Heavy duty airlock valve (HDX) Extra-Tough Drop-Thru rotary airlock valves are designed to withstand high temperatures and pressure differentials up to 22 PSI. This legendary design sets the standard by which all others in the industry are measured. It offers the heaviest gauge rotor vane stock of any competing product, extra thick end plates, flanges and housing walls, along with outboard mounted oversize bearings that are pre-lubricated and permanently sealed to ensure low maintenance and prolonged life. The heavy duty airlock valve (HDX) is available with 6-vane or 8-vane rotor design. Square or round flange housing with cast iron, 304/316 stainless steel or Ni-hard construction.