Aerotech Fans
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Technical answers to common questions about dust collection.
A bleed-in (or dilution) damper is an automated safety valve installed upstream of a high-temperature baghouse. If the exhaust gas temperature spikes dangerously close to the melting point of the filter bags, the damper rapidly opens to draw in cool ambient air, quenching the gas stream instantly.
Yes, it is possible to retrofit a shaker baghouse into a continuous pulse-jet system. The upgrade requires removing the shaker mechanism, installing a compressed air header with diaphragm valves, and upgrading to a thicker, non-woven felt filter media that can withstand the pneumatic shockwave.
Woodworking generates a mix of heavy chips and fine sawdust. The optimal solution is a two-stage system: a primary Cyclone Dust Collector to drop out the heavy abrasive chips via centrifugal force, followed by a Pulse-Jet Baghouse to capture the hazardous sub-micron respiratory dust.
Instead of firing compressed air on a continuous timer, Pulse-on-Demand uses a differential pressure transmitter (like a Photohelic gauge). The PLC only fires the pulse-jet valves when the dust cake resistance crosses a specific threshold, drastically reducing compressed air consumption and extending filter bag life.
PTFE (Teflon) membrane filter bags are required when handling highly abrasive dust, sticky/agglomerative particulates, or extreme temperatures up to 260°C. The slick membrane forces surface filtration, preventing dust from penetrating the core fabric and ensuring flawless pulse-jet cleaning.
Non-woven felted bags (like standard 16 oz polyester) are thick and provide high-efficiency depth filtration, making them standard for pulse-jet systems. Woven bags are thinner, rely strictly on the dust cake for filtration, and are used primarily in older mechanical shaker dust collectors.
The air-to-cloth (A/C) ratio dictates the filtration velocity. If the A/C ratio is too high (too much air, too little fabric), the interstitial velocity prevents the dust cake from falling into the hopper during pulsing, causing permanent bag blinding and a massive spike in motor energy consumption.
Hygroscopic dusts (like sugar or fertilizers) absorb moisture and turn into sticky agglomerations that blind standard filters. To extract them safely, a baghouse must utilize PTFE-membrane coated filter bags for a non-stick surface, and the housing must be heavily insulated or heat-traced to prevent internal condensation.
Silica dust acts as a highly abrasive sandblasting agent. To prevent the lower cone of the cyclone from eroding, the internal apex and impact zones are often lined with replaceable cast basalt tiles or vulcanized rubber, which absorb the kinetic energy and extend the cyclone's lifespan indefinitely.
If your facility transitions to handling combustible dust, your existing dust collector must be retrofitted with ATEX/NFPA 68 compliant explosion relief vents, a rotary airlock valve for isolation, and anti-static (epitropic) filter bags to prevent catastrophic deflagration.
Explosion vents on a dust collector are sized strictly according to NFPA 68 standards. The calculation requires the Kst value (explosive severity) and Pmax (maximum pressure) of the specific dust, matched against the total internal volume of the baghouse housing.
Bridging occurs when hygroscopic or interlocking dust forms an arch over the rotary airlock, blocking discharge. It is prevented by designing the hopper with a steep 60-degree angle of repose, and installing pneumatic fluidizers or mechanical vibrators to continuously agitate the dust cake.
