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Home » Oil Sampling » //Primary vs Secondary Sampling Ports


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Primary vs Secondary Sampling Ports

Where Should You Sample From?

Oil samples need to be an accurate reflection of the equipment they are taken from. The samples taken should be repeatable, comparable, and data rich. When samples are taken from the same spot each time, the collected data will deliver a statistically significant result and will establish trends over time. This will provide data-rich analysis that can be relied on for proactive decision making. Installers should look for the spot they can grab the most useful data about the entire system.


On circulating systems there are two types of sampling locations that serve different purposes:

Primary Sampling Ports

The goal is to grab a sample that will be a snapshot of the entire system. By sampling from this one spot, it can check the wear debris and particle count to get an idea of the total amount of contaminants in the system. 



  • This will be your main, most used port

  • The ideal location will vary from system to system but it will typically be located on the return line before the sump or reservoir and before the filter

  • In most cases remote access solutions are available so that samples can be taken from the best location


A sample from the primary port will let you know there is a problem, but it will be the secondary port diagnoses the problem.

Secondary Sampling Ports


Secondary sample ports should be installed on most systems. The goal of these sample ports is to locate the individual source for of the elevated particles shown on an oil analysis report.



  • These ports allow you to focus  on individual components

  • Secondary sampling ports should be installed upstream after each system component to isolate the source of wear debris or particles

  • Secondary ports can also be used to monitor the performance of filters - the primary valve will show what is going into the filter, the secondary will show how the filter is working


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