Chromatography Forum

To automate a manual operation I need to open and close a solenoid valve at pre-set times during an analysis.

According to the instruction book (page 218) this shuld be possible using the programmable external valve control of the 6890N GC, but what is conspicuously absent from the instructions is the location of the connector to which the valve has to be connected.

What I need is the location of the controller outputs for external valves 1-4 which give 13 W at 24 V.

Agilent's only suggestion is that I buy something from them ! (is any Agilent owner surprised ?) which I do not want to do until I know that what I am trying to do with the valve actually solves the problem it is supposed to.

Does anyone know how to do this - preferably in terms of "the connector is at the top/bottom left/right of the board next to the gizmo and under the whatsit"

Thanks Peter

Peter,
We have a "No vent" system set up on our 6890 ms. This operates a valve which allow the flow of carrier gas to be diverted. I am not sure if it can be opened and closed automatically (never tried). It might be worthwile trying to get hold of fitting instructions for this and see if this switch is any use.

Peter,

You should be aware that there are 8 controls for 'external' control on the 6890. Valves 1-4 are 13W and are connected internally. Valves 5 to 8 are available at the rear of the GC

BUT

Valves 5 and 6 will supply about 75mA for a solenoid valve. Valves 7 and 8 are contact closures. You should also be aware that the system switches on the ground return line of the solenoid valve, which means that there will always be 24 Volts on the solenoid.

Gasman

Hi Gasman

The valve that I have draws 7 W at 24 V, therefore I need to run it from one of valve controllers 1 - 4. As you say, the connections for valves 7 - 8 come out at the back of the instrument, the mystery that I need to solve is the location of the connections for 1 - 4; to quote the Agilent manual "The wiring for these appears at a set of connectors inside the right cover of the GC." I have scoured the manual for more information, and contacted Agilent via their local suppliers, but the mystery remains !

The switching on the ground return ("neutral") will not be a problem.

Regards Peter

Peter,

You need the connector P22, which I believe is marked on the board.

For Valve 1 use pins 5 and 13
For Valve 2 use pins 6 and 14
For Valve 3 use pins 7 and 15
For Valve 4 use pins 8 and 16

Gasman

It works !!

GasMan you are a scholar and a gentleman !

Thanks Peter