Table 3. Sample type and measured flow rates (LPM) for various critical orifices^17–36.

Sample				Critical orifice	Flow rates (LPM)
Type	Contaminant	Reference	Media	Needle gauge (G)	Reference range	Measured mean (range)	CV (%)
Ammonia	NH3	Donham and Popendorf, 1985; Donham 1993, Pratt 1993	Silica	27	0.1–0.5 (OSHA 188; Bishop et al., 1986)	0.16 (0.10–0.32)	36.6
OP pesticidesa	Chlorpyrifos	Lu et al., 2000; Li 2007; Armstrong et al., 2013; Fenske et al., 2009	PUF	20	1.0–5.0 (NIOSH 5600, EPA TO-10A)	3.37 (2.74–3.91)	10.6
	Malathion Azinphos methyl Parathion
Total dust	Bacterial endotoxin	Clark et al., 1983; Heederik and Sigsgaard, 2005	PVC (47 mm)	18	2.0–4.0 (Milton et al., 1995, ACGIH 1989)	4.06 (3.52–4.69)	10.0
	Pollen	Sofiev and Bergmann, 2013	PVC (47 mm)	18	1.0–3.0 (NIOSH 0500)	3.96 (3.59–4.52)	7.48
	Fungal spores	Clark et al., 1983; Pratt et al., 1990
	Animal dander	Kline and Schwartz, 1998; Willams et al., 2011
Respirable dust	Levoglucosan (wood smoke)	Simpson et al. 2004; Naeher et al., 2007; Allen et al., 2008	Teflon (37 mm)	18	2.2–2.5; 4 μm dia. (NIOSH 0600), 3.2–3.5; 3.5 μm dia. (NIOSH 0600)	4.15 (3.70–5.20)	8.83
	1-Nitropyrene (diesel)	Hoppin et al., 1994			4.0–5.0; ≤2.5 μm dia. (Chan and Lippman, 1977)

^aOP = Organophosphorus.