Rubber O-rings seal out leaks in engines, hydraulics, plumbing, and aerospace systems. They come in 12 materials and in standard, metric, and custom sizes. Rubber Xperts supplies rubber products like O-rings with specific material specifications according to your requirements.
A rubber O-ring is a round elastomer ring that seals the gap between two parts, compressing in a groove to block liquids and gases.
10% discount for bulk orders over $1,000
Types of Rubber O-Rings We Produce
We produce rubber O-rings in 12 materials. The material sets chemical resistance, temperature range, and cost, so it is the first choice to get right. Pick a card to see the material, and select it to request a quote.
Silicone O-Rings
Silicone O-rings are molded from VMQ elastomer prized for performing reliably across an unusually wide temperature range while remaining safe for food, medical, and electronic contact. Whether the application runs bitterly cold or intermittently hot, silicone O-rings hold their seal without cracking or losing flexibility.
Applications: Food and beverage equipment, medical devices, electronics enclosures, HVAC, aerospace components
Materials: Silicone (VMQ)
Temperature Resistance: -60°C to 200°C (short-term up to 230°C)
Hardness: 40 – 80 Shore A (most commonly 50–70)
Sizing: AS568 and metric ISO 3601 standard sizes, custom sizes available
EPDM O-Rings
EPDM O-Rings are built from ethylene propylene diene monomer rubber, a compound that resists water, steam, and outdoor weathering far better than most general-purpose elastomers. For potable water systems, HVAC, and outdoor seals, EPDM O-Rings stay pliable and leak-free season after season.
Applications: Potable water systems, HVAC equipment, outdoor and weatherproof seals, brake systems using non-petroleum fluids
Sizing: AS568 and ISO 3601 standard sizes, custom sizes available
Neoprene O-Rings
Neoprene O-Rings, made from chloroprene rubber, balance moderate oil resistance with solid weathering and flame resistance, making them a dependable general-industrial choice. When a seal needs to handle everyday exposure to oils, ozone, and outdoor conditions without a premium price tag, neoprene O-rings are the practical fit.
Applications: Refrigeration systems, general industrial machinery, outdoor equipment, moderate oil and fuel exposure
Materials: Neoprene (CR – chloroprene rubber)
Temperature Resistance: -40°C to 120°C
Hardness: 40 – 85 Shore A (most commonly 60–70)
Sizing: AS568 and ISO 3601 standard sizes, custom sizes available
Fluorosilicone O-Rings
Fluorosilicone O-rings combine silicone's extreme-temperature flexibility with meaningful fuel and oil resistance, a pairing few compounds offer. Fluorosilicone O-rings excel in applications where standard silicone is inadequate, providing reliable sealing for aerospace and military systems that require durability against both cold temperatures and direct exposure to fuel.
Applications: Aerospace and military fuel systems, aircraft hydraulics, low-temperature fuel-exposed seals
Materials: Fluorosilicone (FVMQ)
Temperature Resistance: -70°C to 175°C (short-term up to 200°C)
Hardness: 40 – 80 Shore A (most commonly 60–70)
Sizing: AS568 and ISO 3601 standard sizes, custom sizes available
FKM O-Rings
FKM O-Rings (often known by the brand name Viton) are the go-to fluorocarbon compound for sealing against aggressive fuels, oils, and chemicals at sustained high temperatures. FKM O-rings keep their seal integrity long after standard nitrile degrades in demanding chemical-processing and fuel-system environments.
Temperature Resistance: -20°C to 200°C (special low-temperature grades to -40°C)
Hardness: 60 – 90 Shore A (most commonly 75)
Sizing: AS568 and ISO 3601 standard sizes, custom sizes available
HNBR O-Rings
HNBR O-Rings are hydrogenated nitrile compounds engineered for higher heat and abrasion resistance than standard nitrile offers. Automotive and hydraulic systems that push seals harder and hotter than average rely on HNBR O-Rings to keep running without unplanned downtime.
Sizing: AS568 and ISO 3601 standard sizes, custom sizes available
Buna (NBR) O-Rings
Buna (NBR) O-Rings are the industry's workhorse nitrile compound, offering solid resistance to oils, fuels, and hydraulic fluids at a cost-effective price point. For everyday automotive and hydraulic sealing where extreme conditions aren't in play, Buna (NBR) O-Rings remain the most widely specified choice.
