The main valve disc is usually a thick polyurethane material that is designed to be the seal for the valve.  This disc, held in place by the valve ball, forms the seal around the main valve seat. 

This disc is an important part of fire hydrant operation and is one of the replacement components in a complete restoration of a fire hydrant. 

A question that can help you discern the status of your fire hydrant is:

Have you had your fire hydrants restored in the last 3-5 years?

If not, please contact us today and our licensed technicians will be able to restore your fire hydrants to help increase their life expectancy.