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The AS4059 Hydraulic System Cleanliness Classification System: Replacement of NAS1638

  • 발행 : 2012.06.01

초록

The NAS 1638 cleanliness classification system was originally developed in 1966 by the US Aircraft Industries of America to both simplify reporting of particle count data and to control the introduction of dirt during the assembly of aircraft fluid systems. The numbers of particles at stated sizes are represented by broad bands where the interval was generally a doubling of contamination. A number of systems have been introduced since this to suit differing requirements. NAS 1638 and AS4059 are used in other industrial sectors such as the Off-shore & Sub-Sea and the Primary Metal Industries. The changes to ISO contamination measurement standards controlled by ISO/TC131/SC6 in 1999 meant that a revision of most of these classification systems was necessary. The body responsible for NAS 1638 decided to withdraw it for new installations and replace it with an update of an existing standard, SAE AS 4059. This paper details the philosophy behind the contamination coding systems, the reasons for the changes to the ISO contamination standards and explains the workings of AS 4059, the replacement for NAS 1638. It goes on to detail the latest changes to this standard.

키워드

참고문헌

  1. NAS 1638 "Cleanliness requirements of parts used in Hydraulic systems", Aerospace Industries of America, Washington DC., USA, 2001.
  2. ISO 4406 "Hydraulic Fluid Power - Fluids - Method For Coding Level of Contamination by Solid Particles", International Standards Organisation, Geneva, Switzerland, 1999.
  3. ISO 11171 Hydraulic fluid power - Calibration of automatic particle counters for liquids, International Standards Org, Geneva, Switzerland, 1999.
  4. SAE ARP598 The determination of particulate contamination in liquids by the particle count method, SAE, Warrendale Pa, USA, December 1986.
  5. M. J. DAY & J. RINKINE "Contaminant monitoring of hydraulic systems - the need for reliable data", Presented at 10th International Congress and Exhibition on Condition Monitoring and Diagnostic Engineering Management, Helsinki, June 1997.
  6. SAE AS4059 Aerospace Fluid Power - cleanliness classification for hydraulic fluids, SAE, Warrendale, Pa, USA.
  7. ISO 11218 "Aerospace - Cleanliness classification for aeronautical fluids", International Standards Organisation, Geneva, Switzerland, 1993
  8. ISO 4402 "Hydraulic fluid power - Calibration of automatic count instruments for particles suspended in liquids - Method using classified AC Fine Test Dust", International Standards Organisation, Geneva, Switzerland, 1991.
  9. ISO TR16386 "Hydraulic fluid power- Impact of changes in ISO fluid power particle counter, contamination control and filter test standards, International Standards Organisation, Geneva, Switzerland, 1999.