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Measuring Capillary Column Flow: “To ProFLOW or not to ProFLOW, that is the question”

29 Dec 2014

Occasionally the Restek Technical Service group gets a request from a customer for information on how to measure the carrier gas flow from their capillary column with the Restek ProFLOW 6000 Electronic Flowmeter.




Although this electronic flowmeter is designed to measure volumetric flow for gases across a range of 0.5–500 mL/minute, there are more accurate ways of determining capillary column flow that we recommend.


Injecting a “non-retained” substance to calculate average linear velocity is one way of making this determination. Instructions for this can be found at the “Setting Optimum Flow Rates” section of the Restek Capillary Column Installation Guide. It is recommended you have the column oven temperature set to about 150°C (make sure never to exceed a column’s maximum allowable temperature) when injecting the compound used to determine dead time to minimize the small amount of retention that might occur, especially with thick film columns.


Another option is to use the EZGC Flow Calculator, which allows you to calculate carrier gas flow rate (and average linear velocity) based on your column’s dimensions and instrument parameters.





The Restek ProFLOW 6000 Electronic Flowmeter is the ideal tool to use to measure split vent flow, septum purge flow, FID fuel gas flows, or to verify your GC packed/micropacked column carrier gas flow. The ProFLOW 6000 is an easy to use, NIST traceable flowmeter with many uses, but we recommend using one of the methods described above to determine the carrier gas flow rate from a capillary column.


Thank you for reading!