Hello!
I am trying to create a multisampling air unit for GC sampling in our lab. I currently am using an SKC AirCheck 2000 sampling pump at around 900cc/min and splitting the flow with barbed t elbow connectors twice for 4 tubes going into Dwyer 30-200cc/min value flow meters for a sampling of 50cc/min out of each end. My concern is I see a large degree of error when I take the sample tubes out and put in new tubes (18%). However when I put the old tubes back on the readings don't go back to their previous measurements before the switch.
Considerations:
Each tube length for each section is the same length
Sampling tubes should have the same resistance
SKC Sample pump variation is around 10% ( says 5% in the manual but is experiencing more error)
Does the removing of the tubes cause a resistance change that alters the Valve and then creates different readings? Or is my initial higher flow pumps error getting compounded as the line gets split? Any suggestions on improving the accuracy of my system?
Thanks!
I am trying to create a multisampling air unit for GC sampling in our lab. I currently am using an SKC AirCheck 2000 sampling pump at around 900cc/min and splitting the flow with barbed t elbow connectors twice for 4 tubes going into Dwyer 30-200cc/min value flow meters for a sampling of 50cc/min out of each end. My concern is I see a large degree of error when I take the sample tubes out and put in new tubes (18%). However when I put the old tubes back on the readings don't go back to their previous measurements before the switch.
Considerations:
Each tube length for each section is the same length
Sampling tubes should have the same resistance
SKC Sample pump variation is around 10% ( says 5% in the manual but is experiencing more error)
Does the removing of the tubes cause a resistance change that alters the Valve and then creates different readings? Or is my initial higher flow pumps error getting compounded as the line gets split? Any suggestions on improving the accuracy of my system?
Thanks!
