ASTM D7685-11(2016)

4.4.1 In-line full flow non-intrusive inductive metal detector with no moving parts.

4.4.2 Detects both ferromagnetic and non-ferromagnetic metallic wear debris.

4.4.3 Detects 95 % or more of metallic wear debris above some minimum particle size threshold.

4.4.4 Counts and sizes wear debris detected.

4.6.1 Firstly, bearing failures on rotating machines tend to occur as events often without sufficient warning and could be missed by means of only periodic inspections or data sampling observations.

4.6.2 Secondly, since it is the larger wear metallic debris that are being detected, there is a lower probability of false indication from the normal rubbing wear that will be associated with smaller particles.

4.6.3 Thirdly, build or residual debris from manufacturing or maintenance actions can be differentiated from actual damage debris because the cumulative debris counts recorded due to the former tend to decrease while those due to the latter tend to increase.

4.6.4 Fourthly, bearing failure tests have shown that wear debris size distribution is independent of bearing size. 1.1 This practice covers the minimum requirements for an in-line, non-intrusive, through-flow oil debris monitoring system that monitors ferromagnetic and non-ferromagnetic metallic wear debris from both industrial aero-derivative and aircraft gas turbine engine bearings. Gas turbine engines are rotating machines fitted with high-speed ball and roller bearings that can be the cause of failure modes with high secondary damage potential. 1.2 Metallic wear debris considered in this practice range in size from 120 μm (micron) and greater. Metallic wear debris over 1000 μm are sized as over 1000 μm.

1.3 This practice is suitable for use with the following lubricants: polyol esters, phosphate esters, petroleum industrial gear oils and petroleum crankcase oils.

1.4 This practice is for metallic wear debris detection, not cleanliness.

1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.