Learn about gas monitoring and detection using Gastec tubes in this document prepared by a1-cbiss

1. Gastec Standard Detector Tubes
Gastec detector tubes are used worldwide in factories, refineries, chemical plants, dry cleaners and other work
places where employee protection and gas detection are of paramount importance. From acetaldehyde to xylene,
the gastec precision pump and detector tubes can detect and accurately measure over 500 gases and vapours.
Why Gastec?
The most accurate detector tube system available
Minimal pump strokes required
Precision piston pump
Easy draw, single pup stroke action
Clear, precise and easy-to-read colour change
Long tube shelf-life
Low measurement cost
Complies with British standard BSEN1231:1997
ISO Registered
NATO Approved
99% tubes stock
Next day delivery for orders placed before 3pm (subject to availability)
Batch number traceability
Fast Access to technical solutions and advice
The gastec tube system comprises of the following:
Gastec colorimetric glass filled with an absorbent material, usually silica gel impregnated with a chemical
reagent
Air is drawn through the tube using the Gastec precision pump (GV-100S) and reacts in the presence of the
target gas to produce a colour change
The length of colour stain produced is proportional to the concentration of target gas present. By using a
calibration scale printed on the tube, the concentration may be read immediately, without the need for
laboratory analysis
Gastec standard detector tube specifications:
Hermetically sealed
Long shelf life – 70% of tubes have a 3 year shelf life
Calibration scales printed directly on to the tubes for each production lot, thus eliminating variations in tube
diameter and reagent specifications
Contains small particles of sampling media for clearer determination of colour change and gas concentration

2. Designed so the specificity of the detector tube depends upon the gas being measured and the chemical
reagent. Some reagents are specific to only one gas but others respond to a group of similar or related gases.
Available to buy online by clicking here
Gastec tubes contain two types of filling reagent:
1) Detecting Reagents: which are located behind the calibration scale. They are special chemicals absorbed onto a
media such as silica gel or silica sand. They produce a distinct layer of colour change by reacting with the target
substance
2) Pre-treatment Reagents: which are located in front of the detecting agents to make the samples more
sensitive to the detecting reagents.
Gastec detector tubes can be classified into 3 types (please see below) according to the filling reagent:
1) Single Reagent: Filled with a detecting reagent
2) Single Reagent: Filled with a pre-treatment reagent and detecting reagent
3) Twin Tubes: Consist of a pre-treatment tube filled with a pre-treatment reagent and a separate detector tube
filled with a detecting reagent. These are joined together with a rubber connector.
Reading Gastec Tubes
1) During sampling, a colour change will occur within the tube in the presence of the target gas
2) Once the sampling time has elapsed, remove the tube from the pump and immediately mark the colour change
demarcation on the tube with a pen
3) From this endpoint, read the concentration of the gas detected from the printed scale on the tube
4) Make a note of the concentration and the date, time and place of measurement.
Hints for detector tube reading
A) When the colour change is FLAT. Read the value at the end of the layer. This reading would be 5
B) When the end of the colour change is SLANTED. Read the value in the middle of the slant. This reading would
be 5

3. C) When the end of the colour change is PALE. Read the value in the middle between the dark layer and the pale
end. This reading would be 5
Mesh Correction Factor
*
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Colour Change
Gas or Vapour to be Measured/
Chemical Formula
Gastec Tube
Number
Gastec Tube Name
Measuring
Range (ppm)
Original
Stain
Shelf Life
(Year)
A
Acetaldehyde CH₃CHO
92
Acetaldehyde
5-750
Yellow
Red
2*
92M
Acetaldehyde
2.5-100
Yellow
Red
2*
92L
Acetaldehyde
1-20
Yellow
Brown
2*
81
Acetic Acid
1-100
Pink
Yellow
3
81L
Acetic Acid
0.125-25
Pink
Pale Yellow
2*
81
Acetic Acid
0.6-15
Pink
Yellow
3
81L
Acetic Acid
0.15-6
Pink
Pale Yellow
2*
151
Acetone
0.05-2%
Orange
Dark Green
3
Acetone CH₃COCH₃
151L
Acetone
50-12000
Yellow
Red
2*
Acetone Cyanohydrin
(CH₃)₂C(OH)(CN)
Acetylene HC=CH
12L
Hydrogen cyanide
2.88-69
Yellow
Red
2
171
103
Acetylene
0.05-4%
White
Brown
3
Hydrocarbons (Lower
Class)++
0.075-3.6%
Yellowish Brown
Greenish Brown
2
172
Ethylene
32.5-1040
Pale Yellow
Blue
3
80
Acid Gases
See 1,2-Dichloroethylene
1-80
Pale Bluish Purple
Yellow
2
93
Acrolein
81
Acetic Acid CH₃CO₂H
Acetic Anhydride (CH₃CO)₂O
Acetylene Dichloride
Acid Gases
Acrolein CH₂:CHCHO
Acrylic Acid CH₂:CHCO₂H
Yellow
Red
2*
Acetic Acid
2-50
Pink
Yellow
3
81L
Acrylonitrile CH₂:CHCN
3.3-800
Acetic Acid
0.45-18
Pink
Pale Yellow
2*
191
Acrylonitrile+
2-360
Yellow
Red
3

4. 191L
Acrylonitrile+
0.1-18
Yellow
Pink
3
102L
140
n-Hexane
Aliphatic
Hydrocarbons
0.06-1.44%
6-3000
Orange
Yellow
Dark Green
Dark Brown
3
2
180
Amines
8.5-170
Pink
Yellow
3
180L
Amines
0.4-8
Pink
Yellow or Pale
Orange
2
101L
Gasoline (Petrol)
0.1-3.4%
Orange
Dark Green
3
131L
Vinyl Chloride+
3.2-48
Yellow
Reddish Brown
2*
Allyl Isothiocyanate CH2:CHCH₂NCS
Amines R ∙NH₂ Calibration
149
180
Methyl Methacrylate
Amines
5-200
5-100
Yellow
Pink
Pale Blue
Yellow or Pale
Orange
2
3
Amines CH₃NH₂ Calibration
180L
Amines
0.5-10
Pink
Yellow or Pale
Orange
2
Aliphatic Hydrocarbons
Allyl Amine CH₂:CHCO₂H
Allyl Chloride CH₂:CHCH₂Cl
2-Aminethanol
See Ethanolamine
Mesh Correction Factor
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Gas or Vapour to be Measured/
Chemical Formula
Colour Change
Gastec
Tube
Number
Gastec Tube Name
3H
Measuring
Range (ppm)
Original
Stain
Shelf Life
(Year)
Ammonia
0.2-32%
Purple
Yellow
3
3HM
Ammonia
0.05-3.52%
Pink
Yellow
3
3M
Ammonia
10-1000
Purple
Yellow
3
3LA
Ammonia
2.5-200
Purple
Yellow
3
3L
Ammonia
0.5-78
Pink
Yellow
3
180
Amines
1.5-30
Pink
Yellow
3
Amyl Acetate CH₃CO₂(CH₂)₄CH₃
147
Amyl Acetate
10-200
Yellow
Pale Blue
2
Aniline C₆H₅NH₂
181
Aniline
1.25-60
Pale Yellow
Pale Green
3
Arsine A₅H₃
Aromatic Hydrocarbons
19LA
120
Arsine
0.04-10
0.4-200
Yellow
White
Red
Brown
2
3
Benzaldehyde C₆H₅CHO
Benzene C₆H₆
91L
Formaldehyde
4-92
Yellow
Reddish Brown
3*
121
Benzene
2.5-120
White
Dark Green
3
121L
Benzene+
0.1-65
White
Dark Green
3
121S
Benzene+
2-312
White
Dark Green
3
121SL
Benzene+
1-100
White
Dark Green
3
Ammonia NH₃
Aromatic
Hydrocarbons
B

