| abstract |
An improvement in an on-site foam generating apparatus which includes storage tanks for supplying the foam-forming reactants, a mixing chamber, and means for conveying the reactants through the mixing chamber. The improvement comprises means for automatically cleaning and flushing the mixing chamber. When the foam gun head containing the mixing chamber is at rest and inverted in an opening on the top of a solvent storage tank, solvent is continuously recycled through the mixing chamber. When the foam gun head is removed from the tank, a proximity switch senses the absence of metal and actuates an electrical circuit to operate a solenoid valve to divert the solvent from the mix chamber to a by-pass back to the tank. Additionally, a time delay relay is actuated which operates a solenoid valve for a predetermined period to supply purging gas to and through the mixing chamber upon removal of the foam gun head from the tank. |