Connecting a Restek ProFLOW 6000 Electronic Flowmeter to an Agilent Split Vent or Septum Purge

The Restek ProFLOW 6000 Electronic Flowmeter is a very useful tool for the measurement of any type of gas commonly used in chromatography. The tubing coming out of the ProFLOW 6000 is made of a flexible elastomer about 28” long with a ¹⁄₄’’ OD and a ¹⁄₈’’ ID. We occasionally get questions about how to connect this tubing to the split vent or septum purge outlet ports on an Agilent GC. These GC connections are ¹⁄₈’’ male threads, which are compatible with Swagelok ¹⁄₈’’ tube fitting nuts. You should not try to stretch the flowmeter’s tubing over the threaded fitting on the split vent or septum purge because some of the gas will find its way through the threads, and you won’t get an accurate reading. Besides, it is rather difficult to get this tubing to stretch over these fittings.   All that is needed to connect the ProFLOW 6000 to the split vent or septum purge outlet is a short piece (about two inches is enough) of ¹⁄₈’’ OD tubing; a ¹⁄₈’’ nut; and a ¹⁄₈’’ ferrule. Most labs have short pieces of ¹⁄₈’’ OD tubing and ¹⁄₈’’ nuts stashed somewhere in a drawer or cabinet, but of course if you don’t, you can get them from Restek. I would recommend using a PTFE or Vespel/graphite ferrule. Slide a ¹⁄₈’’ nut and ferrule over the short piece of tubing, insert the tubing into the split vent or septum purge exit port, and tighten the nut about one full turn. The tubing from the flowmeter will fit nicely over this extension from the split vent and septum purge and you will be able to get accurate readings.

The end result looks like this.

 

¹⁄₈’’ tube fitting nuts are catalog number 23101 for Swagelok.

¹⁄₈’’ ferrules are catalog number 21126 for PTFE and 20219 for Vespel/graphite.

PTFE tubing, ¹⁄₈’’ OD, is catalog number 27844.