5. 121SP
Benzene+
0.2-20
White
Brown
2
171
Acetylene
0.03-0.6%
White
Brown
3
Benzyl Bromide C₆H₅CH₂Br
136L
Methyl Bromide+
10-100
White
Yellow
2
Benzyl Chloride C₆H₅CH₂Cl
132L
Trichloroethylene
1.6-20
Yellow
Purple
2*
Boron Trichloride BCl₃
12L
Hydrogen Cyanide
0.5-20
Yellow
Red
2
Bromine Br₂
8LA
Chlorine
0.05-0.8
White
Pale Pink
3
Bromochloromethane
Bromoform CHBr₃
1,3-Butadiene CH₂:CHCH:CH₂
See Chlorobromomethane
1-50
White
Yellow
2
1,3-Butadiene
50-800
Pale Yellow
White
3
174L
1,3-Butadiene
2.5-100
Pale Yellow
White
3
174LL
1,3-Butadiene
0.5-5
Pink
Pale Yellow
3*
104
103
Butane
Hydrocarbons (Lower
Class)++
25-1400
0.035-1.68%
Orange
Yellowish Brown
Dark Green
Greenish Brown
3
2
1-Butanol CH₃CH₂CH₂CH₂OH
114
1-Butanol
10-150
Yellow
Pale Blue
3
2-Butanol CH₃CH₂CH(OH)CH₃
115
2-Butanol
5-150
Yellow
Pale Blue
3
Butane CH₃(CH₂)₂CH₃
2-Butanone
Butyl Acetate CH₃CO₂(CH₂)₃CH₃
136L
Methyl Bromide+
174
See Methyl Ethyl Ketone (MEK)
142
Butyl Acetate
0.05-0.8%
Orange
Dark Green
3
142L
Butyl Acetate
10-300
Yellow
Dark Brown
2
Mesh Correction Factor
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Gas or Vapour to be Measured/
Colour Change
Gastec Tube Name
Hexane
142L
Butyl Acetate
180
Chemical Formula
Gastec
Tube
Number
102L
Measuring
Range (ppm)
0.05-1.2%
Original
Orange
Stain
Dark Green
Shelf Life
(Year)
3
7-210
Yellow
Dark Brown
2
Amines
8-160
Pink
180L
Amines
0.55-11
Pink
Greyish Red to
Brown
Yellow or Pale
Orange
180
Amines
5.5-110
Pink
Pale Brown
3
136H
Methyl Bromide+
24-360
White
Yellow
3
136L
Methyl Bromide+
10-100
White
Yellow
2
136LA
Methyl Bromide+
1-43.2
White
Yellow
2
70L
Mercaptans
0.16-12.8
Yellow
Red
2
tert-Butyl alcohol (CH₃)₃COH
Butyl Acrylate CH₂:CHCO₂C₄H₉
Butylamine CH₃(CH₂)₃NH₂
tert-Butylamine (CH₃)₃CNH₂
n-Butyl Bromide C₄H₉Br
Butyl Mercaptan CH₃(CH₂)₃SH
3
2

6. tert-Butyl Mercaptan (CH₃)₃CSH
75
tert-Butyl Mercaptan
2.5-150mg/m³
Yellow
Red
2
75L
tert-Butyl Mercaptan
0.5-30mg/m³
Yellow
Pink
2*
77
TBM and DMS
1-15mg/m³
Yellow
Pink
2*
70L
Mercaptans
0.1-8
Yellow
Red
2
Butyric acid CH₃CH₂CH₂CO₂H
81L
Acetic Acid
0.325-13
Pink
Pale Yellow
2*
Butyronitrile CH₃CH₂CH₂CN
191L
Acrylonitrile
6-180
Yellow
Pink
3
2HH
Carbon Dioxide
2.5-40%
Orange
Yellow
3
2H
Carbon Dioxide
0.5-20%
White
Purple
3
2L
Carbon Dioxide
0.13-6%
White
Purple
3
2LL
Carbon Dioxide
300-5000
Pale Blue
Purple
3
2LC
Carbon Dioxide
100-4000
Pale Red
Yellow
2
13M
Carbon Disulphide
20-4000
Purple
Yellow
3
13
Carbon Disulphide
0.63-100
Blue
Yellow
3
1HH
Carbon Monoxide
1-50%
White
Blackish Brown
3
1H
Carbon Monoxide
0.1-10%
White
Blackish Brown
3
1M
Carbon Monoxide
0.05-4%
White
Pale Brown
3
1LM
Carbon Monoxide
25-2000
White
Pale Brown
3
1L
Carbon Monoxide
2.5-2000
Yellow
Blackish Brown
3
1LA
Carbon Monoxide
8-1000
Yellow
Blackish Brown
3
1LC
Carbon Monoxide
1-30
White
Pale Pink
2
1LK
Carbon Monoxide (In
Hydrogen)
5-600
White
Pale Brown
3
1LL
Carbon Monoxide
5-50
Yellow
Blackish Brown
3
C
Carbon Dioxide CO₂
Carbon Disulphide CS₂
Carbon Monoxide CO
Mesh Correction Factor
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Colour Change
Carbon Tetrachloride CCl₄
Carbonyl Chloride
Carbonyl Sulphide COS
Gastec
Tube
Number
Gastec Tube Name
134
134L
Chemical Formula
Measuring
Range (ppm)
Original
Stain
Shelf Life
(Year)
Carbon Tetrachloride+
0.5-60
White
Yellow
1*
Carbon Tetrachloride+
0.25-12
White
Yellow
1*
Blue
Yellow
2*
See Phosgene
Carbonyl Sulphide+
21LA
Chlorine Cl₂
21
Carbonyl Sulphide+
8HH
Chlorine
5-200
2-125
Bluish Purple
White
2*
0.25-10%
Reddish Purple
Yellow
3

7. 8H
3
Chlorine
0.1-16
White
Pale Pink
3
Chlorine
0.025-2
White
Pale Green
1*
Acid Gases
0.7-14
Pale Bluish Purple
White
2
23M
Chlorine Dioxide
0.1-10
White
Pale Pink
3
23L
Chlorine Dioxide
0.025-1.2
White
Pale Green
1*
8H
Chlorine
25-250
White
Vermilion
3
8LA
Chlorine
0.3-4.8
White
Pale Pink
3
126
Chlorobenzene
2-500
White
Grey
3
126L
0.5-43
Yellow
Pale Purple
2*
135
Chlorobenzene
1,1,1-Trichloroethane+
(Methyl Chloroform)
22-110
White
Reddish Orange
3
136H
Methyl Bromide
18-270
White
Yellow
3
136L
Methyl Bromide
11-110
White
Yellow
2
136LA
Chlorocyclohexane C₆H₁₁Cl
Vermilion
80
Chlorobromomethane CH₂BrCl
White
8LL
Chlorobenzene C₆H₅Cl
25-1000
8LA
Chlorine Dioxide ClO₂
Chlorine
Methyl Bromide
0.7-12.6
White
Yellow
2
102L
Hexane
50-1200
Orange
Dark Green
3
1-Chloro-2, 3-epoxy propane
See Epichlorohydrin
2-Chloroethanol
See Ethylene Chlorohydrin
Chloroethylene
Chloroform CHCl₃
See Vinyl Chloride
137
Chloroform+
4-400
White
Orange
3
137LA
Chloroform+
0.5-30
White
Pale Purple
1*
137LL
Chloroform+
0.3-4.5
White
Pale Purple
1*
Chloropicrin Cl₃NO₂
134
Carbon Tetrachloride+
2.5-60
White
Yellow
1*
m-Cresol C₆H₄(CH₃)OH
61
o-Cresol
1-25
Pale Yellow
Grey
2*
o-Cresol C₆H₄(CH₃)OH
61
o-Cresol
0.4-62.5
Pale Yellow
Grey
2*
p-Cresol C₆H₄(CH₃)OH
61
o-Cresol
1-25
Pale Yellow
Grey
2*
Cumene C₆H₅CH(CH₃)₂
Cyclohexane C₆H₁₂
122L
Toluene
2-100
White
Brown
3
102H
Hexane
0.015-1.2%
Orange
Dark Green
3
102L
Hexane
60-1440
Orange
Dark Green
3
118
Cyclohexanol
5-100
Yellow
Pale Blue
2
154
Cyclohexanone
2-75
Pale Yellow
Yellow
2*
Cyclohexanol C₆H₁₁OH
Cyclohexanone C₆H₁₀O
Mesh Correction Factor
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Gas or Vapour to be Measured/
Colour Change
Gastec
Tube
Number
Gastec Tube Name
Cyclohexanone C₆H₁₀O
91L
Formaldehyde
Cyclohexene C₆H₁₀
151
Acetone
Chemical Formula
Measuring
Range (ppm)
Original
Stain
Shelf Life
(Year)
10-470
Yellow
Reddish Brown
3*
0.05-0.8%
Orange
Brownish Green
3

