Labconco 3940200 User Manual - page 62

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Chapter 6: Maintaining Your Filtered Enclosure

syringe represents a 100-ml sample and corresponds to the number 

of strokes necessary to give the indicated color changes. Due to the 

wide variety of organics and varying TWA’s, it is recommended 

that specific detector tubes be purchased directly from Sensidyne, 

Draeger or your laboratory supply dealer.  Alternate detector 

pumps can also be purchased from your laboratory supply dealers.  

The vast majority of detector tubes available start measuring at the 

TWA.  When a user observes a color change in the tube, they 

should replace the filter immediately.  If no detector tube for your 

specific chemical is available, other means of detection must be 

used. 

Time - For applications that have very consistent inlet 

concentrations and operating time, “Time” can be used to 

anticipate saturation or TWA levels based on prior experience.  

However, this does not replace the need for sampling.  Consult 

Labconco technical specialist for an estimate of carbon filter life 

based on chemical usage.  Detector tubes, or analytical 

instrumentation should always be used to determine concentrations 

in the carbon filter.  It is recommended that the carbon filters be 

checked with detector tubes or other means at intervals of 20% of 

the total estimated filter life.  The exception to the 20% 

recommendation is formaldehyde and any carcinogen or suspected 

carcinogen.  These more hazardous chemicals must be checked at 

least every 10% of the total estimated time. 

Analytical Instrumentation - This is the most accurate means of 

measuring concentrations of any chemical.  It is the method of 

choice when no detector tubes are available or the tubes are not 

sensitive enough to measure at the TWA concentration for the 

chemical.  This method is also to be used to determine saturation 

when the chemical concentration is below the measurement range 

of detector tubes. 

Odor Control Carbon Filter Replacement Procedure – See 

Figures 4-1 and 4-2 for Carbon Filter Replacement. 

1.  The carbon filters are replaced by first removing the two 

screws, which hold the clips to secure the upper diffuser 

screen.  Remove the screws, clips and upper diffuser 

screen. 

2.  Remove the carbon filter in a careful way to avoid the flow 

switch and HEPA filter.