6 Common Types of Seals and How They Work

Hydraulic seals

Seals are an important part of many machines. They are commonly used around fluid- and gas-carrying hoses. As the fluid or gas inside of a hose heats up, it will expand. This thermal expansion can cause the fluid or gas to leak from mating surfaces. Seals prevent this from happening. They will reinforce the mating surfaces where the fluid- and gas-carrying hose connects to the machine or equipment. Below are some of the most common types of seals and how they work.

#1) O-Ring

O-rings are seals with a circular shape. You can find them in different materials and sizes. Regardless, all O-rings feature a circular shape, making them ideal for hoses. You can place an O-ring around a hose, after which you can connect the hose to a machine. The O-ring will seal the mating surface between the hose and the machine. Even as the hose becomes pressurized, it shouldn’t leak with the O-ring in place.

#2) Lip

Lip seals are characterized by the presence of a lip. They look like O-rings from afar. When inspecting a lip seal up close, though, you’ll notice there’s a lip around it. Lip seals are commonly used around shafts. Also known as rotary seals, they feature lubricant within the lip that protects shafts from friction-related damage.

#3) Backup

As the name suggests, backup seals are used to protect fluid- and gas-carrying hoses from leaks in the event that the main seal fails. Backup seals are used in conjunction with another, main seal. The main seal sits inside of the backup seal. If the main seal fails, the backup seal will prevent a leak from occurring.

#4) Hydraulic

Some machines use hydraulic seals. Consisting of a soft elastomer material, they are used in hydraulic applications. Hydraulic seals are designed to seal and protect leaks in hydraulic cylinders.

#5) Gasket

Gaskets are a common type of seal. The term “gasket” refers to any mechanical seal that’s designed for use on a flat surface. Some gaskets are circular, meaning they fall under the category of O-rings. Other gaskets are square or rectangular shaped.

#6) Vulcanized

There are vulcanized seals available. Vulcanized seals are characterized by their use of vulcanized rubber. Most of them look like O-rings, but they are made of vulcanized rubber. Vulcanization is a hardening process. It involves the use of heat, pressure and chemicals to strengthen and harden rubber. Vulcanized seals are made of this hardened, heat-treated rubber.

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