Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
API MPMS 11.1.13 (1980 scan): Historical Standard for Combined Temperature and Pressure Correction of Petroleum Liquid Densities
A Technical Overview of the 1980 Edition of the API Manual of Petroleum Measurement Standards Chapter 11.1.13 for Combined Volume Correction Factors
API Manual of Petroleum Measurement Standards (MPMS) Chapter 11.1.13, published in the 1980 edition, provides a unified methodology for correcting measured volumes and densities of liquid petroleum to standard reference conditions by simultaneously accounting for both temperature and pressure effects. This historical standard remains a key reference for understanding the evolution of combined correction factors (CCF) used in custody transfer, inventory reconciliation, and process engineering.
Scope of API MPMS 11.1.13 (1980)
The standard defines the Combined Correction Factor (CCF) to convert observed volumes and densities at service conditions to standard conditions of 60 °F and 14.696 psia. It applies to three principal categories of liquid petroleum:
- Generalized Crude Oils – across a wide range of API gravities (typically 10°–50° API).
- Refined Products – including gasolines, kerosenes, diesel fuels, and fuel oils.
- Lubricating Oils – covering both automotive and industrial grades.
The 1980 edition replaced earlier separate temperature-only and pressure-only correction tables with a single integrated factor, improving calculation efficiency and reducing interpolation errors for scenarios where both temperature and pressure depart significantly from standard conditions.
Technical Requirements for Combined Correction Factors
Reference Conditions
All corrections refer to a base temperature of 60 °F (15.56 °C) and a base pressure of 14.696 psia (101.325 kPa). The user must first determine the base density (or API gravity) of the liquid at these reference conditions.
Empirical Coefficients
The standard provides tables of thermal expansion coefficients (α) and isothermal compressibility coefficients (γ) as functions of base density and product category. These coefficients are derived from experimental data sets representing typical petroleum fluids. Table 1 illustrates the typical value ranges found in the 1980 edition.
| Product Category | Density Range (lb/gal) | Thermal Expansion α1 (×10⁻⁶ / °F) | Isothermal Compressibility γ2 (×10⁻⁶ / psi) |
|---|---|---|---|
| Generalized Crude Oils | 6.5 – 8.5 | 400 – 600 | 3.0 – 5.5 |
| Refined Products (light fractions) | 5.8 – 6.5 | 650 – 750 | 6.0 – 8.0 |
| Lubricating Oils | 7.0 – 9.0 | 350 – 500 | 2.5 – 4.0 |
1 Coefficient of thermal expansion at 60 °F. 2 Isothermal compressibility at 60 °F.
Calculation Procedure
The Combined Correction Factor (CCF) is computed from a polynomial expansion of temperature and pressure deviations:
CCF = exp[ −α (T − 60) + γ (P − 14.696) + Q(T,P) ]
where Q(T,P) represents cross‑terms and a small correction for non‑linearities. The standard includes specific equation forms for each product category, which may require iteration for the most accurate results. The observed volume is then multiplied by the CCF to yield volume at standard conditions.
Implementation and Compliance Highlights
Implementation Tip: When applying the 1980 factors, always match the base density (or API gravity) to the exact product category. Small deviations in density can lead to significant errors in the combined correction, especially near the boundaries of the table.
Caution: The 1980 edition does not cover modern products such as biodiesel blends, highly paraffinic or waxy crudes, or liquids with vapour pressures near the temperature range. Extrapolation beyond the stated density and temperature limits is not recommended.
Historical Value: The 1980 edition is an important historical reference. Reproducing its coefficients for legacy databases or for auditing older custody transfer records remains a valid practice when recommended by the mutual agreement of parties.
Compliance Note: For new custody transfer installations or regulatory reporting, refer to the latest edition of API MPMS Chapter 11.1 (current versions of 11.1.1 and 11.1.4 supersede the combined table approach of the 1980 11.1.13). Using an outdated standard may result in measurement inaccuracies and non‑compliance.
Software and Legacy Data
Many measurement calculators developed in the 1980s and 1990s implemented the formulas from this edition. When legacy software is still in use, validation against the original scanned tables is recommended. Modern implementations typically rely on API’s Compressibility and Thermal Expansion Calculation Program (CTEC) which reflects the latest correlations.
Frequently Asked Questions
Q: What is the difference between API MPMS 11.1.13 (1980) and Chapter 11.1.1?
A: Chapter 11.1.1 provides temperature-only volume correction factors (VCF) without pressure influence. Chapter 11.1.13 integrates both temperature and pressure into a single Combined Correction Factor, making it more suitable for high‑pressure systems or when significant temperature deviations coexist with pressure variation.
A: Chapter 11.1.1 provides temperature-only volume correction factors (VCF) without pressure influence. Chapter 11.1.13 integrates both temperature and pressure into a single Combined Correction Factor, making it more suitable for high‑pressure systems or when significant temperature deviations coexist with pressure variation.
Q: Is the 1980 edition of API MPMS 11.1.13 still accepted for custody transfer?
A: Generally, no. The 1980 edition has been superseded by later revisions (e.g., 2003, 2012, 2020). Unless specified in a contractual agreement, current editions or the use of separate temperature and pressure correction factors from the latest API MPMS chapters should be applied.
A: Generally, no. The 1980 edition has been superseded by later revisions (e.g., 2003, 2012, 2020). Unless specified in a contractual agreement, current editions or the use of separate temperature and pressure correction factors from the latest API MPMS chapters should be applied.
Q: Which product groups are covered by this standard?
A: The standard covers three broad categories: generalized crude oils (across a wide API gravity range), refined products (including gasoline, kerosene, diesel, and fuel oils), and lubricating oils. Each category has its own set of expansion and compressibility coefficients.
A: The standard covers three broad categories: generalized crude oils (across a wide API gravity range), refined products (including gasoline, kerosene, diesel, and fuel oils), and lubricating oils. Each category has its own set of expansion and compressibility coefficients.
Q: Why does the 1980 edition still matter?
A: Many older pipeline and refinery measurement systems, custody transfer records, and historical data sets depend on this edition. Understanding its coefficients and limitations is essential for accurate data reconciliation and for ensuring compatibility with legacy storage tanks and meters.
A: Many older pipeline and refinery measurement systems, custody transfer records, and historical data sets depend on this edition. Understanding its coefficients and limitations is essential for accurate data reconciliation and for ensuring compatibility with legacy storage tanks and meters.
Article prepared for technical reference purposes. The information presented reflects the content of the scanned 1980 edition of API MPMS 11.1.13. Always consult the official API publication for definitive requirements.
Last updated: 2026.