CHARACTERISTICS: Air flow constant regulators for circular ducts. Automatic mechanical functioning, without auxiliary energy to maintain air flow constant within a differential pressure range. UTILIZATION: For all ventilation systems to maintain air flow constant, independently of the pressure variations within the range of accepted values. DETAILS: Material: galvanised steel. Finish: zinc coated. Working temperature: -20° +70°C. Special uses: Version RPVC/Z with acoustic insulation 50 mm thickness.