⛽ Fuel lubricity HFRR
In short
Assessment of diesel fuel lubricity properties using HFRR (High Frequency Reciprocating Rig) apparatus by measuring wear scar diameter on steel ball. The test is performed according to PN-EN ISO 12156-1:2023; Wear scar diameter (WSD): 350–700 µm (applicability range). The procedure comprises 12 steps (about 1 h 54 min in total); it is used for: Quality control of diesel fuel according to PN-EN 590 (WSD1.4 ≤ 460 µm), Testing effect of FAME biocomponents on fuel lubricity, Evaluation of lubricity improver additives effectiveness.
At a glance
- Standard: PN-EN ISO 12156-1:2023
- Category: Petrochemistry
- Procedure steps: 12
- Total time of stages: 1 h 54 min
- Wear scar diameter (WSD): 350–700 µm (applicability range)
- Limit per PN-EN 590: WSD1.4 ≤ 460 µm
- Test temperature: 60 ± 2°C
Overview
Lubricity of diesel fuel is a critical quality parameter that defines the fuel's ability to protect tribological pairs in injection pumps and injectors from excessive wear. Modern common rail systems operate under pressures up to 2500 bar, and working elements are lubricated only by fuel flowing through the system.
The HFRR (High Frequency Reciprocating Rig) method is the standard procedure for assessing diesel fuel lubricity. It involves loading a steel ball with a 200 g mass and subjecting it to reciprocating motion (1 mm stroke, 50 Hz frequency) on a steel plate submerged in a fuel sample for 75 minutes at 60°C. After the test, the wear scar diameter (WSD — Wear Scar Diameter) on the ball is measured using an optical microscope or digital camera.
The PN-EN 590 standard requires that the WSD1.4 value (corrected to 1.4 kPa relative humidity) does not exceed 460 µm. Fuels with low lubricity (high WSD) can cause accelerated wear of injection pumps, leaks, and failures. This problem intensified after introduction of fuel desulfurization to levels <10 ppm sulfur, since sulfur compounds naturally present in crude oil served as natural lubricity additives.
The HFRR apparatus is manufactured by PCS Instruments (United Kingdom) and is the only device referenced in ISO 12156, ASTM D6079, and ASTM D7688 standards. The test result is expressed as the arithmetic mean of the major and minor axes of the elliptical wear scar.
Method principle
A steel ball (6 mm diameter, AISI 52100 steel) is pressed with a force of 200 g (1.96 N) against a stationary steel plate submerged in 2 mL of test fuel maintained at 60°C. The ball executes reciprocating motion with 1 mm stroke at 50 Hz frequency for 75 minutes. As a result of friction, an elliptical wear scar forms on the ball surface, whose dimensions (major axis and minor axis) are measured under a microscope or with a digital camera. Wear scar diameter WSD = (d1 + d2) / 2, then corrected to standard relative humidity of 1.4 kPa: WSD1.4 = WSD + F(RH), where F is the humidity correction function.
Applications
- Quality control of diesel fuel according to PN-EN 590 (WSD1.4 ≤ 460 µm)
- Testing effect of FAME biocomponents on fuel lubricity
- Evaluation of lubricity improver additives effectiveness
- Quality control of fuels in refineries and fuel terminals
- Development research of new fuel formulations
- Lubricity assessment of alternative fuels (HVO, GTL, BTL)
- Complaints and disputes regarding fuel quality
Key parameters
| Parameter | Value |
|---|---|
| Wear scar diameter (WSD) | 350–700 µm (applicability range) |
| Limit per PN-EN 590 | WSD1.4 ≤ 460 µm |
| Test temperature | 60 ± 2°C |
| Load | 200 ± 1 g (1.96 N) |
| Test duration | 75 min |
| Repeatability | r = 63 µm (for WSD approx. 400 µm) |
Standard
- Standard number
- PN-EN ISO 12156-1:2023
- Title (PL)
- Olej napedowy — Ocena smarnosci przy uzyciu urzadzenia z czestotliwoscia tarcia posuwisto-zwrotnego (HFRR) — Czesc 1: Metoda badania
- Title (EN)
- Diesel fuel — Assessment of lubricity using the high-frequency reciprocating rig (HFRR) — Part 1: Test method
Step-by-step procedure
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Preparation of test elements
Clean new ball and test disc with heptane, then acetone. Dry with air stream. Do not touch working surfaces with fingers.
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Sample conditioning
Bring fuel sample to room temperature (20–25°C). Gently mix by inverting container.
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Ambient conditions measurement
Measure and record temperature and relative humidity in laboratory. Humidity should be in range 0.5–1.8 kPa (water vapor pressure).
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Sample mounting
Place test disc in reservoir holder. Add 2 ± 0.2 mL fuel using syringe.
