Watts LF174A 110 3 4 Part of the LF174A Series ZC100F 6NH Injected molded Polyethylene construction Injected molded Polyethylene construction This cover repair kit is used to repair or replace the cover on a 2 inch lead free reduced pressure zone assembly used to prevent the reverse flow of polluted water from entering into the potable water supply due to backsiphonage and or backpressure This 3 4 inch lead free boiler pressure relief valve is used in hot water heating and domestic supply boiler applications to protect against excessive pressures on all types of hot water heating supply boiler equipment and prevents water and sediment from being trapped in the seat