Inflatable Seals

Mechanical Research & Design is the industry leader when it comes to producing high quality pneumatic seals, inflatable door seals and other custom air seals.


Seal Profiles Document PDF

How Pneumatic Seals / Inflatable Seals Work

An inflatable seal, also known as a pneumatic seal, is a fabric-reinforced hollow elastomeric tube designed to form a liquid or airtight barrier between a mounting and a striking surface. Depending on the application, they can be molded in a concave, convoluted, or flat configuration.

Inflatable seals introduce a pressurized medium from an external source into the cavity of the hollow seal. This inflation pressure causes the seal to displace in three primary directions: axial, radial in, and radial out.

Once fully inflated, the tubing forms a positive seal between the mounting and striking surfaces. When the inflation pressure is removed, the seal deflates and retracts to its original “memorized” configuration, allowing free relative movement between surfaces.

The most common medium used to inflate seals is air, but some applications may also use various gases, liquids, or gels. The inflation medium is usually administered to the seal via a fitted flexible hose or tubing system.

Why Use an Inflatable Seals

The most beneficial feature of inflatable seals is their ability to apply their own seal pressure. Conventional sealing methods typically rely on the compression of elastomer gaskets to create an effective seal between the surfaces. This compressive stress usually involves the use of bolts or other clamping methods to maintain the compressive stress. The subsequent clamping and unclamping of mating surfaces can be inconvenient and time-consuming.

Inflatable seals, on the other hand, can displace as needed to fill gaps of various shapes and sizes in seconds, forming seals in a fraction of the time compared to conventional sealing methods.

Despite their name, inflatable seals, can be used for applications other than sealing. Some alternative uses include:

  • Applying squeezing forces to materials to assist in the movement of objects
  • Producing holding or clamping mechanical forces
  • Acting as expandable brake calipers to stop rotating equipment
  • Moving objects by applying a pushing force similar to an actuator on a conveyor belt
  • Gripping and lifting objects when inflated

Because of their versatility, inflatable seals are employed in a wide range of industrial applications, including:

  • Bulkhead perimeter seals
  • Chemical barriers
  • Radiation barriers
  • General manufacturing, sealing, and packing
  • Underwater installations
  • Drilling fluid contamination seals

Inflatable Seal Materials

For seals to operate at maximum efficiency, they need to be able to respond appropriately to  environmental and geometrical constraints. Different materials offer varying degrees of durability and shape retention characteristics depending on the application.

As soon as the typical conditions to which the seal will be exposed are known, an inflatable seal made with appropriate materials can be selected. Some of the most widely used seal materials include butyl, natural rubber, chloroprene, nitrile, silicone, and polyurethane. Each of these materials has its own set of advantages and limitations. For example, butyl possesses extremely low permeability to liquid and gases, making it ideal for sealing purposes.  Because butyl is a petroleum-based product, however, it also has poor resistance to hydrocarbon solvents and oils.

Inflatable seals are a versatile product whose uses extend well beyond the sealing of mating surfaces. Selecting an appropriate material is critical to a seal’s performance in a given application.

At Mechanical Research and Design, we’re committed to supplying our customers with innovative solutions to their operational challenges. Regardless of your needs, our qualified engineers will thoroughly asses your situation to help you find the elastomer that best suits your performance criteria.

If you would like to know more about our inflatable seal products, feel free to contact us or request a quote. Our technical team would be happy to assist you on your next project.

Inflatable Seal Features:


Inflatable Seals have a Pressure Tight Closure



Featuring the Virtually-Indestructable Inflatable Seals "Double-Acting" Inflatable Ring



Simple Design Minimizes Close Tolerance Requirements (Straight/Curved/Round)


Inflatable Seal Applications:


General sealing and packing



Bulkhead perimeter seals



Underwater installations



Radiation barriers



Automated lifting and gripping processes



Yacht and ship hatch seals



Oil drilling mud containment seals



Industrial leak testing and pressure decay



Chemical barriers


Strips can be in closed ends, mitered ends, and continuous loops. Mechanical Research & Design can produce inflatable seals from many elastomers including Butadiene Styrene (SBR), Chloroprene (Neoprene), Ethylene propylene (EPDM) and Fluorinated Hydrocarbon (Viton®). Viton(R) is a registered trademark of DuPont Dow Elastomers.

Inflatable seals accessory items such as machined seal housings and inflation control devices are available. Inflatable seals are available for immediate delivery from stock. CUSTOM SHAPES AND SIZES ARE ALSO AVAILABLE UPON REQUEST.


Mechanical Research & Design has patented the Sealfast® "Double-acting" Ring Principle.

Patent Numbers: 4250926, 4342336.

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