SAE AS 5857A:2017 pdf free

SAE AS 5857A:2017 pdf free.Gland Design, O-ring and Other Elastomeric Seals, Static Applications
Limitations: Some of the smaller sizes have the possibility of exceeding 5% stretch and/or 30% squeeze at worst case tolerances. See Table 1B. Those sizes should be avoided unless the designer is confident that the chosen elastomer will work under those conditions. Use of O-rings like NAS1611 which have tighter tolerances than AS568 will reduce the extremes of stretch and squeeze.
NOTE: The use of 0-ring seals with a nominal cross section of less than 0.103 inch is problematic for two reasons: (1) The O-ring and gland tolerances are a large percentage of the nominal gland dimensions and the percentage increases as the O-ring cross section decreases. This causes a large range of resultant stretch and squeeze. (2) The ratio of area to volume of O-rings increases significantly as the 0-ring cross section decreases. At the same time, the volume of the O-ring is decreasing. This makes the smaller cross section seals much more sensitive than large cross section seals to the rate of attack by the fluid to which they are exposed. Published data shows that some small cross section nitrile seals exposed to red oil have significantly more loss of swell and therefore loss of cross section diameter than larger cross section seals when exposed to the fluid for the same length of time at high temperature. Any seal material that suffers from loss of swell after exposure to a fluid will provide a more reliable seal if a larger cross section seal is used. Therefore, the use of O-ring sizes with a nominal cross section smaller than 0.103 inch or their equivalent proprietary shapes, is not recommended due to the increased possibility of leakage and the subsequent decrease in relability of the installation.
The groove surfaces must be free from all machining iregularities exceeding the above values. Groove edges shall be smooth and true and free of nicks, scratches, and burrs, etc. Glands for pneumatic applications may require smoother finishes.SAE AS 5857A pdf free download.