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ISO fluid cleanliness codes for hydraulic and lubrication systems

When setting target ISO fluid cleanliness codes for hydraulic and lubrication systems, it is important to keep in mind the objectives that need to be achieved, comments Craig FitzGerald from ISO-Reliability Equipment.

Maximising equipment reliability and safety, minimising repair and replacement costs, extending useful fluid life, satisfying warranty requirements, and minimising production downtime are attainable goals. “Once a target ISO cleanliness code is set, following a progression of steps to achieve that target, and if it is monitored and maintained accordingly, the benefits stand to be considerable,” says FitzGerald.

The first step to identify a target ISO code for a lubrication system is to identify the most sensitive component supplied by the reservoir. If a central reservoir supplies several systems, the overall cleanliness must be maintained, or the most sensitive component must be protected by filtration, which cleans the fluid to the target ISO cleanliness before reaching that component.

Conservative target ISO cleanliness codes are based on several component manufacturers’ guidelines and extensive field studies for standard industrial operating conditions in systems using petroleum-based fluids.

If a non-petroleum-based fluid is used (that is, water glycol) the target ISO code should be set one value lower for each size. If a combination of the following conditions exists in the system, the target ISO code should also be set one value lower:

  • The component in question is critical to safety or overall system reliability.
  • Frequent cold start.
  • Excessive shock or vibration.
  • Other severe operation conditions.

Once the target ISO fluid cleanliness code is established, it is critical to properly measure the actual cleanliness of the system. A well-formulated plan to achieve cleanliness can be undermined if steps are not taken to ensure accurate and repeatable oil analysis. When sampling the oil, a wide range of variables can affect the outcome, yielding inaccurate results.

In terms of oil sampling methods and practices, bottle samples analysed by independent laboratories is common and widely accepted as a method of quantifying fluid cleanliness. “However, there are many variables associated with bottle sampling that can cause inaccurate readings,” notes FitzGerald.

Connecting an on-line particle counter directly to the hydraulic or lube system through sampling ports provides the most accurate snapshot of fluid cleanliness and eliminates many of the inherent variables associated with bottle sampling. Some particle counters can function with system pressure as low as 20 psi (1.42 bar) at certain viscosities for sampling pressure line, return line, or lubrication system.

There are also particle counter options available to draw (sip) the fluid from a reservoir, tote, or other container directly into the particle counter when system pressure is unavailable. “Monitor sample port cleanliness in real-time to know when the sample is truly representative of the system and not tainted with sample port contaminate build-up,” advises FitzGerald.

Maintaining control of the sampling and analysis procedures increases the accuracy of results, eliminates the waiting game to get samples back from a laboratory, allows quicker response to contamination related issues, and even saves costs on oil sample kits. “No one knows your system better than you. Once armed with the right oil analysis approach and diagnostic equipment, you can make considerable improvements in reliability,” highlights FitzGerald.

Just as sampling technique and method can compromise results, sampling port and location can also be a challenge. Sampling ports are often contamination collection points and must be flushed for up to six minutes before a truly representative sample is captured. Without a proper port flush, the results can be affected. Port location is also critical to obtain a good sample. Locating of the sampling port where there is turbulent flow will provide more realistic results than a laminar area or directly from the tank itself.

Setting target ISO fluid cleanliness codes for hydraulic and lubrication systems maximises equipment reliability and safety. Maintaining the recommended ISO cleanliness level reduces the risk of component wear, system failure, and unplanned downtime.

Clean fluids ensure proper lubrication, prevent premature wear, and extend equipment life, minimising repair and replacement costs. Contaminated fluids result in increased operating costs and higher wear rates on components such as pumps, valves, and bearings.

“Regularly achieving the target ISO cleanliness code reduces the need for costly repairs and parts replacements and vastly extends useful fluid life. Clean fluids last longer and perform better,” says FitzGerald.

Achieving the target ISO code ensures that the fluid remains effective, reducing the frequency of oil changes. In addition, many original equipment manufacturers specify cleanliness levels for warranty coverage. Meeting these requirements ensures that warranty claims are valid, and equipment remains protected.

“The task of reaching ideal target ISO cleanliness codes is really not achievable with present in-line filtration technologies. Filter dirt holding capacities are low and these strainer type filters still allow large volumes of contamination through, when found to be under the filter efficiency rating,” says FitzGerald.

To combat these challenges and make what was previously an almost impossible task, ISO-Reliability Partners has developed class-leading offline microfine filtration systems that simplifies the process and makes these targets easy to achieve.

Oil supplied to a gold processing plant by a major refiner was found to have an ISO cleanliness of 21/20/18 which is too contaminated for use without causing significant wear and high in-line filtration costs. Shortly after system integration the oil in question was tested to an ISO cleanliness of 15/12/10, highlights FitzGerald.

ISO-Reliability Partners’ reputation and success spans 25 years, with it owning and managing the iconic Filter Focus™ brand, and FitzGerald having incorporated all his intellectual property into the new company. It is an own emblem manufacturer (OEM) of class-leading micro fine oil filtration solutions, vacuum dehydration systems, automated water removal for compressed air and high efficiency industrial air scrubbing.

ISO-Reliability Partners Contact

Craig FitzGerald

Phone: +27 10 449 6414



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