Particle contamination is responsible for up to 80% of lubrication-related machinery failures. Particle ingress can lead to abrasion which generates wear debris. Increasing generation of wear debris warns any technician of approaching failure. A simple patch test allows technicians to discover the degree of severity of contamination in any system.
Patch testing is said to be the first method used for examining solid impurities and wear debris in a used oil sample. The majority of these procedures provide the basis for ASTM and ISO methodologies that were recently approved. These approaches are required by a contemporary and well-engineered oil analysis system.
Microscopic Particle Counting
Some labs use microscopic particle counts as the last option after receiving a high reading from an automated particle counter. Technicians who have the difficult task of counting particles one by one despise the method. The ability to get a particle count as well as a photomicrograph of the particles is undoubtedly a complete evaluation of total solids. Microscopic Particle Count is a simple, direct test procedure, and allows for shape analysis. However, this method cannot exactly be relied on to provide accurate representation and test results for ultra-fine particles.
Gravimetric analysis uses a laboratory scale to weigh particles and silt on a membrane. The bulk of the particles on the membrane are organic "soft" particles such as resins and sludge. Some laboratories use a series of solvent washes to remove soluble fractions from the membrane. Solvents including pet ether, toluene, trichloromethane, and methanol are commonly used for this.
The most expensive elements are a muffle furnace and occasionally platinum crucibles, although determination may be done with quite affordable equipment. Gravimetry allows for extremely minimal instrumental error and does not need a set of criteria for calculating an unknown. Many elements' atomic masses were determined with six-figure precision via gravimetric analysis.
Particle Micro-Patch Imaging
Optical imaging technologies have been developed to rapidly scan and digitize particles on a membrane for evaluation by computer algorithms. Each particle is scanned individually, classified by form, and, if required, visually reviewed by an analyst. These instruments measure particles based on the longest cord or equivalent spherical diameter, according to ISO 16232 7/8. Without the time-consuming process of manually counting, sizing, and classifying individual particles, the PMPI combines the advantages of microscopic particle counting with patch ferrography.
A simple patch maker, microscope, and imaging package will cost no more than a few hundred dollars. Purchase a microscope with the ability to capture images on a computer, then trend the images. It is a good option where heavy water contamination makes an optical particle count difficult or even impossible.
Insoluble additives are frequently degraded as a result of in-service exposures such as heat and water. This attribute is sometimes measured via filterability tests on new oil. Flowing dry or wet oil through a membrane until a specific terminal pressure drop is reached is how the test is done.
Pore Blockage Method
Pore blockage devices may be used with dark oils and oils containing emulsified water. Similar to optical particle counts, there is no information on the shape or composition of the particles. Consider utilizing this procedure for oils that have been contaminated with water or for dark-colored oils that need to be monitored.
The PAMAS S40 AVTUR is a portable particle counter for the analysis of turbine fuels, petrol, and diesel. It has its own device-specific analysis method that has derived from the Energy Institute London, namely IP 577. The instrument fully complies with DEFSTAN 91-091 and IP PM FA.
The Cold Corrosion Test Kit provides an accurate measure of the parts per million (ppm) value of Fe2+ and Fe3+ compounds in used oil. Knowing the specific ppm of corroded iron allows informed decisions to should you need to schedule parts replacement or conduct urgent action by cleaning the oil or sweetening the oil.