If I don't have the answer. I will ask someone and find out. Humility is a great thing to possess. Nobody knows it all and being hard headed will only hurt you in the long run.
Why do Analyzer Technicians exist? Three main Reasons.

So the plant can optimize the process and squeeze out all the profits it can.
Strict environmental regulations that must be monitored.
Safety. To hopefully limit or prevent the plant from fires and explosions.

Question???? Does the plant really want to do all three of these?
If the valve is off, flow will go through the solid lines. Any time the valve is off we will have a line over the SV1 or the CV1 depending on who is off. At time zero, we stop sample flow into the analyzer with the Sample Shutoff Valve. The sample will equalize to atmospheric pressure for 8 seconds and then we will inject the sample. CV1 on and SV1 on. Carrier gas and in this example we will say He, will enter on port 1 of CV1, go to port 6, enter port 4 of SV1, go to 5, sweep the sample loop and go from port 2 to port 3. Carrier will then push our sample into column one. The smaller light components will exit first and travel to the ITC.
At time 16, the SSO and SV1 will turn off and fresh sample will begin flowing through the sample loop and ready for the next injection. At this time our components are being pushed through column one and into column two. Column two is longer than column one and our three components in the sample are separated out and go across our main detector, the sense. The three components in this case were Methane, Ethane, Propane and in that order. My question to you, why do we equalize to atmospheric pressure?
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Learn all you can in life but do not forget what is important.
You will not think later in life that " Damn I wish I had worked more OT."

Kiss the ones you love every chance you get.​​​​​
  JDC
​Analyzer Techs INC has merged with JDC.