⛽ Total contamination in diesel fuel
Determination of total contamination (insoluble matter) in diesel fuel by gravity filtration through a membrane. Critical quality parameter for fuels.
Overview
Total contamination in diesel fuel is the total content of solid particles insoluble in the fuel, expressed in mg/kg. This parameter is crucial for the proper operation of injection systems in high-pressure diesel engines, especially modern common rail systems, where tolerances between working elements of injectors are on the order of a few micrometers.
The PN-EN 12662 standard defines a method of filtering a fuel sample (800 mL) through a pre-weighed filter membrane with 0.8 µm porosity. After filtration, the membrane is rinsed with heptane to remove residual oil, dried, and weighed again. The difference in membrane mass represents the contamination content. The method is applicable to middle distillates, diesel fuels with up to 30% (V/V) FAME addition, and pure methyl esters.
Quality requirements for diesel fuel according to PN-EN 590 specify a maximum total contamination level of 24 mg/kg. Exceeding this value can lead to clogging of fuel filters, accelerated wear of pumps and injectors, and failure of the engine fuel supply system. In the era of biofuel components (B7, B10, B20), monitoring this parameter is especially important because FAME tends to form deposits and increase contamination.
The working range of the method is from 12 to 26 mg/kg, established based on international studies according to EN ISO 4259-1. The method is applicable to products with kinematic viscosity not exceeding 8 mm²/s at 20°C or 5 mm²/s at 40°C.
Method principle
The method consists of filtering a measured volume of fuel sample (800 mL) through a previously dried and weighed filter membrane with nominal porosity of 0.8 µm, using vacuum created by a vacuum pump. Insoluble matter is retained on the membrane surface. After filtration is complete, the membrane is rinsed with solvent (heptane) to remove adsorbed oil, then dried in an oven and weighed on an analytical balance. The difference in membrane mass before and after filtration, related to the mass of the filtered sample, constitutes the result of total contamination determination expressed in mg/kg.
Applications
- Quality control of diesel fuel according to PN-EN 590 (max 24 mg/kg)
- Testing fuels with FAME biocomponents (B7, B10, B20, B100)
- Monitoring fuel purity in the logistics chain (refinery-terminal-station)
- Control of storage impact on fuel quality
- Evaluation of filtration system efficiency in fuel installations
- Quality complaints and commercial disputes regarding fuels
- Type testing and homologation testing of fuels
Key parameters
| Parameter | Value |
|---|---|
| Working range | 12–26 mg/kg (according to international validation) |
| Sample volume | 800 mL |
| Membrane porosity | 0.8 µm |
| Limit per PN-EN 590 | max 24 mg/kg |
| Precision (repeatability) | r = 5.2 mg/kg (at 24 mg/kg level) |
| Precision (reproducibility) | R = 11.8 mg/kg (at 24 mg/kg level) |
Standard
- Standard number
- PN-EN 12662:2014
- Title (PL)
- Ciekle przetwory naftowe — Oznaczanie zanieczyszczenia ogolnego destylatow srednich, olejow napedowych i estrow metylowych kwasow tluszczowych
- Title (EN)
- Liquid petroleum products — Determination of total contamination in middle distillates, diesel fuels and fatty acid methyl esters
Step-by-step procedure
1. Membrane preparation
Rinse membrane with heptane, dry in oven (105°C, 30 min), cool in desiccator to room temperature. Weigh with 0.1 mg accuracy.
2. Assembly of filtration set
Place membrane on fritted funnel, attach funnel to suction flask. Connect vacuum pump. Check connections for leaks.
3. Sample preparation
Thoroughly mix fuel sample by inverting container. Measure 800 mL with graduated cylinder.
4. Sample filtration
Turn on vacuum pump. Slowly pour sample onto membrane, maintaining constant liquid level above membrane. Filter entire 800 mL.
5. Membrane rinsing
After filtering entire sample, rinse membrane 3 × 20 mL with heptane to remove adsorbed oil. Continue suction until solvent is removed.
6. Membrane drying
Remove membrane from funnel with tweezers, place in oven (105°C, 30 min). Cool in desiccator to room temperature (min. 30 min).
7. Membrane weighing
Weigh membrane on analytical balance with 0.1 mg accuracy. Record final mass.
8. Result calculation
Contamination [mg/kg] = (m2 - m1) × 1000 / (V × d), where m2 = final mass, m1 = initial mass of membrane [mg], V = sample volume [mL], d = sample density [g/mL].
9. Quality control
Perform blank test (filtration of heptane through membrane). Membrane mass difference should not exceed 0.3 mg.
10. Recording and reporting
Record result in mg/kg with accuracy to 1 mg/kg. Compare with PN-EN 590 limit (max 24 mg/kg). Include data on sample temperature and density.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Vacuum filtration set | Millipore, Sartorius, Pall — suction flask, fritted funnel | 2,000–5,000 PLN |
| Vacuum pump | KNF Laboport N 810, Vacuubrand ME 1C | 3,000–8,000 PLN |
| Filter membranes 0.8 µm | Millipore AAWP, Sartorius (diameter 47 mm, cellulose) | 150–400 PLN / 100 pcs |
| Analytical balance (d = 0.1 mg) | Mettler Toledo XPR205, Sartorius Secura 225D | 8,000–25,000 PLN |
| Laboratory oven | Binder FD 56, POL-EKO SLW 32, Memmert UF 30 | 4,000–12,000 PLN |
| Graduated cylinder 1000 mL | DURAN class A, borosilicate glass | 80–200 PLN |
| Desiccator with desiccant | Glass desiccator 200 mm + silica gel | 300–800 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| n-Heptane (purity min. 99%) | 142-82-5 | Solvent for rinsing membrane after filtration, analytical grade, 1–2.5 L per determination |
| Acetone | 67-64-1 | For preliminary rinsing of apparatus, purity min. 99% |
| Toluene | 108-88-3 | Alternative solvent for rinsing, purity min. 99% |
Health and safety (OHS)
- n-Heptane — flammable (R11), use away from ignition sources, work under fume hood
- Toluene — toxic by inhalation (R20), use only under fume hood
- Acetone — flammable, may cause eye irritation
- Diesel fuel — harmful, avoid skin contact, use nitrile gloves
- Vacuum pump — risk of solvent vapor explosion, ensure ventilation