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Chapter 6
Pressure/Velocity Mode
6.1 Mode Summary
Mode
Application
Pressure/Velocity
Multi-purpose pressure
(PR/ V)
and air velocity
measurements.
6.2 Overview of Pressure/Velocity Mode
The Pressure/Velocity mode is a multi-purpose mode used to
measure a pressure signal on Channel A and/or measure an air
velocity reading from a pitot tube connected to Channel B.
To select the Pressure/Velocity mode, press the
MODE button until the selected operating mode
shown on the gauge display is PR/ V. When first entering this mode, the default air velocity unit on
Channel B is feet per minute (FPM). Channel A always displays pressure readings in Pascals when in the PR/ V
mode.
6.3 Changing the Air Velocity Units
When in the PR/ V operating mode, the DG-700 can display air velocity readings on Channel B in
units of feet per minute or meters per second. To change the air velocity units for Channel B, press
the UNITS button. The selected units are shown on the Channel B display directly below the channel
reading.
6.4 Changing the Time Averaging Period
To change the selected time averaging period for both Channel A and B, press the TIME AVG button.
The selected time averaging period is shown in the TIME AVG portion of the gauge display. (See
Section 1.5 above for a complete description of the time averaging periods.)
6.5 Air Velocity Calculations Used in the DG-700
The following equations are used to calculate air velocity from a pitot tube connected to Channel B. Note: The
pitot tube should be set up to measure velocity pressure in order for the DG-700 to correctly display air velocity
readings.
Air Velocity
=
1096.2
(feet/minute)
Channel A Display
Pressure in Pascals.
0.50
Velocity
Pressure (in. wc)
3
0.075 (lb/ft
)
Chapter 6
Channel B Display
Air velocity in units chosen
(FPM, m/s).
Air Velocity
=
1.4142
(meters/second)
23
Pressure/Velocity Mode
0.50
Velocity
Pressure (Pa)
3
1.204 (Kg/m
)
Operating Instructions
for the DG700
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