Evaluation of a passive optical based end of service life indicator (ESLI) for organic vapor respirator cartridges

Figures & data

Figure 1. Sensor cross-section and constructive interference.

Table 1. Minimum Indication Limit (MIL).

Organic Vapor	MIL (ppm)
Acetone	1400
sec-Butanol	83
n-Butyl acetate	2
Heptane	12
Methyl ethyl ketone	175
Methyl isobutyl ketone	5
Tetrachloroethylene	20
Trichloroethylene	66
Toluene	8
Xylene	2

Figure 2. Progression of the ESLI Indicator Bar.

Figure 3. Experimental setup.

Table 2. ESLI and service life for six organic vapors.

	Inlet Concentration	Breakthrough Concentration	ESLI	Predicted Service	Measured Service
Vapor	(ppm)	(ppm)	(min)	Life (min)	Life (min)
Heptane	85	42.5	628±47	1090	1271±12
	1000		64±7	109	111±4
Methyl isobutyl ketone	20	10	2295±148	4298	5303±58
	1200		51±10	102	99±1
Toluene	20	10	1765±77	4906	5197±97
	1000		67±13	141	140±3
Tetrachloroethylene	25	12.5	1935±160	4476	4986±339
	500		106±14	294	277±2
n-Butyl acetate	150	75	308±33	828	869±10
	1700		28±8	79	75±2
sec-Butanol	100	50	650±137	1172	1398±6
	1700		38±5	95	90±2

Tabe 3. ESLI and service life at different relative humidifies.

	Inlet Concentration	Breakthrough Concentration	RH	ESLI	Predicted Service	Measured Service
Vapor	(ppm)	(ppm)	(%)	(min)	Life (min)	life (min)
Heptane	85	42.5	25	616 ± 71	1090	1291 ± 3
			50	628 ± 47	1090	1271 ± 12
			70	433 ± 76	670	1216 ± 7.5
	1000		25	48 ± 4	109	109 ± 1
			50	64 ± 7	109	111 ± 4
			70	58 ± 5	91	104 ± 3
Toluene	20	10	25	1960	4906	5293
			50	1765 ± 77	4906	5197 ± 97
			70	1580	2213	4551
	1000		25	60	141	139
			50	67 ± 13	141	140 ± 3
			70	57	119	134
MEK	200	100	25	250	405	544
			50	210 ± 42	405	558 ± 10
			70	175	118	464
			85	150 ± 12	64	349 ± 13
	1400		25	47	86	105
			50	43 ± 5	86	105 ± 2
			70	45	48	99
			85	31 ± 12	36	91 ± 1

Table 4A. ESLI and service life, with and without pre-humidification. Testing done at 50% RH.

	Inlet Concentration	Breakthrough Concentration		ESLI	Predicted Service	Measured Service
Vapor	(ppm)	(ppm)	Pre-humidified	(min)	Life (min)	life (min)
Heptane	85	42.5	Yes	575 ± 65	NA	1252 ± 14
			No	628 ± 47	1090	1271 ± 12
	1000		Yes	42 ± 8	NA	87 ± 1
			No	64 ± 7	109	111 ± 4
Toluene	20	10	Yes	1805 ± 173	NA	5263 ± 131
			No	1765 ± 77	4906	5197 ± 97
	1000		Yes	28 ± 3	NA	104 ± 1
			No	67 ± 13	141	140 ± 3
MEK	200	100	Yes	210 ± 43	NA	587 ± 6
			No	210 ± 42	405	558 ± 10
	1400		Yes	21 ± 6	NA	79 ± 1
			No	43 ± 5	86	105 ± 2

Table 4B. ESLI and service life, with and without pre-humidification. Testing Done at 70% RH.

	Inlet Concentration	Breakthrough Concentration		ESLI	Predicted Service	Measured Service
Vapor	(ppm)	(ppm)	Pre-humidified	(min)	Life (min)	life (min)
Heptane	85	42.5	No	434 ± 76	670	1216 ± 8
			Yes	505 ± 73	NA	1200 ± 23
	1000		No	58 ± 5	91	104 ± 3
			Yes	44 ± 16	NA	81 ± 1
Toluene	20	10	No	1580	2213	4550
			Yes	1150	NA	4031
	1000		No	57	119	134
			Yes	35 ± 7	NA	101 ± 5
MEK	200	100	No	175	118	464
			Yes	120 ± 37	NA	475 ± 19
	1400		No	44 ± 5	48	98 ± 4
			Yes	20	NA	64

Table 5. ESLI and service life at different temperatures.

	Inlet Concentration	Breakthrough Concentration	Temperature	ESLI	Predicted Service	Measured Service
Vapor	(ppm)	(ppm)	(°C)	(min)	Life (min)	life (min)
Toluene	1000	10	0–5	85 ± 9	145	147 ± 3
			20–25	66	141	139
			30–35	48 ± 14	137	127 ± 7
MEK	200	100	0–5	297 ± 59	574	732 ± 109
			20–25	215 ± 35	405	556 ± 8
			30–35	160 ± 18	332	426 ± 15
	1400		0–5	51 ± 9	104	115 ± 8
			20–25	41 ± 1	86	103 ± 2
			30–35	37 ± 2	77	93 ± 3

Table 6. Effect of cyclic vs. constant flow on ESLI and service life.

	Inlet Concentration	Breakthrough Concentration	RH	Flow Rate	Flow	ESLI	Predicted Service	Measured Service
Vapor	(ppm)	(ppm)	(%)	(L/min)	Type	(min)	Life (min)	life (min)
Heptane	165	42.5	50	20	Cyclic	440	NA	927
					Constant	440	946	1005
			85		Cyclic	250	NA	616
					Constant	270	533	806
	1000		50	32	Cyclic	43	NA	98
					Constant	47	109	102
			85		Cyclic	52	NA	91
					Constant	46	85	93

Table 7. ESLI and service life for organic vapor mixture.

Vapor	Inlet Concentration	Breakthrough Concentration	First OV	RH	ESLI	Predicted Service Life	Measured Service life
Mixture	(ppm)	(ppm)	Observed	(%)	(min)	for first observed OV (min)	for first observed OV (min)
MEK	200	100	MEK	25	78	152	212
Toluene	200	10		50	101	152	209
Xylene	200	50		75	84	54	174
MEK	200	100	MEK	50	220	262	490
Xylene	100	50		75	110	69	254
Cyclohexane	300	50	Cyclohexane
Methyl isobutyl ketone	300	10		50	92	117	127
Toluene	300	10		75	63	69	110
Acetone	350	250	Acetone
Trichloroethylene	350	10		50	32	62	101
Xylene	350	50		75	31	10	98

Figure 4. Rollup in a mixture of 350 ppm each of acetone, tricholoroethylene, and xylene at 50% RH.