Volume I - Section IV - Experimental Work and Verification of CFD Methodology 
Page IV - 9 
The SF 6 was injected through Teflon tubing. Teflon was used to prevent SF6 absorption/ 
readmission problems that are characteristic of that class of gas. 
Three SF 6 samples were removed from both the front and back locations of the cage using 
syringes (GASTIGHT #1750). The syringes pierced a rubber septum in the tubing that ran to the 
billows pump and was connected to the tubing by a T-joint. After piercing the septum, each 
syringe was repeatedly filled and emptied into the tube three times before an approximately 
0.5mL (3.05e-2in 3 ) sample was withdrawn. 
The SF 6 concentrations were measured with a Varian 3700 Gas Chromatograph (GC) with an 
Electron Capture Detector. The 0.25mL (1.53e-2in 3 ) samples of standard gas mentioned above 
were injected from precision syringes into the Varian through a frequently changed septum. The 
Varian was attached to a printer that produced a concentration peak graph and gave the SF 6 
concentration. Syringe labels were recorded on the graph and the process repeated. After every 
syringe concentration had been recorded, each syringe was dismantled and cleaned by blowing 
compressed air through it and onto its pull. 
The GC was calibrated using a one-point calibration with a 500 ppb standard gas. 0.25ml (1.53e- 
2in 3 ) samples of standard gas were injected into the GC repeatedly until consistent, sharp peaks 
were obtained on the output chart. The calibration was checked with the standard gas after every 
three sets of injections. The GC was recalibrated when the expected sharp, consistent peaks were 
not seen on the output chart. 
To monitor the possibility of SF6 buildup in the test room, wind tunnel entrance samples were 
taken to measure the background SF6 concentration. To further safeguard against SF 6 buildup, all 
air exiting the billows pump was bagged. Along with these measures all exhaust air from the 
wind tunnel was ducted outside of the room. 
In both series, data were collected using a randomized complete block design with the tracer gas 
and air velocity level being randomized. 
Series Set Three 
The same injection/sampling procedure was followed as for series set base. Data were collected 
using a randomized complete block design with the heater state and air velocity level being 
randomized. 
Series Sets Four and Five 
A standard concentration of CO 2 [99.8 percent] was used as the tracer gas. Injection rate was set 
at 100 mL/min (3.53e-3 ft 3 /min). The injection rates were calibrated using a digital flow meter 
(Humonics 650 Digital Flowmeter). Digital flowmeter measurement, time, and date were 
recorded for each calibration. The injection rate was measured continuously with a correlated 
flowmeter (Gilmont, tube size 1, accuracy + 1-2 percent of reading). Tracer gas was injected 
