Selection of a novel mine tracer gas for
assessment of ventilation systems in
underground mines
Susanne Underwood, Rosemary Patterson,
Kimberly Jackson, Kray Luxbacher, Harold McNair
February 21,
2012
Acknowledgements
This publication was developed under Contract No.
200-2009-31933, awarded by the National Institute
for Occupational Safety and Health (NIOSH). The
findings and conclusions in this report are those of
the authors and do not reflect the official policies of
the Department of Health and Human Services; nor
does the mention of trade names, commercial
practices, or organizations imply endorsement by
the U.S. Government.
Outline
Background
• Ventilation surveys using trace analysis
• Tracer characteristics
• Previous uses of considered tracer elements
Application
• Results of tracer analysis
• Selection of a tracer element
• Development of analysis method
Summary
• Future work
• Conclusions
Background
Project Objective
• To select a safe novel tracer
• Novel tracer must have similar sensitivity to
current tracers
• Develop one analysis method to allow for
concurrent deployment of tracers
Background
Tracer Technique
• Directly measures air quantity
• When traditional point measurement of
velocity cannot be used including
– Where cross-sectional area cannot be easily
measured
– Locations deemed unsafe due to emergency
– Places with very low or irregular flow
Background
How does the tracer technique work?
• Tracer is directly released into atmosphere
• Gas chromatography analysis
• Two methods
– Continuous tracer release
– Pulse tracer release
• Limited applications due to time
Background
How will a novel tracer help?
• Increase ventilation survey versatility
• Simultaneous analysis of airways/leakages
• Reduces the time limitations of traditional
tracer analysis
Background
Tracer Requirements
• Easily detected and analyzed
• Absent from mine air
• Nonreactive, nontoxic, noncorrosive, nor
explosive
• Readily attainable
• Easily transported
• Highly sensitive
Background
Tracers Considered
• Industry standard is Sulfur Hexafluoride (SF6)
• Freons
– Carbon Tetrafluoride (CF4)
– Octofluoropropane (C3F8)
• Perfluorocarbon tracers
Background
Previous Tracer Applications
• Freon testing in mines
• Perfluorocarbon Tracers
– Urban environments
– European Tracer Experiment
– Oil and gas reservoirs
– Home ventilation systems
– No evidence that PFTs have been used in mines
Background
PMCH Characteristics
•
•
•
•
•
•
C7F14
Volatile liquid
Boiling point of 67⁰C
Biologically inert
Molecular weight of 350 g/mol
Very low ambient backgrounds
Application
Experimental Design
• Shimadzu 2014 Gas Chromatograph
• Electron Capture Detector
• Columns tested for Freons
–
–
–
–
SBP-1 Sulfur
ZB-624
TG Bond Q+
TG Bond Q
• PMCH tested using HP-AL/S column
Application
Goals
• Achieve separation between peaks
• Attain Gaussian shaped peaks
• Apply an acceptable method
Column
SBP-1 Sulfur Column
ZB-624 Column
TG Bond Q+ Column
TG Bond Q Column
HP-AL/S Column
Average Retention Time (min)
Column
Temperature (⁰C)
O2
SF6
CF4
C3 F8
PMCH
40
1.1
1.22
1.1
1.2
---
20
1.08
1.19
1.1
1.24
---
40
2.14
2.22
---
2.23
---
20
2.14
2.22
---
2.27
---
0
2.14
2.24
---
2.17
---
40
1.94
2.22
2.12
3.49
---
20
1.96
5.22
---
5.22
---
0
1.96
9.65
---
9.84
---
60
2.3
3.1
---
3,09
---
50
2.33
3.42
---
3.41
---
40
2.24
3.88
---
3.88
---
20
2.27
5.74
---
5.7
---
0
2.27
10.6
---
---
---
70
2.09
2.43
---
---
9.61
67
2.07
2.44
---
---
9.69
65
2.08
2.48
---
---
9.74
Column
SBP-1 Sulfur Column
ZB-624 Column
TG Bond Q+ Column
TG Bond Q Column
HP-AL/S Column
Average Peak Area of Gases
Column
Temperature (⁰C)
SF6
CF4
C3 F8
PMCH
40
8.91x107
1.43x104
1.44x104
20
7.69x107
1.56x104
1.30x104
-----
40
5.93x107
2.07x103
1.02x104
20
6.12x107
---
8.63x103
0
6.57x107
---
2.20x105
40
5.93x107
2.79x103
1.15x105
20
1.091x108
---
6.15x104
0
1.100x106
---
4.13x104
60
2.56x107
---
3.34x105
50
2.60x107
---
4.18x105
40
7.26x106
---
3.88x103
20
4.50x106
---
0
3.70x106
---
1.960x103
---
-----------
70
3.44x107
---
---
4.95x107
67
4.24x107
---
---
6.34x107
65
6.18x107
---
---
7.97x107
-------------
Application
Chromatogram Results
µV(x10,000)
min
Application
Chromatogram Results
µV(x100,000)
min
Application
Chromatogram Results
µV(x10,000,000)
Column Name HP-AL/S
Column Type Capillary
Column Length
30 m
Inner Diameter 0.250 mm
Film Thickness
5 µm
Split Injector Temperature
150⁰C
Split Ratio
50:1
Pressure
16.2 psi
Carrier Gas
He
Total Flow
60.8 mL/min
Make Up Gas
N2
Column Flow
1.15 mL/min
Linear Velocity
30 cm/s
Septum Purge Flow
2.0 mL/min
Detector Temperature
200⁰C
Initial Column Temperature 67⁰C hold 2.75 min
Ramp
120⁰C/min
Final Column Temperature 180⁰C hold 12.30 min
Total Program Time
15.99 min min
Summary
Future Work
• PMCH vulnerabilities to sample loss
• Methods of release
– Permeation tubes
– Fluoroelastomer plug source
– Gas Cylinders
Summary
Conclusions
• Unsuccessful separation when using Freon
gases
• PMCH is a favorable tracer selection
– Successful separation
– Encouraging previous applications
• A simple GC method has been developed
Summary
Thank you
Questions?