Patent ID: 7740423

Claim:
A vacuum modulating air control valve apparatus for controlling an amount of air supplied to a vacuum pneumatic conveying system at a feedpoint to thereby control a ratio of particulate material to air within the conveying system, the apparatus comprising: a hollowed valve body; an air output port in fluid communication between the valve body and the feedpoint and allowing for communication of air through said valve body and to said feedpoint; a valve member positioned within the hollowed valve body and configured to selectively seal the air output port; a pneumatic cylinder having a piston and presenting a vacuum chamber; a rod disposed between and connecting the piston and the valve member and extending through the valve body; a spring positioned on the rod and configured to urge the valve member toward the air output port for sealing engagement with the output port in a fully closed condition; a clean vacuum line in pneumatic communication between the vacuum conveying system and the pneumatic cylinder; and at least one air intake port associated with the valve body and allowing communication of ambient air through the intake port and to the valve body, wherein upon application of a vacuum in the pneumatic cylinder by the clean vacuum line, the piston retracts so as to retract the rod, thereby compressing the spring, wherein upon retraction of the rod, the valve member is at least partially retracted from the output port, such that ambient air is allowed to enter the valve body via the at least one air intake port, wherein upon ambient air entering the valve body, air is supplied to the feedpoint through the air output port in proportion to a level of vacuum in the vacuum conveying system.