Johnson Controls York Stack Fan, Operating Manual, Page: 12 / 15

10
Piezometer Ring Data
YORK
®
STACK FAN
K Factor
Fan Size
iCorus & Corus
DDP
Efficient
Silent Array
105 592 592
122 842 842
135 963 963
150 1147 1147
165 1450 1450
182 1671 1671
200 2087 2087
222 2458 2458
245 2941 2941
HOW IT WORKS
The Piezo Ring system is based on the principle of a flow nozzle. The inlet funnel of the fan is used
as the flow nozzle, and the flow can be calculated by measuring the static pressure drop through the
inlet funnel. The pressure drop is measured from the tap located on the face of the inlet funnel to the
piezometer ring in the throat. The inlet tap is connected to the high-pressure side of the transducer
and the piezometer ring is connected to the low-pressure side (see diagram below).
A B
Front Pressure Tap
HIGH PRESSURE
Piezometer Ring
LOW PRESSURE
A
B
MEASUREMENT OF AIRFLOW
Several factors affect the accuracy of
this method of determining flow. The
equations below assume the following:
• There are no vanes or other
obstructions in or near the inlet
• Impeller to inlet funnel overlap
• Flow entering the funnel (no pre-
swirl) contains no pressure.
• Accurate determination of air density
at the inlet