ASHRAE FUNDAMENTALS IP CH 11-2013 Air Contaminants.pdf
《ASHRAE FUNDAMENTALS IP CH 11-2013 Air Contaminants.pdf》由会员分享,可在线阅读,更多相关《ASHRAE FUNDAMENTALS IP CH 11-2013 Air Contaminants.pdf(24页珍藏版)》请在麦多课文档分享上搜索。
1、11.1CHAPTER 11AIR CONTAMINANTSClasses of Air Contaminants 11.1PARTICULATE CONTAMINANTS 11.2Particulate Matter 11.2GASEOUS CONTAMINANTS 11.8Volatile Organic Compounds. 11.12Semivolatile Organic Compounds . 11.14Inorganic Gases . 11.14AIR CONTAMINANTS BY SOURCE . 11.15Outdoor Air Contaminants. 11.15In
2、dustrial Air Contaminants 11.15Nonindustrial Indoor Air Contaminants 11.16Flammable Gases and Vapors 11.18Combustible Dusts 11.18Radioactive Air Contaminants . 11.19Soil Gases. 11.20IR contamination is a concern for ventilation engineers whenA it causes problems for building occupants. Engineers nee
3、d tounderstand the vocabulary used by the air sampling and building aircleaning industry. This chapter focuses on the types and levels of aircontaminants that might enter ventilation systems or be found asindoor contaminants. Industrial contaminants are included only forspecial cases. Because it is
4、not a building air concern, the effects ofrefrigerants on the atmosphere are not included in this chapter; seeChapter 29 for discussion of this topic.Air is composed mainly of gases. The major gaseous componentsof clean, dry air near sea level are approximately 21% oxygen, 78%nitrogen, 1% argon, and
5、 0.04% carbon dioxide. Normal outdoor aircontains varying amounts of other materials (permanent atmosphericimpurities) from natural processes such as wind erosion, sea sprayevaporation, volcanic eruption, and metabolism or decay of organicmatter. The concentration of permanent atmospheric impurities
6、 var-ies, but is usually lower than that of anthropogenic (i.e., caused byhuman activities) air contaminants.Anthropogenic outdoor air contaminants are many and varied,originating from numerous types of human activity. Electric-power-generating plants, various modes of transportation, industrial pro
7、-cesses, mining and smelting, construction, and agriculture generatelarge amounts of contaminants. These outdoor air contaminants canalso be transmitted to the indoor environment. In addition, the indoorenvironment can exhibit a wide variety of local contaminants, bothnatural and anthropogenic.Conta
8、minants that present particular problems in the indoor en-vironment include allergens (e.g., dust mite or cat antigen), tobaccosmoke, radon, and formaldehyde.Air composition may be changed accidentally or deliberately. Insewers, sewage treatment plants, agricultural silos, sealed storagevaults, tunn
9、els, and mines, the oxygen content of air can become solow that people cannot remain conscious or survive. Concentrationsof people in confined spaces (theaters, survival shelters, submarines)require that carbon dioxide given off by normal respiratory functionsbe removed and replaced with oxygen. Pil
10、ots of high-altitude air-craft, breathing at greatly reduced pressure, require systems thatincrease oxygen concentration. Conversely, for divers working atextreme depths, it is common to increase the percentage of helium inthe atmosphere and reduce nitrogen and sometimes oxygen concen-trations.At at
11、mospheric pressure, oxygen concentrations less than 12% orcarbon dioxide concentrations greater than 5% are dangerous, evenfor short periods. Lesser deviations from normal composition can behazardous under prolonged exposures. Chapter 10 further detailsenvironmental health issues.Although lack of ox
12、ygen can be a danger in confined spaces, it isunlikely ever to be a problem in naturally and mechanically venti-lated buildings. Although the amount of oxygen consumed approx-imates the amount of carbon dioxide produced by respiration, thelevel of oxygen in the air is so much greater than that of ca
13、rbon diox-ide to start with that there is effectively no change in oxygen contentbetween air intake and exhaust.CLASSES OF AIR CONTAMINANTSAir contaminants are generally classified as either particles orgases. Particles dispersed in air are also known as aerosols. In com-mon usage, the terms aerosol
14、, airborne particle, and particulatecontaminant are interchangeable. The distinction between particlesand gases is important when determining removal strategies andequipment. Although the motion of particles is described using thesame equations used to describe gas movement, even the smallestparticl
15、es are much larger and heavier than individual gas molecules,and have a much lower diffusion rate. Conversely, particles are typ-ically present in much fewer numbers than even trace levels of con-taminant gases.The particulate class covers a vast range of particle sizes, fromdust large enough to be
16、visible to the eye to submicroscopic particlesthat elude most filters. Particles may be liquid, solid, or have a solidcore surrounded by liquid. The following traditional particulate con-taminant classifications arise in various situations, and overlap. Theyare all still in common use. Dusts, fumes,
17、 and smokes are mostly solid particulate matter,although smoke often contains liquid particles.Mists, fogs, and smogs are mostly suspended liquid particlessmaller than those in dusts, fumes, and smokes.Bioaerosols include primarily intact and fragmentary viruses,bacteria, fungal spores, and plant an
18、d animal allergens; their pri-mary effect is related to their biological origin. Common indoorparticulate allergens (dust mite allergen, cat dander, house dust,etc.) and endotoxins are included in the bioaerosol class.Particulate contaminants may be defined by their size, such ascoarse, fine, or ult
19、rafine; visible or invisible; or macroscopic,microscopic, or submicroscopic.Particles may be described using terms that relate to their interac-tion with the human respiratory system, such as inhalable andrespirableThe gaseous class covers chemical contaminants that can exist asfree molecules or ato
20、ms in air. Molecules and atoms are smaller thanparticles and may behave differently as a result. This class coverstwo important subclasses:The preparation of this chapter is assigned to TC 2.3, Gaseous Air Con-taminants and Gas Contaminant Removal Equipment, in conjunction withTC 2.4, Particulate Ai
21、r Contaminants and Particulate Contaminant RemovalEquipment.11.2 2013 ASHRAE HandbookFundamentalsGases, which are naturally gaseous under ambient indoor or out-door conditions (i.e., their boiling point is less than ambient tem-perature at ambient pressure)Vapors, which are normally solid or liquid
22、under ambient indooror outdoor conditions (i.e., their boiling point is greater than ambi-ent temperature at ambient pressure), but which evaporate readilyThrough evaporation, liquids change into vapors and mix with thesurrounding atmosphere. Like gases, they are formless fluids thatexpand to occupy
23、 the space or enclosure in which they are confined.Air contaminants can also be classified according to their sources;properties; or the health, safety, and engineering issues faced by peo-ple exposed to them. Any of these can form a convenient classifica-tion system because they allow grouping of a
24、pplicable standards,guidelines, and control strategies. Most such special classes includeboth particulate and gaseous contaminants.This chapter also covers background information for selectedspecial air contaminant classes (Chapter 10 deals with applicableindoor health and comfort regulations).Outdo
- 1.请仔细阅读文档,确保文档完整性,对于不预览、不比对内容而直接下载带来的问题本站不予受理。
- 2.下载的文档,不会出现我们的网址水印。
- 3、该文档所得收入(下载+内容+预览)归上传者、原创作者;如果您是本文档原作者,请点此认领!既往收益都归您。
本资源只提供5页预览,全部文档请下载后查看!喜欢就下载吧,查找使用更方便
10000 积分 0人已下载
下载 | 加入VIP,交流精品资源 |
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- ASHRAEFUNDAMENTALSIPCH112013AIRCONTAMINANTSPDF

链接地址:http://www.mydoc123.com/p-454697.html