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FEP/PFA Encapsulated O-Rings

Encapsulated O-rings combine an elastomeric core (Silicone/FKM) with a seamless FEP/PFA jacket. This hybrid construction merges universal chemical resistance with high-resilience sealing, significantly outlasting standard rubber seals in extreme thermal and corrosive environments.

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Description

Material Selection Matrix: FEP vs. PFA

The outer jacket is the primary barrier. We offer two distinct fluoropolymers based on thermal and mechanical requirements.

Performance Metric	FEP (Fluorinated Ethylene Propylene)	PFA (Perfluoroalkoxy)
Continuous Service Temp	-60°C to +205°C	-60°C to +260°C
Mechanical Strength	Standard	Excellent (High Creep Resistance)
Permeability	Low	Ultra-Low (Semiconductor Grade)
Chemical Resistance	Universal (pH 0-14)	Universal (pH 0-14)
Typical Applications	Pumps, General Chemical, Food/Bev	Semiconductor, Aerospace, High-Temp Valves

Core Selection Logic:

Solid FKM Core (90-95 Shore A): Optimized for high-pressure systems where superior compression set resistance is mandatory.
Solid Silicone Core (85-90 Shore A): General-purpose industrial standard with excellent thermal stability.
Hollow Silicone Core (75-80 Shore A): Designed for low-torque, low-pressure applications requiring high flexibility.

Technical Specifications & Tolerances

We manufacture to AS568, JIS B2401 (P/G/S/V), and Metric standards.

Cross-Section (C/S) Range	Dimensional Tolerance (±)	Typical Application
1.00 – 1.79 mm	0.07 mm	Micro-valves / Precision Instruments
2.65 – 3.54 mm	0.09 mm	Standard Hydraulic/Pneumatic Systems
5.30 – 6.99 mm	0.13 mm	Large Bore Flanges / Pressure Vessels
10.01 – 15.00 mm	0.25 mm	Heavy-Duty Chemical Reactors

Engineering Best Practices: Groove Design

Groove geometry is critical to prevent jacket cracking. Dimensions vary depending on the media (Liquid vs. Gas).

Groove Design Guidelines (Sample Values):

C/S (mm)	Groove Depth (Liquid)	Groove Width (Liquid)	Groove Depth (Gas)	Groove Width (Gas)
2.62	2.30 mm	3.10 mm	2.35 mm	3.10 mm
3.53	3.10 mm	4.20 mm	3.25 mm	4.20 mm
5.33	4.70 mm	6.40 mm	4.95 mm	6.40 mm
6.99	6.30 mm	8.40 mm	6.60 mm	8.40 mm

Lead-in Chamfers: Essential for assembly. Recommended angle: 15° to 20°
Pre-heating: For tight installations, immerse the seal in hot water ( $60℃-80℃$ ) for 5 minutes to increase jacket flexibility.

Pressure Performance Matrix

Maximum allowable pressure is a function of hardness, cross-section, and the radial clearance gap.

Hardness (Shore A)	35 KG/CM² (3.5MPa)	105 KG/CM² (10.5MPa)	210 KG/CM² (21MPa)	350 KG/CM² (35MPa)
70 Shore A	Max Gap 0.15mm	Max Gap 0.05mm	-	-
80 Shore A	Max Gap 0.20mm	Max Gap 0.10mm	Max Gap 0.03mm	-
90 Shore A	Max Gap 0.25mm	Max Gap 0.13mm	Max Gap 0.08mm	Max Gap 0.03mm

Failure Prevention Analysis

- Rapid Gas Decompression (RGD): Not recommended for high-pressure gas cycles with sudden pressure drops; high risk of jacket rupture.
- Chemical Swelling: Ensure core compatibility. If a medium permeates the jacket and the core swells, internal tension will cause delamination.
- Mechanical Erosion: Manage clearance gaps according to the hardness table to prevent extrusion into the gap.

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