Dean Switch program for Agilent 7890A

[push]

Hi.
I try to configure Dean Switch program for Agilent 7890A. The primary column is connected to the middle Dean switch port and to the back inlet, the secondary column is connected to the down Dean switch port and to the front NPD, a restrictor is connected to the upper Dean switch port and to the back FID.
How can I configurate this system, i.e. what do I need to write in the "INLET" cell for the seconary column:
INLET- PCM C-1 and in the"OUTLET" for the primary column- OUTLET -PCM C-1?

[GasMan]

Push,

I see that you are using a PCM as the source of your switching gas in the Deans switch. If you going to work in constant flow mode for your capillary columns you should be aware of the following. All FLOWS in a capillary column are controlled by pressure. The pressure is calculated from the length and internal diameter of the column, the carrier gas and the temperature of the column. It is possible to configure one channel of the PCM to be in constant flow mode. This is intended for use with packed columns, so make sure that you have the PCM channel configured as forward pressure control. Now configure the columns as follows:

1. Primary column. This is the column that you will inject the sample into before going to the Deans switch. Set the inlet to inlet that you are using and the outlet to the PCM that you are using. Set the column mode to 'constant flow', unless you are planning to backflush the primary column.

2. Secondary column. Set the inlet to the PCM channel that used in step 1. Set the outlet to the detector that you will be using. Set the flow to be about 50% higher than the flow used for the primary column. Set to constant flow mode.

3. Restrictor. I usually set this up EXACTLEY the same as for the secondary column, except for the detector that is being used. Remember that this restrictor must give the same pneumatic resistance as the secondary column, otherwise the Deans switch will not be balanced and will not work. If your secondary column is a PLOT column, then you will need to 'calibrate' the column, as the effective internal diameter of the column may NOT be as stated on the column label. You should then cut the restrictor so that it will have the same resistance.

Gasman