8. Cyclohexylamine C₆H₁₃N
180
Amines
7-140
Pink
Salmon Pink
3
180L
Amines
0.5-10
Pink
Yellow or Pale
Orange
2
Cymene C₁₀H₁₄
141L
Ethyl Acetate
5.6-224
Yellow
Blackish Brown
2
n-Decane CH₃(CH₂)₈CH₃
Diacetone Alcohol
(CH₃)₂C(OH)CH₂COCH₃
105
Hydrocarbons
(Higher Class)
200-6000
White
Blackish Brown
3
154
Cyclohexanone
2.5-100
Pale Yellow
Yellow
2*
Diacetyl CH₃COCOCH₃
92
Acetaldehyde
25-1500
Yellow
Red
2*
D
1,2-Diaminoethane
See Ethylenediamine
Diborane B₂H₆
22
Diborane
1, 1-Dibromoethane CH₃CHBr₂
136L
0.02-5
Methyl Bromide+
Dibromomethane CH₂Br₂
Di-n-butylamine (CH₃CH₂CH₂CH₂)₂NH
Red
2
7-70
1,2-Dibromoethane
Yellow
White
Yellow
2
See Ethylene Dibromide
136L
Methyl Bromide+
5-50
White
Yellow
2
180
Amines
5-100
Pink
3
180L
Amines
0.4-8
Pink
Pale Orange
Yellow or Pale
Orange
m-Dichlorobenzene C₆H₄Cl₂
127
o-Dichlorobenzene
2.5-300
White
Light Brown
3
o-Dichlorobenzene C₆H₄Cl₂
127
o-Dichlorobenzene
2.5-300
White
Light Brown
3
p-Dichlorobenzene C₆H₄Cl₂
127
o-Dichlorobenzene
2.5-300
White
Light Brown
3
1,1-Dichloroethane CH₃CHCl₂
135
1, 1, 1-Trichloroethane+
90-450
White
Reddish Orange
3
1,2-Dichloroethane
See Ethylene Dichloride
1, 1-Dichloroethylene
1,2-Dichloroethylene ClCH:CHCl
2
See Vinylidene Chloride
139
1,2-Dichloroethylene
5-250
Yellow
Reddish Purple
2*
132HA
Trichloroethylene
80-800
Yellow
Reddish Purple
2*
132LL
Trichloroethylene
0.4-6
Yellow
Purple
2*
Dichloromethane
See Methylene Chloride
1,2-Dichloropropane
1,3-Dichloropropene ClCH₂CH:CHCl
See Propylene Dichloride
Trichloroethylene
45-450
Yellow
Reddish Purple
2*
131LA
Diethylamine (C₂H₅)₂NH
132HA
Vinyl Chloride
0.5-10
Yellow
Reddish Brown
2*
180
Amines
5.5-110
Pink
Pale Brown
3
2
180L
Amines
0.45-9
Pink
Yellow or Pale
Orange
Diethylaminoethanol
(C₂H₅)NCH₂CH₂OH
180L
Amines
0.6-12
Pink
Yellow or Pale
Orange
2
Diethyl Benzene C₆H₄(C₂H₅)₂
122L
Toluene
2-150
White
Brown
3
Mesh Correction Factor
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Gas or Vapour to be Measured/
Colour Change
Gastec
Tube
Number
Gastec Tube Name
Diethylenetriamine
H₂NCH₂CH₂NHCH₂CH₂NH₂
180L
Diethylethanolamine
(C₂H₅)₂NC₂H₄OH
180
Chemical Formula
Measuring
Range
(ppm)
Original
Stain
Shelf
Life
(Year)
Amines
0.95-19
Pink
Greyish Purple
2
Amines
6-120
Pink
Pale Brown
3
Diethyl Ether
Diisobutylene (CH₃)₃CCH:C(CH₃)₂
Diisobutyl Ketone
[(CH₃)₂CHCH₂]₂CO
See Ethyl Ether
Dimethylbenzene
Dimethylethanolamine
(CH₃)₂NCH₂CH₂OH
3
102L
Hexane
0.2-1%
Orange
Dark Green
3
Formaldehyde
0.58-29
Yellow
Reddish Brown
3*
180
Amines
5-100
Pink
Pale Orange
3
Amines
0.3-6
Pink
Yellow or Pale Orange
2
141L
Ethyl Acetate
10-400
Yellow
Blackish Brown
2
184
N, N-Dimethyl Acetamide
1.5-240
Pink
Pale Yellow
3
3H
Ammonia
1.2-19.2%
Purple
Yellow
3
Amines
5.5-110
Pink
Salmon Pink
3
Amines
0.45-9
Pink
Yellow or Pale Orange
2
180L
Amines
0.65-13
Pink
Yellow or Pale Orange
2
180
Amines
0.6-12
Pink
Yellow or Pale Orange
2
180L
N,N-Dimethylaniline
C₆H₃(CH₃)₂(NH₂)
Dark Green
180L
2-Dimethylaminoethanol
(CH₃)₂NCH₂CH₂OH
Dimethylaminopropylamine
(CH₃)₂NCH₂CH₂CH₂CH₂NH₂
White
180
N,N-Dimethyl Acetamide
CH₃CON(CH₃)₂
Dimethylamine (CH₃)₂NH
45-540
180L
Diisopropyl Benzene
C₆H₅N[CH(CH₃)₂]₂
Benzene
91L
Diisopropylamine [(CH₃)₂CH]₂NH
121
Amines
8-160
Pink
Greyish Red
3
181
Aniline
2.5-30
Pale Yellow
Pale Green
3
See Xylene
6.5-130
Pink
Pale Orange to Yellow
3
Amines
0.65-13
Pink
Pale Orange
2
180
Amines
4-80
Pink
Yellow
3
180L
N,N-Dimethyl Formamide
HCON(CH₃)₂
Amines
180L
N,N-Dimethylethylamine
C₂H₅N(CH₃)₂
180
Amines
0.3-6
Pink
Yellow or Pale Orange
2
183
N,N-Dimethyl Formamide
0.8-90
Pink
Pale Red
3
2,6-Dimethyl-4-heptanone
See Diisobutyl Ketone
Dimethylhydrazine NH₂N(CH₃)₂
185
Hydrazine
0.1-2
Pink
Yellow
3
Dimethyl Sulphide (CH₃)₂S
1,4-Dioxane C₄H₈O₂
77
TBM and DMS
1-15mg/m³
Pink
Pale Yellow
2*
159
Tetrahydrofuran
25-140
Pink
Pale Blue
3
163
Ethylene Oxide
0.1-6%
Orange
Green
3

