Installation manual

62 5975 Series MSD Operation Manual
3 Operating in Electron Impact (EI) Mode
Controlling Column Flow
Carrier gas flow is controlled by head pressure in the GC. For a given head
pressure, column flow will decrease as the GC oven temperature increases.
With electronic pneumatic control (EPC) and the column mode set to Constant
Flow, the same column flow is maintained regardless of temperature.
The MSD can be used to measure actual column flow. You inject a small
amount of air or other unretained chemical and time how long it takes to
reach the MSD. With this time measurement, you can calculate the column
flow. See page 73.