1. Application of product: The manhole with core is installed in the lower part of the middle tank manhole, facilitate the hole entry; in order to increase the supporting force plate, increasing convex cross shaped structure on the cover plate, improve the quality and the safety coefficient of the manhole, and ensure the safe operation of storage tank, pressure control: +200 mm =-45 mm water column, indicate the product name, model when ordering, graph numbers; ordering units can provide standard HG/T 21514 ~ 21535-2005 and non-standard manholes drawing processing production.

2. Specifications of product: