Title: Unit 3 Outline
Course: HET 230 - Spring 2015 > Section: HET 230 - Spring 2015

Unit 3 Outline

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Unit 3 Outline

Introduction:

Last week, we discussed how to calculate duct sizing, and to measure air quality and velocity, including common vocabulary terms.  A knowledgeable technician relies on a keen understanding of the methodology used in accurately size ductwork, necessary for proper airflow and movement.

This week, you will understand how air flows through ducts, and how improper sizing can lead to poor performance.  You will also learn, and reinforce, new vocabulary to help you gain a better understanding of these concepts.  In addition, you will be provided a PowerPoint a presentation, weekly study materials. You will also participate in weekly discussions and complete all assignments and a content assessment quiz.  Not only does pressure and velocity inside ducts affect the size and gauge of the sheet metal, it creates other factors such as noise.  You will become familiar with the three pressures acting on a duct system.  You will be able to describe the two factors of pressure loss.  You will understand zero point and its relationship to atmospheric pressure. You will become familiar with the two patterns of airflow, what a Reynolds Number is, and how air flows through square and radius elbows, as well as describe the types and parts of an elbow.  Learning these subjects will allow you to form a solid foundation for the next week’s session, Sizing Ductwork & Calculating Pressure Losses in Ductwork.

Objectives:

On completion of this week’s assignments, the student should be able to:

- name the three air pressures in a duct system
- define Static Pressure in a duct system
- define Velocity Pressure in a duct system
- define Total Pressure in a duct system
- name the two  factors of pressure loss
- define Dynamic Loss and its relationship to duct size change
- define Friction Loss and how it is created in a duct system
- define Zero Point as it applies to atmospheric pressure
- name the two patterns of airflow
- describe Laminar Flow
- describe Turbulent Flow
- state what a Reynolds Number is, and what it used to determine
- name the types and parts of an elbow
- describe how air flows through Square and Radius Throat duct elbows

Review the vocabulary terms listed below and look up their definitions / descriptions before taking the Vocabulary Quiz.

Vocabulary

Cheek

Dynamic Loss

Friction Loss

Heel

Laminar Flow

Negative Duct Pressure (-P)

Offset

Positive Duct Pressure (+P)

Radius Throat Elbow

Resistance

Reynolds Number

Static Pressure (SP)

Square Throat Elbow

Throat

Total Pressure (TP)

Transition

Turbulent Flow

Vanes

Velocity Pressure (VP)

Zero Point