Air Supply And Reagent Connections - Hach BioTector B3500C User Manual

5.3

Air Supply and Reagent Connections

The orientation of the ferrules inside each fitting of BioTector is critical for the correct operation of the system.
Incorrect ferrule orientation may create gas/liquid leak and/or introduce air bubbles into the system lines.
Therefore, the ferrules on all carrier gas, reagents, drain, exhaust and vent fittings have to be fitted with the
correct orientation. Failure to do so will have an impact on the system operation and analysis responses.
Figure 11 shows the fitting side and the nut side of SS-316 (stainless steel), PFA and PVDF fittings and their
corresponding correct ferrule orientation.
Figure 11 The correct ferrule orientation of SS-316, PFA and PVDF fittings on BioTector
When tightening brand new stainless steel fittings, first fully insert the tube into the fitting, tighten the nut
initially finger tight, then tighten a further 1¼ turns using an appropriate size spanner or an adjustable wrench.
Stainless steel fittings used on 1/8" PFA tubing should be tightened only a further ¾ turns after finger tight.
When re-tightening stainless steel fittings, which were already tightened during reassembly or after service,
initially tighten the nut up to the point it was tightened previously, then tighten slightly more using an
appropriate size spanner or an adjustable wrench.
When tightening brand new PFA fittings, first fully insert the tube into the fitting, tighten the nut initially finger
tight, then tighten a further ½ turn using an appropriate size spanner or an adjustable wrench. When re-
tightening PFA fittings, which were already tightened during reassembly or after service, initially tighten the
nut up to the point it was tightened previously, then tighten slightly more using an appropriate size spanner or
an adjustable wrench.
When tightening Swagelok PFA TEE fittings with blue nuts, first fully insert the tube into the fitting, tighten the
nut initially finger tight, then tighten further using an appropriate size spanner or an adjustable wrench until the
nut stops or until it is not possible to tighten the nut any further. These TEE fittings with blue nuts, used on the
1/8" PFA tubing, contain only one ferrule with no back cutting ring or no back ferrule. Acid and Base pump
fittings, which also contain one CTFE ferrule, should be tightened fully finger tight, assuring a strong
connection.
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