Safety relief valve

Abstract From the Canadian patent

Abstract of the Disclosure A safety relief valve for relief of overpressure in an incompressible liquid having a displaceable disc cooperating with an annular valve seat for opening and closing the valve to fluid flow. Included is a cylindrical orifice defined in the flow passage coaxially surrounding the valve seat immediately downstream of the seat and in series flow relation thereto. The orifice is of controlled size and length able to substantially maintain the overpressure value of liquid flow exposed to said disc in the disc area immediately beyond the valve seat to significantly increase disc lift after only initial disc lift occurs.