Comparison of melt-blown and glass-fiber HEPA asbestos filters based on ISO filter classes, filtration efficiency, power consumption, and face velocity

Figures & data

Table 1. Parameters and values of automated filter tester and particle filtration

	Parameter	Value
Particle filtration (TOPAS, PAF 111)	Test dust	A2 fine dust
	Aerosol size, Dp (μm) Particle density (g m^−3) Particle ratio (Length:Width) Particle concentration (mg m^−3)	0.1–10 1.4 ± 0.1 >3:1 10
	Flow rate (m^−3h)	252, 506, 756
	Face velocity (m s^−1)	1, 2, 3
	Tested area (m^2)	1.12
	Temperature (℃)	23 ±2
	Relative humidity (%) Pleated module (mm)	45 ±5 277 × 361 × 25

Figure 1. Schematic diagram of the TOPAS air filter test system.

Figure 2. Layout of melt-blown filter assembly by class 11, 12, 13.

Figure 3. Fractional efficiency of melt-blown filters by particle size with 1 m/s face velocity through class E11, E12, and H13 filters.

Figure 4. Fractional efficiency of melt-blown filters by particle size with 2 m/s face velocity through class E11, E12, and H13 filter.

Figure 5. Fractional efficiency of melt-blown filter by particle size with 3 m/s face velocity through class E11, E12, and H13 filters.

Figure 6. Variation of pressure in HEPA filter by dust loading amount at 1 m/s by classes (a), and H13 class by face velocity (b).

Figure 7. Morphological structures of melt-blown and glass-fiber media (H13) taken before and after dust loading using an electronic microscope.

Figure 8. Comparison of power consumption between melt-blown and glass-fiber media by increasing flow rate through class H13 filters (p < .05).

Table 2. Characteristics of filter media by class

Class	Media	Mean fiber diameter dav (μm)	Basis weight (g m^−2)	Thickness (mm)	Pore size (μm)
E11	Melt-blown Glass-fiber	1.61 1.66	20.1 78.0	0.32 0.42	0.8 0.8
E12	Melt-blown Glass-fiber	1.28 1.23	22.7 70.0	0.36 0.47	0.6 0.6
H13	Melt-blown Glass-fiber	1.26 1.22	30.4 70.0	0.40 0.47	0.4 0.4

Table 3. Comparison of efficiency by particle size, between melt-blown and glass-fiber filters in a negative air machine

Type	Particle Size(μm)	N	Fractional efficiency (%)
			Mean	Std. Dev.	Min	Max	P-value
Melt blown (H13)	0.3	10	99.33	0.08	99.16	99.42	<.05
	0.5	10	99.53	0.41	98.82	100
	1.0	10	100	0	100	100
Glass fiber (H13)	0.3	10	98.91	0.11	98.72	99.07	<.05
	0.5	10	99.21	0.74	97.71	100
	1.0	10	100	0	100	100

Table 4. Application of melt-blown filter media in negative air machines to asbestos removal sites

Removal site	Machine operation	Air volume	PCM	TEM	Asbestos type
		(L)	Concentration (fiber cm^−3)	Structure cm^−1
School classroom	Before	10	0.004	< 0.02	ND
	After	10	0.003	< 0.02	ND
Office	Before	10	0.003	< 0.02	ND
	After	10	0.001	< 0.02	ND

ND: Not detected.