Check valves are designed to allow the flow of fluid through a piping system or port in a single direction. These are reactive valves, that is, they are activated by the amount and pressure of the fluid present in the system environment. These valves are typically used in backflow prevention applications, flood prevention environments, and wastewater treatment facilities.
In 1984, the Environmental Protection Agency (EPA) mandated the testing of a new type of check valve; the one that stands out as a clear alternative to the flapper valves. The new valve included an internal duckbill elastomer sleeve that responded to changes in fluid pressure. The valve sleeve is closed in response to the discharge pressure, forming a seal that prevents debris from entering the water courses.
Other tests have shown that the duckbill design also offers superior performance in trapping pollutants, durability, stopping leaks and various capabilities. self-cleaning. Now the duck elastomer check valve is commonly used in swirl and waterway prevention applications. The curved shape of the internal valve spout can regularly reach a tight closing position, providing excellent sealing against debris in delivery applications. Various models of duckbill have been designed for low pressure applications, and for pollution prevention efforts on larger waterways.
How does a check valve work?
Non-return valves are designed to meet pressure differences. During the life cycle of the valve, there are instances where the fluid pressure passing through the valve is greater than the pressure through the valve mechanism. The upstream water force creates a high differential pressure across the body of the inner valve, so that the valve opens up, allowing the currents towards the front to pass through. However, backflow water lowers the differential pressure across the valve body, so the duckbill elastomer valve flexes and closes the debris.
Modern valves are designed to respond to modest pressure changes. These new valves respond to slight variations in differential pressure before or after reflux, making them useful in various environments. Unlike check valves with metal components, such as check valves, duck elastomer valves require much less maintenance – they lack internal metal components that can rust or become corroded.
For which applications could non-return valves be used?
Duck-billed valves can be used in a variety of wastewater, stormwater and backflow prevention applications. An excellent case study involved a well-known large retail store in St. Louis. Petersburg, FL. This store had a large holding pond, or artificial pond designed to collect rainwater. The pond has been decorated with freshwater vegetation, as are many retention basins in this part of the southeastern United States. The pond was equipped with three drainage pipes that ended in Tampa Bay.
Turbulent weather provided to be a problem for this store. During periods of heavy rain and high tide, the waters of Tampa Bay flow into the pond, causing dieback and death of vegetation. The pond was equipped with three 36-inch check valves. Since these valves responded to subtle pressure differentials, they have proven to be an excellent solution for preventing backflow of salt water.
Duckbill valves are also suitable for a variety of other applications. Some models are ideal for sewer and end-of-pipe installations. Others are installed for the purpose of sewerage control and the prevention of sewer backflow. Still others are used for stormwater control, as illustrated by the case study of retail stores; Egypt, for wastewater treatment applications. Some models of duckbill can be used in industrial applications, such as handling corrosive sludge, caustic chemical applications and high temperature chemical reactions.
The design and structure of duckbill check valves make them widely applicable in pressurized fluid environments. The elastomer invoice design is low maintenance, rust free, and can be very sensitive to very subtle pressure variations across the line fluid. These valves do not require any source of energy or external action to function. As a result, they are very versatile and very durable.