Electromagnetic shielding O-rings and washers
EMI/RFI Shielded O-Rings
EMI/RFI Shielded O-Rings are engineered sealing solutions designed to provide both environmental sealing and electromagnetic interference (EMI) / radio frequency interference (RFI) shielding. Unlike conventional elastomer O-rings, these seals are manufactured from conductive silicone or fluorosilicone compounds filled with metal or metal-coated conductive particles, creating a continuous electrical path between mating surfaces.These conductive seals are widely used in aerospace, military, telecommunications, medical electronics, automotive electronics, and industrial control systems where equipment must remain protected from both moisture ingress and electromagnetic emissions.
Why EMI Shielded O-Rings Are Important
As electronic devices become more compact and operate at higher frequencies, unwanted electromagnetic interference can affect system reliability, signal integrity, and regulatory compliance.
An EMI shielding O-ring creates:
- Continuous conductive contact between enclosure surfaces
- Effective EMI/RFI attenuation across a broad frequency range
- Environmental sealing against dust, moisture, and contaminants
- Long-term vibration resistance
- Protection without sacrificing enclosure accessibility
Many applications require a sealing solution capable of achieving both IP-rated environmental protection and electromagnetic shielding within the same component.
Common Conductive Materials
The base elastomer determines environmental resistance, while conductive fillers determine shielding performance.
| Base Material | Key Advantages | Typical Applications |
|---|---|---|
| Conductive Silicone | Wide temperature range, excellent weather resistance | Electronics, aerospace, defense |
| Conductive Fluorosilicone | Fuel and solvent resistant | Aircraft fuel systems, military equipment |
Typical conductive fillers include:
- Silver-Aluminum
- Silver-Copper
- Nickel-Aluminum
- Nickel-Graphite
Silver-based fillers provide the highest conductivity and shielding effectiveness, while nickel-filled compounds offer a more economical solution for commercial equipment.
Compounds for electromagnetic shielding O-rings and gaskets
| Compound Name | Compound Composition | Cost | Durometer | MAX VR | MIN Shielding Effectiveness 20 MHZ to 10 GHZ (MIL-DTL-83528) | Features | Parker Chomerics Compound Interchange |
|---|---|---|---|---|---|---|---|
| EMI-2368 | Silver Aluminum in Silicone | $$$$ | 65 | .008 ohm/cm | 100 dB | Meets MIL-DTL-83528, TYPE B | 1285 |
| EMI-550, EMI-2486 | Silver Aluminum in Fluorosilicone | $$$$ | 70 | .012 ohm/cm | 100 dB | Meets MIL-DTL-83528, TYPE D Fuel and Solvent Resistant | 1287, 1298 |
| EMI-2569 | Silver Copper in Silicone | $$$$ | 65 | .0015 ohm/cm | >145 dB | Highest Conductivity and Shielding Available | 1215 |
| EMI-2529 | Nickel Aluminum in Silicone | $$$ | 70 | .15 ohm/cm | 100 dB | Corrosive Resistant | 6502 |
| EMI-2551 | Nickel Aluminum in Fluorosilicone | $$$ | 70 | .25 ohm/cm | 100 dB | Corrosive Resistant, Fuel and Solvent Resistant | 6503 |
| EMI-502F | Nickel Graphite in Fluorosilicone | $$ | 60 | .1 ohm/cm | 100 dB | Fuel and Solvent Resistance | L6303 |
| EMI-502 | Nickel Graphite in Silicone | $ | 65 | .1 ohm/cm | 100 dB | Lowest Cost with High Shielding | 6308 |
How to Select the Right EMI O-Ring
Selecting the proper conductive seal involves more than choosing the correct size.
Consider the following factors:
Operating Environment
Determine whether the seal will encounter:
- Water or humidity
- Fuel exposure
- Hydraulic fluids
- Cleaning chemicals
- UV or ozone
Fluorosilicone is generally preferred for applications involving fuels or aggressive chemicals.
Shielding Requirement
Higher shielding effectiveness may require silver-filled compounds, particularly in aerospace and defense applications.
Commercial electronic equipment often performs well with nickel-graphite filled materials that offer an excellent balance between performance and cost.
