Lubricity test for Diesel by HFRR under ASTM D6079 method: The lubricity of ultra-low sulfur diesel fuel can be determined by the ASTM 6079 method, with the help of a high-frequency reciprocating system (HFRR) that meets all the requirements of ASTM 6079 in the least possible space and cost.
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High-frequency reciprocating rig (HFRR) is a computer-based tribological machine that is used for determination of friction or wear of two surfaces under lubricated condition by means of a microscope
Lubricity test for Diesel by HFRR parameters:
Typical Specification of ASTM D 6079 Method
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S.N.
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PARAMETERS
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SPECIFICATIONS as per ASTM D 6079
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1.
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Key parameter
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Wear scar on ball due friction b/w ball and disc
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2.
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Sample Volume
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2 ml
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3.
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Load
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200 gm or as per test specification
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4
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Temperature
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Ambient 25 degree or upto 60 degree C higher temperature upto 400 degree can also be used if required and your HFRR machine heating element is compatible for this
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5
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Time
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75 Minutes
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6
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Ball
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Motion-Reciprocating
Material-Alloy Steel
diameter-6mm
Frequency-50Hz
Stroke length-1 mm(+/- 0.2)
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7
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Disk
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Motion: Stationary
Size: 10 mm
Material – Alloy & polished Steel
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8
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Contact Surface
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Contact surface is submerge in sample/fuel
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9
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Repeatability
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Aprox 62 µm @ 25 oC
Aprox 80 µm @ 60 oC
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10
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Reproducibility
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Aprox 125 µm @ 25 oC
Aprox 136 µm @ 60 oC
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Why we need to develop the HFRR technique
As we all know that sulphur is the element present in diesel oil, that is accountable for the lubricity of fuel. more the quantity of sulphur fuel works higher as efficient lubricants that prevent the wear and tear of engine fuel components. though sulphur provides better lubricity to the fuel however it emits a number of waste product that causes a problem of public health. Inline to emphasize the technology of low sulphur content fuel production several countries are advising to their refineries for developing technology of ultra-low sulphur diesel to scale back emission of pollutants within the atmosphere.
Refining processes tend to scale back sulphur as fuel parts that offer natural lubricity. Because the sulfur levels decrease, the chance of insufficient lubricity will increase. The low lubricity is decreased the potential of the machinery and its parts.
To maintain the acceptable lubricity of fuel, it’s essential to feature some additive to the ultra low sulfur diesel to enhance lubricity and therefore ensure its correct performance of diesel oil.
For this reason, it’s the great challenge for the petrochemical industry to own an acceptable procedure and technology to validate quality standards of the lubricity additives.
Description of lubricity test for diesel by ASTM 6079 test method
The lubricity of ultra low sulfur diesel fuel can be determined by the ASTM 6079 method, with the help of high-frequency reciprocating system (HFRR) that meets all the requirements of ASTM 6079 in the least possible space and cost.
High-frequency reciprocating rig (HFRR) is a computer-based tribological machine that is used for determination of friction or wear of two surfaces under lubricated condition by means of a microscope
ASTM 6079 is a method to determine the lubricity in middle distillates fuels in line of ASTM specification D 975. The method consists of placing 2mL of test fluid as a contact medium between two surfaces that must be at a controlled temperature of 60 ° C.
When the temperature stabilizes, a metal ball loaded with a weight of 200 grams must stroke over a fixed disk submerged on the test fluid. The metal ball must rub the test disc with a straight displacement of 1 mm at a frequency of 50 Hz for 75 min.
At the finish of the test, the ball is disconnected from the vibrating arm holder and cleaned. Once the ball is clean, it placed under lenses of high-resolution microscope which is connected to computer dimensions of the wear marks caused by frictional motion between both surfaces during the test are measure and these results are used to calculate the lubricity of the fluid Used for the test.
Some system restrictions are that the displacement on the disc must be 1 mm with a tolerance of + – 02 mm, that there is no commercially available sensor to measure the percentage of film and that the mink system must be able to amplify the image captured from the ball at least 30 times.
Taking all of the above into account, a computer-based system was built where the temperature, force, film percentage, and acceleration signals were managed under the compactdaq platform.
A high-resolution data acquisition module (24 bits) was required to measure the percentage of film since the transducer we made to meet the specification has a 0-1V voltage output with 1 micro steps Volt
The computer allowed executing algorithms to calculate the frequency and the coefficient of friction as well as control algorithms to assurance the displacement of the reciprocating arm within the specifications of the standard and to execute a PID to control the temperature of the system.
In the software part, the application consists of a program made with a user-friendly interface where, by means of the information contained in the vision module, and its flexibility to handle dynamic information with an electronic microscope that allows the user to make the measurements of the wear on the surface of ball With the parameters obtained, the computer automatically calculates the lubricity of the fluid under test and it is represented in terms of wear scar. More the wear scar poorer is the lubricity of the fuel.
Once the lubricity parameter is obtained, a report is automatically generated with all the instrumentation values, the wear images, and the results obtained from the lubricity calculation.
The software represents graphics where the end-user can see the instrumentation trend line (coefficient of friction, temperature, acceleration, and film percentage) to predict fluid qualities a can compare data as per requirement.
Summary of the Test:
In this test method, friction takes place between a disk (fixed surface) and a ball (moving surface) where the ball must be in motion 1 mm (+/-0.02 mm) over the disk(fixed surface) at a temperature of 60 0C under the specific controlled parameters such as a provided load of 200 grams, 50 Hz frequency for 75 minutes.