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# Quantity Conversion

Quantity conversions are calculations which convert a given bulk product quantity value to another quantity value, where the two quantities involved are different.

#### Details – Oil and gas quantity conversions:

##### Converting a gross volume quantity value of crude oil to a net standard weight quantity value of crude oil:

An oil tank is measured via tank dipping to contain 10 640.6 barrels at 95 °F (gross observed volume – GOV) of crude oil. What is the net standard weight (NSW) in long tons of the crude oil in the tank?

This is not a straightforward calculation:

To determine the net standard weight, we require the crude oil density (in air and in vacuum), potentially a sediment and water correction factor and a correction factor for the effect of temperature (and pressure) on the liquid product (CT(P)L) and unit conversion factors.

Quantity conversions of crude oil and products (including  LPG) thus require four distinct kinds of petroleum measurement standards:

• Unit conversion standards
• Standards that define the CT(P)L factors
• Standards that define the mass-to-weight conversion
• Standards that define the right sequence (and rounding) for the conversion calculation steps – the calculation model

For each of these four kinds of standards, a variety of measurement standards (including historical versions and national versions) is available, which, when combined, explain why quantity conversions are complex.

##### Converting an observed volume quantity value of natural gas to a superior standard energy quantity value of natural gas:

For a pipeline transmission of a dry natural gas batch the volume quantity value is measured via orifice metering to be 1 450 809 ft³ at 45 °F and 505 PSI (average temperature and pressure values). What is the superior standard energy value at 60 °F (and 14.696 PSI) combustion reference temperature?

This is not a straightforward calculation:

To determine the superior energy, we require the compression factor of the gas at observed and reference conditions, UoM conversion factors, the heating value of the gas at reference conditions and the chemical composition of the gas.

Quantity conversions of natural gas and LNG also require four distinct kinds of gas measurement standards:

• Unit conversion standards
• Standards that define the calculation of compression factors
• Standards that define the right sequence (and rounding) for the conversion calculation steps – the calculation model

Natural gas and LNG quantity conversions do not require mass-to-weight conversions but an additional type of gas measurement standards:

• Standards defining calculations of densities and heating values from chemical composition of the natural gas (and LNG), including physical property data management