Compression Design
Proper gland design is critical. Excessive compression can shorten seal life, while insufficient compression may reduce both sealing performance and electrical continuity.
Performance Advantages
- Excellent EMI/RFI shielding capability
- Simultaneous environmental sealing
- Low contact resistance
- Reliable conductivity over repeated compression cycles
- Compatible with complex enclosure geometries
- Available in custom molded or vulcanized configurations
- Suitable for harsh industrial environments
| AS568 0-Ring Size - 002 | Cross-Section (CS - Inch) | Cross-Section (CS - Metric) | Inside Diameter(ID- Inch) | Inside Diameter(ID-Metric) | MIL-DTL-83528 Part Number | KODA O-Ring Part Number |
|---|---|---|---|---|---|---|
| 007 | 0.07 | 1.78 | 0.145 | 3.68 | M83528/002X007 | EMI-002-007-XXXX |
| 011 | 0.07 | 1.78 | 0.301 | 7.65 | M83528/002X011 | EMI-002-011-XXXX |
| 012 | 0.07 | 1.78 | 0.364 | 9.25 | M83528/002X012 | EMI-002-012-XXXX |
| 013 | 0.07 | 1.78 | 0.426 | 10.82 | M83528/002X013 | EMI-002-013-XXXX |
| 014 | 0.07 | 1.78 | 0.489 | 12.42 | M83528/002X014 | EMI-002-014-XXXX |
| 015 | 0.07 | 1.78 | 0.551 | 13.99 | M83528/002X015 | EMI-002-015-XXXX |
| 017 | 0.07 | 1.78 | 0.676 | 17.17 | M83528/002X017 | EMI-002-017-XXXX |
| 018 | 0.07 | 1.78 | 0.739 | 18.77 | M83528/002X018 | EMI-002-018-XXXX |
| 019 | 0.07 | 1.78 | 0.801 | 20.34 | M83528/002X019 | EMI-002-019-XXXX |
| 020 | 0.07 | 1.78 | 0.864 | 21.94 | M83528/002X020 | EMI-002-020-XXXX |
| 021 | 0.07 | 1.78 | 0.926 | 23.52 | M83528/002X021 | EMI-002-021-XXXX |
| 022 | 0.07 | 1.78 | 0.989 | 25.12 | M83528/002X022 | EMI-002-022-XXXX |
| 024 | 0.07 | 1.78 | 1.114 | 28.3 | M83528/002X024 | EMI-002-024-XXXX |
| 026 | 0.07 | 1.78 | 1.239 | 31.47 | M83528/002X026 | EMI-002-026-XXXX |
| 028 | 0.07 | 1.78 | 1.364 | 34.65 | M83528/002X028 | EMI-002-028-XXXX |
| 114 | 0.103 | 2.62 | 0.612 | 15.54 | M83528/002X114 | EMI-002-114-XXXX |
| 115 | 0.103 | 2.62 | 0.676 | 17.17 | M83528/002X115 | EMI-002-115-XXXX |
| 117 | 0.103 | 2.62 | 0.799 | 20.29 | M83528/002X117 | EMI-002-117-XXXX |
| 126 | 0.103 | 2.62 | 1.362 | 34.59 | M83528/002X126 | EMI-002-126-XXXX |
| 128 | 0.103 | 2.62 | 1.487 | 37.77 | M83528/002X128 | EMI-002-128-XXXX |
| 132 | 0.103 | 2.62 | 1.737 | 44.12 | M83528/002X132 | EMI-002-132-XXXX |
| 134 | 0.103 | 2.62 | 1.862 | 47.3 | M83528/002X134 | EMI-002-134-XXXX |
| 142 | 0.103 | 2.62 | 2.362 | 59.99 | M83528/002X142 | EMI-002-142-XXXX |
| 145 | 0.103 | 2.62 | 2.55 | 64.77 | M83528/002X145 | EMI-002-145-XXXX |
