Custom Colorimetric Indicators
(STEL & TWA Measurements
)

We manufacture custom colorimetric indicators for wide variety of toxic gases and vapors in air. These indicators are most suited for OSHA Time Weight Average (TWA) measurements and Short Term Exposure Limit (STEL) measurements. The indicators are uniformly coated for reproducibility and accuracy.

 

Features:

  • Irreversible color change
  • Real-time and direct-read
  • Detection limit at or below OSHA permissible exposure limits
  • Accurate and reproducible (overall accuracy, better than ±25% at the 95% confidence level)
  • Selective to target chemical
  • Stabilized for longer service life and shelf life

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Available Indicators

Item No.

Chemical Name

Part No.

Minimum Detectable

(ppm●hr)

Service Life

(Years)

Shelf Life (Years)

Cross Interferences

1

Acetone (Methyl Ketones Indicator)

533

5

9 months

1

a

2

Acids

511

0.07

14 months

1

b

3

Ammonia

517

10

2

2

None known

4

Aniline

513

0.2

8 hours

1

c

5

Aromatic diisocyanates

515

0.005

1

1

None known

6

Arsine

516

0.02

8 hours

1

d

7

Basic vapors

512

0.05

14 months

1

e

8

Chlorine (Halogens Indicator)

519

0.2

9 months

1

Other halogens

9

Chlorine dioxide (HS)

520

0.3

1

1

Strong Oxidants

10

Chlorine dioxide (LS)

544

10

1

1

Strong Oxidants

11

Dimethyl hydrazine (-1,1) (UDMH)

522

0.004

8 hours

1

f

12

Ethyl chloroformates

523

0.02

72 hours

1

g

13

Fluorine (Halogens Indicator)

519

0.2

9 months

1

Other halogens

14

Formaldehyde

525

0.3

1

1

h

15

Hydrazine (HS)

526

0.004

8 hours

1

i

16

Hydrazine (LS) Water Proof

545

0.15

2

2

None known

17

Hydrazine (LS) Water Proof, two sides

526

0.15

2

2

None known

18

Hydrogen chloride

527

0.5

1

1

None known

19

Hydrogen fluoride

524

0.5

1

1

None known

20

Hydrogen sulfide

525

0.05

2

2

None known

21

Hydrogen sulfide Water Proof

546

0.5

2

2

None known

22

Hydrogen sulfide Water Proof, two sides

548

0.5

2

2

None known

23

Iodine (Halogens Indicator)

519

0.2

9 months

1

Other halogens

24

Mercury

531

0.3mg/m3●hr

1

1

j

25

Methyl chloroformate

532

0.2

72 hours

1

k

26

Methyl ethyl ketone

533

5

9 months

1

a

27

Monomethyl hydrazine

534

0.004

8 hours

1

l

28

Nitrogen dioxide HS

535

0.005

8 hours

1

m

29

Organic Vapors

540

 

1

1

n

30

Ozone

537

0.005

8 hours

1

o

31

Phosgene

538

0.015

72 hours

1

p

32

Phosphine

539

0.02

8 hours

1

q

33

Sulfur dioxide HS

541

0.2

8 hours

1

None known

34

UV Light ink (irreversible)

547

r

r

r

r


HS = High Sensitivity, LS = Low Sensitivity

a. Other methyl ketones

b. Basic vapors impair the acid indicator

c. Other aromatic amines react with approximately the same sensitivity. Hydrazine and monomethyl hydrazine show color formation at 8.5ppb·hr. Unsymmetrical dimethyl hydrazine shows color formation at 60ppb·hr. No other interferences are known.

d. Mercury, stibine and other hydrides.

e. Acids impair the basic vapors indicator.

f. Mono methyl hydrazine, hydrazine and aromatic amines.

g. Benzoyl chloride, carbonyl bromide, cyanuric chloride, methyl chloroformate and phosgene are known interferences. No other    interferences are known.

h. Acrolein and aldehydes found in cigarette smoke react with approximately the same sensitivity. The formaldehyde indicator was   exposed to atmospheres containing at least two times the Occupational Safety and Health Administration (OSHA) Permissible  Exposure Limit (PEL) for the following substances: alcohols (methanol, ethanol and isopropanol), aromatic hydrocarbons (benzene,  toluene and xylene), halogenated hydrocarbons (chloroform, methylene chloride and carbon tetrachloride), ammonia, carbon  monoxide, chlorine, glutaraldehyde, hydrogen sulfide, nitrogen dioxide, phenol and sulfur dioxide. These substances showed no effect  on the performance of the formaldehyde indicator. No other interferences are known.

i. Mono methyl hydrazine, dimethyl hydrazine (-1,1) (UDMH) and aromatic amines

j. Hydrides and strong oxidizers.

k. Benzoyl chloride, carbonyl bromide, cyanuric chloride, ethyl chloroformate and phosgene are known interferences. No other        interferences are known.

l. Hydrazine, dimethyl hydrazine (-1,1) (UDMH) and aromatic amines.

m.  Other nitrogen oxides and strong oxidizers.

n. Please contact us at info@chemteq.net

o. Hydrogen peroxide and nitrogen oxides.

p. Benzoyl chloride, carbonyl bromide, cyanuric chloride, ethyl chloroformate and methyl chloroformate are known interferences. No   other interferences are known.

q. Mercury, stibine and other hydrides.

r. Irreversible quantification of ultra violet exposure.

 

If you require an application not listed, please contact us at info@chemteq.net or call us at 877-CHEMTEQ 

Operating Temperature: 4oC to 40oC (39oF to 104oF)

Operating Humidity: 5 to 90 %RH
STEL and TWA Measurements. STEL and TWA Measurements. STEL and TWA MeasurementsSTEL and TWA Measurements. Toxic Gases In Air. Toxic Gases In Air. Toxic Gases In Air. Toxic Gases In Air. Colorimetric indicators
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If you require an indicator for an application not listed above, please contact us