Operating Instructions

Controlling Laboratory Air Flow
Siemens Building Technologies, Inc. 3-17
Problem 2: Ventilation Alarm
If there is a ventilation alarm, complete the following steps:
1. Verify that there is a problem by checking to see if the supply flow is low. If it is not, then
the alarm is probably just a nuisance alarm. Adjust the limit (VENT ALM LVL) or delay the
alarm (VENT ALM DEL). Be sure, however, to coordinate these actions with the safety
officer.
NOTE:
The alarm setup points are in the Alarm report.
On the other hand, if the supply flow is low, proceed with Step 2.
2. Using the Pressure report, check to see if the supply flow is at set point. By reading the
supply flow values you can determine whether or not the flow is stable and near the
setpoint. CIS and trend graph work the best for this.
If the supply flow is at the set point, then the setpoint is low. Look for an override (SUP
VOL STPT). Also, check the exhaust flow values (TOTAL EXH). If the exhaust flow is too
low, it forces the LRC to keep the supply flow low.
If the supply flow is not at the set point, go to Step 3.
3. Check to see if the supply flow is fluctuating back and forth past the set point or if it is
staying low. If the supply flow is staying low, look for an override (SUP DMPR CMD). If
there is no override, check the supply flow capacity by briefly opening the damper. You
will need to troubleshoot the air supply system if you do not get enough flow with the
damper open. Contact your Siemens Building Technologies, Inc. representative for
assistance.
If the supply flow is fluctuating back and forth past the set point, use the process
described in
Problem 4: Unstable Airflow
to troubleshoot, or contact your Siemens
Building Technologies, Inc. branch for assistance.
Problem 3: Pressurization Alarm
If there is a pressurization alarm, complete the following steps:
1. Verify that there is a problem by checking to see if the pressurization value (VOL
DIFFRNC) is too low. If it is not, then the alarm is probably a nuisance alarm. Adjust the
level (DIF ALM LVL) or delay the alarm (VOL DIF DEL). Be sure, however, to coordinate
these actions with the safety officer. Use the Alarm Report to access these points.
If the pressurization value is low, then refer to step three in
Problem 1: Observed Positive
Pressurization
.