Title: Unit 6 Outline
Course: HET 230 - Spring 2015 > Section: HET 230 - Spring 2015

Unit 6 Outline

Unit 6 Outline
Unit 6 Outline

Introduction:

Last week, we discussed the importance of fan safety and the types of fans.  A knowledgeable technician knows that working safely is very important.  Locking and tagging out, and or using proper blocking techniques assure one’s safety while working on not only small systems, but on the very large systems where one could be inside.  Knowing the different types of fans, blades and rotation is also important as we enter into this week.

This week, you will learn about fan curves and fan tables, as well as their use, including common vocabulary terms.  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.  It is not particular that a technician be a walking technical guide.  Understanding how to read fan curves and where to get the tables needed to make your calculations is important.  Many manufacturers’ have data sheets and guides to assist a technician in finding the proper data needed for choosing, identify and detuning the system effects that are unique to each type of fan.  Although, many of the manufacturers’ have tables made, a technician should know how to plot and calculate a fan curve and the operation parameters of a selected fan, as well as its effects on system static pressures.  You will become familiar with system effects, transitions and proper outlet conditions.  Learning these subjects will allow you to form a solid foundation for the next week’s session, Fan Laws for CFM, RPM, Sheave Diameters, SP, and Bhp.

Objectives:

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

- understand the function of Fan Curves
- recognize the difference between a General Fan Curve and a specific Fan Curve
- use Fan Tables to verify the proper performance  of a selected fan
- understand the how to read the scales located on a Fan Curve Table
- outline the steps in developing and plotting the scales on a Fan Curve Table
- identify the recommended and optimum operating range for a fan selection
- describe the term “riding the curve” and how it is used
- describe the term “fan surge” what it indicates
- understand how a designer calculates System Resistance and System Effect Factor
- describe how to calculate Total System Resistance by using Equivalent Resistance and System Resistance
- understand Static Regain, its cause and results, and how to calculate 100% - Effective Duct Length
- understand the causes of System Effect through uneven flow and spinning air at the fan inlet
- understand the effects of obstructions at an inlet or outlet
- describe the proper outlet connections
- understand correcting deficiencies of fan performance by adding a Gradual Transition or Evasé (ev-a-say’)
- describe the proper outlet connections