10. Mesh Correction Factor
*
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Refrigerator Store
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Gas or Vapour to be Measured/
Chemical Formula
Dipropylamine (CH₃CH₂CH₂)₂NH
Colour Change
Gastec
Tube
Number
Measuring
Range (ppm)
Original
Stain
Shelf
Life
(Year)
Gastec Tube Name
180
Amines
4-80
Pink
Yellow
3
180L
Amines
0.35-7
Pink
Yellow or Pale Orange
2
Divinyl Benzene C₆H₄(CH:CH₂)₂
Divinyl Methoxysilane
(CH₂:CH₂)₂CH₃OSi
124L
Styrene
1-15
White
Yellow
3
113L
Isopropyl Alcohol
2.5-40
Pink
Pale Blue
3
Epichlorohydrin CH₂OCHCH₂Cl
163L
Ethylene Oxide+
1.2-120
Yellow
Reddish Brown
1*
E
1,2-Epoxypropane
See Proylene Oxide
Ethanethiol
Ethanol C₂H₅OH
See Ethyl Mercaptan
Ethanol
0.01-7.5%
Pink
Pale Blue
3
112L
Ethyl Alcohol
Ethanolamine H₂NCH₂CH₂OH
112
Ethanol
50-2000
Pink
Pale Blue
3
See Ethanol
Pink
Yellow
3
Amines
1.95-39
Pink
Greyish Purple
2
141
Ethyl Acetate
0.1-1.5%
Orange
Dark Green
3
Ethyl Acetate
25-800
Yellow
Blackish Brown
2
141L
Ethyl Acetate
8-320
Yellow
Blackish Brown
2
180
Amines
5-100
Pink
Yellow
3
180L
Ethyl Benzene C₆H₅C₂H₅
7-140
141L
Ethyl Acrylate CH₂:CHCO₂C₂H₅
Ethylamine C₂H₅NH₂
Amines
180L
Ethyl Acetate CH₃CO₂C₂H₅
180
Amines
0.45-9
Pink
Yellow or Pale Orange
2
122
Toluene
11-330
White
Brown
3
1-70
White
Brown
3
122L
Toluene
p-Ethyl Benzylchloride
C₆H₄(C₂H₅)CH₂Cl
131LA
Vinyl Chloride+
2.5-50
Yellow
Reddish Brown
2*
Ethyl Bromide C₂H₅Br
136L
Methyl Bromide+
2.5-200
White
Yellow
2
Ethyl Chloride C₂H₅Cl
138
Methylene Chloride+
15-150
White
Pale Pink
3
Ethyl Chloroformate ClCO₂C₂H₅
Ethylene CH₂:CH₂
131LA
Vinyl Chloride+
7-140
Yellow
Reddish Brown
2*
172
Ethylene
25-1680
Pale Yellow
Blue
3
172L
Ethylene
Hydrocarbons
(Lower Class)++
0.2-100
Pale Yellow
Blue
3
0.35-16.8%
Yellowish Brown
Greenish Brown
2
103

11. 171
Brown
3
Methanol
20-200
Pink
Pale Blue
3
Amines
14-280
Pink
Yellow
3
180L
Amines
0.9-18
Pink
Yellow or Pale Orange
2
136H
Methyl Bromide+
14-210
White
Yellow
3
136L
Ethylene Dibromide BrCH₂CH₂Br
White
180
Ethylenediamine H₂NCH₂CH₂NH₂
0.1-2%
111L
Ethylene Chlorohydrin ClCH₂CH₂OH
Acetylene
Methyl Bromide+
8-80
White
Yellow
2
Mesh Correction Factor
*
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Gas or Vapour to be Measured/
Colour Change
Ethylene Glycol Monoethyl Ether
Acetate CH₃CO₂CH₂CH₂OC₂H₅
Ethylene Glycol Monomethyl
Ether CH₃OCH₂CH₂OH
Ethylene Glycol Monomethyl
Ether Acetate
Ethylene Oxide C₂H₄O
1,1-Trichloroethane+
400-2000
White
Reddish Orange
3
1,1-Trichloroethane+
104-1040
White
Pale Pink
2
165L
Ethylene Glycol+
10-100mg/m³
Yellow
Reddish Brown
3*
113L
Isopropyl Alcohol
30-1000
Pink
Pale Blue
3
Isopropyl Alcohol
23-230
Pink
Pale Blue
2
113L
Isopropyl Alcohol
62.5-1000
Pink
Pale Blue
3
Isopropyl Alcohol
15.2-152
Pink
Pale Blue
2
113L
Isopropyl Alcohol
6-96
Pink
Pale Blue
3
113L
Isopropyl Alcohol
15-900
Pink
Pale Blue
3
113LL
Ethylene Glycol Monoethyl Ether
C₂H₅OCH₂CH₂OH
Stain
113LL
Ethylene Glycol HOCH₂CH₂OH
Ethylene Glycol Monobutyl Ether
CH₃(CH₂)₃OCH₂CH₂OH
Original
Shelf
Life
(Year)
113LL
Ethylene Dichloride ClCH₂CH₂Cl
Measuring
Range (ppm)
135L
Chemical Formula
Gastec
Tube
Number
Gastec Tube Name
135
Isopropyl Alcohol
20-200
Pink
Pale Blue
2
See 2-Methoxyethyl Acetate
0.05-3%
Orange
Green
3
Ethylene Oxide
0.4-350
Yellow
Reddish Brown
1*
163LL
Ethylene Oxide
0.1-10
Yellow
Pale Orange
1*
136L
Methyl Bromide+
2.5-200
White
Yellow
2
161
Ethyl Ether
0.04-1%
Orange
Dark Green
3
161L
Ethylidene Chloride
Ethyl Mercaptan C₂H₅SH
Ethylene Oxide
163L
Ethyl Bromide BrCH₂CH₃
Ethyl Ether (C₂H₅)₂O
163
Ethyl Ether
10-1200
Yellow
Pale Blue
2
See 1,1-Dichloroethane
72
Ethyl Mercaptan
0.5-120
White
Yellow
3
72L
Ethyl Mercaptan
0.2-75
Yellow
Red
2
70
Mercaptans
0.5-120
White
Yellow
3
70L
Mercaptans
0.1-8
Yellow
Red
2

