Để hiểu hạt điều khiển, người đầu tiên phải hiểu một số khái niệm cơ bản và tính chất của hạt | 19 Fundamentals of Particulate Control To understand particulate control one first must understand some fundamental concepts and properties of particulate. Figure shows common terms associated with particulate material as a function of particle diameter. Particles of concern to air pollution are typically measured in microns . micrometers or 1 X 10-6 m . Large or coarse particles are those considered to be well above 10 microns. Note for perspective that the diameter of a human hair is approximately 50 to 110 microns. Very small or fine particles are considered to be those less than one micron or submicron. This size range includes smoke and fumes. Also notice that the size range considered lung damaging dust ranges from approximately to 7 microns. Dust in this size range gets into lungs and is the most difficult dust to collect with particulate control equipment for reasons that will be discussed later in this chapter. PARTICLE-SIZE DISTRIBUTION Particles frequently are described by their diameter. The amount of the particulate of a given diameter is very informative. But pay attention to the number distribution and the mass distribution. Table illustrates the distinction. Given 100 000 particles of one micron diameter and assigning each particle a unit mass of one gives a total mass of 100 000 units. Adding 1 000 particles with a diameter of 10 microns plus 10 particles with a diameter of 100 microns provides a size distribution consisting of one 10 and 100 micron particles. There are 101 010 particles of which 99 are one micron in diameter. Because the volume and therefore the mass of each particle varies with the cube of the diameter the mass of one-micron particles is only 9 are the total mass of all particles. Size distributions commonly are expressed in terms of the mass distribution. It is always best to be very clear whether the distribution is a mass or a number distribution. Sample particle size distribution data are listed in Table
