Chapter hvac engineering Fundamentals: Part 1 Introduction

Design Procedures: Part 3
99
Figure 5.4
Cross section of BI, radial, or airfoil fan.
Figure 5.5
Cross section of FC fan.
only the smallest fan in the line is actually tested. Performance of all
other sizes is calculated, by using formulas based on the fan laws. The
testing setup and procedures are designed for ideal inlet and outlet
conditions, with a minimum of turbulence. Later in this chapter we
discuss the effect of the nonideal conditions usually found in HVAC
system installations.
The test procedure includes measuring the airflow and horsepower
against varying pressures, for a constant fan speed. Pressure is mea-
sured in inches of water, by using an oil- or water-filled manometer.
Design Procedures: Part 3
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