Abstract: A vacuum receiver having a first elongate tube oriented along a vertical axis with a second tube of sufficiently greater girth encircling the first tube and forming an annular passage therebetween. A first conduit extends through the side wall of the first and second tubes and opens outwardly inside the first tube. The first tube has a top wall closing off the upper end and an open lower end. A second conduit extends coaxial with the first tube and is smaller in diameter than the first tube and terminates above the top wall. The second conduit communicates with the second tube leading a fluid stream from the passage at a location directly above the top wall. Adjustment structure is provided for varying the effective vertical spacing between the terminal end of the second conduit and the top wall of the first tube to thereby enable a varying of the velocity of the fluid stream in the passage to accommodate a specified material without causing the material to exit the second tube via the second conduit.