Magseal News
O-RING COMPATIBILITY ISSUES WITH HTS OILS
Fluorocarbon O-ring Compatibility with Aircraft Engine Lubricating Oils, per MIL-PRF-23699 (Supersedes MIL-L-23699) and MIL-PRF-7808 (Supersedes MIL-L-7808)
The majority of all MAGSEALS were designed and approved with our standard aerospace fluorocarbon (FKM) o-ring material. Our o-ring part number identifies these materials with any one of the following suffixes: 507, 517, 527, and 537. These o-ring materials are compatible with the MIL-PRF-23699 Class STD (NATO 0-156) and Class C/I (NATO 0-156/0-152) and MIL-PRF-7808 Grade 3 (NATO 0-148) oils. However, they are NOT compatible with the newer high thermal stability oils per MIL-PRF-23699 Class HTS (NATO 0-156/0-154) and MIL-PRF-7808 Grade 4 (NATO 0-163) oils that contain amine oxidants and dispersants additives which causes embrittlement of this material. This is true for all FKM-A o-rings per AMS7276 (AS3209-size) and AMS-R-83248 Type I Class I (M83248/1-size) that are exposed to the HTS oils.
Our standard o-ring material will degrade over time when exposed to the following high thermal stability oils listed in QPL-23699 and QPL-7808: Mobil Jet Oils 254 and 291, Royco Turbine Oil 560, BP (Exxon) Turbo Oil 2197, AeroShell Turbine Oil 560, Mobil RM 284A, NYCO S.A. Turbonycoil 400 and Hexagon Enterprises Metrex AF Oil 04.
SAE Technical Papers 2001-01-2974, Fluoroelastomer Compatibility with Advanced Jet Engine Oils, and 2003-01-3029, Fluoroelastomer and Perfluoroelastomer Compatibility with Advanced Gas Turbine Lubricants, explain the technical details of this compatibility issue.
We do have an o-ring material that is compatible with all of the MIL-PRF-23699 and MIL-PRF-7808 oils. It meets our MSC-547 specification that is similar to AMS-R-83485 for the Improved Performance at Low Temperatures Fluorocarbon Elastomer. Our o-ring part number identifies this material with the 547 suffix. A revision to the MAGSEAL design will be required to change from the original aerospace fluorocarbon o-ring to the MSC-547 o-ring material.
Direct any further questions regarding this issue to Paul Ryan at Magnetic Seal Corp. Telephone No. 401-247-2800 extension 123 Fax. No. 401-247-2805 e-mail: pryan@magseal.com
Reference Documents:
SAE Documents are available from SAE 400 Commonwealth Drive,
Warrendale, PA 15096-000l http://www.sae.org
| AMS7276G |
Rings, Sealing, Fluorocarbon (FKM) Rubber, High-Temperature-Fluid Resistant, Low Compression Set, 70 to 80 |
| AMS-R-83485 |
Rubber, Fluorocarbon Elastomer, Improved Performance at Low Temperatures |
| 2001-01-2974 |
Fluoroelastomer Compatibility with Advanced Jet Engine Oils |
| 2003-01-3029 |
Fluoroelastomer and Perfluoroelastomer Compatibility with
Advanced Gas Turbine Lubricants |
|
Us Government Documents available from DODSSP, Subscription Services Desk, Building 4D, 700 Robins Avenue, Philadelphia, PA 19111-5094.
http://assist.daps.mil/ |
| MIL-PRF-23699F |
Performance Specification, Lubricating Oil, Aircraft Turbine Engine Synthetic Base, NATO Code Number 0-156 |
| QPL-23699-19 |
Qualified Products List of Products Qualified Under Performance Specification MIL-PRF-23699 |
| MIL-PRF-7808L |
Performance Specification, Lubricating Oil, Aircraft Turbine Engine, Synthetic Base |
| QPL-7808-38 |
Qualified Products List of Products Qualified Under Performance Specification MIL-PRF-7808 |
| MIL-R-83248C |
Rubber, Fluorocarbon Elastomer, High Temperature, Fluid and Compression Set Resistant |
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