NuAire LabGard NU-540-300E, Operation And Maintenance Manual

Page: 37 / 63

OM0280 Page 37 of 63
Rev 3 July/2021
7.5.3 Airflow Calibrations
Failure to calibrate airflow to the specified requirements may
result in unsafe conditions of performance (i.e. product and/or
personnel protection, noise and vibration)
The NU-540E airflow calibration consists of adjustments to balance the airflow within the cabinet. THIS WORK
SHOULD BE DONE ONLY BY A QUALIFIED TECHNICIAN WHO CAN MEASURE THE AIRFLOW FROM THE FILTERS
WITH A SUITABLE VELOMETER.
NuAire provides two adjustments to balance the airflow within the cabinet.
These are:
a. PWM signal adjust via calibration parameter menu
b. exhaust filter choke
The PWM signal or blower speed adjustment establishes the motor speed controls curve starting point of the
programmed internal reference performance curve while the choke adjusts or balances the exhaust airflow as well
as makes up for filter resistance tolerances. Since it has been NuAire's experience that the filters may not "load"
evenly, choke adjustments may be necessary for proper cabinet airflow balance and performance.
DC ECM motor PWM signal DC voltage should also be monitored and recorded upon final calibration. The DC
voltage may be measured using a digital voltmeter. The two test points to measure DC ECM motor voltage are
located on the DC motor connector on the main control board.
The cabinet is considered to be certifiable if the following airflow measurements are present:
a. Downflow average: 60 LFPM

5 LFPM (.30 m/s

.025 m/s).
b. Inflow average: 105 LFPM

5 LFPM (.53 m/s

.025 m/s) using the direct inflow measurement
method or constricted 3 inch (76mm) high access opening measurement method.
Note: It is recommended to perform the airflow calibration process at least annually to optimize both the
airflow control and PresurFlow™ monitor systems.

CAUTION
!