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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Chemical Name

Part No.

Minimum detectable limit (ppm•hr)

Service Life

(Months)

Shelf life (Years)

Cross interferences

1

Acetone

510

5

8

1

Other methyl ketones

2

Acids

511

0.05

12

2

Bases impair the indicator

3

Ammonia

517

3

24

1

Primary aliphatic amines

4

Aniline

513

0.2

12 hours

2

See attached document

5

Aromatic Amines

514

0.015

12 hours

2

See attached document

6

Aromatic diisocyanates

515

0.005

12

1

None known

7

Arsine

516

0.02

8 hours

1

Mercury, stibine and other hydrides

8

Bases

512

0.5

12

2

Acids impair the indicator

9

Carbon monoxide

518

8

8 hours

1

Acetylene, Ethylene, H2S and H2

10

Chlorine

519

0.2

8

1

Br2 and F2, HCl impair the indicator

11

Chlorine dioxide (HS)

520

0.3

12

1

None known

12

Chlorine dioxide (LS)

544

200

12

1

None known

13

Dimethyl amine

521

5.0

 

1

Other secondary amines

14

Dimethyl hydrazine (-1,1)

522

0.01

8 hours

2

MMH and hydrazine

15

Ethyl chloroformates

523

0.02

72 hours

1

See attached document

16

Fluorine

524

0.2

12

1

Cl2, Br2 and I2, HCl impair the indicator

17

Formaldehyde

525

0.4

12

1

See attached document

18

Hydrazine (LS)

526

0.150

24

2

MMH and UDMH

19

Hydrazine (HS)

545

0.005

8 hours

2

MMH and UDMH

200

Hydrogen chloride

527

0.05

12

2

None known

21

Hydrogen fluoride

528

0.05

12

2

None known

22

Hydrogen sulfide

529

0.3

24

2

None known

23

Hydrogen sulfide WP

546

0.3

24

2

None known

24

Iodine

530

0.2

8

1

Br2, HCl impair the indicator

25

Mercury

531

0.3mg/m3•hr

12

1

Hydrides

26

Methyl chloroformate

532

0.02

72 hours

1

See attached document

27

Methyl ethyl ketone

533

5

8

1

Other methyl ketones

28

Monomethyl hydrazine

534

0.005

8 hours

2

Hydrazine and UDMH

29

Nitrogen dioxide HS

535

0.005

8 hours

1

Nitrous acid and O3

30

Ozone

537

0.01

8 hours

1

H2O2 and NO2

31

Phosgene

538

0.015

72 hours

1

See attached document

32

Phosphine

539

0.005

8 hours

1

Other hydrides

33

Organic Vapors

540

**

12

1

See attached document

34

Sulfur dioxide

541

0.2

8 hours

1

None known


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