Oil Patch Test

To manage costs effectively, many companies opt for in-house patch analysis testing on lubricating oils, coolants, diesel fuel, and greases, facilitating easy visual monitoring of particulate contamination.

While in-house testing may not offer the intricate analysis of a dedicated oil analysis laboratory, commercially available kits provide users with a valuable indication of the condition of their industrial fluids in real time. Commonly referred to as a 'patch test,' this process involves using MCE filters to gather and isolate debris for evaluation (colloquially known as 'patches' in the oil analysis industry). Upon completion, a patch test allows users to visually assess fluids, determining cleanliness according to ISO 4406:99 or NAS Class Cleanliness Codes. The ISO recognises the crucial connection between contaminated oils and component life, offering a cleanliness code and various standard methods, such as ISO 4406:99, as references for testers to determine acceptable particulate levels.

The test fluid undergoes a meticulous filtration process as it traverses a filter membrane patch via a vacuum pump. Following this, it undergoes drying and is positioned in a membrane holder, poised for visual assessment. The kit includes comparator charts to establish and approximate ISO/NAS Cleanliness Levels in fluid samples.

For the assurance of a representative sample:

• It is recommended to extract the sample from the oil or tank reservoir midpoint to avoid 'dynamic carry over' in flow lines. This prevents contaminants from lingering in the oil flow rather than entering the sample bottle.
• If sampling from a drain port is a minimess type sample point, it is advisable to let approximately half a liter of oil flow out of the sample valve before collecting the actual sample.
• Rinse the sample bottle thoroughly with the oil, repeating the process to eliminate any existing dust, ensuring a pristine sample.
• A minimum of 25ml of oil is required for the  oil analysis.

Analyse your oil as soon as possible for prompt insights into its condition.

Evaluate the total contaminants in mg dirt per 100ml of oil by visually assessing discolouration and comparing it with the provided charts. It's crucial to emphasize that the evaluation focuses on the overall density of contaminants rather than specific colours.

Estimate an ISO or NAS Code by inspecting under a 50/100 x pocket microscope and comparing it with the provided charts. The grid lines on the patches, which are 100μ micron wide, serve as a reference, facilitating the identification of various contaminants.

Please take note:

Even when using a 25mm patch and collecting only 25ml of oil, express the overall contamination levels as mg contamination per 100ml. This is because the exposed area of the 25mm membrane to the sample is approximately 25% of the area exposed for a 47mm membrane, aligning with the standard laboratory test using 100ml of oil.