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HEATING VENTILATING^ CONDITIONING r,,,nC ,o,,.
The lower limit of size of particle visible to the naked eye cannot be stated definitely. It depends not only upon the individual, but also upon the shape and color of the particle and upon the intensity of light. Under
Fig. 1. Sizes and CharacteriCsotmicpsileodpbAy Wir.-BG.oFrrnanekSolidCsopyrighted.
ideal conditions a particle 10 microns, or even less, may be recognized, while under less favorable conditions it may be difficult or even impos sible to recognize a particle of SO microns. The lower limit of visibility should, therefore, be considered as within a range (as above) or optimum conditions stated.
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CHAPTER 28. AIR POLLUTION
Mineral particles, such as grains of sand, bits of rock, volcanic ash, or fly-ash, can be transported long distances under unusual circumstances. Thus, the dust storms of 1935 in the Kansas district resulted in vast amounts of fine top soil being thrown high into the air. Solar illumination
Table X. Approximate Limits op Inflammability op Single Gases and Vapors in Air at Ordinary Temperatures and Pressures3
Gas oa Vapob
Lower Loot Hnsnnt T mpr
Volume m Volume In
PebCkkt
Peb Cknt
Gab ob Vapob
joweb Limit Eighbr Limit
Volume in
Volume in
Psb Cent
Peb Cent
AcetoneAcetylene____ .______ Allyl alcohol______ ;__ Ammonia..... -
Butyl acetate (30 C)__
Carbon disulphidel___ Carbon monoxide.___ Croton aldehyde... Cyclohexane.________ Decane_____________ Dichlorethylene._____ Diethyl selenide._____ Dioxan______________
Ethyl alcohol________ Ethyl chloride._______ Ethylene dichloride.__ Ethyl ether____:_____ Ethyl formate.. ____
Gasoline__-_________ Heptane____________
4.0
3.0 2.5 2.5 2.3 2.4
16.0
1.2 1.4
1.6 1.4
1.1 35.0
1.9 1.7 1.7 1.7 1.2
12.5 2.1 1.3 2.4
0.7 9.7 2.5 2.0 3.2
2.0 3.3 6.7
4.0 6.2 3.0
1.8 2.7
3.0 3.0 21 1.4 1.0
57.0 1.2 6.9
13.0 Hydrocyanic acid____ 5.6
40.0
4.1 74.0
80.0 Hydrogen sulphide.-^. 4.3
45.5
5.3 31.0
Iso-amyl alcohol.____ 1.2
27.0 Iso-butane._________ 1.8
8.4
1.8
1.3
1.8 7.8
6.7 Iso-propyl alcohol-.-- 2.6
5.3 14.0
74.0 510 15.0
8.4 3.1 15.5
7.6 Methyl alcohol
6.7 36.0
13.5 14.5
9.0 1.2 8.0
50.0 Methyl chloride_____ 8.0
19.0
74.0 Methyl cyclohexane^- 1.2
15.5 Methyl ethyl ether___ 2.0
10.1
8.3 Methyl ethyl ketone- 1.8
10.0
10.3 Methyl formate.- __ 5.0
23.0
Methyl propyl ketone 1.5
8.5
12.8 Natural gas. -- . 4.8
13.5
Nonane...................... 0.8
22.0 Octane
0.9
_____
12.5 1.0 6.0
11.5 1.3
19.0 Pentane
. 1.4 7.8 `
11.2 2.4 9.5
14.8 Propyl acetate______ 1.8
8.0
15.9 Propyl alcohoL.______ 2.5
___
29.0 2.0 . 11.1
36.5 Propylene dichloride- 3.4
14.5
16.5 Propylene oxide_____ 2.1
21.5'
1.8 12.4
80.0 1.3 6.7
' 1.7
27.0
6.5 Vinyl chloride__-____ 4.0 : 22.0
Water gas__________ 6 to 9 55 to 70
"Limits of Inflammability of Gases and Vapors, by H. F. Coward and G. W. Jones (17. S. Bureau of Mina, Bulletin No. 279. 1939).
^Turbulent mixture.
as far east as Boston was affected noticeably and particles as large as 40 to 50 microns were actually carried half way across the continent before they settled out. In similar manner volcanic ash has been carried even further. It is not surprising, therefore, that fly-ash from furnace gases, cement dust ,and the like, can be carried for-considerable distances and
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