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NAFA CAFS SAMPLE QUESTIONS
1 millionth of a meter is called a _____? - ANSWER - Micrometer or Micron The air we breath is composed mainly of ______? - ANSWER - Nitrogen The size of particles in outdoor air are mainly _____ and smaller
- ANSWER - 1 micrometer ___________ (size) particles behave like a gas, have negligible settling rates, and are affected by Brownian Motion. - ANSWER
- Particles less than 0.1 micrometers Rated flow of air through a filter at specified pressure drop is called _____? - ANSWER - Capacity The four principles of air filtration are? - ANSWER - 1. Impingement
- Interception
- Diffusion
- Straining If Static Pressure goes up, Velocity Pressure goes _______? - ANSWER - Down (SP + VP = TP) In the filter industry, a manometer is used to measure? - ANSWER - Pressure drop across a filter An Electronic Air Cleaner collects particles by? - ANSWER - Electrostatically charging them and collecting them on oppositely charged plates. What is the formula for expressing air flow through a duct? - ANSWER - Q=A*V Quantity = Area of the Duct * Velocity of Air _____________ is the pressure within the duct that is capable of bursting the duct and may be positive or negative. - ANSWER
Which of the following would be the best description of the straining filtration principle? - ANSWER - Static pressure is measured in which direction? - ANSWER - All directions Air flows because the fan creates what? - ANSWER - It creates a positive pressure to the duct system What happens to our pressure if we enlarge a portion of the duct work to twice the size? - ANSWER - Static Pressure goes up Velocity Pressure goes down Total Pressure remains the same When a filter loads static pressure goes _____, and the velocity pressure goes ______. - ANSWER - up; down Adhesives add what to a filter? - ANSWER - They give a force to better hold capture particles.
Brownian motion is best descried as - ANSWER - Particles bounce into one another as they flow through an air stream. Impingement filters are characterized by _________ and ____________. - ANSWER - Relatively high velocities, low pressure drop The velocity of the air through any one square foot of media in an extended surface filter is called? - ANSWER - Media Velocity Having larger fibers on the air entering side and smaller fibers on the air exit side is called? - ANSWER - Graduated density Baffle grease filters must meet the requirements of NFPA Standard? - ANSWER - 96 Lofted Glass Media can be found most often in what style(s) of filters? - ANSWER - Pocket Filters or Rigid Filters
One advantage of a self-contained ESP is? - ANSWER - Washable cell/capture of smaller particles/good for source capture/portable ANSI/ASHRAE 52.2 averages particles sizes in how many broad composite categories? - ANSWER - Three - E1, E2 & E What are the ranges of the ASHRAE 52.2 averages? - ANSWER - 0.3 to 1.0 / 1.0 to 3.0 / 3.0 to 10. What is the name of the current European Air Filter Standard? - ANSWER - EN779: Minimum efficiency for filter to be a HEPA? - ANSWER - 99.97% on 0.3 micrometer particles European Standard for HEPA and ULPA filters is? - ANSWER - EN Difference between Hot DOP and Cold DOP? - ANSWER - Size of particle challenge
Testing HEPA filters after installation is called? - ANSWER - In- place Leak Testing or Cold DOP Test Name two types of cleanrooms? - ANSWER - Non-unidirectional (conventional) and unidirectional (laminar flow) A Breather Filter protects content of? - ANSWER - Storage tanks -- air moving both in and out of the tank Gas turbine supply air must be free of 5 micrometer particles because? - ANSWER - They stick to and foul the turbine blades - 10 micrometer particles erode the blades. Tuberculosis patients must be kept in rooms that are ______ pressure - ANSWER - Negative to the outer rooms(s) Even though smaller than 0.3 microns, HEPA filters can remove ________? - ANSWER - viruses Bacteria reproduce by? - ANSWER - Cell division
What percent of the total cost of a filter is energy costs? - ANSWER - 81% Fan efficiency, Drive efficiency and Motor efficiency calculate into what cost? - ANSWER - Energy cost Underrating a filter may have the unintended consequence of? - ANSWER - Changing the efficiency curve Running filters to their maximum pressure drop may? - ANSWER - Cost more in energy than the cost to change it sooner A drawback of PCO may be the? - ANSWER - High initial cost of equipment PCO has how many types of reactor configurations? - ANSWER
A PCO advantage is it's? - ANSWER - 1. Reaction at ambient temperatures
- Small addition of resistance to the HVAC system
- Complete destruction of contaminant into harmless elements Metal Working Fluids are used to? - ANSWER - To cool, lubricate, and clean production parts A typical Oil Mist Electrostatic precipitator has what sections? (inlet to outlet) - ANSWER -- Baffle Section
- Ionizer Section
- Collecting Section
- Fan Section
- Optional After Filter Dust Separation is used for two objectives? - ANSWER - 1. Recover valuable product form plant processes that generate dust
- Clean air to stay in compliance with OSHA & EPA requirements
Air spray through a booth must be: - ANSWER - High enough to keep the concentration of VOC vapor held below 25% of its lower explosive limit