12. 71H
100-3800
White
Yellow
3
Amines
5-100
Pink
Yellow
3
180L
Amines
0.3-6
Pink
Yellow or Pale Orange
2
17
Hydrogen Fluoride
0.5-50
Yellow
Brown
3
91
Formaldehyde
2-100
White
Brown
3
91M
Formaldehyde
8-6400
Yellow
Red
2*
91L
Formaldehyde
0.1-40
Yellow
Reddish Brown
3*
91LL
Formaldehyde
0.05-1
Yellowish Brown
Reddish Brown
1*
81
Acetic Acid
5.2-130
Pink
Yellow
3
81L
N-Ethyl Morpholine C₆H₁₃NO
Methyl Mercaptan
180
Acetic Acid
0.5-20
Pink
Yellow
2*
154
Cyclohexanone
2-30
Pale Yellow
Yellow
2*
F
Fluorine F₂
Formaldehyde HCHO
Formic Acid HCO₂H
Furfural C₅H₄O₂
Mesh Correction Factor
*
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Gas or Vapour to be Measured/
Chemical Formula
Colour Change
Gastec
Tube
Number
Gastec Tube Name
101
Measuring
Range (ppm)
Original
Stain
Shelf Life
(Year)
Gasoline (Petrol)
0.015-1.2%
Orange
Dark Green
3
101L
Gasoline (Petrol)
30-2000
Orange
Dark Green
3
1M
Carbon Monoxide
0.1-2%
White
Pale Brown
3
101
Gasoline (Petrol)
0.015-1.2%
Orange
Dark Green
3
101L
Gasoline (Petrol)
30-2000
Orange
Dark Green
3
103
Hydrocarbons (Lower
Class)++
0.035-1.68%
Yellowish Brown
Greenish Brown
2
105
Hydrocarbons (Higher
Class)
90-2700
White
Blackish Brown
3
180L
Amines
1.55-31
Pink
Greyish Purple
2
102H
n-Hexane
0.015-1.2%
Orange
Dark Green
3
102L
n-Hexane
4-1200
Orange
Dark Green
3
103
Hydrocarbons (Lower
Class)++
0.025-1.2%
Yellowish Brown
Greenish Brown
2
G
Gasoline (Petrol) CnHm
H
Heptane CH₃(CH₂)₅CH₃
Hexamethylenediamine H₂N(CH₂)₆NH₂
Hexane CH₃(CH₂)₄CH₃

13. 105
Hydrocarbons (Higher
Class)
Hexone
80-2400
White
Blackish Brown
3
See Methyl Isobutyl Ketone
2-Hexyl Alcohol CH₃(CH₂)₃CH(OH)CH₃
Hexylamine CH₃(CH₂)₅NH₂
141L
Ethyl Acetate
60-2400
Yellow
Blackish Brown
2
180
Amines
9-180
Pink
Pale Orange
3
180L
Amines
0.65-13
Pink
Yellow or Pale Orange
2
Hydrazine N₂H₄
185
Hydrazine
0.05-2
Pink
Yellow
3
Hydrocarbons (Higher Class)
105
Hydrocarbons (Higher
Class)
100-3000
White
Blackish Brown
3
Hydrocarbons (Lower Class)
103
Hydrocarbons (Lower
Class)++
0.05-2.4%
Yellowish Brown
Greenish Brown
2
Hydrogen H₂
30
Hydrogen
0.5-2%
Yellow
Yellowish Brown
3
Hydrogen Bromide HBr
Hydrogen Chloride HCl
15L
Nitric Acid
0.8-16
Yellow
Reddish Purple
3
14R
Hydrogen Chloride
50-5000
Purple
Yellow/Pale Pink
3
14M
Hydrogen Chloride
10-1000
Yellow
Red
3
14L
Hydrogen Chloride
0.2-76
Yellow
Pink
3
80
Acid Gases
8-160
Pale Bluish Purple
Pale Reddish Purple
2
8HH
Chlorine
1.5-30%
Reddish Purple
Yellow
3
Mesh Correction Factor
*
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Gas or Vapour to be Measured/
Colour Change
Measuring
Range (ppm)
Original
Stain
Shelf Life
(Year)
12H
Hydrogen Cyanide
0.05-1.6%
Yellow
White
3
Hydrogen Cyanide
17-2400
Yellow
Red
3
12L
Hydrogen Cyanide
0.36-120
Yellow
Red
2
12LL
Hydrogen Cyanide
0.2-7
Yellow
Pink
2
17
Hydrogen Fluoride
0.25-100
Yellow
Brownish
Pink/Deep Pink
3
17L
Hydrogen Cyanide HCN
Gastec Tube Name
12M
Chemical Formula
Gastec
Tube
Number
Hydrogen Fluoride
0.09-72
Yellow
Brown
2
32
Hydrogen Peroxide
0.5-10
White
Yellow
3
4HT
Hydrogen Sulphide
1-40%
Pale Blue
Blackish Brown
3
4HP
Hydrogen Sulphide
0.25-20%
Pale Blue
Blackish Brown
3
Hydrogen Fluoride HF
Hydrogen Peroxide H₂O₂
Hydrogen Sulphide H₂S

14. 4HH
0.1-4%
Pale Blue
Blackish Brown
3
4H
Hydrogen Sulphide
10-4000
White
Brown
3
4HM
Hydrogen Sulphide
25-1600
White
Brown
3
4M
Hydrogen Sulphide
12.5-500
White
Brown
3
4L
Hydrogen Sulphide
1-240
White
Brown
3
4LL
Hydrogen Sulphide
0.25-120
White
Brown
3
4LB
Hydrogen Sulphide
0.5-12
Pale Yellow
Pink
2
4LT
Hydrogen Sulphide
0.1-4
Pale Yellow
Reddish Brown
2*
4LK
Hydrogen Sulphide
1-40
White
Brown
3
45S
Hydrogen Sulphide + Sulphur Dioxide
(Total Quantification) H₂S+SO₂
Hydrogen Sulphide
Hydrogen Sulphide+
H2S:1.25-120
White
Brown
3
45H
Hydrogen Sulphide +
Sulphur Dioxide
0.02-8%
Brown
Pale Yellow
3
4-Hydroxy-4-methyl-2-pentanone
C₆H₁₂O₂
See Diacetone Alcohol
I
Iodine I₂
9L
Yellowish Orange
3
0.12-2.4
White
Pale Bluish
Purple
80
Light Bluish Grey
2
Isoamyl Acetate
10-200
Yellow
Pale Blue
2
117
Isoamyl Alcohol
5-300
Yellow
Pale Blue
3
103
Hydrocarbons (Lower
Class)++
0.035-1.68%
Yellowish Brown
Greenish Brown
2
104
Butane
55-3080
Orange
Dark Green
3
Isobutene (CH₃)₂C:CH₂
101L
Gasoline (Petrol)
0.07-2.2%
Orange
Dark Green
3
Isobutyl Acetate CH₃CO₂CH₂CH(CH₃)₂
144
Isobutyl Acetate
10-300
Yellow
Blackish Brown
2
Isoamyl Acetate
CH₃CO₂(CH₂)₂CH(CH₃)₂
Isoamyl Alcohol (CH₃)₂CH(CH₂)₂OH
Isobutane (CH₃)₃CH
Nitrogen Dioxide
Acid Gases
148
Mesh Correction Factor
*
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0.2-12
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Gas or Vapour to be Measured/
Colour Change
Gastec
Tube
Number
Gastec Tube Name
Isobutyl Acrylate
CH₂:CHCO₂CH₂CH(CH₃)₂
142L
Isobutyl Alcohol (CH₃)₂CHCH₂OH
116
Chemical Formula
Measuring
Range (ppm)
Original
Stain
Shelf Life
(Year)
Butyl Acetate
2.6-78
Yellow
Dark Brown
2
Isobutyl Alcohol
10-150
Yellow
Pale Blue
3

