• Car engines require valve seals in order to create sufficient pressure to run properly.car engine image by itsallgood from Fotolia.com
  
  A valve seal is a necessary part of most motors and mechanical equipment. In simple applications, such as attaching a hose to a gas tank, a valve seal provides a vacuum pressure to seal in the gaps so pressure, and gas, do not escape. Valve seals are also necessary components in car engines, where they seal the space between parts to keep pressure tight, and keep gas and oil from escaping. While all valve seals operate on a similar principle, many types of valve seals can be used in a number of mechanical applications.
  
  

O-Ring Valve Seal

• The O-ring valve seal is also sometimes called an "umbrella" valve seal. These are the most typically used of all the types of valve seals. While there is much variety in the shape, size and material with which these seals can be made, they have the same basic structure. They are made to sit between two or more parts in a groove, creating a seal at the interface. O-rings are shaped like a torus, a circle with the middle cut out. Their popularity is due to the versatility of the design, their simple mounting requirements and the fact that they can withstand thousands of pounds per square inch of pressure. O-rings are typically manufactured out of either a synthetic rubber or a type of thermoplastic, such as polyurethane polyether. Besides the classic circular O-ring shape, O-ring valves can be made in an X-shaped or square-shaped profile. Custom shaped O-rings can be manufactured to fit almost any part in need of a seal.
  
  

Air Seals

• Air seals, or annular seals as they are also called, fit over a pipe and into the sleeve through which it passes. The outside of the seal is made of a material such as lightweight aluminum and the inflatable valve out of a material such as synthetic rubber or thermoplastic, depending on the conditions the valve must withstand. When the air seal is in place, the rubber seal is inflated. The seal can simply be deflated and reused in other applications. Air seals are rated for 200 psi and come in a variety of sizes for a number of applications in piping industries.
  
  

Ball Valve Seals

• Ball valve seals are typically used in industries where the flow of liquid needs to be shut off periodically. They are made to withstand a high pressure of up to 700 bars and temperatures of up to 200 degrees Celsius. The ball valve seal has two places for pipes to screw in, and in the middle sits a tight-fitting ball, which usually is made of plastic, coated with chromium and contains a hole in the middle. An outside valve moves the ball into two positions. When the valve is "open," the ball is in a position so that liquid can move through the hole in the middle. When the valve is "closed," the ball is moved so that the hole is not lined up and liquid cannot pass. The ball valve seal can be made of metal or plastic.