Unique seals for demanding applications

Aug. 3, 2000
Inflatable seals are not simple rubber extrusions.

Inflatable seals are not simple rubber extrusions. They are molded to fit the particular application, which ensures structural integrity and reliability. Although air is the most common inflation medium, liquid may also be used. The seals are constructed from a variety of elastomers, depending on the application. Common materials include butyl, chloroprene (neoprene), natural rubber, EPDM, and silicone. The elastomers are reinforced with fabrics such as Dacron, Kevlar, and nylon.

Engineers who face challenging sealing problems should consider inflatable seals. The devices seal a variety of gases, liquids, and vacuum, as well as chemicals, slurries, and powders. Inflatable seals are fabric-reinforced elastomeric tubes molded in concave, convoluted, or flat shapes and when inflated — typically with air — they expand between the mating surfaces and create a positive seal. Inflation is through a stem, usually a flexible hose, secured to a fitting molded in the seal.

Inflatable seals hold several advantages over other sealing methods. For instance, they provide a leak-proof interface yet when the inflation medium is removed, they return to their deflated shape and allow free movement of one or both adjacent components. They also simplify design and manufacturing because the seals do not require close tolerances on mating components. Another advantage is that they do not suffer from compression set, a common problem with other seals.

Finally, inflatable seals can be installed in different planes: radially in, radially out, axially, and in any combination of these to conform to many different contours. The seals are made in strips with closed ends or continuous loops. Various bend radii are available and, if a design demands sharp or mitered corners, the seal can be molded to the required configuration. This versatility permits the use of custom-built seals in a wide variety of applications.

Inflatable seals are used virtually anywhere a positive seal between two surfaces is needed, such as a sliding door. Other applications include actuators, brakes, valves, clutches, and wipers in aerospace, automotive, medical, construction, and many other industries.

This information supplied by Sealmaster, Kent, Ohio.

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