15. Isooctane (CH₃)₃CCH₂CH(CH₃)₂
101
Gasoline (Petrol)
0.027-0.54%
Orange
Dark Green
3
Isopentane (CH₃)₂CHCH₂CH₃
103
Hydrocarbons (Lower
Class)++
0.045-2.16%
Yellowish Brown
Greenish Brown
2
Isopentyl Acetate
See Isoamyl Acetate
Isopentyl Alcohol
See Isoamyl Alcohol
Isophorone C₉H₁₄O
154
Cyclohexanone
2-30
Pale Yellow
Yellow
2*
Isopropyl Acetate CH₃CO₂CH(CH₃)₂
Isopropyl Alcohol (IPA)
CH₃CH(OH)CH₃ (i-C₃H₇OH)
146
Isopropyl Acetate
10-500
Yellow
Blackish Brown
2
113
Isopropyl Alcohol
0.02-5%
Pink
Pale Blue
3
113L
Isopropyl Alcohol
25-800
Pink
Pale Blue
3
113LL
Isopropyl Alcohol
20-440
Pink
Pale Blue
2
180
Amines
5.5-110
Pink
3
180L
Amines
0.45-9
Pink
Salmon Pink
Yellow or Pale
Orange
141L
Ethyl Acetate
22.5-720
Yellow
Blackish Brown
2
161
Ethyl Ether
0.018-0.45%
Orange
Dark Green
3
70
Mercaptans
10-240
White
Yellow
3
81
Acetic Acid
2-50
Pink
Yellow
3
81L
Acetic Acid
0.38-15
Pink
Pale Yellow
2*
LPG (Liquidfied Petroleum Gas)
100A
LPG
0.02-0.8%
Orange
Blackish Green
3
Maleric Anhydride C₄H₂O₃
Mercaptans R ∙ SH
81
Acetic Acid
0.8-20
Pink
Yellow
3
70
Mercaptans
0.5-120
White
Yellow
3
70L
Mercaptans
0.1-8
Yellow
Red
2
2-Mercaptoethanol HSCH₂CH₂OH
75L
tert-Butyl Mercaptan
Yellow
Pink
2*
Mercury Vapour Hg
40
Mercury Vapour
0.5-7.5
0.0513.2mg/m³
White
Pale Orange
3
Mesityl Oxide (CH₃)₂C:CHCOCH₃
Methacrylic Acid CH₂:C(CH₃)COOH
141L
Ethyl Acetate
27-1080
Yellow
Blackish Brown
2
81
Acetic Acid
1.8-45
Pink
Yellow
3
81L
Acetic Acid
0.35-14
Pink
Pale Yellow
2*
192
Methacrylonitrile
0.2-32
Yellow
Red
3
Isopropyl Amine (CH₃)₂CHNH₂
Isopropyl Ether [(CH₃)₂(CH)₂O
Isopropyl Mercaptane (CH₃)₂CHSH
Isovaleric Acid (CH₃)₂CHCH₂CO₂H
2
L
M
Methacrylonitrile CH₂:C(CH₃)CN
Mesh Correction Factor
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16. Gas or Vapour to be Measured/
Chemical Formula
Methaldehyde (CH₃CHO)n
Methanethiol
Methanol CH₃OH
Colour Change
Gastec
Tube
Number
Gastec Tube Name
91L
Formaldehyde
Measuring
Range (ppm)
Original
Stain
Shelf Life
(Year)
0.065-3.25
Yellow
Reddish Brown
3*
See Methyl Mercaptan
Methanol
0.002-4.5%
Pink
Pale Blue
3
111L
Methanol
20-1000
Pink
Pale Blue
3
111LL
Methanol
2-56
Pale Yellow
Pale Bluish Green
2
113L
Isopropyl Alcohol
20-1300
Pink
Pale Blue
3
113L
Isopropyl Alcohol
50-800
Pink
Pale Blue
3
113LL
2-Methoxyethyl Acetate
CH₃CO₂CH₂CH₂OCH₃
1-Methoxy-2-Propanol
CH₃OCH₂CH(OH)CH₃
111
Isopropyl Alcohol
15.2-152
Pink
Pale Blue
2
Methyl Alcohol
See Methanol
Methyl Acrylate CH₂:CHCO₂CH₃
141L
Ethyl Acetate
8-320
Yellow
Blackish Brown
2
2-Methyl Allyl Chloride
CH₃CH₂:CHCH₂Cl
Methylamine CH₃NH₂
131LA
Vinyl Chloride
2.8-55
Yellow
Reddish Brown
2*
180
Amines
5-100
Pink
Pale Brown/Yellow
3
180L
Amines
0.5-10
Pink
Yellow or Pale Orange
2
181
Aniline
3.5-42
Pale Yellow
Pale Green
3
136H
Methyl Bromide
10-600
White
Yellow
3
136L
Methyl Bromide
2.5-200
White
Yellow
2
136LA
Methyl Bromide
1-36
White
Yellow
2
191L
Acrylonitrile
0.4-12
Yellow
Pink
3
N-Methyl Aniline C₆H₅NHCH₃
Methyl Bromide CH₃Br
2-Methyl-3-Butenenitrile
(CH₃)₂CHCH:CHCN
Methyl Chloroform
See 1, 1, 1-Trichloroethylene
Methyl Chloroformate ClCO₂CH₃
131LA
Vinyl Chloride
58-1160
Yellow
Reddish Brown
2*
Methylcyclohexane C₆H₁₁CH₃
102H
n-Hexane
0.04-0.84%
Orange
Dark Green
3
Methylcyclohexanol CH₃C₆H₁₀OH
119
Methylcyclohexanol
5-100
Yellow
Pale Blue
2
Methylcyclohexanone C₇H₁₂O
Methylene Chloride CH₂Cl₂
155
Methylcyclohexanone
2-100
Pale Yellow
Yellow
2*
138
Methylene Chloride
20-500
White
Pale Pink
3
138L
Methylene Chloride
4-150
White
Pale Pink
2
Methylene Iodide CH₂I₂
121L
Benzene+
0.22-22
White
Dark Green
3
Methyl Ether CH₃OCH₃
Methyl Ethyl Ketone (MEK)
CH₃COC₂H₅
161
Ethyl Ether
0.03-0.85%
Orange
Dark Green
3
152
Methyl Ethyl Ketone
0.02-0.6%
Orange
Dark Green
3
152L
Methyl Ethyl Ketone
10-384
Yellow
Reddish Purple
2*
151L
Acetone
21-1680
Yellow
Red
2*
185
Hydrazine
0.6-12
Pink
Yellow
3
Methyl Hydrazine H₂NNHCH₃

17. Mesh Correction Factor
*
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Gas or Vapour to be Measured/
Chemical Formula
Colour Change
Measuring
Range (ppm)
Original
Stain
Shelf Life
(Year)
Methyl Iodide
100-34800
White
Dark Brown
2
230
Methyl Iodide
0.5-108
White
Grey
1*
121L
Benzene+
0.32-32
White
Dark Green
3
153
Methyl Isobutyl Ketone
0.05-0.6%
Orange
Dark Green
3
153L
Methyl Isobutyl Ketone
2.5-130
Pale Yellow
Pale Blue
1
71H
Methyl Mercaptan
20-2700
White
Yellow
3
71
Methyl Mercaptan
0.25-140
White
Yellow
3
70
Mercaptans
0.35-84
White
Yellow
3
70L
Mercaptans
0.1-8
Yellow
Red
2
149
Methyl Methacrylate
10-500
Yellow
Pale Blue
2
180
Amines
5-100
Pink
Yellow
3
180L
Amines
0.3-6
Pink
Yellow or Pale Orange
2
4-Methyl Pyridine C₆H₇N
182
Pyridine
0.38-10.5
Pink
Yellow
3
N-Methyl Pyrrolidone C₅H₉NO
180
Amines
50-270
Pink
Yellow
3
Methyl Iodide CH₃l
Methyl Isobutyl Ketone
(CH₃)₂CHCH₂COCH₃
Methyl Mercaptan CH₃SH
Methyl Merthacrylate
CH₂:C(CH₃)CO₂CH₃
N-Methyl Morpholine
CH₃N(C₂H₄)₂O
Monochlorobenzene
Morpholine NH(C₂H₄)O
Gastec Tube
Number
Gastec Tube Name
230H
See Chlorobenzene
180
Amines
9-180
Pink
Yellow
3
180L
Amines
0.5-10
Pink
Yellow or Pale Orange
2
60
Phenol
0.5-14
Pale Yellow
Grey
2*
15L
Nitric Acid
0.1-40
Reddish Purple
3
80
Acid Gases
5-100
Yellow
Purple Bluish
Purple
Pale Red Purple
2
9L
Nitrogen Dioxide
0.5-125
White
Yellowish Orange
3
10
NO + NO₂+ (Separate
Quantification)
2.5-200
Yellowish Orange
3
80
Acid Gases
0.2-4
White
Pale Bluish
Purple
Pinkish Grey
2
Nitric Oxide NO
10
NO + NO₂+ (Separate
Quantification)
2.5-200
White
Yellowish Orange
3
Nitrogen Oxides NO+NO₂
11HA
Nitrogen Oxides (Total
Quantification)
50-2500
White
Green
2
N
Napthalene C₁₀H₈
Nitric Acid HNO₃
Nitrogen Dioxide NO₂

