The ACO Q-Flap is a robust, lightweight non-return valve designed to let water discharge freely while preventing backflow. Mounted to a wall or headwall, it is typically installed above the waterline at outfalls, where dependable one-way flow control is essential.

The gravity-operated flap opens quickly under outgoing flow and closes automatically as soon as the head of water changes, helping protect networks from tidal surges, rising rivers, and flood events. Its smooth, responsive action supports free-flow systems without trapping debris, reducing the risk of silt build-up and keeping pipework clear over time. With durable HDPE construction, ACO Q-Flap delivers long-term performance in demanding drainage, wastewater, and coastal environments, with minimal maintenance required.

When required ACO can offer alternative mounting options. 

ACO Q-Flap HD

Technical Info

Wall Mounted - Other options available (see below)

Permament meter water column: 1Mwc (above opening)

72 hours meter water column: 5Mwc (from invert level)

Standard available sizes: DN 100-2000M

50 Year Design Life

Weilded Hinge Construction

Includes DN 400 Stainless Steel Reinforcement 

Custome made designs possible (see below)

ACO Q-Flap SD

Technical Info

Wall Mounted - Other options available

72 hours meter water column: 1Mwc (above opening)

5 hours meter water column: 5Mwc (from invert level)

Standard available sizes: DN 100-500M

Faster Install time - only four fixing points

Bolted Construction

Other Mounting Options

Alongside the standard Q-Flap HD range ACO offers additonal wall mounting options and sizes on request. The different wall mounting options are shown below: 

• Wall mounting with an angle of 10°
• Flange connection
• Spigot end for connecting with socket/coupling or to be inserted in existing pipe
• Opening moments of the flap valve can be adjusted on request.

For further information inofmration please contact ACO using the contact form below: