GFS2102™ OPERATION AND MAINTENANCE MANUAL
© 2007 DH Instruments, a Fluke Company
Page 14
2.6
GFS TOOLS
The user interface for operating GFS2102 is GFS Tools software. GFS Tools handles all collection of
data from the GFS system components and devices under test and calculation and reporting of mass flow
and errors. Some operating principles of GFS Tools are described in Section 4.1 and 4.2 and GFS Tools
is described in detail in Section 5.
2.7
HEAT EXCHANGER
At flows above 1 slm in N2, the calibration gas is discharging from the Reference Gas Cylinder quickly
enough that the cooling of the gas from decompression can effect the regulator, MFC, and molbloc(s)
downstream of the GFS. This in turn can effect the stability and control of the flow, and ultimately the
overall accuracy. To significantly reduce these effects a heat exchanger is used. A fully assembled heat
exchanger consists of a 3.2 Qt. stainless steel can filled with water or a water/antifreeze mix with
approximately 7-10 feet of ¼” stainless tubing coiled up and submerged in the liquid. For shipping
purposes the exchanger is shipped without liquid and needs to be prepared prior to use. Preparation of
the heat exchanger is described in Section 3.3.14.
2.8
GFS-FS REFERENCE GAS CYLINDER FILL STATION
A specialized filling station is provided with the GFS2102 system to help users fill the reference gas
cylinders safely and slowly with minimal heating of the cylinder. The design of the fill station allows the
user to quickly set the desired fill pressure and the cylinder is filled at a slow rate that is controlled by a
flow limiter. The user can view the set pressure that the cylinder will ultimately achieve and the current
cylinder pressure as it fills.
Figure 11.
GFS-FS Reference gas cylinder fill station
See Section 4.3 for details on GFS-FS operation and connections.
2.9
MASS FLOW CONTROLLERS
Four mass flow controllers are included with the GFS-2102 system. There are (1) 10 sccm MFC, (1) 100
sccm MFC, (1) 1 slm MFC, and (1) 10 slm MFC all adjusted to operate in these ranges for N2. These
can be used for any gas that they can reasonably operate with by applying the K factors found in GFS
Tools. When working with gases other than N2, in most cases a test will have to be sectioned into two or
more tests in order to work with multiple MFC’s.