Measurement Of Air Volume - VTS Medical Systems VENTUS COMPACT VVS021c Instructions For Use Manual

CHECKING THE OPERATION OF THE WATER HEATER VALVE ACTUATORS
Check that the heater valve actuator responds to the control signal - manually actuate the valve from the
controller's service menu and observe whether it causes the valve to open/close accordingly.
To do this, set parameter D to ON and parameter A to the desired percentage in the corresponding screen
in the service menu, depending on the type of heater you have and the function it performs [screens A01,
A03, A05, A06. (See "DESCRIPTION OF THE UPC3 CONTROLLER MASKS")
CHECKING THE OPERATION OF THE WATER HEATER CIRCULATION PUMP
Check that the heater circulation pump responds to the control signal - manually set the valve from the
controller's service menu and observe whether it causes the pump to switch on/off accordingly.
! Remember to restore the original settings of the D and A (Auto) parameters after the test.
7.2.8

MEASUREMENT OF AIR VOLUME

The measurement of air volume is an essential measurement for:
•
commissioning and technical acceptance of the air handling unit,
•
if the system does not perform as required and expected,
•
periodically check the operation and efficiency of the air handling unit,
•
replacement of fan assembly components.
Before taking measurements and making adjustments, make sure, that the dampers on all grilles or
gates are positioned as designed.
Determination of the amount of airflow is most often based on the measurement of the average airflow
velocity in a test cross-section of a duct. One of the most common methods for determining the average
flow velocity is the cross-sectional sounding method using a Prandtl tube and measuring the flow
velocity-related mean dynamic pressure.
Key factors that affect measurement accuracy are:
•
the position of the cross-section to be measured in relation to the elements causing distortion
of the flow velocity (elbows, orifices, tees, butterfly valves, etc.),
•
the number and location of test points in the cross-section to be measured,
•
stable and constant airflow,
The measurement must be carried out in a section of duct with parallel walls and straight sections at
least 6 times the hydraulic diameter of the duct or the corresponding diameters upstream of the test
point and no less than 3 diameters downstream of this point. In a real ventilation system, finding such a
long straight section may be a problem. In this case, the position of the cross-section should be
determined at the point where the least flow disturbance is expected, increasing the number of
measurement points. The location of the measuring cross-section should be determined at the system
design stage.
An estimate of the measurement result is considered sufficient if it does not differ by more than ±10%
from the design value. In the case of greater discrepancies, an approximation of the measurement result
to the design value may be obtained by:
•
adjustment of the ventilation duct network,
•
changing the setting of the main throttle,
•
changing the fan speed
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