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Ball mounting
Mount ball in vibrating arm holder. Lower arm onto disc. Apply 200 g load.
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Parameter setting
Set parameters: temperature 60°C, frequency 50 Hz, stroke 1 mm, time 75 min. Start heating.
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Running test
After reaching 60°C, start automatic test. Apparatus records friction coefficient and temperature in real time.
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Test completion
After 75 minutes, apparatus automatically stops test. Remove load and vibrating arm. Take out ball with tweezers.
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Ball cleaning
Gently clean ball with heptane to remove fuel residue. Do not touch wear scar. Dry with air stream.
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Wear scar measurement
Place ball under microscope or in WSD camera. Measure diameter of major axis (d1) and minor axis (d2) of wear scar with 1 µm accuracy.
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WSD calculation and correction
WSD = (d1 + d2) / 2. Apply humidity correction: WSD1.4 = WSD + 60 × (1.4 - p), where p = water vapor pressure [kPa].
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Result reporting
Record WSD1.4 in µm. Compare with PN-EN 590 limit (max 460 µm). Include friction coefficient vs. time graph.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| HFRR apparatus | PCS Instruments HFRR (only manufacturer per ISO standard) | 120,000–200,000 PLN |
| Measurement microscope / WSD camera | PCS Instruments Wear Scar Camera, optical microscope 100× | 15,000–40,000 PLN |
| AISI 52100 test balls | PCS Instruments (d = 6 mm, Ra < 0.05 µm), pack of 100 pcs | 500–1,200 PLN / 100 pcs |
| AISI 52100 test discs | PCS Instruments (10 × 10 × 3 mm, Ra < 0.02 µm), pack of 50 pcs | 800–1,500 PLN / 50 pcs |
| Laboratory hygrometer | Testo 608-H1, Rotronic HygroPalm | 500–2,000 PLN |
| Dosing syringe 2 mL | Hamilton glass syringe, disposable Pasteur pipettes | 50–200 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| n-Heptane (purity min. 99%) | 142-82-5 | For cleaning balls, discs and sample reservoir before and after test |
| Acetone | 67-64-1 | Solvent for degreasing test elements, purity min. 99% |
| Toluene | 108-88-3 | Alternative solvent for cleaning apparatus elements |
| Reference fuel CEC RF-06-03 | — | Reference fuel with known lubricity for apparatus verification |
Health and safety (OHS)
- Diesel fuel — harmful upon prolonged skin contact, use nitrile gloves
- n-Heptane and acetone — flammable, work away from ignition sources
- HFRR apparatus — moving parts, do not insert hands in working zone during test
- Hot disc/reservoir (60°C) — risk of burns during disassembly
- Use safety glasses and laboratory coat
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-EN ISO 12156-1:2023 — “Diesel fuel — Assessment of lubricity using the high-frequency reciprocating rig (HFRR) — Part 1: Test method”.
How does this method work?
A steel ball (6 mm diameter, AISI 52100 steel) is pressed with a force of 200 g (1.96 N) against a stationary steel plate submerged in 2 mL of test fuel maintained at 60°C.
What is the measuring range and accuracy?
Wear scar diameter (WSD): 350–700 µm (applicability range); Limit per PN-EN 590: WSD1.4 ≤ 460 µm; Test temperature: 60 ± 2°C; Load: 200 ± 1 g (1.96 N).
How long does the test take?
The times given for the individual stages add up to approximately 1 h 54 min. The procedure comprises 12 steps.
What equipment is required?
HFRR apparatus, Measurement microscope / WSD camera, AISI 52100 test balls, AISI 52100 test discs, Laboratory hygrometer, Dosing syringe 2 mL. Indicative cost of the core instrument (HFRR apparatus): 120,000–200,000 PLN.
Where is this test used?
Quality control of diesel fuel according to PN-EN 590 (WSD1.4 ≤ 460 µm); Testing effect of FAME biocomponents on fuel lubricity; Evaluation of lubricity improver additives effectiveness; Quality control of fuels in refineries and fuel terminals; Development research of new fuel formulations; Lubricity assessment of alternative fuels (HVO, GTL, BTL); Complaints and disputes regarding fuel quality.
What safety precautions apply?
Diesel fuel — harmful upon prolonged skin contact, use nitrile gloves; n-Heptane and acetone — flammable, work away from ignition sources; HFRR apparatus — moving parts, do not insert hands in working zone during test; Hot disc/reservoir (60°C) — risk of burns during disassembly; Use safety glasses and laboratory coat.
Which laboratory can perform this test?
The test is performed by laboratories accredited to ISO/IEC 17025. On LabCoda you can find them by the standard number PN-EN ISO 12156-1.