Gardner Denver DHP externally heated series is designed for applications that were previously forced to accept a -40° F pressure dew point when simple protection against seasonal freezing is the issue. The standard design delivers ISO 8573.1 dew points between Class 2 and Class 3 automatically. Class 2 (-40°) dew points protect against freezing during low ambient conditions and class 3 (-4° F) dew points keep your air system bone dry during the heat of summer. Applications that require class 2 (-40°) dew points year round simply need to select controller A or B.