Applications: Automotive fuel and oil seals, hydraulic systems, general industrial sealing
Materials: Nitrile (NBR)
Temperature Resistance: -40°C to 120°C
Hardness: 40 – 90 Shore A (most commonly 70)
Sizing: AS568 and ISO 3601 standard sizes, custom sizes available
Polyurethane O-Rings
Polyurethane O-rings stand out for abrasion resistance and load-bearing toughness beyond standard rubber compounds. In pneumatic and hydraulic systems where seals face constant friction and mechanical wear, polyurethane O-rings outlast softer elastomers by a wide margin.
Applications: Pneumatic systems, hydraulic equipment, heavy machinery, high-wear and abrasive environments
Materials: Polyurethane (AU/EU)
Temperature Resistance: -30°C to 80°C (short-term up to 100°C)
Hardness: 70 – 95 Shore A
Sizing: AS568 and ISO 3601 standard sizes, custom sizes available
Santoprene O-Rings
Santoprene O-Rings are thermoplastic vulcanizates that deliver rubber-like sealing performance with better resistance to repeated compression cycling and UV exposure than many traditional compounds. For outdoor equipment and appliances that see constant thermal cycling, Santoprene O-Rings hold their shape and seal longer.
Applications: Outdoor equipment, household appliances, water-handling components, general fluid sealing
Materials: Polyurethane (AU/EU)
Temperature Resistance: -60°C to 135°C
Hardness: 55 – 90 Shore A
Sizing: AS568 and ISO 3601 standard sizes, custom sizes available
Butyl Rubber O-Rings
Butyl rubber O-rings offer some of the lowest gas permeability elastomers, making them the natural choice wherever a seal holds against air or gas migration rather than aggressive chemicals. Vacuum systems and pressurized containers depend on butyl rubber O-rings to maintain that seal over long service life.
Applications: Vacuum systems, pressurized gas containers, insulating glass seals, chemical drum seals
Materials: Butyl rubber (IIR)
Temperature Resistance: -40°C to 120°C
Hardness: 40 – 80 Shore A
Sizing: AS568 and ISO 3601 standard sizes, custom sizes available
Natural Rubber O-Rings
Natural rubber O-rings deliver elasticity and tear resistance that synthetic compounds often can't match, making them ideal for seals that face constant flexing or shock loading rather than chemical exposure. Where abrasion and vibration are the main concerns, natural rubber O-rings hold up longer than most alternatives.
Applications: General mechanical sealing, vibration and shock dampening, abrasion-heavy applications
Materials: Natural rubber (NR)
Temperature Resistance: -50°C to 80°C
Hardness: 30 – 90 Shore A
Sizing: AS568 and ISO 3601 standard sizes, custom sizes available
AEM O-Rings
AEM O-Rings are ethylene acrylic elastomer seals purpose-built for automotive powertrain and drivetrain applications exposed to hot transmission and axle fluids over long service intervals. Where standard nitrile would harden and crack under sustained heat, AEM O-Rings keep sealing reliably.
Applications: Automotive powertrain seals, transmission and axle housings, hot-oil-exposed components
Materials: Ethylene acrylic elastomer (AEM)
Temperature Resistance: -40°C to 150°C (short-term up to 175°C)
Hardness: 50 – 85 Shore A
Sizing: AS568 and ISO 3601 standard sizes, custom sizes available
Bulk O-Ring Orders
Buy High-Quality Rubber O-Rings in Bulk Today From Rubber Experts Inc
Need O-ring suppliers who can ship in volume? Rubber Xperts supplies standard, metric, and custom O-rings in bulk, with packaging set to your requirements.
Your Custom Rubber O-Rings Journey - From Selection to Delivery
Ordering a custom O-ring doesn't have to mean guessing at a spec sheet. Here's how the process runs from your first call to the part landing on your dock:
01
Consultation and Selection
We start by reviewing your application. Liquids or gases, temperature range, pressure, and movement (static or dynamic) then narrow down the compound and size that fit.
02
Quote and Engineering
Once the material and dimensions are set, our team engineers the O-ring to your tolerances and provides a firm quote covering material, tooling (if needed), and lead time.
03
Custom Manufacturing
Your O-rings are made to spec in-house, with in-process checks on dimensions and cure to keep every part within tolerance.
