At receipt, the density at 15 °C of the product must be within ±3.0 kg/m³ of the density at 15 °C printed on the invoice. MDG 2024 clause 1.2 (iv) sets the limit and names ASTM Table 53B as the way to find the density at 15 °C.
The rule
MDG 2024, clause 1.2 (iv): the dealer is to check “that the Density of product @ 15°C using ASTM Tables (53B) is within +/- 3.0 Kg/M3 as compared with the Invoice density for ascertaining quality of product.”
How to check it
- Drain about 20 litres from the manifold of each compartment into a clear glass container.
- Read the hydrometer and the temperature for each compartment.
- Convert each to density at 15 °C with Table 53B.
- Compare each with the invoice density. Allowed: −3.0 to +3.0 kg/m³.
- Record each compartment in the register.
The density variation calculator does steps 3 and 4.
Example
Invoice density at 15 °C: 745.6. Your reading: 737.5 at 27 °C. Table 53B gives 748.2 at 15 °C. Difference: +2.6 kg/m³. Within the limit.
If it fails
- Do not decant.
- Take a fresh sample and repeat. Check the hydrometer is the right range and the thermometer reads true.
- If it still fails, contact the supply location or your area officer, as clause 1.2 (ix) says, and keep the samples.
Figures here are for reference. Your oil company’s certified calibration chart, approved instruments and the Marketing Discipline Guidelines always prevail.
Questions
Is the ±3 kg/m³ on the hydrometer reading?
No. It is on the density at 15 °C. Convert your reading with Table 53B first. The raw reading can be 10 kg/m³ or more away from the invoice on a hot day and still be right.
Is there a limit between the morning density and the last load?
The MDG does not set one in clause 1.2, but inspectors compare the density in your tank with the reference density in your register. Large unexplained changes invite questions.