NRV Installation
Client: Various
The Problem
Many older commercial properties and factory units have internal drainage systems that discharge directly into public drains or local water courses, streams and rivers. In the event of a flood, these pipes and conduits provide one of the first lines of access for flood water to enter a property and, if unprotected, can cause widespread flooding from manholes, gullies and through ground level toilets.
Rising water in existing drains and water courses prevents gravity flow from emptying existing systems, and water flows uphill until manhole accesses and gully pots fill up to a point where surcharge water begins to discharge through surface covers and low level toilet washroom facilities, creating localised flooding.
The Solution
Backflow into pipes and culverts can be prevented by installing non-return valves or flap valves within drainage systems. These can be either surface mounted on outlet walls or internally installed inside manholes at any point in a drainage run. NRVs and flap valves are available in a variety of sizes, from 50mm through to 1.8m diameters and larger if custom specified.
NRVs and flap valves allow water to flow normally under gravity when flows are low; however, as soon as water levels begin to rise above invert level, the valves self-seal and prevent water ingress into the system. They are often used in conjunction with a flood alarm to provide early warning of potential flooding.
The solutions installed included:
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