily Maximum and Minimum Liquid 
Surface Temperatures, i, TLN 
The daily maximumand minimum liquid surface tem- 
peratures, TM and TLN, respectively, are used for cal- 
culating the stock vapor pressures Pm and PvN. 
(Y 
If data on these liquid surface temperatures are not avail- 
able, they may be estimated from Equations 24 and 25: 
Tu = Tu + 0.25 ATv (24) 
TM = T u - 0.25 AT" (25) 
Where: 
Tu = daily maximum liquid surface temperature, in 
Tu = daily average liquid surface temperature, in 
Tu = daily minimum liquid surface temperature, in 
ATv = daily vapor temperature range, in degrees 
degrees Rankine. 
degrees Rankine. 
degrees Rankine. 
Rankine. 
19.1.2.2.2.8 Vapor Molecular Weight, Mv 
The stock vapor molecular weight, M v , can be deter- 
mined by analysis of vapor samples or by calculation 
from the composition of the liquid. 
19.1.2.2.2.8.1 Petroleum Liquid Stocks 
The vapor molecular weight of selected petroleum 
liquids (multicomponent stocks) is given in Table 6 . 
19.1.2.2.2.8.1.1 Refined Petroleum Stocks 
In the absence of specific information, a typical value 
of 64 pounds per pound-mole can be assumed for 
gasoline. 
19.1.2.2.2.8.1.2 Crude Oil Stocks 
In the absence of specific information, a typical value 
of 50 pounds per pound-mole can be assumed for U. S . 
midcontinent crude oils (including both reactive and 
Table 6-Properties (Aßv, Wvc, Pv, A, B) of Selected Petroleum Liquids 
Condensed 
Vapor Vapor Density Vapor Pressurea Vapor Equation Temperature Range 
Molecular Weight (at 60°F) (at 60°F) Constantsb For Constants A and B 
Minimum Maximum 
( O F ) ("FI 
A B MV wvc pv Petroleum Liquid (Ibilb-mole) (Ib/gal) (psia) (Dimensionless) ("R) 
C C - 
C c - 
- Refined petroleum stocks - - - 
Cnide oil stocks - 
Jet naphtha (JP-4) 80 5.4 1.27 11.368 5,784.3 40 100 
Jet kerosene i 30 6.1 0.00823 12.390 8,933.0 40 100 
Distillate fuel oil no. 2 130 6.1 0.00648 12.101 8,907.0 40 100 
Residual oil no. 6 190 6.4 0.0000430 10.104 10,475.5 40 100 
- - - 
a Vapor pressure calculated at 60°F using constants A and B . 
The vapor pressure equation is Pv = exp[A - @ / T L ) ] , where Pv is the vapor pressure in psia, TL is the liquid surface temperature in OR, and exp is the 
exponential function. 
C The vapor pressure equation constants A and B are listed in Equations 29 and 30 for refined petroleum stocks, and Equations 32 and 33 for cmde oil 
stocks. These constants are from Reference [4]. 
Sources: The vapor pressure equation constants A and B were developed from a correlation of the vapor pressures given in Reference [ 5 ] (except as indicated 
in Note b). The other properties are also from Reference [ 5 ] . 
a 
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16 CHAPTER 1 EVAPORATI TIVE Loss MEASUREMENT 
nonreactive fractions). Since a large variability in vapor 
molecular weights has been observed in foreign crude 
oils, no average value has been developed for these 
stocks. 
19.1.2.2.2.8.2 Petrochemical Stocks 
For single-component petrochemical stocks, the molecu- 
lar weight of the vapor is equal to the molecular weight 
of the liquid, which is given in Table 7 for selected 
petrochemicals. 
19.1.2.2.2.9 Daily Maximum, Average, and Minimum 
Vapor Pressures, Pw, PvA, PvN 
The stock vapor pressure must be determined at three 
differed temperatures: 
a. The daily maximum liquid surface temperature, Tu. 
b. The daily average liquid surface temperature, TLA. 
c. The daily minimum liquid surface temperature, TLN. 
These three liquid surface temperatures are discussed in 
19.1.2.2.2.5 and 19.1.2.2.2.7. The corresponding three 
stock vaporpressures, Pvx, PvA, and PvN, can be calculated 
from Equations 26, 27, and 28, respectively: 
Where: 
P, = stock vapor pressure at the daily maximum 
liquid surface temperature, in pounds per 
square inch absolute. 
