Image Number 12 for United States Patent #7775231.
The present invention relates to methods and devices for retrofitting fire hydrants with additional structure for reducing the potential that those with ill intent can foul municipal water supplies by introducing toxins or other materials into fire hydrants. Various embodiments include a replacement hydrant body having an enlarged diameter portion that can be installed to replace an existing hydrant body. The replacement hydrant body can include a secondary valve comprising a seat, biasing structure, and a restriction member to close off portions of the hydrant otherwise available for receipt of toxic or other materials when the fire hydrant nozzle cap is unscrewed and open.
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