Openchannelflow offers several top styles to allow you to customize our fiberglass manholes to suit your specific site needs.

Each top style is designed for a specific type of application or to solve a particular access requirement.

​Of the top styles offered, the Aluminum Top and Domed Top styles are "complete" in that no additional components are required to finish the installation.

The H-20 Traffic Reducer requires grade rings, a frame, and a cover to complete the installation. These can be either locally sourced, or Openchannelflow can provide a composite stack with the fiberglass manhole for a complete solution.

Open Top manholes typically require a dedicated equipment shelter over them - or some other protection - to limit unauthorized access and the possibility of inflow.

Aluminum Top

• For pedestrian walkways or low-profile installations
• Available in watertight and non-watertight areas
• An array of accessories available
• Sizing:
  • Flush with or just above the surface grade
• Available for:
  • 4', 5', 6', and 8' [1.22, 1.52, 1.83, and 2.44 m] diameters

Fiberglass Domed Top

• For grassy (non-traffic/pedestrian) areas
• Most popular
• Fully opening for maximum access
• Easy entry / exit
• Heavy-duty stainless steel hardware
• Sizing:
  • 12 to 18-inches [30.48 to 45.72 cm] above the surface grade
• Available for:
  • 4', 5', and 6' [1.22, 1.52, and 1.83 m] diameters

H-20 Traffic Reducer

• For traffic / parking lot / loading dock / warehouse floor areas
• Large 31 3/4-inch [80.65 cm] standard opening
• 22 1/2 and 38-inch [57.15 and 96.52 cm] openings available
• Optional composite grade rings, frames, and covers available for a full composite solution
• Sizing:
  • 12-inches [30.48 cm] below the surface grade
  • For customer supplied grade rings, frame, and cover
• Available for:
  • 4', 5', and 6' [1.22, 1.52, and 1.83 m] diameters

Open Top

• Like the name implies, an open area at the top of the manhole
• Typically covered with a hinged, narrow opening fiberglass grating
• A good idea when the manhole is covered by a shelter or has access restricted
• Wide array of accessories available
• Sizing:
  • Usually flush with or just above the surface grade
• Available for:
  • 4', 5', 6', and 8' [1.22, 1.52, 1.83, and 2.44 m] diameters