I have had good luck (touch wood) with Valco 4 port zero volume switching
valves. To get four peripherals on our system we have two SGE valves (from
the factory) with a Valco up stream of each SGE. The "EA Valco" switches a
TC/EA and an EA (before the Conflo) and the "GC Valco" switches a GasBench
and a GC-C. I even get a nice leak free connection using the two hole
composite GC ferrules with the Valco nuts. We mounted the "GC Valco" under
the hood with about 1 foot of stainless tubing connecting it to the SGE.
The "GC Valvo" configuration:
port2= GasBench sample and reference capillaries (2 hole ferrule)
port3= to SGE #1 (1/16" stainless tubing)
port4= GCC sample and reference capillaries (2 hole ferrule)
Everyone (the peripherals) seems pretty happy with this set-up and the
chromatography is not degraded. With gas flowing continuously through
all peripheral capillaries in stand-by, the recovery time after switching
is fairly short. On the "EA Valco" we have a long chunk of capillary at the
waste port to restrict He flow of the TC/EA in stand-by.
I think the manual Valco runs ~$400. If you want to get super tricky, for a
bit more cash you could get the electrical actuator and operate switching
through ISODAT NT.... theoretically.
Don't recall specific part numbers etc., but I would be glad to look them
up if you are interested. Of course I will probably be busy for the next 3
months trying to fix a nasty leak at the Valco having now said that it all
works so well!!
At 09:59 AM 12/9/2003 -0800, you wrote:
>Bill, and others who might have answers:
>I am just adding a PreCon to our Delta Plus XL which already has a Gas
>Bench and Conflo II attached. The Gas Bench and Conflo II each have a SGE
>valve, but it will be necessary to unscrew the capillary from the Gas Bench
>to attach the Precon, and vise versa. It is immediately apparent that this
>is going to be tedious and not a good idea in the long term. Has anyone
>successfully attached three valves for three continuous flow peripherals to
>a Delta Plus XL?
>Thanks in advance,
>Paul D. Brooks,
>Center for Stable Isotope Biogeochemistry,
>Dept. Integrative Biology MC3140,
>3060 Valley Life Sciences Building,
>UC Berkeley, Ca. 94720-3140.
>[log in to unmask]
Department of Earth and Environmental Sciences
University of Illinois at Chicago (MC-186)
845 West Taylor Street
Chicago, Illinois 60607-7059
email: [log in to unmask]