FLUID POWER: Offending odors from sewer systems can be prevented from escaping with lightweight Tideflex® Check Valves while water is still allowed to discharge as needed. This unique Tideflex® Check Valve Series 37G is designed to be installed inside a pipe that is buried or otherwise inaccessible. The valve is simply slipped into the pipe and is secured by an expandable clamp. This allows the Series 37G to be installed from inside a manhole to prevent backflow into the structure. The valve is constructed entirely of rubber, making it virtually immune to rust, corrosion and weathering. Sizes are available to 72 inch.