| 155 | 0.103 | 2.62 | 3.987 | 101.27 | M83528/002X155 | EMI-002-155-XXXX |
Profile 001: Solid O-ring extrusion
| Solid 0-Shape Extrusion Size - 001 | Dimension A (Inch) | Dimension A (Metric) | MIL-DTL-83528 Part Number | KODA O-Ring Part Number |
|---|---|---|---|---|
| 001 | 0.04 | 1.02 | M83528/001X001 | EMI-001-001-XXXX |
| 002 | 0.053 | 1.35 | M83528/001X002 | EMI-001-002-XXXX |
| 003 | 0.062 | 1.57 | M83528/001X003 | EMI-001-003-XXXX |
| 004 | 0.07 | 1.78 | M83528/001X004 | EMI-001-004-XXXX |
| 005 | 0.08 | 2.03 | M83528/001X005 | EMI-001-005-XXXX |
| 006 | 0.093 | 2.36 | M83528/001X006 | EMI-001-006-XXXX |
| 007 | 0.103 | 2.62 | M83528/001X007 | EMI-001-007-XXXX |
| 008 | 0.119 | 3.02 | M83528/001X008 | EMI-001-008-XXXX |
| 009 | 0.125 | 2.18 | M83528/001X009 | EMI-001-009-XXXX |
| 010 | 0.139 | 3.53 | M83528/001X010 | EMI-001-010-XXXX |
| 011 | 0.188 | 4.78 | M83528/001X011 | EMI-001-011-XXXX |
| 012 | 0.216 | 5.49 | M83528/001X012 | EMI-001-012-XXXX |
| 013 | 0.25 | 6.35 | M83528/001X013 | EMI-001-013-XXXX |
Profile 011: Hollow O-ring Extrusion
| Hollow O-Shape ExtrusionSize - 011 | Dimension A (Inch) | Dimension A (Metric) | Dimension B (Inch) | Dimension B (Metric) | MIL-DTL-83528 Part Number | KODA O-Ring Part Number |
|---|---|---|---|---|---|---|
| 001 | 0.125 | 3.18 | 0.13 | 3.3 | M83528/011X001 | EMI-011-001-XXXX |
| 002 | 0.156 | 3.96 | 0.16 | 4.06 | M83528/011X002 | EMI-011-002-XXXX |
| 003 | 0.25 | 6.35 | 0.255 | 5.71 | M83528/011X003 | EMI-011-003-XXXX |
| 004 | 0.312 | 7.92 | 0.317 | 8.05 | M83528/011X004 | EMI-011-004-XXXX |
| 005 | 0.375 | 9.53 | 0.38 | 9.65 | M83528/011X005 | EMI-011-005-XXXX |
| 006 | 0.125 | 3.18 | 0.13 | 3.3 | M83528/011X006 | EMI-011-006-XXXX |
| 007 | 0.103 | 2.62 | 0.107 | 2.72 | M83528/011X007 | EMI-011-007-XXXX |
| 008 | 0.177 | 4.5 | 0.182 | 4.62 | M83528/011X008 | EMI-011-008-XXXX |
Profile 003 Solid D-shaped extrusion
| Solid D-Shape Extrusion Size -003 | Dimension A (Inch) | Dimension A (Metric) | Dimension B (Inch) | Dimension B (Metric) | Dimension C (Inch) | Dimension C (Metric) | MIL-DTL-83528 Part Number | KODA 0-Ring PartNumber |
|---|---|---|---|---|---|---|---|---|
| 001 | 0.031 | 0.78 | 0.062 | 1.57 | 0.068 | 1.73 | M83528/003X001 | EMI-003-001-XXXX |
| 002 | 0.047 | 1.19 | 0.094 | 2.39 | 0.078 | 1.98 | M83528/003X002 | EMI-003-002-XXXX |
| 003 | 0.039 | 0.99 | 0.078 | 1.98 | 0.089 | 2.26 | M83528/003X003 | EMI-003-003-XXXX |
| 004 | 0.047 | 1.19 | 0.094 | 2.39 | 0.094 | 2.39 | M83528/003X004 | EMI-003-004-XXXX |
