Commissioning Instructions

Table Of Contents
Before You Begin
Range of Airflow Control Application 2942
24
Siemens Industry, Inc. Start-up Procedures 140-1321
Restricted 2015-11-04
Range of Airflow Control — Application 2942
CAUTION
You must confirm that the correct, specified minimum and maximum airflows can be
reached before the Venturi Air Valve is calibrated.
Otherwise, calibration could be wrong, in which case the valve will not work correctly
once proper airflow is achieved. If the min/max flows cannot be reached, the fan
system must be adjusted.
Example:
The schedule shows a maximum flow of 2000 cfm. If you can only get 1000 cfm out of
the Venturi (because there is not enough fan static) and calibrate, then your controller
will never let the Venturi go to 2000 cfm, even after the static is increased. You must
calibrate it again.
NOTE:
Set FLOW MIN AND FLOW MAX to the desired values as described earlier in the
document.
1. Make sure that the exhaust Air Velocity Sensors are operating normally (EXH AIR
VOL has a status of NORMAL), and that the Air Velocity Sensor has been
calibrated.
2. Set EXH AO3 to 10 volts and verify that EXH AIR VOL can reach EXH MIN.
3. Set EXH AO3 to 0 volts and verify that EXH AIR VOL can reach EXH MAX.
4. Release EXH AO3.
Configuring Airflow Control — Application 2942
Before setting up airflow, you should read and understand the sections on
Venturi Air
Valve Calibration
and
Table Statement Editing
in the Application Note document;
Fume
Hood Controller
Application 2942 (140-1320) this information is located on InfoLink or
Asset Portal. This is especially important if you need to edit the Venturi table statement
during start-up.
Venturi Operational Modes
Mode 1 Operates with both a PID loop and a Venturi table.
This mode provides the best control and is the most commonly used mode for these
applications. In this mode, the embedded Venturi table statements work together with a
PID feedback loop to operate the Venturi air valve so that the measured air velocity is
maintained at setpoint. The following sections describe this mode.