5890 packed column pressure drop

[caryjm]

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

[GasMan]

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

Gasman

[Peter Apps]

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

Peter

[chromatographer1]

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