BMI fabricates counterflow virtual impactors based on a design developed by Drs. Daniel Murphy and Dan Cziczo at the NOAA Earth System Research Laboratory. The unit is designed to operated at pressures between 20 and 600 mb. Use of the CVI at higher pressures may not provide the desired cut size performance.

Key features of the counterflow impactor include:

• Separation of larger sized particles and/or droplets from smaller particles into two separate flows (between 0.6 and 22 lpm each) from a single inlet flow (6-17 lpm) and a counterflow (2-8 lpm)
• Adjustable cut-size (0.2 to 2.8 micron D50) provided through adjustment of flow rates
• Low counterflow flow rate requirement (2-8 lpm)
• Compact design, 2" long by 1.5" diameter stainless steel construction
• Custom pre-impactor available with user-specified diameter cutpoint
• Easy connections with five 1/16" NPT thread fittings and one 1/8" compression fitting
• May be purchased with BMI's laminar flow elements for integrated flow measurement capability
• May be purchased with BMI's low pressure drop automated airflow valve(s) for flow control capability