PvA = stock vapor pressure at the daily average liquid 
surface temperature, in pounds per square inch 
absolute. 
PvN = stock vapor pressure at the daily minimum 
liquid surface temperature, in pounds per 
square inch absolute. 
Tu = daily maximum liquid surface temperature, in 
degrees Rankine. 
Tu = daily average liquid surface temperature, in 
degrees Rankine. 
TLN = daily minimum liquid surface temperature, in 
degrees Rankine. 
A = constant in the vapor pressure equation 
(dimensionless). 
B 
exp = exponential function. 
= constant in the vapor pressure equation, in 
degrees Rankine. 
19.1.2.2.2.9.1 Petroleum Liquid Stocks 
For selected petroleum liquid stocks, the stock vapor 
pressure may be calculated from Equations 26, 27, and 
28, where the constants A and B are listed in Table 6. 
19.1.2.2.2.9.1.1 Refined Petroleum Stocks 
For refined petroleum stocks, the stock vapor pressure 
may be determined from Figure 5 or calculated from 
Equations 26, 27, and 28. For refined petroleum stocks, 
the constants A and B are functions of both the Reid 
vapor pressure, RVP, and the ASTM Distillation Slope, 
S . The constants A and B can be determined from Fig- 
ures 3 and 4 or calculated from Equations 29 and 30, 
respectively: 
A = 15.64 - 1.854SO.’ - 
(0.8742 - 0.3280 So.’) ln(RVP) (29) 
B = 8742 - 1042 So.’ - 
(1049 - 179.4 So.’) ln(RVP) (30) 
RVP = stock Reid vapor pressure, in pounds per 
square inch. 
S = stock ASTM-D86- Distillation of Petroleum 
Products distillation slope at 10 volume per- 
cent evaporated, in degrees Fahrenheit per 
volume percent. 
Where: 
In = natural logarithm function. 
The slope, S , is the slope of the ASTM-D86 distilla- 
tion data at 10 volume percent evaporated and can be 
calculated from the distillation data using Equation 3 1 : 
T1.5 - T.5 
10 
S = 
Where: 
S = stock ASTM-D86 distillation slope at 10 vol- 
ume percent evaporated, in degrees Fahrenheit 
per volume percent. 
T5 = temperature at which 5 volume percent is 
evaporated, in degrees Fahrenheit. 
TI , = temperature at which 15 volume percent is 
evaporated, in degrees Fahrenheit. 
The constant, 10, in Equation 31 has units of volume 
percent. 
In the absence of ASTM-D86 distillation data on 
refined petroleum stocks, approximate values of the 
distillation slope, S , from Table 8 may be used. 
COPYRIGHT American Petroleum Institute
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COPYRIGHT American Petroleum Institute
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API f lPf lS*LS-L 9 3 0732290 0538738 094 
SECTION 1 -EVAPORATIVE LOSS FROM FIXED-ROOF TANKS 17 
T 
C 
c 
o o o o o o c 
r 4 - m - o m v 
m m m - o - d m 
96.19 
I l I I I 
. - * W O N 
r - v i d d N 
m o m d r 
m m m - - 
9991- d w w m c 
r - m m m z 
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A P I MPMS*LS.L 91 0732290 0538739 T20 H 
18 CHAPTER 1 E EVAPORA TIVE Loss MEASUREMENT 
gl 
E = - .E E' 
.* L 
c O- 
E 
a m 
mi-1000 - N o m o m m o - m m - % z z o 8 g 
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SECTION 1 -EVAPORATIVE LOSS FROM FIXED-ROOF TANKS 19 
\ .- 
I l I I I I I l 
- ASTM D86 distillation slooe at 
’c- I I I t 1 O volume percent evaporated S (“F/VO~.~/O) . L. .. 
o. 1 0.2 0.4 0.6 0.8 1 2 4 6 8 1 0 20 
Reid vapor pressure, RVP (psi) 
Figure 3-Vapor Pressure Function Coefficient (A) of Refined Petroleum Stocks 
With a Reid Vapor Pressure of 1 to 20 psi, Extrapolated to 0.1 psi 
o. 1 0.2 0.4 0.6 0.8 1 2 4 6 8 1 0 20 
Reid vapor pressure, RVP (psi) 
Figure 4-Vapor Pressure Function Coefficient (B) of Refined Petroleum Stocks 
With a Reid Vapor Pressure of 1 to 20 psi, Extrapolated to 0.1 psi 
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A P I MPMS*LS=L 71 = 0732290 05L874L