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How can I change the number of decimals (rounding) of my VCF / CTL ?

The Volume Correction Factor (VCF), also known as Correction for the effect of Temperature on Liquid (CTL), is defined in various measurement standards – whereby product specific standards and historical versions need to be considered. Therein, the calculation procedure and the number of decimals, to which the VCF shall be rounded, are specified.

Historically, volume correction factors have been defined as printed table values. Starting with ASTM D1250-80, implementation procedures for software programs became the primary standard, not the printed tables any more.

Examples: Printed tables print the VCF with 3 or 4 decimals (e.g. ASTM D1250-52 prints 4 decimals, ASTM D1250-80 Table 34 (LPG) prints 3 decimals, ASTM D1250-80 (Crude oil & products) prints 4 decimals, also defines calculation and rounding to 4 decimals (*), GPA 8217 / TP-27 defines calculation and rounding to 5 decimals, ASTM D1250-04 defines calculation and rounding to 5 decimals – and with the latest Addendum 2 to ASTM D1250-19, application of a non-rounded VCF/CTL is required.

Thus, you typically cannot change the number of decimals of the VCF for a given standard.


(*) There is one major exception: ASTM D1250-80 implementations (for crude oil and products) allow either 4 decimal rounding (consistently for all temperatures), as with the printed tables, or a 5 decimal rounding for temperatures above the standard reference temperature (60 °F, 15 °C or 20 °C)). Thus, in the conversion group configuration you may select either 4 or 5 decimal rounding for such conversion groups, which determines the actual VCF rounding after VCF calculation:

Note: For Asphalt (ASTM D4311) conversion groups and DIN 51757 X Table conversion groups , this setting also selects a 4 or 5 decimal rounding after VCF calculation.

For all other conversion groups, this setting has no effect.

For all other measurement standards (products and versions), the number of decimals for the VCF is fixed as defined in the respective standard.

For some of the MQCI template conversion groups, this fixed definition is implemented/secured and extended to alternate VCF via a dedicated MQCI model function:


IMPORTANT: With ASTM D1250-19, Addendum 2, the rounding of the VCF has been removed and a non-rounded VCF shall be utilized for the calculations; thus you are able to disable the VCF rounding for conversion groups that are configured to utilize ASTM D1250-04 implementations:

Note: If you decide to disregard the measurement standard VCF rounding definition for ASTM D1250-04 conversion groups, you may do so by first defining a 4 decimal rounding, save your settings and then disable the rounding:

Then, you may assign the 4 decimal rounding function to your MQCI function module sequence:

IMPORTANT: Such a configuration change should only be performed by certified BCP consultants. Also, since such a configuration change is not supported by ASTM D1250-04/19, customers must be made aware of that fact. A requirement for 4 decimals VCF is typically an indicator that ASTM D1250-80 calculations are required, not ASTM D1250-04.

Categories: BCP Configuration FAQs | Oil & Gas Quantity Conversion Basics FAQs

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