Inflatable seals are rubber gaskets that inflate instead of compress to seal-out the environment. They conform well to irregular or misaligned surfaces and require low closure force. Typically, inflatable seals are filled with air; however, some products use gases, liquids, or gels instead. The medium is delivered through a hose and then pressurized so that the inflatable seal expands. Depending on the specific seal type, clamps may be needed to hold the gasket in the channel.
Because they apply their own sealing pressure, pneumatic seals are effective at filling gaps with unusual shapes or sizes. They can be molded or extruded from various elastomers and, in the case of molded seals, reinforced with fabric for added strength. Elasto Proxy can supply the inflatable seals that you need along with many other industrial rubber products, including elastomeric compressive seals, molded plastic parts, and thermal and acoustic insulation.
Contact us and let us know what you need or keep reading to learn how to select an inflatable seal in five steps.
Step 1: MTAP
For any type of rubber seal, it’s important to begin with MTAP, Elasto Proxy’s easy-to-remember acronym for Media (M), Temperature (T), Application (A), and Pressure (P). The table below contains some key questions that you’ll need to ask and answer.
Media | Are any chemicals involved? Is contact with this media intermittent, or does it involve full immersion? |
Temperature | What are the minimum and maximum operating temperatures? Are there rapid changes in temperature? |
Application | What is the industry in which the inflatable seal will be used? What will the seal be installed within the application? |
Pressure | What are the pressures that seal must withstand? Will the seal be subjected to high pressure or vacuum conditions? |
Because inflatable seals are used in many different applications, it’s important to consider the entire environment. For example, inflatable seals can be used with the doors on food processing equipment, commercial laundry machinery, flood protection systems, and airplanes. Some of these environments involve exposure to greases and chemicals, while others involve demanding temperature and pressure conditions.
Step 2: Configuration
The configuration of an inflatable seal refers to the seal’s basic shape and determines the diameter you’ll need to specify. There are four basic configurations.
- circular
- rectangular
- U-shaped
- straight
With the exception of straight profiles, inflatable seals can expand outward, inward, or radially. The direction of expansion determines whether you need to specify the inner diameter (ID), outer diameter (OD), or center line (CL) diameter during seal selection. If the corner radii are tight, you may need an inflatable seal with molded or pre-formed corners.
Step 3: Profile
The seal’s profile describes its cross-section along with other important characteristics, such as fastening. Numbered types provide a standard way to identify inflatable seals by profile. The table below explains.
Type | Description |
1 | Footed seal that fastens in place and has a good range of travel. |
2 | Racetrack seal that’s held in place by friction. Used in tight spaces. |
3 | Snap-in seal with a large travel for its width, which allows it to seal large gaps. |
4 | Inflatable seal that sits in a channel and inflates outward to fill a large gap. |
7 | Mounts in a groove and is designed for heavy-duty applications. |
10 | Heavy-duty profile for high pressures and smaller gaps. |
22 | Molded bladders for small-diameter sealing. |
Step 4: Material
Inflatable seals come in compounds such as butyl, chloroprene, EPDM, natural rubber, nitrile, silicone, and polyurethane. Each compound has advantages and limitations. For example, butyl is excellent for sealing because it has low permeability to liquids and gases; however, this type of rubber has poor resistance to hydrocarbon solvents and oil.
Yet, compound alone isn’t the only material consideration. If you need a seal with added strength, you can choose nylon or Kevlar for reinforcement. For mass transit applications such as buses and rail, you may need a seal material with low smoke and flame resistance. There are also inflatable seals for medical and pharmaceutical applications that meet USP Class VI requirements for cleanliness.
Step 5: Air Connectors
Inflatable seals use four main types of air connectors:
- flexible hose connectors
- solid shank end connectors
- mechanical connectors
- molded-in-place connectors
Typically, the location of the seal determines the connector type. Most hoses are made of polyurethane, and additional specifications include hose length, color, fittings, and whether the hose is supplied loose.
Inflatable Seals from Elasto Proxy
Elasto Proxy provides one-stop shopping for all of your industrial rubber products. In addition to inflatable seals, we offer compressive elastomeric seals, solid and sponge rubber profiles, finished gaskets, and silicone hose connectors – just to name a few. Whether you’re a machine builder, a robot manufacturer, or part of the marine, aerospace, or semiconductor industries, let us know what you need.
