Emerson VSG, VSSG manual Installation, Not Preferred

Section 3 • Installation

Intake Velocity

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Figure 3-11. Leg Height

The equation used to calculate the leg height in Figure

3-11 is as follows:

Leg Height = (Total Airflow/Intake velocity)/Intake Perimeter

Leg Height = (247,000CFM/500FPM)/82ft

Leg Height = 6ft

In this particular case the calculated minimum height is 6 feet to maintain an intake velocity of 500FPM or less based on having the coolers place 1 fan diameter away from the nearest obstruction. Let’s look at an instal- lation where the coolers need to be placed next to the building as in Figure 3-12.

Based on the information above, we are going to solve for the leg height that will provide an intake velocity of 500FPM. We know the following:

•The total airflow of the installation is 247,000CFM

•We have an intake perimeter of 3 sides 16ft, 16ft, and 25ft which totals 57’

•Our intake velocity guideline is 500FPM

The equation used to calculate the leg height in Figure

3-11 is as follows:

Leg Height = (Total Airflow/Intake velocity)/Intake Perimeter

Leg Height = (247,000CFM/500FPM)/57ft

Leg Height = 8.667ft

We would round the leg height up to 9ft for this particu- lar situation.

NOT PREFERRED

TOTAL INTAKE PERIMETER = 57 FEET

Figure 3-12. Installation of Coolers - Next to Buildling

VSG/VSSG • Installation, Operation and Maintenance Manual •Vilter/Emerson • 35391SSG 3 – 13