Remember the rounding? If we divide that by , we get 41ish. When we divide that by , we get 82ish. If we divide that by , we get 2. When we divide that by , we get 5ish. This is where we need to be careful. That is why it is important to get sampling over time. Table 1 shows the code numbers and what they mean.
The number color matches the highlighted row on the table. Now that we have a way of describing the contamination level, how do we determine what the level ought to be? Different components have a different tolerance for contamination. A system with a gear pump, poppet valves, and cylinders will not require the same cleanliness as a system using piston pumps, servo valves, and piston motors.
Studies were done to determine the cleanliness level required for various fluid power components. This resulted in Table 2, which helps us know how clean a particular system needs to be. We can now set a target cleanliness level based on the contamination tolerance level of the most sensitive component in the filtered fluid stream. We can also isolate and target super sensitive components and provide them with their own dedicated filtration systems. The chart below shows how ISO codes correspond to volume measurements.
While every situation is different, we are often aiming for ISO code ranges that land somewhere between for the first number, on the second, and for the third AFTER fluid reconditioning. Imagine how much less wear and tear on your critical components that is. This is why fluid reconditioning helps extend the life of equipment and has many other benefits.
The most sensitive component in the group is the servo valve. Directly connecting an online laser particle counter to the hydraulic system through sample ports provides the most accurate analysis of the cleanliness as it provides the exact ISO count with little effort. The vacuum patch test kits include pictures of patch samples at various ISO codes and you, via a microscope, visually match your patch to closest ISO rated sample. An added benefit of the vacuum patch kit is that it can help you identify the source of contamination based on the material viewed via the microscope.
You should change your filter to a finer micron, but which micron rating should you choose to meet your target ISO Code? However, in the lubrication and analysis world, too much value is placed on the ISO cleanliness code; some laboratories have begun to report only the ISO code value, and there is a heavy reliance on this value by the end-user analyst. The ISO code should play only a secondary role when it comes to evaluating used oil sample data.
When oil analysis samples are submitted to particle counting, automatic particle counting APC is typically used — the current calibration standard for APC is ISO In APC, particles are counted through either laser or pore blockage methods. Different laboratories may report different particle count micron levels. As an example, a lab report may include levels greater than 4, 6, 10, 14, 21, 38, 70 and microns. ISO is the reporting standard for fluid cleanliness. According to this standard, a code number is assigned to particle count values derived at three different micron levels: greater than 4 microns, greater than 6 microns and greater than 14 microns.
The ISO code is assigned based upon Table 1. This can be seen in the example on the left. However, without seeing the raw data, the only thing the ISO code can positively identify is whether a sample has achieved the desired target value. The ISO code does nothing to help determine any real trend information unless the value of the raw data at the given micron levels changes enough to raise or lower the ISO code. At each row, the upper limit for each code is approximately double that of the lower limit for the same code.
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