Pulse-Bac LD - The Pulse-Bac LD (Light Duty) vacuum is a 20-gallon, continuous-duty unit offering 135-CFM at 80" wg. The unit features a unique internal filter arrangement of 3, 10" long, spun bond polyester cartridges that are 95% efficient to 0.1 micron. The unit's patented filtration system pulses one of the three filters every five seconds in rotation to ensure continuous operation in demanding environments that call for the collection of fine dust. Pulse-Bac vacuums also feature a highly stable 5-caster base that can support up to 300 pounds. The Light Duty Pulse-Bac is ideal for lighter weight floor surfacing and grind dust collection but it is also ideal for shop and job site clean up. Please note that an extension fitting is available to fit the Pulse-Bac vacuum lid assembly to 40 and 55-gallon drums.