Abstract: An apparatus for pneumatically conveying bulk material includes a conveyor line for transporting the bulk material and a secondary line which carries clean gas and is multiply connected via branch line and a plurality of check valves with the conveyor line for allowing introduction of clean gas when the pressure difference as measured between adjacent pressure transmitters exceeds a predetermined value. Adjacent pressure transmitters are operatively connected with a differential pressure switch which actuates a valve regulating the flow of clean gas through the branch line. The differential pressure switch opens the valve as soon as the pressure difference exceeds the predetermined value.

Abstract: Material to be mixed is fed into the upper portion of a container from where the material descends by means of the force of gravity. The container is provided with a partition extending across the interior of the container and operative to divide the descending material into two separated substreams. The container is further provided with two outlets which are adjustable so as to separately control the respective speeds of descent of the material of the two substreams in the container. The material which is withdrawn at the lower portion of the container is returned back to the upper portion of the container for further mixing. Because of the two substreams in the container, the relative elevations of arbitrarily selected samples, located in respective ones of the substreams, changes during material descent, thereby improving mixing action.

Abstract: Apparatus for discharging bulk material into a pneumatic conveyor conduit has two chambers, one disposed above the other, the upper chamber having an inlet orifice controllable by a pivotal closure flap and the lower chamber communicating with an outlet orifice from the upper chamber, also controllable by a pivotal closure flap. The flaps are balanced as by counterweights so as to leave their respective orifices virtually completely open in the absence of outside force acting on the flaps, and pressure nozzles are disposed adjacent the flaps in their fully open position, to assist movement towards their closed positions as required. A level sensing means is arranged in the lower chamber to sense when material therein drops to a predetermined level, for re-filling of the chamber from the upper chamber.

Abstract: A method for pneumatically conveying material through a conveyor conduit comprises automatically interposing into the conveying operation cleaning phases in which no material is introduced into the conduit, to remove material previously deposited in the conduit. Apparatus has a timing means which rhythmically interrupts the introduction of material, and the strength of the air flow in the cleaning phases can be greater than that of the air flow during the conveying phases.