Sealing Washers and O-Rings
Flat Sealing Washers and O-Rings for Threaded Conduit Fittings
Sealing washers and O-rings are used with threaded conduit fittings to create a reliable sealing interface between the fitting and the mounting surface. These components help prevent the ingress of moisture, dust, and contaminants into electrical enclosures and equipment housings.
Different sealing materials and designs are available to accommodate various thread types, environmental conditions, and installation requirements.
Flat sealing washers are commonly used for static installations, while O-rings provide flexible sealing for both static and limited dynamic applications.
FLEXAquick® quick-connect fittings and ROHRflex® flexible corrugated conduits are flagship product lines from IBIS Electro-Products Corp., specializing in high-performance electrical conduit systems.
FR Series – General Purpose Flat Sealing Washers
FRH Series – Centellen® High-Performance Flat Sealing Washers
FLEXA FRH-P
PG Centellen flat sealing washers for high-reliability environmental sealing
View ProductsMulti-FR Series – Large Fitting Sealing Rings
OR Series – O-Ring Seals
Choosing the Right Flat Sealing Washer or O-Ring
| Product Family | Seal Type | Material | Thread Types | Temperature Range | Protection Rating |
|---|---|---|---|---|---|
| FR | Flat sealing washer | Buna-N (NBR) | Metric / NPT / PG | −30°C to +100°C | IP54-IP65 |
| FRH | Reinforced flat washer | Centellen® | Metric / NPT / PG | −40°C to +180°C | IP68 |
| Multi-FR | Large sealing ring | Foam rubber / NBR | FLEXAquick multi large fittings | −30°C to +100°C | IP65-IP68 |
| OR | O-ring seal | Buna-N (NBR) | Metric / PG | −30°C to +100°C | IP54-IP65 |
How Sealing Washers and O-Rings Work
Sealing washers and O-rings create a compressed sealing interface between conduit fittings and mounting surfaces such as electrical panels, enclosures, and equipment housings.
Flat sealing washers are installed between the fitting and the mounting surface to prevent water, dust, and debris from entering the enclosure.
O-rings provide a flexible sealing solution where slight movement or vibration may occur.
Specialized sealing rings are also used with larger conduit fittings where increased sealing surface area is required.
Typical Applications
• Industrial automation systems
• Electrical control panels
• Railway vehicle wiring systems
• Machine tool installations
• Outdoor electrical enclosures
• Cable entry points in equipment housings
Frequently Asked Questions About Sealing Washers and O-Rings
When should flat sealing washers be used instead of O-rings?
Flat sealing washers are typically used in static sealing applications, where a threaded conduit fitting is mounted through a panel, enclosure wall, or machine housing. When the fitting is tightened, the washer compresses between the fitting shoulder and the mounting surface, creating a reliable seal against dust, moisture, and contaminants.
O-rings are better suited for applications where a round elastomer seal is required or where limited movement may occur, although most conduit installations rely on flat sealing washers.
What is the difference between FR and FRH sealing washers?
FR sealing washers are general-purpose flat sealing washers made from Buna-N (NBR) rubber. They provide reliable environmental sealing for many industrial conduit installations.
FRH sealing washers are made from Centellen®, a reinforced material composed of aramid fibers bonded with nitrile rubber. These washers offer higher mechanical strength, wider temperature tolerance, and higher sealing performance, making them suitable for demanding industrial environments.
Are sealing washers required for IP-rated conduit fittings?
Yes. In many installations, sealing washers are necessary to achieve the intended environmental protection rating, such as IP65 or IP68. The washer creates the seal between the threaded fitting and the enclosure wall, preventing moisture, dust, and contaminants from entering the enclosure.
Without a proper sealing washer, the conduit fitting may not provide the specified environmental protection level.
Can sealing washers be reused?
Sealing washers are generally not recommended for reuse. When compressed during installation, the sealing material deforms to create a tight seal. Reusing the washer may reduce its sealing effectiveness and compromise environmental protection.
For reliable performance, it is best practice to install a new sealing washer when reinstalling or replacing conduit fittings.
What temperature range do Centellen sealing washers support?
Centellen® sealing washers are designed for high-performance sealing applications and can typically withstand temperatures ranging from approximately −40°C to +180°C, depending on the specific product design and installation conditions.
Their reinforced construction also provides excellent resistance to mechanical stress, vibration, and environmental exposure.
Can sealing washers be used with cord grips, cable glands, and strain relief fittings?
Yes. Flat sealing washers and O-rings can be used with many threaded electrical components including cord grips, cable glands, strain relief fittings, and conduit fittings. As long as the thread type and sealing surface are compatible, sealing washers help prevent the ingress of moisture, dust, and contaminants into electrical enclosures and equipment housings.
For best results, the washer material and thread size should match the fitting and installation environment.
Need Help Selecting the Right Sealing Washer?
Our technical team can help you select the correct sealing washers for your conduit fitting installation.