Retrotec DM-2 - Manual (Page 15)

Page 15 of 72
©Retrotec Inc. 2012
the gauge will continuously display the updated average pressure, and the sampling
duration on the screen. The more the pressure is fluctuating, the longer the baseline will be
sampled for.
2. Press [Enter] to accept the current measurement, usually after approximately 60 seconds.
If there is a lot of fluctuation, let the baseline acquire for longer than 60 seconds. The
current baseline measurement, and the time taken to acquire it, is displayed at the bottom
of the Main Screen.
3. Pressing [Exit] will clear the measurement.
When numerical input is required, the [Baseline] key functions to input the number four, [4] .
2.1.9 Time Avg
When Time Averaging is active, the gauge will display results and pressures that are
averaged over the time period selected, on both channels. Regardless of the averaging
value, the display will update with a new value every second. This can provide
significantly more accurate results.
The gauge includes nine time averaging settings. Press [Time Avg] to scroll through the following time
averaging settings: Off, 1s, 2s, 4s, 8s, 10s, 20s, 1m, and 2m.
Caution: When changing the fan speed, set pressure, or taking a reading after making any other
changes, wait for twice the time averaging period to elapse before taking a reading. Taking a reading
too quickly can lead to recording incorrect results.
Notice that the [Time Avg] key is located in the middle of all the arrow keys on the keypad. As a user
friendly feature, while in the Setup Menu, the [Time Avg] key can be used to select menu items, just as
you would using the [Enter] key.
When numerical input is required, the [Time Avg] key functions to input the number five, [5] .
2.1.10 Auto Zero
Over time, the reading on Channel A and Channel B will start to drift away from zero.
The longer the gauge is turned on, the larger this error can become. With Auto Zero
on, the gauge will automatically zero the gauge every 8 seconds. In general, the DM-2
should be used with auto zero feature on. However, the function does consume extra
battery power. Turning auto zero on, only at the start of each data acquisition cycle, will maximize
battery life, gauge performance and data transfer rates.
Press [Auto Zero] to turn the Auto Zero function on or off.
When numerical input is required, the [Auto Zero] key functions to input the number six, [6] .
2.1.11 Set Pressure
The gauge can automatically control the fan speed on Retrotec systems to achieve a
user chosen building pressure. This is the easiest method to achieve a specific test
pressure.
To use the Set Pressure function