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4)
PRESSURE UNITS: Pressure measurements can be shown in millibar (mbar), inches of water (inWC),
millimeters of water (mmWC), millimeters of mercury (mmHG), inches of mercury (inHG), pounds
per square inch (psi) or kilopascal (kPa).
1 mbar = 0.10 kPa = 0.40 inWC = 10.2 mmWC = 12.95 inHg = 0.75 mmHg = 1.45 PSI
5)
VELOCITY & AIRFLOW UNITS: (Velocity Option) Select between feet per second (FPS), meters per
second (MPS), cubic feet per minute (CFM), or cubic meter per minute (CMM).
AIR VELOCITY AND DIFFERENTIAL PRESSURE CAN NOT BE MEASURED SIMULTANEOUSLY.
USER MUST CHOOSE ONE OR THE OTHER.
To change the selection, hit the
SETUP
key. Using the
DOWN
arrow key, scroll Down to
VELOCITY PROBE
and hit
OK
. The
OFF/ON
selection will be highlighted. Use the Up & Down arrow
keys to change the selection from OFF to ON or vice versa. With the Velocity Probe Selection
OFF
, the
SI-AQ VOC will measure
Differential Pressure (∆P)
automatically. With the Velocity Probe Selection
ON
, the SI-AQ VOC will measure
Air Velocity (VEL)
automatically. When you have your selection
chosen, hit the
OK
button and the entire Velocity Probe will be highlighted again. Hit the
MEASURE
Button to get back to the Main Measurement screen once you are complete.
6)
DUCT SIZE: (Velocity Option). Estimate the cross-section area of your Ducts in square inches (in
2
)
and set this value to obtain automatic & accurate Air Flow measurements in m/s or m
3
/min.
NOTE: When using the Velocity Feature on the SI-AQ VOC it is recommended to ZERO the
readings BEFORE using the Pitot tube to ensure proper Velocity measurements. See Chapter
9 for instructions on Zeroing the SI-AQ VOC. (Zero Gas Sensors)
Connecting Pitot Tube
: In air conditioning, heating and ventilating work, it is helpful to understand
the techniques used to determine air velocity. In this field,
air velocity (distance traveled per unit of
time) is usually expressed in meters per minute (m/min). By multiplying air velocity by the cross section
area of a duct, you can determine the air volume flowing past a point in the duct per unit of time.
Volume flow is usually measured in cubic feet per minute (m
3
/min). To make Air Velocity
measurements using the SI-AQ VOC, you will need to use the
Optional 12” Pitot tube. Follow Steps #5
& #6 above to (1) turn the Velocity Probe option ON (VEL will appear on the unit’s main screen) and (2)
set up your Duct Size. Connect the supplied hoses from the Pitot tube to the (-) and/or (+) PRESSURE
connections on the bottom of the SI-AQ VOC.
7)
PUMP: Pump status is displayed:
a)
AUTO – Automatic sample mode is selected
b)
OFF – The internal Pump is turned off.
8)
DISPLAY CONTRAST: Select the best value for viewing the LCD screen.
9)
BAUDRATE: The communication speed for both the USB port and the Bluetooth
®
connection is set
here. The default setting is 115 kbps.
