Engineering: Section 7: Compression Set Resistance and Misc Info: M-Cor Inc ENCAP-O-SEAL, Teflon® Encapsulated O-Ring
Compression set is a very important sealing factor. It is a measure of the expected loss of resiliency or “memory” of a seal. Compression set is determined by compressing an O-ring between two plates that are heated for a specified time. When released, compression set is calculated as a ratio of non-recovered thickness, expressed as percent. *See Groove Assistant™ for gland dimensions.
Cross-section squeeze is defined as the compression of the seal cross-section, which is a result of the gland depth being less than the seal cross-section diameter. It is recommended that static seals have a squeeze percentage of 20-25% at maximum gland fill. This range ensures that the sealing footprint and sealing force are sufficient for the application. For dynamic seals, a squeeze percentage of 12-18% is recommended to reduce friction and abrasion. Percent-squeeze is calculated according to this formula:
Squeeze% = [(O-ring Cross Section – Groove Cross-Section) / (Seal O-ring Cross-Section)] x 100%
*See Groove Assistant™ for gland dimensions.
GLAND VOLUME FILL
Gland volume fill is defined as the amount of gland volume occupied by the seal in a compressed state. It is usually expressed as a percentage of gland volume. The recommended ranges for gland volume fill percentage is: Static applications: 85-90% Dynamic applications: 80-85%
These ranges allow for tolerance variations, thermal expansion and fluid volume. They also prevent excessive movement of the seal in the gland. The calculation for gland volume fill percentage is:
Gland Fill % = [(O-ring Volume) / (Groove Volume)] x 100%
The ENCAP-O-SEAL™ Teflon® encapsulated O-ring can be utilized in a wide range of industries:
Chemical Process Industries
Paint & Coating Operations
Air Operated Pumps
Tank Cars & Trucks
Encapsulation material: FEP: Tetrafluoroethylene – Hexafluoropropylene. PFA: Tetrafluoroethylene – Perfluoro (Propyl Vinyl Ether).
Core material: Silicone or Viton® Type A500 or 3M Dyneon Fluoroelastomer equivalent.
Continuous service temperature: FEP 400F/204C, PFA 500F/360C
Coefficient of friction: 1 to 2.
Elongation at break: 100% – 156%.
Water absorption: <0.01.
Average total shore A hardness.
85-90 shore A for solid silicone core.
90-95 shore A for solid Viton® core.
75-80 shore A for hollow silicone core.
FDA Compliance: The clear FEP encapsulation of the ENCAP-O-SEAL, Teflon® encapsulated O-ring complies with part 177 of the Title 21 of the Food and Drug Administration’s regulations for safe use as articles or components of articles for producing, manufacturing, processing, preparing, treating, packaging, transporting or holding food in accordance with regulation 177.1550.
Specific gravity (ASTM-D792) FEP-2.12-2.17, PFA 2.13-2.16.