T-ABVA Manual |Rev.C, JULY 2017 Page 7
Pre-Calibration
Mute Button
The Mute Button has three functions, which are selected based on the time duration the button is held.
Calibration Button
To prevent accidental contact, the Calibration Button is located below the hole in the front lower right
corner of the ABVA. In order to press the Calibration Button, simply straighten the end of a small paper
clip and insert straight into the hole.
Calibration Modes
The ABVA has two different modes for calibrating the alarm set point. Mode 1 calibrates the alarm set
point to the velocity at which the fume hood is presently operating and Mode 2 calibrates the alarm set
point to 20% less than the operating velocity.
NOTE: Mode 2 was added in April 2008. Units sold
prior to April 2008 include Mode 1 only. (
Serial #’s > 1500 have MODE 1 & 2)
Mode 1 should be used if the desired alarm set point can be achieved by either modulating the exhaust
flow or by positioning the fume hood sash. Mode 2 should be used if the desired alarm set point can not
be achieved and is 20% less than operating velocity. Two examples are provided below for selecting
which Mode is suited best for your application.
Example 1:
Desired Alarm Set Point: 80 FPM
Fume Hood Type: Constant Exhaust Volume
Face Velocity Range: When Sash is 100% Open the Face Velocity is measured at 80 FP.
Calibration Mode: Select Mode 1; because the desired alarm set point can be achieved by opening the sash 100%.
Example 2:
Desired Alarm Set Point: 80 FPM
Fume Hood Type: Variable Exhaust Volume
Face Velocity Range: Face Velocity is controlled to 100 FPM, regardless of sash position.
Calibration Mode: Select Mode 2; because the desired alarm set point is 20% less than the operating velocity.
Calibration Button
Pressing and releasing;
toggles calibration modes.
Pressing and holding for 5 seconds
; initiates alarm calibration.
Pressing and holding for 10 seconds;
zeros the sensor.
Note: The sensor should not need to be re-zeroed unless directed to do
so by the factory. Re-zero should only be performed with the airflow
sensor blocked.
Mute Button
Pressing and releasing once;
during alarm condition will silence the
horn. Pressing again reactivates the alarm horn.
Pressing and holding for 3 seconds
; provides visual indication of the
present calibration mode. One LED ON = Mode 1, Two LEDs ON =
Mode 2.
Pressing and holding for 15 seconds;
disables the horn with no re-
beep. The horn will remain off until Mute is held again for 15 seconds.
