| 摘要 |
A gate valve box adaptor structure, the present invention provides a permanent support for the key box bonnet that is unaffected by the surrounding environment. The adaptor is supported on the gate valve to a positive location for the key box bonnet at a level which prevents infiltration of soil and moisture into the bonnet. The adaptor is provided with a resilient gasket of a unique design to provide a cushion and to create a seal for the bonnet on the gate valve.A plurality of liquid infiltration prevention structures for preventing liquid infiltration into manhole assemblies.
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