| 005 | 0.031 | 0.78 | 0.062 | 1.57 | 0.1 | 2.54 | M83528/003X005 | EMI-003-005-XXXX |
| 006 | 0.075 | 1.91 | 0.15 | 3.81 | 0.11 | 2.79 | M83528/003X006 | EMI-003-006-XXXX |
| 007 | 0.061 | 1.55 | 0.122 | 3.1 | 0.135 | 3.43 | M83528/003X007 | EMI-003-007-XXXX |
| 008 | 0.059 | 1.49 | 0.118 | 3 | 0.156 | 3.96 | M83528/003X008 | EMI-003-008-XXXX |
| 009 | 0.078 | 1.98 | 0.156 | 3.96 | 0.156 | 3.96 | M83528/003X009 | EMI-003-009-XXXX |
| 010 | 0.089 | 2.26 | 0.178 | 4.52 | 0.175 | 4.45 | M83528/003X010 | EMI-003-010-XXXX |
| 011 | 0.094 | 2.39 | 0.188 | 4.78 | 0.188 | 4.78 | M83528/003X011 | EMI-003-011-XXXX |
| 012 | 0.125 | 3.18 | 0.25 | 6.35 | 0.25 | 6.35 | M83528/003X012 | EMI-003-012-XXXX |
Profile 007 Hollow D-shaped extrusion
| Hollow D-Shape Extrusion Size -007 | Dimension A (Inch) | Dimension A (Metric) | Dimension B (Inch) | Dimension B (Metric) | Dimension C (Inch) | Dimension C (Metric) | Dimension D (Inch) | Dimension D (Metric) | MIL-DTL-83528 Part Number | KODA 0-Ring Part Number |
|---|---|---|---|---|---|---|---|---|---|---|
| 001 | 0.156 | 3.96 | 0.078 | 1.98 | 0.078 | 1.98 | 0.045 | 1.14 | M83528/007X001 | EMI-007-001-XXXX |
| 002 | 0.187 | 4.75 | 0.093 | 2.36 | 0.093 | 2.36 | 0.05 | 1.27 | M83528/007X002 | EMI-007-002-XXXX |
| 003 | 0.312 | 7.92 | 0.156 | 3.96 | 0.156 | 3.96 | 0.062 | 1.57 | M83528/007X003 | EMI-007-003-XXXX |
| 005 | 0.312 | 7.92 | 0.2 | 5.08 | 0.112 | 2.84 | 0.062 | 1.57 | M83528/007X005 | EMI-007-005-XXXX |
| 006 | 0.487 | 12.37 | 0.08 | 2.03 | 0.244 | 6.2 | 0.08 | 2.03 | M83528/007X006 | EMI-007-006-XXXX |
| 007 | 0.25 | 6.35 | 0.125 | 3.18 | 0.125 | 3.18 | 0.065 | 1.65 | M83528/007X007 | EMI-007-007-XXXX |
Profile 009 Rectangular Extrusion
| Rectangle Shape ExtrusionSize-009 | Dimension A (Inch) | Dimension A (Metric) | Dimension B (Inch) | Dimension B (Metric) | MIL-DTL-83528 Part Number | KODA 0-Ring Part Number |
|---|---|---|---|---|---|---|
| 001 | 0.063 | 1.6 | 0.042 | 1.07 | M83528/009X001 | EMI-009-001-XXXX |
| 002 | 0.095 | 2.41 | 0.062 | 1.57 | M83528/009X002 | EMI-009-002-XXXX |
| 003 | 0.12 | 3.05 | 0.075 | 1.91 | M83528/009X003 | EMI-009-003-XXXX |
| 004 | 0.125 | 3.18 | 0.062 | 1.57 | M83528/009X004 | EMI-009-004-XXXX |
| 005 | 0.156 | 3.96 | 0.062 | 1.57 | M83528/009X005 | EMI-009-005-XXXX |
| 006 | 0.25 | 6.35 | 0.062 | 1.57 | M83528/009X006 | EMI-009-006-XXXX |
| 007 | 0.5 | 12.7 | 0.075 | 1.91 | M83528/009X007 | EMI-009-007-XXXX |
| 008 | 0.5 | 12.7 | 0.125 | 3.18 | M83528/009X008 | EMI-009-008-XXXX |