04
Quality Control and Shipping
Finished parts go through final inspection against your spec before they're packed and shipped, with documentation available on request for regulated applications.
Total Turnaround: 7-10 business days | Express bulk O-rings available in 7-10 days
What Are Rubber O-Rings and Why Are They Essential?
Rubber O-rings are circular elastomer seals designed to fit into grooves and prevent the passage of liquids or gases. Also known as O-ring seals or O-ring gaskets, these flexible sealing elements create airtight and watertight barriers by compressing between two surfaces under pressure or movement.
Their primary function is maintaining leak-proof connections in industries ranging from plumbing and automotive to manufacturing and chemical processing. According to a Research Nester Report, the O-ring market in the aerospace equipment segment is expected to gain a 52% share by 2037, highlighting the critical role O-rings play in fueling industrial growth.
The elastomeric properties of O-rings allow them to deform and fill gaps while returning to their original shape, ensuring consistent sealing performance under varying conditions. This adaptability, combined with their cost-effectiveness and ease of installation, makes them indispensable components across countless applications.
What Materials Are Used in Rubber O-Ring Manufacturing?
Rubber O-rings are made from elastomers, and each one trades off chemical resistance, temperature range, wear life, and cost. The same compound families appear in our gasket materials, so a material that works for a gasket in your fluid and temperature usually works as an O-ring. Temperature figures below are typical continuous ranges, and the exact limit depends on the compound.
Buna (NBR): Oils, fuels, and hydraulic fluids. About -30°C to 100°C.
HNBR: Oils plus higher heat and wear resistance. About -30°C to 150°C.
FKM (Viton): Fuels, oils, many acids, and solvents. About -20°C to 200°C.
Silicone: Wide temperature range, clean applications. About -60°C to 200°C.
Fluorosilicone: Fuels and oils at low and high temperatures. About -60°C to 175°C.
EPDM: Water, steam, weather, ozone, alkalis. About -50°C to 150°C.
Neoprene: Weather, ozone, moderate oils, and refrigerants. About -40°C to 100°C.
Polyurethane: Abrasion and tear resistance in hydraulics. About -30°C to 80°C.
Santoprene: Weather, ozone, and mild chemicals. About -40°C to 135°C.
Butyl: Low gas permeability, steam, and vacuum. About -50°C to 120°C.
Natural rubber: High elasticity in water and low-stress use. About -50°C to 80°C.
AEM: Hot oils and transmission fluids. About -30°C to 150°C.
How to Choose the Best Rubber O-ring Material
Choose the material in this order: the conditions the ring faces, the fluid it touches, how it moves, and the rules it must meet.
Temperature Requirements
Check both the lowest and highest temperatures the ring will see, including spikes. Silicone and fluorosilicone handle cold, FKM and silicone handle heat, and NBR suits moderate ranges. A ring used above its limit hardens and loses its seal. Below its limit, it turns stiff and leaks.
Chemical Compatibility
Match the elastomer to the fluid. NBR resists oils and fuels. EPDM resists water, steam, and alkalis but swells in petroleum oils. FKM covers fuels, oils, and many chemicals. A ring that swells, shrinks, or softens in its fluid will fail, so check a compatibility chart for your exact media.
Pressure Conditions
At high pressure, O-rings can be forced into the clearance gap and extrude. Above roughly 1,500 psi, use a harder compound, such as 90 Shore A, or add backup rings. Dynamic seals reach their limit at lower pressure than static ones. High-pressure O-rings also need accurate groove dimensions and tight clearances.
Dynamic vs Static Use
Static seals only need to resist compression set and the fluid. Dynamic seals also face friction, wear, and heat build-up, so they need abrasion-resistant, lubricated materials such as polyurethane, HNBR, or NBR at the right hardness.
Regulatory Compliance
If the ring touches food, drinking water, or patients, it must meet the standard. Common ones are FDA 21 CFR 177.2600 for food contact, NSF/ANSI 61 for drinking water, and USP Class VI for medical use. Aerospace and automotive work often call out AMS or ASTM D2000 material specs.
How to Determine Rubber O-Ring Sizes
To determine the rubber o-ring sizes, consider the following O-ring dimensions:
An O-ring is sized by three dimensions: inner diameter (ID), cross-section (CS), and outer diameter (OD), where OD = ID + 2 × CS. Ring sizes run from micro, tiny, and small rings to large and thick ones, and all use the same three dimensions. Flat and square-profile rings are also specified by ID, OD, and thickness. Match the ring to its groove, because a wrong size leaks or gets pinched.
