Pokorney Manufacturing Co. Since 1908 | (630) 458-0406 - Home - Pokorney Manufacturing in Chicago - Vacuum Check Valves Series 3000 with Minimum Pressure Drop, Stainless Steel Trim. Spring Check Valves Series 1000 with Silicone Rubber Seats, Du Not Viton-A Seats, Cast Bronze Globe, Hex Brass Caps