Gas or Vapour to be Measured Chemical Formula	Réf tube	Gastec Tube No. & Name	Measuring Range (ppm)	No.of Pump Strokes	Shelf Life (year)	Note		TLV- TWA,C (ACGIH) (ppm)
Maleic anhydride C4H2O3	81	Acetic acid	0.8-20	1	3	H		0.25
Mercaptans RESH	70	Mercaptans	5-120	1	3	T		-
			0.5-5	2-10
	70L	Mercaptans	4-8	1/2	2	-
			0.5-4	1
			0.2-0.5	2
			0.1-0.2	4
2-Mercaptoethanol HSCH2CH2OH	75L	tert-Butyl mercaptan	0.5-7.5	1	2*	T		-
Mercury vapour Hg	40	Mercury vapour	6-13.2mg/m3	1/2	3	-		0.025 mg/m3
			0.25-6mg/m3	1
			0.05-0.25 mg/m3	5
Mesityl oxide (CH3)2C:CHCOCH3	141L	Ethyl acetate	33.8-1080	2	2	T		15
Methacrylic acid CH2:C(CH3)COOH	81	Acetic acid	1.8-45	1	3	H		20
Methacrylonitrile CH2:C(CH3)CN	192	Methacrylonitrile	10-32	1	3	+		-
			0.5-10	2
			0.2-0.5	4
Methaldehyde (CH3CHO)n	91L	Formaldehyde	0.065-3.25	3	3*	T		-
Methanethiol	See Methyl mercaptan
Methanol CH3OH	111	Methanol	1.5-4.5%	1/2	3	T		200
			0.02-1.5%	1
			0.004-0.02%	2
			0.002-0.004%	4
	111L	Methanol	40-1000	1	3	T
			20-40	2
	111LL	Methanol	20-56	2	2	T
			2-20	4
2-Methoxyethyl acetate CH3CO2CH2CH2OCH3	113L	Isopropyl alcohol	50-700	2	2	T		5
1-Methoxy-2-propanol CH3OCH2CH(OH)CH3	113L	Isopropyl alcohol	50-800	4	3	T		-
Methyl alcohol	See Methanol
Methyl acrylate CH2:CHCO2CH3	141L	Ethyl acetate	20-400	2	2	T		2
2-Methyl allylchloride CH3CH2:CHCH2Cl	131La	Vinyl chloride	2.8-55	1	2*	+		-
Methyl amine CH3NH2	180	Amines	5-100	1	3	T		5
	180L	Amines	0.5-10	1	2	T
N-Methyl aniline C6H5NHCH3	181	Aniline	3.5-42	2	3	-		0.5
Methyl bromide CH3Br	136H	Methyl bromide	300-600	1/2	3	+		1
			20-300	1
			10-20	2
	136L	Methyl bromide	100-200	1/2	2	+
			10-100	1
			2.5-10	4
	136LA	Methyl bromide	18-36	1	2	+
			1-18	2
2-Methyl-3-butenenitrile (CH3)2CHCH:CHCN	191L	Acrylonitrile	0.4-12	2	3	-		-
Methyl chloride CH3Cl	51	Fluorochlorocarbons (Pyrotectube)	12-480	1	3	+		50
	51L	Fluorochlorocarbons (Pyrotectube)	32-86	1	3	+
			1.6-32	2
Methyl chloroform CH3CCl3	135	Methyl chloroform	500-2000	1/2	3	+T		350
			100-500	1
	135L	Methyl chloroform	200-900	1/2	2	+T
			20-200	1
			6-20	2
	171	Acetylene	0.06-1.2%	1	3	T
Methyl chloroformate ClCO2CH3	131La	Vinyl chloride	58-1160	5	2*	+		-
Methylcyclohexane C6H11CH3	102H	n-Hexane	0.04-0.84%	1	3	-		400
Methylcyclohexanol CH3C6H10OH	119	Methylcyclohexanol	5-100	2	2	T		50
Methylcyclohexanone C7H12O	155	Methylcyclohexanone	50-100	2	2*	T		50
			2-50	3
Methylene chloride CH2Cl2	138	Methylene chloride	50-500	1	3	+T		50
			25-50	2
	138L	Methylene chloride	60-150	1	2	+T
			10-60	2
	51L	Fluorochlorocarbons (Pyrotectube)	1-20	2	3	+
Methylene iodide CH2I2	121L	Benzene	0.4-20	5	3	+		-
Methyl ether CH3OCH3	161	Ethylether	0.03-0.85%	1	3	T		-
Mehtyl ethy l ketone CH3COC2H5	152	Methyl ethyl ketone	0.02-0.6%	2	3	T		200
	151L	Acetone	21-1680	5	2*	T
Methylhydrazine H2NNHCH3	185	Hydrazine	0.6-12	5	3	H		C 0.1
Methyl isobutyl ketone (CH3)2CHCH2COCH3	153	Methyl isobutyl ketone	0.05-0.6%	2	3	T		50
Methylmercaptan CH3SH	71H	Methylmercaptan	1000-2700	1/2	3	-		0.5
			50-1000	1
			20-50	2
	71	Methylmercaptan	70-140	1/2	3	T
			2.5-70	1
			0.25-2.5	2-10
	70	Mercaptans	3.5-84	1	3	T
			0.5-5	2-10
	70L	Mercaptans	4-8	1/2	2	T
			0.5-4	1
			0.2-0.5	2
			0.1-0.5	4
Methyl metacrylate CH2:C(CH3)CO2CH3	149	Methyl metacrylate	200-500	1	2	T		100
			10-200	2
N-Methyl morpholine CH3N(C2H4)2O	180	Amines	5-100	1	3	T		-
	180L	Amines	0.3-6	1	2	T
4-Methyl pyridine C6H7N	182	Pyridine	0.38-10.5	1	3	T		-
N-Methyl pyrrolidone C5H9NO	180	Amines	13.5-270	1	3	T		-
Monochlorobenzene	See Chlorobenzene
Morpholine NH(C2H4)O	180	Amines	9-180	1	3	T		20
	180L	Amines	0.5-10	1	2	T

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