Standard Sizing Systems:
AS568: The US inch standard, with dash numbers such as -214, sets ID and CS.
Metric (ISO 3601): Sizes are written as ID × CS in millimeters.
BS 1806 and JIS B 2401: British and Japanese standards, used for equipment made to those specs.
Measuring Tools:
Digital caliper: Measures ID and CS on a relaxed ring.
O-ring size gauge or cone: Reads the size directly from a tapered or notched gauge.
Pi tape: Wraps around large rings or grooves.
Sizing chart: Matches your measurements to the nearest standard dash or metric size.
The Benefits of Rubber O-Rings
The key features and benefits of the rubber o-rings Rubber Xperts Inc sells are highlighted below:
Reliable Leak Prevention Under Pressure
Because an O-ring compresses and rebounds against the mating surfaces, it maintains a consistent seal even as pressure and temperature fluctuate, cutting down on leak-related downtime and fluid loss.
Cost-Effective and Easy to Install or Replace
O-rings are inexpensive relative to other seal types and require no special tools to install, which keeps both initial part cost and maintenance labor low.
Wide Size Availability in Standard and Metric Dimensions
With standardized sizing systems covering most common applications, replacement parts are easy to source without a custom order in the majority of cases.
Chemical & Heat Resistance for Harsh Environments
The right compound choice lets an O-ring hold its seal in the presence of aggressive chemicals or sustained high heat that would degrade lesser materials.
Versatile for Multi-Industry Applications
The same basic design scales from tiny electronics seals to large industrial hydraulic cylinders, making O-rings adaptable across automotive, aerospace, plumbing, and manufacturing use cases.
How to Install Rubber O-Rings
To install Rubber O-rings, consider the following steps:
1
Step 1: Inspection and Preparation
Clean the groove and surrounding area thoroughly, removing debris, old lubricant, or metal shavings. Inspect the O-ring for cuts, cracks, or deformation that could compromise sealing integrity.
2
Step 2: Lubrication Application
Apply a compatible lubricant to reduce friction during installation. Use silicone-based grease for general applications or synthetic O-ring oil for specialized requirements. Ensure lubricant compatibility with the O-ring material and system fluids.
3
Step 3: Careful Positioning
Position the O-ring without excessive stretching or twisting. Use plastic installation picks from O-ring mounting kits to avoid damage. Roll the O-ring into place rather than pulling aggressively to prevent overstretching.
4
Step 4: Proper Seating
Ensure even seating in the groove with no pinching or bulging. Check alignment to maintain consistent compression across the entire circumference.
5
Step 5: System Testing
Test the assembly under operational conditions to verify sealing integrity. Perform pressure testing according to manufacturer specifications to confirm reliable performance.
Squeeze determines whether an O-ring seals or fails. Use these ranges as a starting point, then check against your gland design and material.
Reliable Leak Prevention Under Pressure
The squeeze on the ring increases as pressure rises, so the seal gets tighter instead of weaker.
Cost-Effective and Easy to Install or Replace
A single molded ring with no moving parts costs little and drops into a groove in minutes, so repairs are quick and cheap.
Wide Size Availability in Standard and Metric Dimensions
Standard inch, metric, and custom sizes are widely stocked, so you can usually find a replacement or order an exact fit.
Chemical & Heat Resistance for Harsh Environments
The right compound resists fuels, oils, steam, acids, or extreme temperatures that would destroy other seals.
Versatile for Multi-Industry Applications
The same ring design works in automotive, industrial, plumbing and HVAC, food and pharmaceutical, marine, aerospace, and electronics equipment.
To maintain rubber O-rings, follow the steps below.
Static Applications
Compress the cross-section by about 15% to 30%. Static seals need a firmer squeeze because nothing moves to wear the ring.
Dynamic Applications
Compress by about 10% to 20%. Less squeeze reduces friction, heat, and wear on moving parts.
Over-compression
Squeezing past these ranges causes compression set, cracking, and extrusion. The ring takes a permanent flat, and the seal weakens.
Under-compression
Squeezing too little leaves gaps and leaks, especially at low pressure or when the ring has shrunk with age or cold.
