Pneumatically operated conveyor systems for pulverulent or particulate materials

A high frequency pneumatic conveying system for pulverulent or particulate material comprising a despatch vessel, a conveying pipe line being connected to said despatch vessel for connecting said despatch vessel with a receiving vessel, a piston and cylinder operated fill valve being mounted in said despatch vessel for admitting material to be conveyed into said despatch vessel, and control means for alternately operating said fill valve and applying pressure air to said despatch vessel for intermittently discharging material in the despatch vessel into said pipe line, said despatch vessel having a non-return outlet valve, air vents in said despatch vessel in the form of permeable low resistance membranes which in one mode of operation permit rapid filling of said despatch vessel by rapid venting of air therefrom and in another mode of operation act as fluidizers for material in the despatch vessel, a control means for ensuring a firm closure of said fill valve before conveying air is admitted to said despatch vessel, and means to regulate said despatch of material in accordance with the air pressure in said conveying pipe line.