Automatic liquid flow control device

摘要

An automatic liquid flow control device for use in the application of building insulation foam is disclosed comprising flow meters to measure the flow of resin and foaming agent through conduits to the application gun, a needle valve connected to the resin conduit and operated by a servo motor, a controller to control the servo motor and having a selector to allow selection of the desired ratio of resin to foaming agent, a comparator to compare the actual ratio of resin flow/foaming agent flow to the selected ratio with the controller automatically controlling the servo motor and needle valve to "slave" the resin flow to the foaming agent flow in order to adjust the resin flow/foaming agent flow to the selected ratio. The comparator also compares the actual flow through the resin and foaming agent conduits to predetermine flow values in order to determine abnormal operating conditions. Visual indicators provide visual indication of these abnormal operating conditions and provide visual indication of deviation from the selected ratio. The controller deactivates the servo motor in response to these abnormal operating conditions or to excessive deviation from the selected ratio. The driving pump for the resin and foaming agent liquids is electrically connectable to the controller so that the controller can also deactivate the pump due to the presence of abnormal operating conditions or excessive deviation of ratio mixture for a predetermined time interval.