For applications where foot traffic may be present, Openchannelflow offers Aluminum Top manholes. These manholes integrate a 2/3rd opening aluminum basin cover with diamond plate surround.
Aluminum Top manholes are suitable for applications where foot traffic is present (sized to be at grade) or where a lower profile than the Domed Top is desired (above grade).
In traffic areas (roads, parking lots, loading dock areas) a H-20 Traffic Reducer Top manhole should be used.
If an Aluminum Top manhole is going to be installed near an area frequented by vehicular traffic, bollards or other protection may be needed to protect the manhole.
4', 5', 6', and 8' [1.22, 1.52, 1.83, and 2.44 m] diameter manholes.
Sizing Aluminum Hatch Manholes
Aluminum Top manholes are sized so that the Top is at or just above surface grade. When used in or near pedestrian walkways it's common to size Aluminum Top manholes to be flush with the surrounding grade.
For low profile applications where surface water may be an issue, the manhole may be sized so that the Top surface is a couple of inches above the surrounding grade. This slight elevation helps to ensure that any ponding water around the Top does not drain into the manhole.
Aluminum Tops are constructed from 1/4-inch [0.635 cm] thick aluminum and are secured to a diamond plate surround with a heavy-duty stainless steel hinge. The Top / surround assembly is then bolted to the manhole barrel.
Access in an Aluminum Top manhole is more restricted than that for a Domed Top - but not as much for a H-20 Reducer. The Top provides 2/3rd open area - with the remaining 1/3rd secured to the manhole barrel. If greater access is required, a Domed or Open Top manhole should be used.
For applications where there is more than 48-inches [121.9 cm] of distance from the underside of the hatch to the top of the flume or structure, an optional pull-up style ladder assist may be mounted to the ladder rungs. The ladder assist rests below the bottom of the hatch when not in use. To use the ladder assist, the operator simply grasps the assist bar, pulls up, and then twists the bar to lock it into place.
Repair and Replacement
Under normal use, Aluminum Tops should not need field replacement. Should a Top become damaged, though, a replacement can be installed by unbolting the damaged Top and bolting on the new Top.