AQ EXPERT Instruction & Operations Manual
Version 1.13
Page 23 of 63
3) GAS MEASURING UNITS: When the cursor is blinking on this line, you can select
any of the following units of measurement for the toxic gas sensors:
•
PPM : Parts per million (volumetric)
•
PPB : Parts per billion (volumetric)
•
MGM: Milligrams per cubic meter (weight)
•
µGM: Micrograms per cubic meter (weight)
Note: Formaldehyde, Ozone and VOCs will always read in PPB (parts per billion)
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 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 AQ Expert will measure
Differential
Pressure (∆P)
automatically. With the Velocity Probe Selection
ON
, the AQ Expert 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 CFM or CMM.
NOTE: When using the Velocity Feature on the AQ Expert 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 AQ Expert. (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 feet per minute (FPM). 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
