Patent ID: 8678777

Claim:
A pump for dry particulate material, comprising: a pump chamber comprising a gas permeable member disposed in a pressure chamber; a first pinch valve and a second pinch valve wherein each said pinch valve comprises a member that defines part of a flow path for material into or out of said pump chamber; a first control valve for controlling application of negative pressure to said pressure chamber and a second control valve for controlling application of positive pressure to said pressure chamber; wherein during pump operation material flows into said pump chamber under negative pressure applied to said gas permeable member under the control of said first control valve and material flows out of said pump chamber under positive pressure applied to said gas permeable member under the control of said second control valve; said first pinch valve and said second pinch valve being operable to control flow of material into and out of said pump chamber, a control circuit that controls operation of each of said first pinch valve, said second pinch valve, said first control valve and said second control valve independently of each other.