Introduction to Energy Management

Week/Lesson 8 Air Cleaning Equipment

After completing this chapter, you will be able to:  List common indoor and outdoor air pollutants  Explain why clean HVAC air is important  Describe the classes of airborne pollutants  Explain three primary methods to remove particulate matter from air Air Cleaning Equipment

 Describe several types of air filters, their media and their uses  Evaluate a filter’s operating performance  Understand the unique problems of defining and reducing gas and odor pollution Air Cleaning Equipment

What is dirty air?  Irritating substances  Gaseous emissions  Offensive odors  Metallic fragments  Concentrations should be minimal Air Cleaning Equipment

 Why clean HVAC air? Protect health of occupants Improve employee productivity Protect sensitive equipment Protect furnishings Protect HVAC equipment Air Cleaning Equipment

Air cleaning methods  Contaminants Inert particles Gaseous pollutants and odors Microorganisms Liquid particles Air Cleaning Equipment

Removing particulates  Inert particles  Range from 0.01 microns to the size of insects  Particle size is most important  Filter must be chosen properly Air Cleaning Equipment

Mechanics of air filtration  Straining Larger particles trapped on the filter surface  Impingement Particles stick to filter fibers  Electrostatic attraction Oppositely charged filters and dust attract Air Cleaning Equipment

Types of air filters  Dry, fibrous media filters  Extended surface, pleated filters  Viscous impingement filters  Disposable/cleanable filters  Stationary/electronic air filters Air Cleaning Equipment

Evaluating air filter performance  Atmospheric dust spot test  ASHRAE standard 52.1 – 1992  Compares stains on paper targets  Dust accumulation increases pressure drop across filter  Manometers/draft gauges read pressure drop Air Cleaning Equipment

Problems of gas and odor pollution  Difficult to predict  Odors cannot be measured  No standards exist for nonindustrial areas  Gases behave independently  Increased ventilation is costly  Responses to gas/odor is subjective Air Cleaning Equipment

Controlling gas and odor pollution  Remove the source  Reduce the source  Increase the HVAC ventilation rate  Use activated charcoal/carbon  Activated carbon is expensive but effective Air Cleaning Equipment

Primary panel filter Secondary filter HEPA or tertiaary filter