Check valves are a key part of stormwater and wastewater systems to prevent backflow. Designed for use with both single- and dual-source applications, they are a simple passive device that allows the flow of water but automatically closes to prevent backflow. They rely on a flow rate or a pressure differential to operate without manual or automated intervention.
They help maintain public safety by preventing backflow, which can lead to flooding and damage to homes and buildings. In addition, they help protect against contaminated water that can enter the municipal water supply, which can affect human health.
There are several different types of check valves available, and choosing the right one for your needs can be difficult. However, understanding the basics of a check valve can be helpful in making an informed decision.
Duckbill Type Valves
Rubber duckbill check valves are a popular choice for stormwater and wastewater applications because they are non-mechanical, have low head loss, do not slam and are resistant to organic contamination such as algae and barnacles. They also have no problems discharging flows containing entrained solids, even those that contain abrasive slurries.
ProFlex 711/731 Slope Bottomed Valves
PROCO’s 711/731 ProFlex(tm) Slope Bottomed Check Valves are engineered for installation on pre-existing pipe lines, such as manholes, outfalls and vaults where the pipe invert is close to the floor. The valves have a sloped bottom to allow 100 percent drainage, eliminating the problem of standing water that can occur with flat bottom valves.
They are easy to install and require zero maintenance. They are also available in a variety of elastomer styles to suit your specific application.
Flap Gate Valve
A flap gate valve is a type of check valve that is installed at the discharge point of a stormwater check valve pump station. This is used to prevent tidal backflow, which is common in low-lying areas such as Charleston’s coastal areas. They are a simple, affordable way to mitigate the impacts of tidal inundation, but need to be regularly maintained to ensure they remain in good working condition.
The City of Charleston has invested in these valves to control tidal flooding, which has become an increasingly frequent problem due to sea level rise and rising tides. Using these valves has helped to prevent floods in areas that often suffer from high tide flooding, such as West Ashley and James Island.
These valves are made of a robust rubber or other elastomeric material and have a flap that is usually closed to prevent backflow into the system. The flap opens and closes with the force of gravity, which allows it to close when the drain is blocked by a buildup of mud or other debris.
The flap is anchored to the valve body by small floatation devices that can move up or down depending on the amount of backflow. This helps to reduce the risk of sewage backflow into the home or office. Floats are also incorporated in the valve to make it more easily accessible for inspection and replacement.