Weir Manholes occupy a unique place in Openchannelflow's manhole lineup.  While Flume Metering Manholes usually can cover flow rates more effectively, there are times when the unique attributes of a weir are needed.  

Weir Manholes take our Weir Channels and integrate them into our fiberglass manholes.  Factory integrated and easy to install, Openchannelflow Weir Manholes allow drop-in place ease at a cost-effective price.  Dig it!  Drop it!  Done!

While Weir Manholes are most commonly used to measure dam seepage flows (where the collection of sediments is important), they can also measure flow on clean industrial discharges.

Keep in mind, as with any weir application, the flow must be sub-critical and non-full pipe as it enters the manhole.

Strength Built In

At the core of each Openchannelflow Fiberglass Weir Manhole is our fiberglass manhole tube.  While manhole configurations may differ, all Openchannelflow manhole tubes are designed to meet or exceed both ASTM D3753 and AASHTO H-20 standards.  The interior of these tubes is smooth and corrosion-resistant.  The light tan coloration of the tube helps to maximize visibility inside the manhole.

To the barrel, we add a cover, base, mounting flange, and, most importantly, a weir sized to measure the flow accurately!

Weir Manhole Advantages

• Accurate low flow measurement
• Solids capture
• Single source responsibility
• Virtually no maintenance
• Minimal downtime 
• A safe environment in which to measure flow

STANDARD WEIR MANHOLE COMPONENTS

• Cover 

• OSHA-complaint fiberglass ladder

• Thru-wall coupling

• Integral base / mounting flange

• Weir channel

• Non-slip fiberglass bench

• Replaceable weir plate

• Inlet / outlet piping

Customization

Openchannelflow Weir Manholes can be configured to your site needs, with a variety of top styles available:

• Domed Fiberglass (for non-vehicle / traffic areas)
• Aluminum Covers (for pedestrian traffic areas)
• H-20 Traffic Reducers (for use with standard grade rings, frames, and covers)

• Open Top (for custom applications where the manhole top needs to be open or provided with a fiberglass grating)

Weir Manholes are available in diameters from 48 to 96-inches [1.22 to 2.44 m] and in depths up to 35-feet [10.7 m].

To complete the customization, a range of manhole and flow accessories are available:

• Integral flow benches
• Grating platforms
• Ventilation 
• Equipment mounting
• Two-piece construction (for oversized manholes)
• Level / flow meter mounts
• Parameter mounts