LQ-BT
Blow-through Rotary Valve
Air-swept design for feeding fine powders into positive pressure pneumatic conveying lines.
Pneumatic Conveying
Rotary Valves for Pneumatic Conveying Systems
In a pneumatic conveying system the rotary valve does two jobs at once: it meters material into the line and it holds the pressure difference between the line and the atmosphere. Positive pressure and vacuum systems put opposite demands on the same component, and the valve should be specified for the regime it will actually see.
Request a QuotePositive pressure systems
Air is injected upstream of the material feed, so the valve discharges into a pressurised line. If the valve is a simple drop-through type, conveying air escapes upwards through the pocket and the material cannot enter — the classic symptom is a line that runs empty while the feeder chokes. A blow-through valve, where the air is introduced into the pocket itself, avoids this. Where the pressure is low, a standard valve with an air injector below it can be adequate and costs less.
Vacuum systems
In a vacuum system the valve discharges from a hopper held below atmospheric pressure, so the leakage direction reverses: air is drawn in through the valve into the hopper. That in-leakage has to be added to the fan duty, and a worn valve will slowly overload a system that was correctly sized when new. Closed rotors, tight clearance, air-purge seals and a rotor speed low enough to fill the pocket properly are the levers here.
Metering stability
Pocket fill is rarely 100 %, and it changes with bulk density, aeration and rotor speed. For a system that must hold a rate, a variable frequency drive with feedback from a weigh scale or a line pressure signal is more useful than a bigger pocket. We size the pocket for the nominal rate and then let the drive handle the variation.
What to send us
Conveying regime (positive or vacuum), line pressure or vacuum level, material, bulk density, required rate, pipe diameter and air volume. With those we can recommend pocket volume and clearance, and say what leakage the fan or blower has to absorb.
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