Savety valve for aerators

摘要

Ventilator unit for waste water biological treatment process. A membrane ventilator (74) safety valve (70) is installed in an air supply pipe (14) receiving compressed air. A back-flow prevention valve (71) is incorporated in the pipe (14) between the membrane ventilator (74) and the compressed air supply. The valve shuts automatically in the event of a failure of the compressed air supply. A shutoff valve (72) is located between the supply of compressed air and the back-flow prevention valve (71). This valve remains open as long as the air flow speed matches the ventilator assembly target requirement. The valve shuts automatically if the flow speed falls below a given speed as compared with the ventilator target requirement and remains shut as long as there is a positive pressure change towards the back-flow prevention valve (71).