What’s the Difference Between a Seal and a Gasket?
Gaskets and seals are words that are commonly heard in engineering conversations and they’re very common in usage in many different fields of engineering and manufacturing. So what is the difference between a seal and a gasket? A gasket is a static seal, that is a component that prevents the leakage of fluids between two components that are static i.e does not move. In contrast, seals are dynamic in that there can be an element of movement or even an entire system in place with several moving components. It’s particularly important to understand the difference if you’re the one purchasing the piece of equipment and understanding what one demands a knowledge of what the other is.
For those of us who work in similar fields or maintain a hobby that requires some knowledge of components, it’s quite useful to know the difference so that you’re looking for the right thing, as for these two elements of design, the purposes aren’t that different, but their application certainly is.
There are many different types of gasket and they vary greatly in size and material including:
Ceramic gaskets can be used for high-temperature applications in various industries such as automotive, boiler and fire trades. The properties of the ceramic material allow this.
Nitrile gaskets are made from a material that isn’t damaged by contact with oils and fuels which make them commonplace in the automotive industry. The material is also good at withstanding temperature extremes, the extent to which is governed by the material’s grade.
Nitrile gaskets aren’t typically used for strength applications.
Neoprene is used to make many things, and neoprene gaskets are ideal for scenarios where strength and flexibility are required so has its uses in construction, lighting and even aerospace technologies.
Good at resisting ageing and seawater, the product has a long effective life under normal working conditions.
Silicone Sponge Gaskets
Used where there needs to be a water and airtight seal. Silicone sponge gaskets are used when a seal is required to prevent heat transfer between components.
The material lends itself to being highly customisable and can withstand large temperature extremes typically between -60 and 200 degrees.
In contrast to silicone rubber, the silicone sponge gasket can be clamped down on more inhospitable sealing surfaces.
EPDM is an acronym for the material Ethylene Propylene Diene Monomer and this type of gasket is used for inhospitable sealing surfaces and can handle strong levels of compression.
In comparison, a seal is a dynamic component or set of components that prevent the leakage of fluids. There are many different types of seal including:
EPDM seals are typically produced in a rubber or sponge variant. The rubber variety doesn’t compress like the sponge variety between the two components but the aim of both types of seal is to prevent fluid seepage.
This type of seal has been recommended for applications such as draft exclusion.
PTFE seals have the second lowest coefficient of friction of any solid material and as such are suitable where moving parts need to glide over surfaces effortlessly and smoothly. Where bearings and gears are concerned, this is a necessity.
PTFE seals are ideal in electrical applications including circuit boards as one of its properties is that PTFE is non-conducting. It is also solvent resistant as it is chemically inert and can perform as required when in contact with strong acids and remains so up until approx 300 degrees.
Components that are often used in the same space as gaskets include strips, sheeting, pads and washers. Each has its own purpose in the build of any component but may often be made of similar materials.