Directly-controlled coaxial valves for high temperatures

Electromagnetic directly-controlled valves are required in many applications – for example, in those cases where neither compressed air nor hydraulics is available. For some 50 years, so-called coaxial, pressure- balanced valve construction has been on the market. This type of construction allows valves with small actuating forces to be constructed for high pressure applications in large nominal sizes. However, the disadvantages are that the temperature of the medium is transferred directly to the coil and the dynamic seals needed to seal the control tube against the pressure of the medium are constantly exposed to the temperature of the medium. It is standard engineering practice therefore to limit the deployment temperature of such valves to about 160 °C. In the new, patented solution described below, the flow of the medium is directed to one end of the control tube. Valves with this type of design can therefore be used at significantly higher temperatures. Even deployment temperatures of 500 °C are possible provided metallic seals are fitted.