Polyethylene Vertical Mixing Tank. Approximate capacity: 2000 gallons. These vertical bulk storage tanks are high-density and ideal for mixing and storing make-up water, chemicals to be added, liquid waste, etc. Made of polyethylene, they offer excellent chemical resistance and can be used inside or outdoors. Manhole diameter: 16 in. Inside straight-wall dimensions: 7 ft. 5 in. dia. x 6 ft. H. Inlets: (1) 16 in. dia. port. Outlets: (1) 2 in. dia. NPT fitting. Overall dimensions: 7 ft. 5 in. dia. x 7 ft. 1 in. H.