I. Selection of size The diameter of the clear hole at the wellhead shall not be larger than the clear hole of the well circle, so as to avoid accidents caused by the bearing surface of the well circle being suspended.
Figure 1 shows an error, and Figure 2 shows a correct one.
Second, installation precautions --- very important 1. When installed under the paved ground, the material around the well circle is the same as the ground material, and the concrete ring can no longer be poured;
2. When installing under non-paved ground, concrete ring should be poured;
3. When installing heavy products, the concrete ring above C20 should be cast around the concrete ring; the thickness of the concrete ring at the bottom of the bearing (shown as D in Figure 3) should be greater than 150mm, and the outer diameter of the concrete ring should be larger than the bottom of the inspection well and outside the ring size;
4. For the installation of super heavy products, the concrete ring above C20 should be poured around the well ring; the thickness of the concrete ring at the bottom of the support (shown as D in Figure 3) should be greater than 200mm, and the outer dimension of the concrete ring should be larger than the bottom of the inspection well and the ring External dimensions;
5. The relative height of the product plane and the surrounding ground (shown in Figure 4) should be within the range of -3 to + 3mm, beyond this range is an error (Figure 5, Figure 6)
6. During the installation and use of the product, the front side of the manhole cover should always be maintained (the front side is flat and has anti-slip marks; the reverse side is curved and smooth). Figure 7 is correct and Figure 8 is incorrect.
Note: 1. Manhole cover or rainwater rafter 2. Well ring 3. Concrete ring