Gasket vs. o-ring: What are the differences?

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What is a gasket?

A gasket is a type of sealing component used to create a barrier between one mating surface and another to prevent the escape or ingress of fluids or gases. To accommodate these flat surfaces, the gasket can be flat or slightly curved. They can also be cut into different shapes to fit precisely between the surfaces they’re meant to seal. They can even be made to fit complex mating surfaces. 

When compressed, gaskets fill in any irregularities or imperfections on the mating surfaces to create a seal. Gaskets must be able to withstand the pressure differentials that occur across the sealing interface. They should maintain their ability to provide an effective seal even under high-pressure conditions to prevent leaks and ensure system integrity.

Gasket seals are sometimes made of flexible materials, such as nitrile rubber and silicone rubber, but can also be made of metal and composite materials, such as rigid polymers. 

Gaskets: common applications

Gaskets are used across different industries that range from automotive to electronics. Applications include:

• Engine components 
• EV battery packs & compartments
• Power generators
• Electronics
• Telecommunication devices 
• Transportation & automotive
• Medical devices
• Food & beverage Industry
• Flange & pipe connections
• Valve covers
• Static joints 

Let’s take a closer look at some examples of where you’ll find gaskets:

Sealing gaskets

Available in EPDM or PVC, these sealing gaskets are typically used to form a protective edge on sheet metal. Ideal for enclosures, they simply clip onto the mating surface to protect against vibrations and ingress of humidity and dirt.

Fan gaskets

Silicone rubber gasket made in a specific shape seals the area between the fan and chassis. The gasket material helps absorb the noise and vibration that otherwise would be transmitted from the fan into the chassis.

Weather Stripping & gasket tape

EPDM foam with an adhesive backing offers excellent resistance to water absorption, ozone and UV ageing. It’s recommended for a maximum 25-50% compression, with an operating temperature range of 20°F to 150°F. Suitable for both indoor and outdoor applications, such as HVACs.

Threaded Protection plug – wide flange

Gaskets made of nitrile rubber provide a liquid tight seal. Excellent resistance to most petroleum based fluids, greases and oils. 

What is an o-ring?

O-rings are mechanical seals that play a crucial role in preventing fluid or gas leakage in various applications. It takes its name from its circular shape, resembling the letter "O". O-rings are typically made of elastomer materials like rubber, silicone, or fluorocarbon.

The primary function of o-rings – sometimes called a packing joint – is to create a seal between two cylindrical-shaped components by being compressed between them. The sealing mechanism of an o-ring relies on compression. When compressed between two surfaces, this mechanical seal exerts radial pressure against the mating surfaces, forming a tight seal that prevents the escape or entry of fluids or gases.

When properly installed, the o-ring fills the gap between the surfaces, effectively blocking the passage of fluids or gases. O-rings are designed to withstand repeated pressure. They can undergo compression and decompression cycles without losing their sealing properties. 

O-ring kits offer the convenience of different ranges at your fingertips, in either imperial or metric sizes. Learn more about these critical components in or Guide to O-Ring Seals. 

O-rings: common applications

Their versatility, effectiveness, and simple design make o-rings a popular choice for sealing applications where leakage prevention is essential. This mechanical seal can be used in static or dynamic applications, across different industries. Specifically, they’re commonly used in:  

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• Hydraulic & pneumatic systems
• Automotive engines, transmissions, fuel systems, braking systems, & air conditioning systems 
• Plumbing & pipe fittings
• Medical & pharmaceutical equipment
• Industrial machinery
• Electronic enclosures

You can see below how o-rings can be used:

O-rings

Available in nitrile rubber or fluoroelastomer. Typically used in hydraulic and pneumatic applications. Also available are o-ring kits, which include a range of sizes. 

Threaded o-ring plug

Nitrile o-ring provides a watertight seal for superior leakage protection for hydraulic fittings. This is what we typically think of how an o-ring looks. 

The red threaded plug’s o-ring is almost indistinguishable from the plug itself. The integral o-ring type bead prevents oil leakage or entrance of contaminants.

O-ring or gasket: What is the best seal for your application?

Is an o-ring a gasket? Technically, yes. But not all gaskets are o-rings. The o-ring and gasket difference comes down to several factors:

• The shape and size of the sealing area can influence the choice between an o-ring and a gasket:      

O-rings: Typically used in circular or cylindrical sealing surfaces
Gaskets: Accommodates irregular or non-circular mating surfaces 

• Evaluate the compatibility of the seal material with the fluid or gas being sealed. 

Gaskets and o-rings are available in various materials, each with specific chemical resistance properties. Consider the chemical composition, temperature range, and potential interactions with the sealing material to ensure compatibility and prevent degradation or leakage.

• Your application might also be affected by pressure and temperature conditions. Generally:

O-rings: Known for their ability to withstand high-pressure applications
Gaskets: May be preferred for extreme temperature conditions or larger sealing surfaces 

• Consider ease of installation and maintenance requirements:

O-rings: Simpler to install and replace, as they’re typically inserted into grooves 
Gaskets: May require careful alignment and bolting

• Evaluate the cost-effectiveness of both seal types: 

O-rings: Generally more cost-effective for smaller sealing applications
Gaskets: Typically costs more to address larger surfaces or unique geometries.

Learn more in our guide, Seals and Gaskets explained. 

Download free CADs and try before you buy

Free CADs are available for most solutions, which you can download. You can also request free samples to ensure the product you’ve chosen is exactly what you need. 

If you’re not quite sure which solution will work best for your application, our experts are always happy to advise you.

Whatever your requirements, you can depend on fast despatch. Request your free samples or download free CADs now.

Questions?

Email us at sales@essentracomponents.co.uk or speak to one of our experts for further information on the ideal solution for your application 0345 528 0474.

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