Image shown is representative and may differ from the actual product in size, proportions, and color shade
0.157 in
(4.00 mm)
4.764 in
(121.00 mm)
FSIL FS75BU50 O-Ring, Size: 4X121
Material: FSIL FS75BU50 O-Ring
Size: Metric 4X121 O-Ring
Part Number: FS75BU50-OR-4X121
Color: Blue
Detailed Description
FS75BU50-OR-4X121 is a Blue, 75 Shore A, Fluorosilicone (FVMQ, FSIL) O-Ring. It is a 75 durometer Fluorosilicone (FVMQ, FSIL). FS75BU50-OR-4X121 is Metric size 4X121 O-Ring also referred to as 4mm (Cross Sectional Diameter (CS)) x 121mm (Inside Diameter (ID)). Material: 75 Durometer FSIL FS75BU50 O-Ring Size: Metric 4X121, 4mm CS X 121mm ID (0.157" CS X 4.764" ID)
| Technical Specification | Value |
|---|---|
| Compound Number | FS75BU50 |
| Material | Fluorosilicone (FVMQ, FSIL) |
| Color | Blue |
| Durometer | 75 Shore A Hardness |
| High Temperature | 175 °C / 347 °F |
| Low Temperature | -70 °C / -94 °F |
| Geometry Specifications | |
| Cross Sectional Geometry | O-Ring |
| Size Standard | Metric |
| Size | 4X121 |
| Cross Section (CS) | 4.00 mm / 0.157 in |
| Inside Diameter (ID) | 121.00 mm / 4.764 in |
Canyon’s FS75BU50 is a 75 Shore A blue Fluorosilicone compound engineered for fuel-resistant sealing applications that require higher hardness, environmental durability, and military specification compliance. Manufactured in accordance with MIL-DTL-25988 and AMS-R-25988, MIL-R-25988 Class 3 Type 1 and Type 2, it provides dependable compression set resistance and elastic recovery while offering excellent resistance to fuels, oils, aging, weathering, and ultraviolet exposure. With a service temperature range of -73°C to 177°C (-100°F to 350°F), FS75BU50 maintains sealing integrity across extreme cold and elevated temperature conditions. Its higher durometer supports improved extrusion resistance and dimensional stability in both static and moderate dynamic sealing environments.
FS75BU50 is commonly used for O-rings and gaskets in aerospace, defense, automotive, and industrial systems exposed to aviation fuels, automotive fuels, and chemically aggressive atmospheres. The fluorosilicone chemistry makes it well suited for applications where standard silicone materials lack fuel resistance, while the MIL-compliant formulation supports use in regulated programs without QPL restrictions. This compound provides a balanced solution for designers seeking fuel compatibility, temperature capability, and military specification alignment.
Common relevant keywords:
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