18. Nitrogen Oxides NO+NO₂
11L
Nitrogen Oxides (Total
Quantification)
Nitrogen Oxides (Total
Quantification)
105
Hydrocarbons (higher
class)
11S
Nitrotrichloromethane
Nonane CH₃(CH₂)₇CH₃
White
Pale Green
2
0.04-16.5
White
Yellowish Orange
3
White
Blackish Brown
3
See Chloropicrin
Mesh Correction Factor
*
5-625
+ Twin Tubes
Refrigerator Store
++ Nine Tubes
130-3900
All Tubes £29.95/€44.33 Per Pack
Always prefix tube number by the letters "GAS" when placing an order
Gas or Vapour to be Measured/
Chemical Formula
Colour Change
Gastec Tube
Number
Gastec Tube Name
Measuring
Range (ppm)
Original
Stain
Shelf Life
(Year)
101
Gasoline (Petrol)
0.036-0.72%
Orange
Dark Green
3
105
Hydrocarbons (Higher
Class)
100-3000
White
Blackish Brown
3
Olefines
100A
LPG
0.34-13.6%
Orange
Blackish Green
3
Oxygen O₂
Ozone O₃
31B
Oxygen
3-24%
Black
White
3
18M
Ozone
4-400
Orange
Pale Yellow
3
18L
Ozone
0.025-3
Blue
White
3
133L
Tetrachloroethylene
40-500
Yellow
Pink
2*
174
1,3-Butadiene
250-4000
Pale Yellow
White
3
174L
1,3-Butadiene
42.5-850
Pale Yellow
White
3
180L
Amines
0.75-15
Pink
Greyish Purple
2
104
Butane
30-1680
Orange
Dark Green
3
103
Hydrocarbons (Lower
Class)++
0.0375-1.8%
Yellowish
Brown
Greenish Brown
2
193
2-Pentenenitrile
0.5-15
Yellow
Red
3
191L
Acrylonitrile
0.24-7.2
Yellow
Pink
3
191L
Acrylonitrile
0.4-12
Yellow
Pink
3
Dark Green
3
Dark Green
3
O
Octane CH₃(CH₂)₆CH₃
P
Pentachloroethane Cl₂CHCCl₃
1,3-Pentadiene
CH₃CH:CHCH:CH₂
Pentamethylenediamine
H₂N(CH₂)₅NH₂
n-Pentane CH₃(CH₂)₃CH₃
2-Pentenenitrile
CH₃CH₂CH:CHCN
3-Pentenenitrile
CH₃CH:CHCH₂CN
Pentyl Acetate
See n-Amyl Acetate
Perchloroethylene
Petroleum Benzine
See Tetrachloroethylene
106
Petroleum Naphtha
Petroleum Distillates
Petroleum Ether
0.5-28mg/l
Orange
See Gasoline (Petrol)
106
Petroleum Naphtha
0.5-28mg/l
Orange

19. Petroleum Naphtha
106
Petroleum Naphtha
Phenol C₆H₅OH
60
Phenol
Phenylethylene
Phosgene COCl₂
Phosphine PH₃
0.5-28mg/l
Orange
Dark Green
3
0.4-187
Pale Yellow
Grey
2*
See Styrene
0.05-20
White
Yellow
1.5*
7H
Phosphine
200-5500
Yellow
Dark Brown
2
Phosphine
2.5-1000
White
Pale Yellow
3
7
Phosphine
2.5-100
White
Pale Yellow
3
7L
Phosphine
0.15-5
Pale Yellow
Purple
3
7LA
Propane CH₃CH₂CH₃
Phosgene
7J
α-Pinene C₁₀H₁₆
16
Phosphine
0.05-9.8
Yellow
Red
2
121
Benzene
95-1140
White
Dark Green
3
103
Hydrocarbons (Lower
Class)++
0.05-2.4%
Yellowish
Brown
Greenish Brown
2
Mesh Correction Factor
*
+ Twin Tubes
Refrigerator Store
++ Nine Tubes
All Tubes £29.95/€44.33 Per Pack
Always prefix tube number by the letters "GAS" when placing an order
Gas or Vapour to be
Measured/
Chemical Formula
Colour Change
0.76-38
Yellow
Reddish Brown
3*
Acetone
24-1880
Yellow
Red
2*
81
Acetic Acid
3-75
Pink
Yellow
3
Acetic Acid
0.25-10
Pink
Pale Yellow
2*
191
Acrylonitrile+
50-1200
Yellow
Red
3
145
Propyl Acetate
20-500
Yellow
Blackish Brown
2
113
Isopropyl Alcohol
0.04-2.5%
Pink
Pale Blue
3
Isopropyl Alcohol
65-1040
Pink
Pale Blue
3
Isopropyl Alcohol
13.6-136
Pink
Pale Blue
2
180
Amines
6-120
Pink
Salmon Pink
3
Amines
0.5-10
Pink
Yellow or Pale Orange
2
100A
LPG
0.02-0.8%
Orange
Blackish Green
3
131LA
Vinyl Chloride+
40-800
Yellow
Reddish Brown
2*
180
Amines
5.5-110
Pink
Yellow
3
180L
Propylene Oxide CH₃CHCH₂O
Formaldehyde
180L
Propylene CH₃CH:CH₂
Propylene Dichloride
CH₃CHClCH₂Cl
Propylene Imine CH₃CHCH₂NH
Shelf Life
(Year)
113LL
Propylamine CH₃(CH₂)₂NH₂
Stain
113L
Propionitrile CH₃CH₂CN
Propyl Acetate
CH₃CO₂CH₂CH₂CH₃
Propyl Alcohol CH₃(CH₂)₂OH
Original
81L
Propionic Acid CH₃CH₂COOH
Measuring
Range (ppm)
151L
Propionaldehyde CH₃CH₂CHO
Gastec Tube
Number
Gastec Tube Name
91L
Amines
0.35-7
Pink
Yellow or Pale Orange
2
163
Ethylene Oxide
0.065-3.9%
Orange
Green
3
163L
Ethylene Oxide
1-100
Yellow
Reddish Brown
1*

