Hach BioTector B3500s User Manual page 61

As can be seen in the figure 13 above, base (Sodium Hydroxide) reagent container does not contain any vent
(breathing) hole. The breathing air into the base container is supplied through the CO filter, which must be
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fitted on the base container lid.
Figure 14 below shows the detailed connections on BioTector base reagent. The purpose of the CO filter is
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to prevent the base reagent coming in contact with atmospheric CO present in the air. The soda lime inside
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the CO filter absorbs the atmospheric CO and prevents the base reagent getting contaminated. If any vent
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hole is accidentally drilled on the lid of the base container and if the fittings are not connected correctly on the
base reagent, contamination will occur and the background CO readings will increase.
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Figure 14 BioTector Sodium Hydroxide reagent dip tube setup
The vent port on the acid reagent dip tube should not be isolated or blocked. Failure to do so may cause the
container to collapse and leak.
The length of the dip tubes in all reagent containers should be adjusted correctly for the optimum usage of the
reagents. If HCl acid is used, stainless steel (SS-316) weights/filters should not be used in the reagent. The
recommended weights/filters for such reagents are PFA.
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