⛽ Total contamination in diesel fuels and middle distillates — membrane filtration

Petrochemistry PN-EN 12662-1

Overview

The standard specifies a method of determining the total contamination as the content of undissolved substances in middle distillates and diesel fuels containing up to 30 % (V/V) of fatty acid methyl esters (FAME). Excessive contamination of the fuel system causes the premature blocking of filters and breakdowns, and for that reason the determination of undissolved substances is a way of keeping that problem under control. The 2024 edition replaced EN 12662:2014 and divided the scope into two parts: part 1 covers middle distillates and diesel fuels with up to 30 % (V/V) of FAME, and part 2 (a separate standard) pure FAME — because the changes introduced in 2014 caused laboratories difficulties in testing FAME and in correlating the results with the previous version; the precision data were also updated after a new statistical analysis according to EN ISO 4259-1 (without FAME samples).

According to the earlier edition (EN 12662:2014) the method applies to contamination contents from about 12 mg/kg to about 30 mg/kg and to products with a kinematic viscosity not exceeding 8 mm²/s at 20 °C or 5 mm²/s at 40 °C (for example diesel fuel according to EN 590); for products of higher viscosity a separate procedure is provided. The total contamination is the undissolved substances retained on the filter after filtration under the conditions of the test.

In Polish practice the test is routine for diesel and heating oils (accredited laboratories give a range of 1–30 mg/kg by the gravimetric method), and the Oil and Gas Institute uses it among other things in studies of the stability of B10 fuels during storage. According to the requirements of PN-EN 590, diesel fuel should not contain more than 24 mg/kg of solid contaminants.

Method principle

A test portion of the sample of 800 ml volume is weighed and filtered with the use of vacuum through a previously weighed membrane filter. The filter with the residue is washed, dried and weighed, and the contamination content is calculated from the difference of the masses of the filters and referred to the mass of the sample in mg/kg. The standard specifies the cleaning of the sample containers and of the filtration assembly, the preparation of the test portion (separately for middle distillates and diesel fuels and for products of a viscosity above 8 mm²/s at 20 °C or 5 mm²/s at 40 °C), the preparation of the filtration assembly and of the filter, and the calculations and the expression of the results.

Applications

• Quality control of diesel fuel according to PN-EN 590 (the limit of 24 mg/kg) and of heating oils
• Testing of B7–B30 fuels with FAME (up to 30 % V/V)
• Assessment of the cleanliness of fuel after storage and in distribution (the blocking of filters)
• Monitoring of the quality of fuels at filling stations (the Trade Inspection, the regulation on the methods of testing the quality of liquid fuels)

Key parameters

Standard

Standard number

PN-EN 12662-1:2024-11

Title (PL)

Ciekłe przetwory naftowe — Oznaczanie całkowitej zawartości zanieczyszczeń — Część 1: Średnie destylaty i oleje napędowe

Title (EN)

Liquid petroleum products — Determination of total contamination — Part 1: Middle distillates and diesel fuels

Step-by-step procedure

1. Sampling

   Take the sample according to EN ISO 3170, EN ISO 3171 or — at a filling station — EN 14275, into a container cleaned in accordance with clause 7 of the standard.

2. Preparation of the filter

   Wash the membrane filter, dry it, cool it in a desiccator and weigh it (clause 10.2).

3. Preparation of the test portion

   Prepare a test portion of 800 ml (for middle distillates and diesel fuels according to 9.2; for products of a viscosity > 8 mm²/s at 20 °C or > 5 mm²/s at 40 °C according to 9.3) and weigh it.

4. Filtration

   Filter the test portion under vacuum through the weighed membrane filter in the prepared filtration assembly (10.1, clause 11).

5. Washing and drying

   Wash the filter with the residue with solvent, dry it and cool it in a desiccator.

6. Weighing and calculation

   Weigh the filter with the residue; calculate the contamination content from the difference of the masses of the filters and the mass of the sample and express it in mg/kg (clauses 12–13).

7. Test report

   Give the result in mg/kg with a reference to PN-EN 12662-1, the identification of the sample and any departures; compare it with the requirement of PN-EN 590 (≤ 24 mg/kg).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Diesel fuel and the washing solvents — work in a fume hood, nitrile gloves, no sources of ignition
• Filtration under vacuum — a filter flask resistant to reduced pressure, a shield
• Dispose of the filters after the test and the washings as petroleum waste

Frequently asked questions