Silicone and LSR
Silicone and liquid silicone rubber are the main choices for flexible umbrella valves. Most designs use material below 55 Shore A, with many applications in the 30 to 40 Shore A range.
Custom Silicone Umbrella Valves
One-piece elastomer check valves for low-pressure sealing, venting, and controlled one-way flow.
- Custom cracking pressure, skirt profile, stem, and seat design
- Silicone, LSR, FVMQ, EPDM, NBR, and CR material options
- Medical, automotive, consumer, and industrial valve support
What Is an Umbrella Valve?
An umbrella valve, also called a mushroom valve or diaphragm check valve, is a one-piece elastomer valve with a flexible circular skirt and a central retaining stem. The stem usually includes a hook or barb that locks the valve into the mounting hole.
At rest, the skirt presses against the valve seat and seals the flow path. When upstream pressure reaches the required cracking pressure, the skirt edge lifts and allows fluid or gas to pass. When pressure drops or reverses, the skirt returns to the seat and closes the valve.
Umbrella Valve Materials
Material selection affects cracking pressure, recovery, sealing life, media resistance, sterilization compatibility, and manufacturability.
FVMQ, EPDM, NBR and CR
FVMQ can be selected for oil and fuel exposure, EPDM for weather and ozone resistance, and NBR or CR for application-specific oil, chemical, or environmental requirements.
Types of Umbrella Valves
Umbrella valve geometry can be adjusted around sealing life, assembly access, flow rate, cracking pressure, and available installation space.
Profile
Gradient-Thickness Skirt
A thicker center and thinner sealing edge improve recovery and reduce the risk of permanent deformation compared with a flat, uniform-thickness diaphragm.
Pull-In
Long-Stem Pull-In Valve
A common manual assembly design. The stem is pulled through the center hole until the retaining feature locks into place.
Push-In
Push-In Umbrella Valve
A practical option when the back side of the center hole is difficult to access, such as deep cavities or compact housings.
Composite
Composite Umbrella Valve
A rigid plastic valve body can be combined with an elastomer umbrella seal when the assembly needs both structural support and flexible sealing.
How Does an Umbrella Valve Work?
The valve opens and closes through pressure differential and elastic deformation of the silicone skirt.
Skirt Seals Against the Seat
With little or no pressure difference, the skirt stays in contact with the valve seat and blocks the flow path.
Forward Pressure Lifts the Edge
When upstream pressure reaches the cracking pressure, the skirt edge flexes away from the seat and fluid passes through the vent openings.
Elastic Recovery Closes the Valve
When pressure falls or reverses, the skirt quickly returns to the seat and restores the one-way seal.
Umbrella Valve Manufacturing
Umbrella valves are commonly produced by silicone compression molding or LSR injection molding. LSR injection molding uses precisely metered two-component silicone and a precision mold to form the thin skirt, sealing lip, stem, and retaining feature in one cycle.
Compression molding is often used for medium-volume programs or larger valve sizes. In both processes, tooling must control the skirt thickness transition and the demolding geometry around the stem and barb to reduce deformation or tearing.
Umbrella Valve Performance
Cracking pressure, material recovery, temperature, and sterilization requirements should be matched to the actual system.
| Property | Typical Guidance | Design Meaning |
|---|---|---|
| Cracking Pressure | Often below 2 psi; low-pressure respiratory designs can be much lower | Controlled mainly by skirt thickness, diameter, seat height, vent geometry, and material stiffness. |
| Hardness | Commonly 30 to 40 Shore A; generally below 55 Shore A | Softer compounds open more easily, while higher hardness can raise cracking pressure and complicate demolding. |
| Temperature Range | Silicone designs commonly target about -40°C to 230°C | The final range depends on the selected material grade and the media being handled. |
| Recovery | Low compression set and high resilience preferred | Good elastic recovery helps the skirt reseal after repeated opening cycles. |
| Sterilization | Suitable medical LSR grades may support autoclave, EO, and gamma processes | Material and valve geometry should be validated against the actual sterilization cycle. |
How to Design for Reliable Sealing
Reliable umbrella valve performance depends on the relationship between the skirt, seat, vent openings, material, and retaining stem.
Skirt Thickness Profile
A thicker center with a thinner edge and defined sealing lip can improve recovery and reduce long-term compression deformation.
Seat and Vent Geometry
Seat height, vent size, vent shape, skirt diameter, and skirt thickness work together to set cracking pressure and maximum flow.
Stem and Barb Design
The retaining feature needs enough holding force without creating excessive demolding stress. Material hardness and draft should be considered together.
Media and Sterilization Compatibility
Choose the elastomer around the fluid, operating temperature, cleaning process, and sterilization method instead of selecting hardness alone.
Umbrella Valve Applications
Umbrella valves are used where a compact, quiet, spring-free one-way valve is needed for gas or liquid control.
Medical Devices
Used in resuscitation masks, breathing circuits, ventilator exhaust valves, infusion systems, and drug-delivery assemblies.
Automotive
Used in fuel-tank venting, PCV systems, vacuum lines, and other compact one-way flow controls.
Consumer Products
Used in soap dispensers, spray bottles, pumps, and inflatable products that require simple inlet or outlet control.
Industrial and Packaging
Used in vent structures, pressure-relief functions, and packaging systems that need compact elastomer sealing.
Need a Custom Silicone Umbrella Valve?
Share your target cracking pressure, flow, media, installation space, and material requirements. Fecision can review the valve geometry and recommend a practical molding approach.