20. Propyl Mercaptan CH₃(CH₂)₂SH
70
Mercaptans
22.5-540
White
Yellow
3
70L
Mercaptans
0.12-9.6
White
Red
2
Pyridine C₅H₅N
182
Pyridine
0.2-35
Pink
Yellow
3
Stoddard Solvent
Styrene C₆H₅CH:CH₂
128
Stoddard Solvent
508000mg/m³
White
Brown (ring)
3
124
Styrene
10-1500
White
Yellow
3
124L
Styrene
2-100
White
Yellow
3
153
Methyl Isobutyl Ketone
0.075-0.9%
Orange
Dark Green
3
5H
Sulphur Dioxide
0.05-8%
Orange
Green
3
5M
Sulphur Dioxide
20-3600
Purple
Yellow
3
5L
Sulphur Dioxide
1.25-200
Blue
Yellow
3
5LA
Sulphur Dioxide
0.5-60
Blue
Yellow
3
5LC
Sulphur Dioxide
0.1-25
Bluish Purple
White
3
5LB
Sulphur Dioxide
0.05-10
Yellowish Green
Yellow
3
S
Sulphur Dioxide SO₂
Mesh Correction Factor
*
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Refrigerator Store
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All Tubes £29.95/€44.33 Per Pack
Always prefix tube number by the letters "GAS" when placing an order
Gas or Vapour to be
Measured/
Colour Change
Gastec Tube Name
45S
Hydorgen Sulphide, Sulphur
Dioxide (Separate
Quantificaton)+
80
Chemical Formula
Gastec
Tube
Number
Acid Gases
35
Sulphuric Acid
135L
1,1,1-Trichloroethane+
131L
Original
Stain
Shelf Life
(Year)
Yellow
3
1.5-30
Yellowish Green
Pale Bluish
Purple
Yellow
2
0.5-5mg/m³
Pale Yellow
Reddish Purple
2
0.92-9.2
White
Pale Pink
2
Vinyl Chloride+
2-30
Yellow
Reddish Brown
2*
133HA
Tetrachloroethylene
7-900
Yellow
Reddish Purple
2*
133M
Tetrachloroethylene
2-250
Yellow
Reddish Purple
2*
133L
Tetrachloroethylene
1-75
Yellow
Pink
2*
133LL
Tetrachloroethylene
0.1-9
Yellow
Purple
2*
132HH
Trichloroethylene
0.075-1.5%
White
Yellowish Brown
3
Sulphur Dioxide SO₂
Sulphuric Acid H₂SO₄
Measuring
Range (ppm)
SO₂: 0.25-20
T
1,1,2,2-Tetrabromoethane
Br₂CHCHBR₂
1,1,2,2-Tetrachloroethane
Cl₂CHCHCl₂
Tetrachloroethylene Cl₂C:CCl₂

21. Tetrachloromethane
Tetrahydrofuran C₄H₈O
See Carbon Tetrachloride
Pink
Pale Blue
3
0.056-1.4%
Orange
Dark Green
3
Tetrahydrothiophene+
10-200
Pink
Pale Yellow
2
Tetrahydrothiophene+
10-100mg/m³
Pink
Pale Yellow
2
76
Tetrahydrothiophene+
1-10
Pink
Pale Yellow
2
180
Amines
8.5-170
Pink
Yellowish Purple
3
180L
Amines
0.8-16
Pink
Grey
2
5LA
Sulphur Dioxide
1.44-21.6
Blue
Yellow
3
122
Toluene
5-690
White
Brown
3
122L
Toluene
1-100
White
Brown
3
161
Thionyle Chloride SOCl₂
Toluene C₆H₅CH₃
20-800
76M
Tetramethylenediamine
H₂N(CH₂)₄NH₂
Tetrahydrofuran
161
Tetrahydrothiophene C₄H₈S
159
Ethyl Ether
76H
Ethyl Ether
0.02-0.8%
Orange
Dark Green
3
5-60
Pale Yellow
Pale Green
3
Toluol
See Toluene
o-Toluidine C₆H₄(CH₃)(NH₂)
181
Aniline
Trichloroacetic Acid CCl₃COOH
15L
Nitric Acid
1-37.5
Yellow
Reddish Purple
3
1,2,4-Trichlorobenzene C₆H₃Cl₃
1,1,1-Trichloroethane CH₃CCl₃
131LA
Vinyl Chloride+
0.65-13
Yellow
Reddish Brown
2*
135
1,1,1-Trichloroethane+
100-2000
White
Reddish Orange
3
135L
1,1,1-Trichloroethane+
6-900
White
Pale Pink
2
171
Acetylene
0.06-1.2%
White
Brown
3
135
1,1,1-Trichloroethane+
220-750
White
Reddish Orange
3
1,1,2-Trichloroethane
Cl₂CHCH₂Cl
Mesh Correction Factor
*
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Refrigerator Store
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All Tubes £29.95/€44.33 Per Pack
Always prefix tube number by the letters "GAS" when placing an order
Gas or Vapour to be
Measured/
Chemical Formula
Colour Change
Gastec
Tube
Number
Gastec Tube Name
132HH
Trichloroethylene
132HA
Trichloroethylene
132M
Measuring
Range (ppm)
Shelf Life
(Year)
Stain
0.05-2.5%
White
Yellowish Brown
3
20-1300
Yellow
Reddish Purple
2*
Trichloroethylene
2-250
Yellow
Reddish Purple
2*
132L
Trichloroethylene
1-70
Yellow
Purple
2*
132LL
Trichloroethylene Cl₂C:CHCl
Original
Trichloroethylene
0.125-8.8
Yellow
Purple
2*
Trichloromethane
See Chloroform
Trichloronitromethane
See Chloropicrin
1,2,3-Trichloropropane
CH₂ClCHClCH₂Cl
Triethylamine (C₂H₅)₃N
135L
1,1,1-Trichloroethane+
36-360
White
Pale Pink
2
180
Amines
4.5-90
Pink
Yellow
3

22. 180L
0.3-6
Pink
Yellow Or Pale Orange
2
Ammonia
25-250
Purple
Yellow
3
180
Amines
3.5-70
Pink
Yellow
3
180L
Amines
0.25-5
Pink
Yellow Or Pale Orange
2
Trimethyl Benzene C₆H₃(CH₃)₃
123
Xylene
10-300
White
Brown
3
Valeric Acid CH₃(CH₂)₃COOH
Vinyl Acetate CH₃CO₂CH:CH₂
81L
Acetic Acid
0.38-15
Pink
Pale Yellow
2*
143
Vinyl Acetate+
5-250
White
Brown
3
141
Ethyl Acetate
0.06-0.9%
Orange
Dark Green
3
Trimethylamine (CH₃)₃N
Amines
3M
V
Vinyl Benzene
Vinyl Chloride CH₂:CHCl
See Styrene
131
Vinyl Chloride
0.025-2%
Orange
Dark Green
3
131LA
Vinyl Chloride+
0.25-54
Yellow
Reddish Brown
2*
131L
Vinyl Chloride+
0.1-6.6
Yellow
Reddish Brown
2*
131LB
Vinyl Chloride
0.25-70
Yellow
Purple
2*
Vinylidene Chloride CH₂:CCl₂
130L
Vinylidene Chloride
0.4-40.6
Yellow
Reddish Brown
2*
Vinyl Trimethoxysilane
CH₂:CHSi(OCH₃)₃
113L
Isopropyl Alcohol
2.5-40
Pink
Pale Blue
3
6
Water Vapour
0.5-32mg/l
Yellowish Green
Purple
3
6L
Water Vapour
0.05-2mg/l
Yellow
Purple
3
6LP
Pipeline Dew Point Tube
3-100LB/MMCF
Yellow
Greenish Purple
3
6LP
Pipeline Dew Point Tube
2-10LB/MMCF
Yellow
Green
3
123
Xylene
5-625
White
Brown
3
123L
Xylene
2-200
White
Brown
3
100A
LPG
0.1-1.2%
Orange
Blackish Green
3
122L
Toluene
2-200
White
Brown
3
Vinyl Cyanide
See Acrylonitrile
W
Water Vapour H₂O
X
Xylene C₆H₄(CH₃)₂