Reading The Flow Sheet ......
Solid Lines When Valve is OFF --
-- Dashed Lines When Valve is ON
Here is a 10 port and a 6 port valco valve. The 10 port is in the off position while the 6 port is on. Follow the flows of carrier A and then carrier A2.
What changeable part in a Valco valve connects the two ports together?
Starts with an R.
In theis pic you cannot see the SSO. Student, what is an SSO? Why do we use the SSO/ARV principal? YES.... To equalize to atmospheric pressure every time. Each sample must be the same size or we are just wasting time. Gas can be condensed, liquid can not. Due to this we have to make sure we are the same size sample from run to run. In our class we have bubbler jars to see the sample flow. Our tubing goes into the water about half an inch. As long as we remain the same half inch every run then we are good. What would happen if we took our tubing out of the tiny bubbler jar and pushed it down into a 55 gallon drum of water? It's going to take more pressure to push the sample through. Will your peaks be bigger or smaller?
Looking at the drawing. When SV turns on, Carrier gas coming in on port 9 will go to port 10. Carrier will then rush into the sample loop where it will push the sample (which has been equalizing to atmospheric pressure) to port 3 over to port 4 and then sending all the components to column one. Known as the precut column. It's typical job is to do some slight slowing down and seperation and hold up components the are large and we want to backflush. Carrier continues pushing and comes in port 8 over to port 7 out and into column two. This is our workhorse column. This column will be doing most all of our seperation. Our lightest/smallest component though goes through this column fairly quickly and easy. It continues on to our 6 port valve entering on port 1. The CV is on so carrier gas takes the light to port 6 and then pushes them into column 3. This column slows down the light component. Carrier continues on to the FID. Our carrier gas is H2. Why is H2 the perfect carrier for this application?
See how the sample loop makes a couple of wraps around the Valco valve. Sample loops vary in size.
We will be looking at a lot of different valves that are used in different G.C.'s but you know that when the valve is OFF. Carrier gas will go through the solid lines.
List some of the valves we will be working with.
Model 11 Mat Valve
Model 50 Slider
Daniels has a 6 port and a 10 port but I dont think they have a
name. See the pic.
Practice knowing flows...