Systems and methods to detect particulate debris in a fluid

A method of detecting particulate wear debris of engine components in a lubricant comprising both particulate wear debris of predetermined size and normal particulate debris having a size smaller than the wear debris in a closed loop engine lubricant circulation system, the method comprising:

• (a) installing an upstream test filtration element and a downstream reference filtration element in series upstream of a primary filtration element in the closed loop engine lubricant circulation system so that engine lubricant flows serially through the test filtration element, the reference filtration element and then through the primary filtration element, wherein the upstream test filtration element has a filtration size rating sufficient to remove a predetermined amount of the particulate wear debris from the lubricant and to allow substantially all of the smaller sized normal particulate debris to pass therethrough, and wherein the downstream reference filtration element has a filtration size rating sufficient to allow both any remaining portion of the particulate wear debris of the predetermined size not removed by the test filtration element and substantially all of the smaller sized normal particulate debris to pass therethrough, and wherein the primary filtration element has a size rating that is smaller than the filtration size rating of at least the test filtration element so as to capture substantially all of any remaining portion of the particulate wear debris and the smaller sized normal particulate debris passing through the downstream reference filtration element;
• (b) measuring differential pressure of the lubricant across each of the test and reference filtration elements;
• and
• (c) comparing the differential pressure across the test filtration element to the differential pressure across reference filtration element to thereby detect presence of the particulate wear debris in the fluid by an increase in differential pressure across the test filtration element in comparison to the differential pressure across the reference filtration element.

A system for detecting presence of target particulates of predetermined size in a fluid comprising both target particulates of the predetermined size and smaller sized non-target particulates, the system comprising:

• a test filtration element having a filtration size rating which is capable of removing a predetermined amount of the target particulates from the fluid yet allow substantially all of the smaller sized non-target particulates to pass therethrough;
• a reference filtration element serially fluid-connected downstream of the test filtration element and having a filtration size rating that is at least comparable to or greater than the filtration size rating of the test filtration element to allow both any remaining portion of the target particulates of the predetermined size not removed by the test filtration element and substantially all of the smaller sized non-target particulates to pass therethrough;
• a primary filtration element fluid-connected in series downstream of the test and reference filtration elements, wherein the primary filtration element has a filtration size rating that is smaller than the filtration size rating of at least the test filtration element so as to capture substantially all of any remaining portion of the target particulates and the smaller sized non-target particulates passing through the downstream reference filtration element;
• pressure transducers for measuring differential pressure of the fluid across each of the test and reference filtration elements and issuing differential pressure signals indicative of the differential pressure across the test and reference filtration elements, respectively;
• and
• data processing circuitry for receiving and comparing the differential pressure signals generated by the pressure transducers to thereby detect presence of the target particulates in the fluid by an increase in differential pressure across the test filtration element in comparison to the differential pressure across the reference filtration element.

A system for detecting particulate wear debris of engine components in a lubricant comprising both particulate wear debris of predetermined size and normal particulate debris having a size smaller than the wear debris in a closed loop engine lubricant circulation system, the system comprising:

• an upstream test filtration element and a downstream reference filtration element serially fluid-connected in the closed loop engine lubricant circulation system so that engine lubricant is capable of flowing serially through the test filtration element and then through the reference filtration element, wherein the test filtration element has a filtration size rating that is sufficient to remove a predetermined amount of the particulate wear debris from the lubricant and to allow substantially all of the smaller sized normal particulate debris to pass therethrough, and wherein the downstream reference filtration element has a filtration size rating sufficient to allow both any remaining portion of the particulate wear debris of the predetermined size not removed by the test filtration element and substantially all of the smaller sized normal particulate debris to pass therethrough;
• a primary filtration element fluid-connected in series downstream of the test and reference filtration elements, wherein the primary filtration element has a filtration size rating that is smaller than the filtration size rating of at least the test filtration element so as to capture substantially all of any remaining portion of the wear debris and the smaller sized normal particulate debris passing through the downstream reference filtration element;
• first and second pressure transducers operatively connected to the test and reference filtration elements for measuring differential pressure of the lubricant across each of the test and reference filtration elements and issuing first and second differential pressure signals indicative of the differential pressures measured across the test and reference filtration elements, respectively;
• and
• data processing circuitry for receiving and comparing the first and second differential pressure signals issued by the first and second pressure transducers to thereby detect presence of the particulate wear debris in the fluid by an increase in the differential pressure across the test filtration element in comparison to the differential pressure across the reference filtration element.