10PCS food grade silicone rubber duckbill check valve anti backflow 11*5.2*20 #s

Fluid Components · Check Valves · Silicone Duckbill · Food Grade · 10-Pack

What Are These Silicone Duckbill Check Valves?

These are food-grade silicone rubber duckbill check valves — one-way, non-return valves that allow fluid or gas to flow in one direction and prevent backflow in the reverse direction. The duckbill shape is a passive elastomeric valve: the flat "beak" end stays closed at rest, opens under forward pressure (as low as a few millibars of cracking pressure), and seals shut when pressure reverses. Dimensions are approximately 11mm outer diameter by 5.2mm inner stem diameter by 20mm total length — compact enough for inline tubing applications. This listing is for 10 pieces.

In short: A pack of 10 small, flexible one-way valves made from food-grade silicone — use them anywhere you need liquid or air to flow one way only, without springs, balls, or mechanical parts that can jam or corrode.

What Makes a Duckbill Different from a Spring Check Valve

1. No Moving Parts to Fail

A spring-loaded check valve has a ball, spring, and seat — any of which can corrode, jam with debris, or fatigue. A duckbill valve is one piece of molded elastomer. The only way it fails is if the silicone tears or takes a permanent set from prolonged exposure to extreme temperatures or aggressive chemicals. In clean fluid applications, duckbill valves routinely outlast mechanical check valves.

2. Self-Clearing of Small Particles

The flexible silicone lips can pass small soft particles that would jam a ball check valve. When the beak opens, the elastomer stretches around the particle; when flow stops, the lips close and can expel debris. This makes duckbill valves popular in peristaltic pump tubing, wastewater sampling, and slurry dosing applications where solids are present.

3. Silent Operation

Spring check valves produce an audible click or chatter — annoying in medical devices, aquarium setups, and office coffee machines. Duckbill valves open and close silently because the silicone absorbs the impact energy rather than transmitting it as sound.

Key Specifications

Temperature range, FDA/NSF certification status, and exact cracking pressure — verify from product packaging or manufacturer datasheet.

Where These Valves Are Used

• Coffee Machines & Beverage Dispensers: Prevent back-siphoning of brewed coffee into the water reservoir
• Aquarium Air Lines: One-way valve on air pump tubing to prevent water from back-flowing into the pump during power outage
• Medical Drainage Bags: Anti-reflux valve in catheter or wound drainage tubing
• Peristaltic Pump Lines: Check valve on the discharge side to prevent siphon backflow when pump stops
• Soap/Lotion Dispensers: Inline one-way valve that prevents air from entering the pump mechanism
• Fuel Lines (Small Engines): Anti-drainback valve to keep fuel from flowing back to tank in gravity-feed systems

Frequently Asked Questions

What is the temperature limit for food-grade silicone?

General-purpose food-grade silicone typically handles -40°C to +200°C continuous, with short excursions to 230°C. However, for these small duckbill valves, the practical limit is usually the lower of the silicone rating and whatever the application demands — above 150°C, the valve lips may lose elasticity over time and fail to seal completely. If you are using these in a steam or boiling-water application, verify the exact silicone grade from the manufacturer.

Can I use these with oils or solvents?

Silicone rubber swells significantly when exposed to many hydrocarbon oils, fuels, and chlorinated solvents. For fuel or oil applications, you want a fluoroelastomer (FKM/Viton) or EPDM duckbill valve, not silicone. Silicone is excellent for water, dilute food acids, alcohols, and mild detergents — it is the wrong choice for gasoline, diesel, mineral oil, or brake fluid.

How much back-pressure can these hold before leaking?

Duckbill valves are not designed for high back-pressure — they seal best at low reverse pressure (under 5-10 psi). At higher reverse pressures, the lips can be forced open. If your application has significant back-pressure (pump discharge, pressurized tank return), use a spring-loaded check valve instead. Duckbill valves excel at preventing gravity backflow, siphon drain, and low-pressure reverse flow.

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