Table 1.

Physical characteristics, flow parameters, and experimental results for the impactor stages.

Stage	Physical characteristics			Flow parameters		Design d50 (μm)	Experimental results
	W (mm)	L (mm)	S/W	Re	V (cm/s)		d50 (μm)	Stk 50	σ	ΔP (kPa)	Response (s)
Bypass Stage 0	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	0	15 ± 4
Impactor Stage 1	3.15	4.47	2.78	313	150	10a	~10a	0.22	2.6	0	7 ± 1
Impactor Stage 2	0.67	2.70	6.81	1470	3309	1.0a	1.0a	0.22	1.6	0.65	10 ± 1
Impactor Stage 3	0.48	0.48	5.67	2051	6447	0.3a	0.4a	0.22	1.5	2.88	8 ± 2
Diffusion Stage 4	n.a.	n.a.	n.a.	25	n.a.	0.016b	0.016b	n.a.	n.a.	2.88	8 ± 1
Diffusion Stage 5	n.a.	n.a.	n.a.	25	n.a.	0.110b	0.056b	n.a.	n.a.	2.88	6 ± 0

W: the nozzle width; L: the nozzle length; S: the distance from impaction plate to nozzle; Re: Reynolds number; d₅₀: 50% stage cutoff diameter; Stk₅₀: Stokes number at 50% collection efficiency; σ: curve sharpness; ΔP: cumulative pressure drop; V: nozzle velocity

^aaerodynamic diameter

^bgeometric diameter; n.a.: not applicable.