Installation & Operation Manual - Model AVC5000
Contents of this Manual are Subject to Change Without Notification
Page 37
Note: How Volume Limits Interact with Fume Hood Face Velocity
When volume limits are not used
, as the sash is opened and closed, the controller will
increase and decrease the airflow volume as required to maintain the face velocity set
point.
When volume limits are used,
the following performance characteristics will apply:
When the volume required to achieve the face velocity set point is between the minimum
and maximum volume limits, the
same performance characteristics as described above
will apply.
When the volume required to achieve the face velocity set point is greater than the
maximum volume limit, the controller will maintain the maximum volume limit resulting
in the face velocity falling below the face velocity set point.
When the volume required to achieve the face velocity set point is less than the
minimum volume limit, the controller will maintain the minimum volume limit resulting
in the face velocity increasing above the face velocity set point. Depending on the type
of fume hood and the bypass area value, as the sash is lowered, the indicated face
velocity can exceed the face velocity high alarm set point. When controlling to the
minimum volume limit, the face velocity measurement is irrelevant; therefore the face
velocity alarms are also irrelevant. Enabling the Face Velocity Alarm Bypass Feature will
temporarily suspend the face velocity alarms during this control sequence and the
AFC5000 display will indicate the controller is maintaining the minimum volume limit
and will display the airflow volume rather than the face velocity. When the sash is raised
to the point where the minimum volume limit is exceeded, the face velocity alarm
functionality will return to normal.
6.6.4.2.5.7 Alarm Mute Reminder
When an alarm condition is indicated, pressing the Mute button on the AFC5000 display will
silence the audible horn until the Mute button is pressed again or the alarm condition is
cleared. The Mute Reminder feature will provide a periodic reminder chirp at regular intervals.
The interval rate of the reminder chirp and the expiration of the reminder are both
programmable using Insight.
6.6.4.2.5.8 Energy Conservation Alarm
(programmable Alarm delays are available)
The Energy Conservation Alarm is available when operating in Fume Hood Mode with a
Presence/Occupancy Sensor connected to either DI-1 or DI-2. The purpose of the Energy
Conservation Alarm is to alert lab occupants that a fume hood sash has been left in the open or
partially open position when nobody is working in front of the hood. The sash % open and time
delay for entering into the alarm condition are both programmable using Insight.
Note:
If the fume hood is controlling to the minimum volume limit, the Energy
Conservation Alarm will not be triggered because the fume hood is already operating at the
lowest airflow volume permitted for the application.
