Views: 74 Author: Site Editor Publish Time: 2022-07-11 Origin: Site
One Way Check Valve
One Way Check Valve, also known as Flow Control Valve, Pressure Relief Valve, which is a device that only allows the flow of fluids in one direction. They have two ports, one as an inlet for the media and one as the output for the media. Since they only allow media flow in one direction, they are commonly referred to as ‘Flow control Valves’ or ‘Non Return Valves.’ The main purpose of a one way check valve is to prevent backflow.
One Way Check Valves Types
Umbrella Valves/ Mushroon Valves: Silicone Umbrella Valves are usually installed on a flat seat whereby the stem is pulled through a hole and the Umbrella valve is locked in place. As pressure is applied, the media passes through the flow holes and lifts the Umbrella Valve skirt allowing the valve to open. When the pressure is reduced, or stopped, the Umbrella Valve skirt returns to its sealing position, thereby stopping the flow.
Duckbill Valve: Silicone Duckbill Valves has special structure like duckbill. It is an air, gas, liquid, water backflow preventer which has the function of forwarding flow in positive direction while non-return in opposite direction. Rubber duckbill check valve is applicable widely to drainage system, sewer, breast pump and manual respirator.
X-Frame/ Cross Slit Valve: Silicone Dispensing Valves are used to open at a pre-determined pressure and closing thereafter in order to dispense a medium once a certain threshold pressure is achieved.
Rubber Flapper Check Valves: Rubber Flap Valves are used to facilitate a unidirectional flow of fluid. Depending upon the application this either causes a forward flow or prevents backflow in a device.
One Way Check Valves Material Choice
For one way valves that are used in medical device and pharmaceutical applications, silicone materials (VMQ) is the best choice. The material we used are certified to pass USP class VI and ISO 10993 biocompetability tests. They are also suitable for Gamma and Steam sterilization.
Food and Water
For food industry application, our standard materials are certified to pass international food and potable water requirements such as FDA, REACH, ROHS.
Applications in automotive fuel including fuel alcohol and other fuel mixtures or in engine oil or automatic transmission oil often use fluorosilicone (FVMQ) and fluoroelastomer(FKM) rubber and NBR.
High and low Temperature
Generally speaking, silicone, fluorosilicone, and perfluoroelastomer can all serve high temperatures up to 200°C. With low temperatures you can use silicone and fluorosilicone. They go well below -40°C. Fluoroelastomer is less suitable for real low temperature applications even though we have certain types that are low temp resistant. Other elastomeric materials like nitrile (NBR) , ethylene propylene (EPDM) generally range between -20 and 120°C.
For general purpose valve applications we often recommend silicone rubber (VMQ).
As far as the resistance of elastomeric materials against chemicals is concerned we refer to the table below. Contact us in case of doubt.
For One Way Check Valves, we should choose lower compression set value and high elastomer silicone material (high tensile strength). Silicone Umbrella Valve is best made from 100% high elasticity silicone material.
One Way Check Valves Working Principle
A One Way Check Valves allow flow in one direction and check flow in the opposite direction. Under specified pressure, the rubber one way valve open and close automatically to control the fluid/air flow in one direction and prevent back flow. The automatic open normally affected by hardness of the silicone rubber material that used, the wall thickness, the initial bearing strength of the sealing surface, and flowing area, etc. Pressure Relief Valve is widely applied in fuel tank, health-care field, emergency mask, medical used fluid control devices, home appliances etc.
Notes: The mechanical and physical properties of fluoro silicone rubber are very similar to silicone, the difference is that fluoro silicone is oil-resistant.
Fluorosilicone rubber & FVMQ is noted for its resistance to fluro organic solvents and petroleum based fluid. Most of automotive & machine's non-return valves are made from fluorosilicone materials.
Umbrella Check Valves Hardness is generally less than 55 Shore A which mainly depends on umbrella hook designs, if the shore A is too high, the hook area can not demould:
Silicone Pressure Relief Valve Packaging: PE Bag with air inside in aim to prevent deformation & out of shape.
Umbrella Valve Seals work with a specific seat design which needs to be integrated into the plastic or metal housing of the application. For example if your valve needs high flow then you make the flow orifices in the seat as large as possible even with slots in the shape of a banana. On the other hand if your valve has low flow or needs to withstand high backpressure, you need only to apply one or more small flow orifices and take care that the outside diameter of the flow surface area doesn't get too close to the edge of the umbrella in order to make sure that there is enough seat surface area to support the diaphragm under backpressure.