INFICON HAPSITE ER Chemical Identification System - Manual (Page 73)

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HAPSITE ER Operating Manual
2.8.3 VX / R-33 Conversion Tube
This procedure describes the steps required to prepare the HAPSITE to sample for
VX or R-33 using the Conversion Tube. To detect VX or R-33, you must insert the
Conversion tube following the guidelines below.
The process of detecting VX or R-33 on the HAPSITE requires the conversion of
VX or R-33 (high boiling point chemicals) to the G analog. The VX or R-33 molecule
is broken at the sulfur bond when it comes in contact with a silver fluoride pad. The
result is the formation of a volatile chemical ethyl methylphosphonofluoridate in the
case of VX, or isobutyl methylphosphonofluoridate in the case of R-33. These
compounds are detected by the HAPSITE as VX-G or R-33-G.
NOTE: Theoretically, other G agents can be detected with the VX conversion pad
in place. However, if other G agents are suspected, the sample should be
also be run without the conversion tube in place.
WARNING
Sulfur mustard cannot be detected with the conversion
tube in place.
2.8.3.1 VX/R-33 Conversion Tube Installation
1 Refer to section 2.8.1, Probe Nut Assembly, on page 2-33 to ensure proper
ferrule orientation in the probe nut.
WARNING
Correct ferrule placement is critical to ensure a leak-free
fit around the conversion tube.
2 Loosen the nut on the end of the probe approximately 1/4 to 1/2 of a turn. See
Figure 2-47 .
Figure 2-47 Loosening the Nut