The HJ3100 fume extraction unit removes the contaminated air directly at the source. ( Loc-Line hose with hood as shown below is included in the package along with an extended life prefilter. The HJ3100 is a high-mass flow, low vacuum system. Contaminated air is captured from the workplace  by the hood and transferred to the HJ3100 unit by flexible duct. Inside the unit, two filters, comprising three stages of filtering, remove the contaminants from the air. The purified air is then returned to the area where the HJ3100 is located.The pre-filter is made of a treated polyester material that removes coarse particles, such as dust, thus extending the life of the main HEPA filter. The HEPA (High Efficiency Particulate Air) filter consists of a pleated fiberglass paper medium, providing the greatest amount of surface area within the volume of the filter case.The standard filters used in the HAKKO HJ3000-series fume extractors contain an activated carbon element built into the filter. This filter is designed to last the life of the main HEPA filter. Carbon filters have absorption ratings of 80-85%. Efficiencies of the various HEPA/carbon filters for the HJ3100 are greater than 98% at 0.3 microns. All tests per the DOP test as stipulated in MIL-STD-282.