Ventilation Measurements
For evaluation, planning, improvements and
changes – ventilation surveys
Air velocity and air pressure most important
Air temperature and specific weight especially
needed in air conditioning
Regular spot checks to check status of system
Continuous monitoring of more threatening
•Ventilation Measurements
• Air Quantity
– Indirect Method (V and A)
• Air Quality
– Dust, DPM, Methane, Moisture
• Temperature
– WB and DB
• Pressure
– Altimeter, Pressure Gauge
• Noise
• Mine-wide Monitoring System
conditions to maintain safety
•Min-218 Lab
Ventilation Instrumentation
• Air Quantity
– Vane and Electronic Anemometer, Sonic Tape
• Pressure
– Altimeter, Manometer, Pitot Tube, Magnehelic Gauge
• Temperature
– Sling Psychrometer, Kata Thermometer, etc.
• Air Quality
– Dust, DPM, Methane, Moisture
• Noise
– Noise Meter
•Accurate Airflow Measurements
• Air Quantity (Q) – Measured Indirectly
– Q=VxA
A – Measuring Tape
V – Velocity Measurement
• Low Velocity (<100 fpm) – Tracer Gas, Smoke
Tube, Low Vel. Anemometer
• Medium Velocity (100-2,500 fpm) –
Anemometers
• High Velocity (>2,500 fpm) – Pitot Tube
•Accurate Airflow Measurements
• Air Quantity (Q) – Measured Indirectly
– Q=VxA
A – Measuring Tape
V – Velocity Measurement
• Low Velocity (<100 fpm) – Tracer Gas, Smoke
Tube, Low Vel. Anemometer
• Medium Velocity (100-2,500 fpm) –
Anemometers
• High Velocity (>2,500 fpm) – Pitot Tube
Accurate Airflow Measurements
• Air Pressure (H): in. W.G.
– Direct Method: Manometer, Pitot Tube,
Hose, & Magnehelic Gage
– Indirect Method: Altimeter
• Air Temperature (T): Wet- and Dry-bulb
Temperatures
– Thermometer
1
Measuring Air Velocity Using Anemometers
Source of Errors . . .
Measuring Air Velocity Using Anemometers
Source of Errors . . . Operator’s Techniques
• Inherent – Bearing Friction
– Frequent Calibration Necessary
• Atmospheric Condition – Dust, Moistures,
etc.
• Operator’s Techniques
– Instrument Position
– Measuring Method
True Velocity vs Angle of Yaw
• Instrument Position
– Anemometer Orientation (Angle of Yaw)
– Operator Proximity (Too Close to Body)
– Operator Position (Block Airway Area)
• Measuring Method
– Location (Stay Away from Bends/Turns)
– Traversing Speed (<10% of Air Velocity)
– Single Reading (Always Take Double Reading)
True Velocity vs. Operator Proximity
25
80
60
40
20
20
60
40
80
Deviation from True Velocity, %
Percent of true velocity
100
27
20
5f
470
15
10
565 fp
m
5
750 fpm
0
1
Angle of yaw, degrees
True Velocity vs. Operator Proximity
20
15
2 fe
et
3 ft with arm
out-stretched
10
5
3 feet
0
600
700
400
500
300
True Velocity of Air Current, fpm
Registered Velocity/True Velocity
Deviation from True Velocity, %
ot
2
Operator Proximity, ft
3
True Velocity vs. Traversing Speed
25
1 fo
pm
fpm
1.2
1.1
1.0
0
0.1
0.2 0.3
0.4 0.5 0.6
Traverse Velocity/True Velocity
2
Taylor and Davis Anemometers
Pitot Tube Readings
Static Pressure (A)
Inclined Manometer
Velocity Pressure (B)
Total Pressure (A + B)
Arrangement for Accurate Pressure Readings
Pitot Tube
Rubber
Stopper
Rigid
Container
Rigid
Container
Rubber
Hose
U-Tube Manometer
or Magnehelic Gage
Rel-tek Gas Detection Monitoring/Control Systems
Software:Millennid-DX
Hardware:
MultiBoss: Pressure Transducer (0-10” W.G.)
SmokeBoss*100 (0-10% Optical Density)
OxyBoss*100 (0-100% Oxygen)
AirBoss*200W (0-2000 fpm)
GasBoss*100/AP (0-5% CH4)
FireBoss*100B (CO: 0-200 ppm)
UPS – Uninterrupted Power System
Work on Most PC System
Rel-tek Gas Detection Monitoring/Control Systems
3