O Rings

About O Rings

O rings are indispensable sealing components found throughout plumbing, automotive, hydraulic, and pneumatic systems. These circular elastomer gaskets create pressure-tight seals between mating surfaces, preventing fluid and gas leakage in everything from domestic tap repairs to commercial hydraulic machinery. For professional tradespeople and DIY enthusiasts alike, having immediate access to the correct O ring size can transform a straightforward maintenance job into a quick, successful repair rather than a frustrating delay.

Tooled-Up.com stocks comprehensive O ring assortment sets from respected manufacturers including Sealey, Draper, and Arctic Hayes. These multi-piece collections contain hundreds of O rings in various sizes and specifications, providing exceptional value and convenience for professionals who require immediate access to multiple dimensions. Available in sets ranging from 144 to 419 pieces, these assortments typically include the most commonly used metric and imperial sizes, organised in compartmentalised storage cases for easy identification and selection.

The rubber compounds featured in quality O ring assortments are engineered to withstand varying temperatures, pressures, and fluid types, making them suitable for diverse applications from domestic plumbing repairs to commercial equipment maintenance. Whether you're servicing compression fittings, maintaining hydraulic systems, repairing automotive components, or tackling home plumbing projects, having a comprehensive O ring kit in your van or workshop ensures you're prepared for any sealing challenge.

Jargon Buster

• Durometer: A measurement of the O ring's hardness or softness, typically rated on the Shore A scale. Higher durometer numbers indicate harder, less flexible rubber suitable for high-pressure applications, whilst lower numbers offer greater flexibility for irregular surfaces.
• Cross-Section: The thickness of the O ring's circular profile—the diameter of the rubber "cord" itself—typically measured in millimetres. Common cross-sections range from 1.5mm to 6mm for standard applications, with proper sizing critical for effective sealing.
• Inside Diameter (ID): The internal measurement of the O ring when laid flat, essential for ensuring proper fit in the groove or around the component being sealed. Accurate ID measurement prevents both compression issues and seal failure.
• Nitrile (NBR): The most common O ring material, offering excellent resistance to petroleum-based oils, water, and a wide temperature range (-30°C to +100°C). This versatile compound suits the majority of plumbing, automotive, and general hydraulic applications.
• Compression Set: The permanent deformation that occurs when an O ring remains compressed over time. High-quality O rings manufactured from superior compounds maintain their shape better, providing longer-lasting, more reliable seals.
• Static vs Dynamic Seals: Static seals operate between non-moving parts such as pipe fittings, whilst dynamic seals must accommodate movement like rotating shafts or sliding pistons, requiring different material properties and installation techniques.

Who Uses O Rings?

• Plumbers: For compression fittings, tap repairs, shower valves, and sealed pipe connections throughout domestic and commercial installations
• Heating Engineers: Servicing boilers, circulation pumps, radiator valves, and central heating systems requiring reliable sealed connections
• Automotive Mechanics: Engine repairs, fuel system maintenance, hydraulic brake components, air conditioning units, and transmission assemblies
• Hydraulic Engineers: Maintaining hydraulic rams, cylinders, pumps, and pressure systems across industrial and mobile equipment
• Commercial Gas Engineers: Creating sealed connections in gas appliances, distribution systems, and pressure regulation equipment
• Agricultural Mechanics: Repairing tractors, combine harvesters, and farm machinery hydraulics subjected to demanding outdoor conditions
• Plant Maintenance Engineers: Servicing industrial machinery, pneumatic systems, and manufacturing equipment requiring consistent uptime
• Pool and Spa Technicians: Maintaining pump seals, filter housings, and water circulation systems in leisure facilities
• DIY Enthusiasts: Tackling home plumbing repairs, washing machine connections, and general property maintenance projects
• Marine Engineers: Boat engine maintenance and marine plumbing systems where reliable sealing prevents costly water ingress

How to Choose the Right O Rings

Size and Dimensions: Accurate measurement is fundamental to successful sealing. Measure the inside diameter (ID) and cross-section thickness of the existing O ring or the groove it occupies. Purchasing comprehensive assortment sets ensures you have multiple sizes readily available, eliminating guesswork during site work and reducing return journeys for incorrectly sized components.

