1
Objectives
 Describe colorimetric science
 Describe common colorimetric detection devices
 Describe the process for det...
Colorimetric Sampling
 Colorimetric tubes
 Detect known and unidentified gases or vapors

 Easy method to narrow down a...
Colorimetric Sampling
 One of the most important concepts of colorimetric

sampling
 They may not be able to tell you wh...
Colorimetric Science
 Reagent filled glass tubes

designed to react with
specific gases and vapors
 Bellows or piston st...
Colorimetric Science
 They can usually detect a wide variety of
substances.
 Most have some cross-sensitivities and will...
Chip System
 In addition to tubes, Dräger

has a Chip Measurement
System (CMS)
 Bar coded strips that function

much lik...
Chip System
 CMS
 Good that there is no human interpretation

 But it is also bad in that there is no human

interpreta...
Detecting of known materials
 Most tubes are designed

 Always read instructions

to read in parts per
million
 Some ar...
Detecting of known materials
 Calibrated for a certain

temperature and humidity
 Correction factors

provided
 Use les...
Detection of unidentified
materials
 Detection of unidentified materials is not an easy task
 Knowledge of colorimetric ...
Detection of unidentified
materials
 If you get a hit on a tube,

 Both Dräger and Mine

there is no need to
continue pu...
Multi-Tube Systems

13
Street Smart Tips
 Major key point - Read the Instructions
 Cross sensitivities are very useful in identifying a

uniden...
Street Smart Tips
 Humidity plays a major
factor in tube response

 Atmospheric pressure also


 Most tubes are calibr...
Street Smart Tips
 More than one gas may be







present
Remember cross
sensitivities of tubes
Know color of tube y...
Summary
 Colorimetric sampling can be a valuable tool if

instructions are followed
 Colorimetric tubes can establish a ...
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Module 6 colormetric sampling, american fork fire rescue

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Module 6 colormetric sampling, american fork fire rescue

  1. 1. 1
  2. 2. Objectives  Describe colorimetric science  Describe common colorimetric detection devices  Describe the process for detection of known materials  Describe the process for detection of unidentified materials 2
  3. 3. Colorimetric Sampling  Colorimetric tubes  Detect known and unidentified gases or vapors  Easy method to narrow down an unidentified material to its chemical family  Can tell you how much of a certain material is present if you know the material 3
  4. 4. Colorimetric Sampling  One of the most important concepts of colorimetric sampling  They may not be able to tell you what is present  But they can certainly tell you what is not present 4
  5. 5. Colorimetric Science  Reagent filled glass tubes designed to react with specific gases and vapors  Bellows or piston style pump used to draw contaminated air across reagent  If target gas or vapor is present there is a color change to the reagent 5
  6. 6. Colorimetric Science  They can usually detect a wide variety of substances.  Most have some cross-sensitivities and will react in much the same fashion as the target material.  Instructions provide cross-sensitivities list. 6
  7. 7. Chip System  In addition to tubes, Dräger has a Chip Measurement System (CMS)  Bar coded strips that function much like the colorimetric tubes, but a reader performs analysis of the tube  With the CMS, a reading is given on a LCD screen and does not need interpretation 7
  8. 8. Chip System  CMS  Good that there is no human interpretation  But it is also bad in that there is no human interpretation  Unable to manipulate the CMS chip, as you can a tube 8
  9. 9. Detecting of known materials  Most tubes are designed  Always read instructions to read in parts per million  Some are in percent by volume  Some only indicate presence of a material  For some materials there are a variety of sampling ranges available for tube  You need to know:  Number of pump strokes  Color changes  Cross sensitivities  Special instructions 9
  10. 10. Detecting of known materials  Calibrated for a certain temperature and humidity  Correction factors provided  Use less pump strokes to decrease sensitivity of tube  Use more pump strokes to increase sensitivity of tube 10
  11. 11. Detection of unidentified materials  Detection of unidentified materials is not an easy task  Knowledge of colorimetric sampling, chemistry, and street sense is essential  Most manufacturers provide a flow chart when looking for unidentified materials $499  Use a combined system of flow charts, with several types of detection tools  When looking for unidentified materials, you are not $595 trying to establish levels of the material  You are only trying to see what may be present 11
  12. 12. Detection of unidentified materials  If you get a hit on a tube,  Both Dräger and Mine there is no need to continue pumping air across the tube that is a positive  Move onto the next tube in the system  More than one material may be present Safety Appliances company allow for multiple tube use  Tubes are preassembled and placed in manifold to draw air across 5 tubes at one time  Detection times extended due to extra tubes that are drawing air 12
  13. 13. Multi-Tube Systems 13
  14. 14. Street Smart Tips  Major key point - Read the Instructions  Cross sensitivities are very useful in identifying a unidentified material  Book of photocopied instructions works much better than 20 sheets  Use additional pump strokes to increase sensitivity of tube 14
  15. 15. Street Smart Tips  Humidity plays a major factor in tube response  Atmospheric pressure also   Most tubes are calibrated for 50 percent humidity  Correction factors can be calculated using the instructions    plays a role Each tube has a specific temperature Age, light, and storage conditions determine accuracy of tubes Tubes typically have a 2-3 year shelf life Consistent storage temperatures are best 15
  16. 16. Street Smart Tips  More than one gas may be     present Remember cross sensitivities of tubes Know color of tube you are sampling and the color it should change to Keep an unbroken tube with you to compare color changes Some may be very subtle  Water vapor may be released from pump  Not uncommon for a tube to heat up and release visible vapor  Some chemical tubes create a very hot chemical reaction or ignition source  Some tubes release irritating gases  Clear pump with strokes in between tubes 16
  17. 17. Summary  Colorimetric sampling can be a valuable tool if instructions are followed  Colorimetric tubes can establish a level of contaminants present  Colorimetric tubes can help identify or at least classify an unidentified material 17
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