Chromatography Forum

Hello - For a specialized analysis we are packing and running 1/4" packed columns on a 5890 with a packed column inlet and a FID detector. To verify the packing consistency and also for use in the end calculations I need to know the pressure drop across the column itself separate from the total head pressure, which as far as I can determine incorporate some unknown pressure drop between the pressure gage on the inlet control panel and the inlet itself. Does anyone either have a feel for how much pressure drop I should expect in this inlet tubing at 25 ml/min or alternately know the ID of this 1.5 mm OD stainless steel tubing connecting the inlet flow control to the weldment? If this ID is ~ 0.5 mm it seems that I can probably ignore this pressure loss and assume that the column head pressure is the pressure drop through my actual packed column, but if this is ~0.25 mm then pressure drop in this inlet tubing is probably the major component of the column head pressure. Any comments would be appreciated!

thanks-
Cary

Most of the 1/16 inch tubing used in the 5890 would have had an internal diameter of 0.030 inches.

Gasman

To measure the actual inlet pressure connect a narrow gauge needle to a pressure gauge and stick the needle through the septum.

Peter

0.030 inch ID (0.75mm) doesn't have much backpressure as long as the length is short. One could always test the column OUTSIDE the GC on a testing stand built for that purpose, no?

best wishes,

Rodney George