Seals and gaskets explained
The purpose of a sealing profile
Sealing profiles include seals, gaskets and edge protectors. All of these protect the edges of doors, windows and machinery from damage while preventing the ingress of dust, debris and moisture. Depending on the material, they can also dampen vibration and noise. In this guide, we’ll explain what you need to know about these critical components, including:
What is the difference between gaskets and seals?
The two terms are often used interchangeably but technically, they are different. They are both sealing profiles and essentially serve the same function. The difference lies in their applications.
For example, a rubber seal strip is used for moving components. Pumps, bearings and rotating shafts are good examples that require a seal profile. Seals are typically round and relatively flat. Shown here are o-rings, which fall into this category. These particular seals are used for hydraulic and pneumatic applications.
Gaskets, on the other hand, are used in static environments to fill the space between flat surfaces. Shown here is a 3D CAD image of a glazing gasket, also called a window seal or window gasket. Gaskets are typically cut into the shape needed to fit the components they’re being affixed to.
How to choose your gasket
Gaskets can be trickier to choose than seals due to their shapes. You’ll need to take into consideration these factors:
- How much force will the two surfaces exert on the gasket?
- Are the surfaces even or uneven? This will determine how thick your gasket should be
- What fluids and potential contaminants will the gasket be exposed to? You’ll need to pay attention to the material you choose.
- How easily can the gasket be compressed? Material plays an important role, and we’ll talk about your choices further on.
Sealing profile types and applications
Here are some examples of different types of sealing profiles, along with their uses.
- Suitable for steel edges that need to be smooth and protected
- Steel spring core
- Flexible PVC – easy to apply by pressing on by hand
- Temperature operating range: -25°C to 90°C
- Easy to bend around corners
Used for: Control panels and windows on generators and other machinery; automotive interiors and underside of car
- Two adjoined surfaces compress the ‘bubble’ to form a seal
- EPDM with steel spring core
- Flexible and easy to apply – press on by hand
- Side or top gasket profiles
- Stops leaks and draughts
- Available with adhesive backing
Used for: Enclosures, junction boxes, double-glazing seal; window seals; door surround weather seal; UPVC door gasket seal
- Available in single or dual flipper gaskets
- Seal is formed by angled flap positioned against a closing surface
- Flexible EPDM – press on by hand
- Provides an excellent compression seal
Used for: Door seal replacement; window seal replacement; double-glazing patio-door seals; UPVC door seals
- Easy-to-fit EPDM
- S profile
- Suitable for lightweight applications
Used for: Window seals for inspection panels where glass or acrylic panels are not subject to high pressure or exposure to weather elements
Weather stripping & gasketing tape
- Closed cell foam provides great barrier protection from moisture and air
- Polyethylene (PE) – flexible at low temperatures
- Excellent resistance to weather and oxidation
- Outstanding conformability
- Also available in low-density PVC and EPDM
Used for: HVACs; white goods; construction; general assembly and UPVC door weather strip
- UPVC sealing strip is closed-cell blend of neoprene, nitrile and PVC
- Excellent resistance to acid, ozone and oxidation
- Operating temperature range: -28°C to 101°C
- Dampens vibration and noise
- Adhesive backing
Used for: HVACs; electrical enclosures; lighting fixtures; door and window sealing strip
- EPDM and PVC provide edge protection and sealing
- Suitable for dampening vibration and noise on sheet metal
- Self-adhesive door-frame seal
Used for: Additional seal on enclosure boxes
- EPDM sponge or EPDM solid profiles offer edge protection and sealing
- Often used in place of o-rings
- Resistance to ozone, weathering, moisture and ageing
- Ideal for outside sealing applications
Used for: Rotary seals; sound-insulation; marine: portholes, hatches and ship window rubber seal
- Clip-on profiles for edge protection and sealing on metal sheets
- PE foam covered in nickel-copper tape
- Protects application against vibration
- Reduces noise
- Reduces radiated emissions
- Low Resistivity 0.8 Ω-cm
- Adhesive base
Used for: enclosures and junction boxes
What is a sealing profile?
Some gaskets and seals contain steel spring cores. These are used when you need a reliable seal in critical applications that operate in typically extreme conditions. A high-temperature application is a good example of when you should choose a gasket with a steel spring core.
The importance of materials for seals and gaskets
Using the right material is critical to the sealing profile’s performance. Each has their own advantage. That said, the same material is not always the same. For example, EPDM produced by one manufacturer could offer better chemical resistance than an EPDM gasket made by another. Always read the manufacturer’s material sheet carefully.
Still, we can talk about materials in general terms as a starting point. The most popular materials for seal profiles are:
EPDM
Ethylene propylene diene monomers, or EPDM, is a synthetic rubber. More specifically, it’s an elastomer, meaning that it has elastic properties. It’s often referred to as ‘EPDM rubber’ due to its similarities to rubber. This makes it ideal for gaskets and seals. Along with its flexibility, it also resists heat and chemicals. You can learn more about this material in our guide, EPDM vs silicone: what’s the difference?
Popular sealing profiles in: Automotive, machinery, generators and HVACs, medical devices, electronics, double-glazing window seal and construction.
Rubber
Generally, rubber is compatible with acids and alkalis, but some rubber seals and gaskets do not stand up well to petroleum fluids. Still other rubber profiles are excellent at standing up to high temperatures. All that said, rubber is excellent as a seal to prevent leaks.
Popular sealing profiles in: Automotive, industrial machinery pumps and valves, and medical-device seals
Closed-cell foam
Common foam materials include polyethylene, polyurethane, neoprene, nitrile and PVC. Two layers of the material are bonded by adhesive tape. These types of gaskets usually cost more than others, but for damping vibration, reducing noise and providing insulation, you can’t do much better.
Popular sealing profiles in: Electronics, enclosures and construction
PVC
Polyvinyl chloride, known as PVC, is available as either rigid or flexible. Obviously for sealing profiles, it’s all about flexibility. Sealing profiles made with PVC resist UV, so they’re especially good for outdoor applications. PVC also absorbs shock and reduces noise.
Popular sealing profiles in: UPVC window seals, glazing seals
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 make sure you’ve chosen 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.