The common issues of rubber O-rings are listed below.
Compression set
The ring takes a permanent flat after long squeeze, heat, or age, so it no longer springs back and seals. Look for a flattened cross-section.
Extrusion
High pressure pushes the ring into the clearance gap, where it gets nibbled or torn. Look for ragged edges on the low-pressure side. A harder compound or a backup ring prevents it.
Chemical attack and swelling
The wrong compound for the fluid swells, softens, shrinks, or dissolves. Look for a ring that has grown, gone sticky, or turned brittle.
Heat hardening
Running above the temperature rating bakes the ring hard and brittle. Look for a hard, dark surface with small cracks.
Cold stiffening
Below its low-temperature limit, a ring loses elasticity and leaks until it warms up.
Ozone and UV cracking
Outdoor exposure cracks natural rubber and standard NBR. Look for fine surface cracks on stretched areas.
Installation damage
Sharp edges, threads, or missing lubrication cut or pinch the ring while it goes in. Look for nicks, spiral twists, or cuts.
Wear and abrasion
Moving parts, rough surfaces, or poor lubrication scrape dynamic rings flat. Look for a worn, shiny flat spot.
To test the rubber O-rings' performance and quality, follow the steps below.
Pressure Testing
Hold the sealed assembly at working and proof pressure and watch for leaks or extrusion.
Chemical Compatibility Testing
Immerse sample rings in your fluid, then measure volume change, hardness, and mass.
Temperature Cycling
Cycle between your lowest and highest temperatures to check for hardening, softening, and leaks.
Compression Set Testing
Compress a ring for a set time and temperature, then measure how much it fails to recover. A low result means a longer-lasting seal.
Need help choosing the best rubber O-Rings for your use case?
Explore Related Categories and Accessories
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Rubber O-rings seal by compression, so material, size, temperature, and fluid compatibility decide which ring fits. These answers cover those factors, plus standards, replacement, and custom orders.
The main difference between an O-ring and a seal is that an O-ring is a specific type of circular sealing element, while a seal is a broader category encompassing various shapes and designs for containing fluids or gases.
You should use Rubber O-rings when the application requires a simple, versatile, and leak-proof solution for sealing under dynamic or static conditions. Conversely, Gaskets are better suited for flat surfaces or irregular shapes requiring a broader sealing area. Rubber O-rings are ideal for pressure systems and fluid containment, while gaskets excel in applications like machinery gaskets or flanged connections.
Yes, rubber O-ring seals can be made from eco-friendly materials by using sustainable rubber compound types derived from natural or recycled sources. Natural rubber or biodegradable alternatives are formulated to meet specific sealing needs, although they might have chemical or heat resistance limitations compared to synthetic rubbers like Viton (FKM). These eco-friendly solutions are increasingly popular in industries prioritising sustainability without compromising seal performance tracking.
Viton/FKM and EPDM O-rings perform best in chemical-heavy environments. Viton excels against solvents and fuels, while EPDM is suitable for water, steam, and some mild chemicals.
Viton/FKM is the most reliable for solvents and fuels, while NBR is suitable for oils and standard fuels but not for harsh chemicals.
Yes. Silicone O-rings can tolerate extreme cold (-60°C), and Viton/FKM can handle up to 200°C or more.
EPDM and Neoprene O-rings are excellent for UV, weather, and marine exposure.
Inspect quarterly for critical systems and replace annually or sooner if exposed to high pressure, heat, or chemicals.
Yes. Rubber Xperts Inc offers custom O-rings and seals for regulated industries and can meet ISO, ASTM, and FDA requirements.
Common causes include over-compression, chemical attack, heat degradation, and improper storage. Use compatible materials and follow installation best practices.
Yes. Store in a cool, dry, and dark place, away from UV exposure, ozone, or chemical vapors.
Yes. We provide bulk supply and OEM support with competitive pricing for industrial buyers.
It’s not recommended. O-rings may deform or pick up debris; replacing them ensures a reliable seal.
Measure the inner diameter (ID), outer diameter (OD), and cross-section using a caliper or O-ring sizing chart.
Yes. Silicone and Viton/FKM O-rings handle the highest temperature ranges.
Replacement depends on material and application. In standard conditions, annual inspection and replacement are recommended.
Yes. Contact us for custom O-ring kits, bulk options, and special size orders.
