| Check valves are engineered to allow the flow of fluid | | | | environments. Unlike check valves with metal |
| across a pipeline system or port in one direction only. | | | | components, such as disc check valves, duckbill |
| They are reactive valves, meaning that they are | | | | elastomer valves require significantly less maintenance |
| activated by the amount and the pressure of the fluid | | | | - they lack interior metal components that can rust or |
| present in the system environment. These valves are | | | | become corroded. |
| typically used in backflow prevention applications, flood | | | | For what applications might check valves be used? |
| prevention environments, and wastewater treatment | | | | Duckbill valves can be used in a variety of |
| entities. | | | | wastewater, stormwater, and backflow prevention |
| In 1984, the Environmental Protection Agency (EPA) | | | | applications. One excellent case study involved a large, |
| commissioned the testing of a new kind of check | | | | well-known retail store in St. Petersburg, FL. This store |
| valve; one that stood out as a clear alternative to | | | | had a large retention pond, or man-made pond |
| flapgate valves. The new valve featured a | | | | designed to collect rainwater. The pond was |
| duckbill-shaped inner elastomer sleeve that responded | | | | decorated with fresh water vegetation, as are many |
| keenly to changes in fluid pressure. The valve sleeve | | | | retention ponds in this part of the American Southeast. |
| closed in response to backflow pressure, forming a | | | | The pond was fitted with three drainage pipes that |
| tight seal that blocked debris from entering waterways. | | | | terminated in Tampa Bay. |
| Further testing proved that the duckbill-shaped design | | | | Turbulent weather proved to be a problem for this |
| also offered superior performance in pollutant | | | | store. During periods of heavy rain and high tides, the |
| entrapment, durability, the stopping of leakage, and | | | | waters of Tampa Bay reverse-flowed into the pond, |
| various self-cleaning capabilities. Now, the duckbill | | | | causing the vegetation to wither and die. The pond |
| elastomer check valve is routinely used in backwater | | | | was fitted with three 36-inch check valves. Since |
| prevention and waterway applications. The curved | | | | these valves responded to subtle pressure |
| shape of the interior valve bill can regularly achieve a | | | | differentials, they proved to be an excellent solution in |
| tight closed position, providing an excellent seal against | | | | preventing salt water backflow. |
| debris in backflow applications. Various duckbill models | | | | Duckbill valves are suitable for a variety of other |
| have been engineered for low pressure applications, | | | | applications, as well. Some models are ideal for |
| and for pollution prevention efforts on larger | | | | manhole and end-of-pipe outfall installations. Others are |
| waterways. | | | | installed for the purposes of sewer system control and |
| How does a check valve work? | | | | sewer backflow prevention. Still others are used for |
| Check valves are designed to respond to pressure | | | | stormwater control, as the retail store case study |
| differences. Throughout the life cycle of the valve, | | | | illustrates; or, for wastewater treatment applications. |
| there are instances where the pressure of the fluids | | | | Certain duckbill models can be used in industrial |
| traveling through the valve is greater than the pressure | | | | applications, such as corrosive slurry handling, caustic |
| across the valve mechanism. The force of upstream | | | | chemical applications, and high-temperature chemical |
| water creates high differential pressure across the | | | | reactions. |
| interior valve body, so the valve opens, allowing | | | | The design and structure of duckbill check valves |
| forward streams to pass through. However, | | | | make them widely applicable in pressured fluid |
| back-flowing water lowers differential pressure across | | | | environments. The elastomer bill design is |
| the valve body, so the duckbill elastomer valve flexes | | | | low-maintenance, rust-free, and can be highly |
| closed, sealing debris out. | | | | responsive to very subtle pressure changes across |
| Modern valves are engineered to respond to modest | | | | line fluid. These valves do not require a power source |
| pressure changes. These newer valves respond to | | | | or any exterior action to operate. As a result, they are |
| slight changes in differential pressure from forward- or | | | | highly versatile and highly durable. |
| backflow, making them useful for a variety of | | | | |