Types of Mechanical Seals

You are responsible for fixing a machine and all the parts seem to be in working order. However, you find fluid everywhere around it. What could be causing this mess? Mechanical seals are part of the intricate design of machinery and their purpose is to keep air, fluid and other substances from leaking out. Here are a few types of seals.

Hydraulic Seals

These types of seals, such as high pressure hydraulic shaft seals, are used to keep fluid trapped in a hydraulic cylinder. Oil or water pushes a shaft forward through the part to make this cylinder work. The seal is vital since the cylinder will fail without it. Hydraulic seals work great under high pressure.

Bonded Seal

Bonded seals are used to make a screw or bolt tighten a little better. Also known as Dowty seal, it is comprised of a washer and a rubbery piece. The two of them are threaded around the bolt or screw and between them seals tight when applied.


This might not seem like a normal type of seal, but sealant is also used to keep fluid or air from escaping a machine. Instead of being in the shape of a rubber washer, sealant typically comes in an aerosol can. You spray it into the crevice or hole you wish to make leak proof and after a small amount of time it creates an airtight seal. This sort of seal is great if you want to close up a hard to reach place.

Pneumatic Seals

This seal performs best in high speed situations that require low pressure. Like hydraulic seals hold back fluid, pneumatic seals hold back air or gas. These parts have to last a long like with little lubrication and stay intact when being exposed to air. They are primarily found being used in a rotary or reciprocating motions.