| 009 | 0.5 | 12.7 | 0.188 | 4.78 | M83528/009X009 | EMI-009-009-XXXX |
| 010 | 0.75 | 19.05 | 0.062 | 1.57 | M83528/009X010 | EMI-009-010-XXXX |
| 011 | 0.88 | 22.35 | 0.062 | 1.57 | M83528/009X011 | EMI-009-011-XXXX |
| 012 | 1 | 25.4 | 0.25 | 6.35 | M83528/009X012 | EMI-009-012-XXXX |
| 013 | 1.18 | 29.97 | 0.062 | 1.57 | M83528/009X013 | EMI-009-013-XXXX |
Profile 010 Channel Extrusion
| Channel Shape Extrusion Size - 010 | Dimension A (Inch) | Dimension A (Metric) | Dimension B (Inch) | Dimension B (Metric) | Dimension C (Inch) | Dimension C (Metric) | Dimension D (Inch) | Dimension D (Metric) | MIL-DTL-83528 Part Number | KODA 0-Ring Part Number |
|---|---|---|---|---|---|---|---|---|---|---|
| 001 | 0.1 | 2.54 | 0.1 | 2.54 | 0.034 | 0.86 | 0.033 | 0.84 | M83528/010X001 | EMI-010-001-XXXX |
| 002 | 0.126 | 3.2 | 0.11 | 2.79 | 0.025 | 0.64 | 0.05 | 1.27 | M83528/010X002 | EMI-010-002-XXXX |
| 003 | 0.126 | 3.2 | 0.225 | 5.72 | 0.02 | 0.51 | 0.075 | 1.91 | M83528/010X003 | EMI-010-003-XXXX |
| 004 | 0.156 | 3.96 | 0.156 | 3.96 | 0.062 | 1.57 | 0.047 | 1.19 | M83528/010X004 | EMI-010-004-XXXX |
| 005 | 0.175 | 4.45 | 0.156 | 3.96 | 0.047 | 1.19 | 0.075 | 1.91 | M83528/010X005 | EMI-010-005-XXXX |
| 006 | 0.327 | 8.31 | 0.235 | 5.97 | 0.062 | 1.57 | 0.115 | 2.92 | M83528/010X006 | EMI-010-006-XXXX |
Profile 008: Hollow P-shaped extrusion
| Hollow P-ShapeExtrusion Size -008 | Dimension A (Inch) | Dimension A (Metric) | Dimension B (Inch) | Dimension B (Metric) | Dimension C (Inch) | Dimension C (Metric) | Dimension D (Inch) | Dimension D (Metric) | MIL-DTL-83528 Part Number | KODA 0-Ring Part Number |
|---|---|---|---|---|---|---|---|---|---|---|
| 001 | 0.2 | 5.08 | 0.08 | 2.03 | 0.065 | 1.65 | 0.062 | 1.57 | M83528/008X001 | EMI-008-001-XXXX |
| 002 | 0.25 | 6.35 | 0.125 | 3.18 | 0.25 | 6.35 | 0.062 | 1.57 | M83528/008X002 | EMI-008-002-XXXX |
| 003 | 0.25 | 6.35 | 0.125 | 3.18 | 0.375 | 9.53 | 0.062 | 1.57 | M83528/008X003 | EMI-008-003-XXXX |
| 004 | 0.25 | 6.35 | 0.15 | 3.96 | 0.375 | 9.53 | 0.062 | 1.57 | M83528/008X004 | EMI-008-004-XXXX |
| 005 | 0.312 | 7.92 | 0.187 | 4.75 | 0.563 | 14.3 | 0.062 | 1.57 | M83528/008X005 | EMI-008-005-XXXX |
| 006 | 0.36 | 9.14 | 0.255 | 6.48 | 0.42 | 10.67 | 0.07 | 1.79 | M83528/008X006 | EMI-008-006-XXXX |
| 007 | 0.2 | 5.08 | 0.08 | 2.03 | 0.275 | 6.99 | 0.062 | 1.57 | M83528/008X007 | EMI-008-007-XXXX |
| 008 | 0.25 | 6.35 | 0.125 | 3.18 | 0.625 | 15.88 | 0.062 | 1.57 | M83528/008X008 | EMI-008-008-XXXX |