METHOD AND DEVICE FOR DELAYING THE RUN-OFF OF FLASH-STORM WATER OR ORDINARY RAINWATER FROM ROOFS AND OTHER SURFACES WITH A WATER-RETENTION CAPABILITY

摘要

In order to retain water on the roofs of buildings (1) with a water-retention basin (7), the invention calls for a vortex-type throttle valve (17) to be fitted on the flat roof (3) and to be connected to a drainpipe (11) leading to a drain. The throttle valve (17) makes it possible to control the rainwater run-off at a given rate determined by the size of the throttle valve (17). If rain falls at a high rate, the excess is retained. Overflow protection can be provided by fitting on top of the throttle valve (17), a length of pipe (35) which permits the unrestricted flow of water through the throttle valve (17). Alternatively, the drainpipe (11) can of course be extended upwards to the maximum permitted water-retention level, thus allowing the water which exceeds this level to pass directly into the drainpipe (11).