Chapter 2
Pressure/Pressure Mode
2.4 Changing the Time Averaging Period
The DG-700 has a choice of 4 time averaging periods which are applied to both pressure measurement
channels. The default time averaging period is
1 second average
. To change the selected time averaging
period, 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
for an overview of the time averaging feature).
2.5 Using the Baseline Pressure Feature
The
Baseline
feature on
Channel A
allows the user to measure and record a
baseline pressure reading, and then display the baseline adjusted pressure reading.
(See
Section 1.6
for an overview of the baseline pressure feature)
2.5.a Example: Measuring Building Depressurization from an Exhaust Fan
A common building performance application requiring use of a baseline pressure reading is determining the extent of
building depressurization caused by turning on an exhaust fan. In order to accurately quantify the building
depressurization, the user first needs to know the building pressure (with reference to outside) prior to the exhaust
fan being turned on. This initial pressure reading, known as the baseline building pressure, can be quickly measured
and then used to adjust the final building pressure reading (after the exhaust fan is turned on) to determine the actual
change in building pressure caused by fan operation.
-
Set up
Channel A
to measure building pressure with reference to outside (e.g. run tubing from the
Channel A
Reference
tap to outside and leave the
Channel A
Input
tap open to the building – assumes the gauge is in the
building).
-
With the exhaust fan off, turn on the gauge and leave it in the
PR/PR
mode.
-
Press the
BASELINE
button. The word “BASELINE” will
begin to flash in the
Channel A
display, indicating that the
baseline feature has been initiated. At this point, the gauge is
monitoring the real-time
Channel A
baseline pressure
reading, but is not recording the reading. The
Channel B
display is not active at this time.
-
Press the
START
button to begin the baseline measurement
procedure on
Channel A
. Once the
START
button is
pressed, the word “BASELINE” stops flashing and the
gauge begins recording a
long term average
baseline
pressure reading on
Channel A
. During the baseline
measurement procedure, the
Channel B
display is used as a
timer to let the user know how long (in seconds) the baseline measurement has been active. The longer the
measurement time, generally the more stable the baseline reading typically becomes. In the screen to the right,
the measured baseline pressure is –2.6 Pascals (measured over the past 45 seconds).
-
Once you are satisfied with the baseline pressure reading,
press the
ENTER
key to accept and enter the baseline
pressure reading into the gauge. After pressing
ENTER
,
Channel A
will now display the baseline adjusted pressure
reading (i.e. the measured baseline pressure reading will be
9
Operating Instructions
for the DG700
