API MPMS Chapter 3.1A (R2018)

This standard describes the following:

a) the procedures for manually gauging the liquid level of petroleum and petroleum products in nonpressure fixed-roof, floating-roof tanks and marine tank vessels;
b) procedures for manually gauging the level of free water that may be found with the petroleum or petroleum products;
c) methods used to verify the length of gauge tapes under field conditions and the influence of bob weights and temperature on the gauge tape length; and
d) influences that may affect the position of gauging reference point (either the datum plate or the reference gauge point).

Throughout this standard the term petroleum will be used to denote petroleum, petroleum products, or the liquids normally associated with the petroleum industry.

This standard is applicable for gauging quantities of liquids having Reid vapor pressures less than 103 kPa (15 psia).

The method used to determine the volume of tank contents from gauge readings is not covered in this standard.

The determination of temperature, density, API gravity, and suspended sediment and water of the tank contents are not within the scope of this standard; however, methods used for these determinations may be found in the API Manual of Petroleum Measurement Standards (MPMS).