Abstract: A wet barrel hydrant check valve has a body containing a dash-pot assembly connected to a flapper valve, spring biased towards the closed condition. A sandwich flange fixed to the hydrant has a member holding the flapper out of the flow passageway, the flange being joined in a break-away connection to the valve body so that upon hydrant upset, as by vehicle impact, the hydrant and holding member are dismounted from the valve body, releasing the flapper into the flow path of escaping water for dash-pot controlled, gradual closure of the valve minimizing water hammer in the line.