Material Compatibility: Most standard O ring assortments available from Tooled-Up feature nitrile rubber (NBR), which suits the vast majority of plumbing, automotive, and general hydraulic applications involving water, petroleum oils, and moderate temperatures. For specialised applications involving extreme temperatures, aggressive chemicals, or specific fluids such as strong acids or solvents, consult material compatibility charts or seek specialist compounds.

Application Type: Determine whether the seal is static (between non-moving parts) or dynamic (accommodating rotating or reciprocating motion). Most assortment sets are suitable for static applications, which cover the majority of plumbing repairs, compression fittings, and general maintenance work undertaken by tradespeople.

Pressure and Temperature: Ensure the O ring material can withstand the system's operating pressure and temperature range. Standard nitrile O rings handle most domestic and light commercial applications effectively, whilst specialised compounds may be required for extreme conditions found in industrial processes or high-performance automotive applications.

Assortment Size: For professional tradespeople, larger sets containing 225-419 pieces offer superior value and comprehensive size coverage for diverse jobs. The Arctic Hayes 144-piece set is specifically curated for plumbing applications, whilst general assortments from Sealey and Draper suit multi-trade requirements across various industries.

Storage and Organisation: Quality assortments include compartmentalised storage cases that protect O rings from environmental degradation whilst enabling quick size identification on site. This organised approach saves valuable time during repairs and prevents mixing of different dimensions.

Popular Accessories

• O Ring Pick Sets: Specialised tools featuring hook and pick configurations for removing O rings from tight grooves without causing damage to sealing surfaces
• Lubricants and Greases: Silicone or petroleum-based lubricants that ease installation, prevent twisting damage, and extend O ring service life
• Digital Callipers: Precision measuring instruments for accurately determining O ring dimensions and verifying groove specifications
• Storage Cases: Additional compartmented organisers for keeping loose O rings sorted by size in workshops and mobile service vehicles
• Compression Fittings: Plumbing fittings that work alongside O rings to create leak-free connections in water and heating systems
• Thread Seal Tape (PTFE): Complementary sealing material for threaded connections where O rings may not be appropriate
• Gasket Sets: Additional sealing solutions for flanged connections, larger assemblies, and applications requiring flat gasket profiles
• Installation Tools: Cone-shaped fitting tools and plastic sleeves that guide O rings into position without nicking or twisting
• Tool Rolls and Pouches: Portable storage solutions for carrying O ring assortments and related tools to site work locations

Frequently Asked Questions

How do I measure an O ring correctly?

Measure the inside diameter (ID) by laying the O ring flat on a surface and measuring straight across the inner hole using callipers or a ruler. Then measure the cross-section (cord thickness) using digital callipers for accuracy. If the O ring is damaged, missing, or unavailable, measure the groove diameter and depth instead. Most standard assortments include size identification charts and reference guides to help match your measurements to the correct replacement.

Can I reuse an O ring after removing it?

Generally, reusing O rings is not recommended for critical sealing applications. O rings are inexpensive components, and reusing them risks leaks due to compression set (permanent deformation), surface damage, nicks, or contamination picked up during removal. For important applications in plumbing, heating, or hydraulic systems, always fit a new O ring. Having a comprehensive assortment kit ensures you'll always have fresh seals available, eliminating the temptation to reuse questionable components.

What's the difference between metric and imperial O rings?

Metric O rings are measured in millimetres for both inside diameter (ID) and cross-section dimensions, whilst imperial O rings use inches or fractional inches. Many comprehensive assortments include both measurement standards, as British plumbing and automotive applications may use either depending on the component's country of origin and manufacturing era. Using close-but-not-exact sizes will generally result in seal failure, so accurate sizing is essential.

How long do O rings last in storage?

When stored properly in cool, dark, dry conditions away from ozone sources (such as electric motors), direct sunlight, and temperature extremes, nitrile O rings typically remain serviceable for 5-10 years. The compartmentalised cases provided with quality assortments from brands like Draper and Sealey help protect O rings from environmental degradation. Avoid storing O rings near solvents, fuels, or in areas with temperature fluctuations.

Why do O rings fail prematurely?

Common failure causes include incorrect sizing (too large or too small for the groove), incompatible materials with the sealed fluid, over-compression or under-compression in the groove, installation damage such as twisting or nicking, excessive operating temperature, chemical attack from incompatible fluids, and age-related hardening. Using the correct size from a quality assortment, applying appropriate lubrication during installation, and following proper fitting techniques prevents the vast majority of premature failures in typical trade applications.