Document X7J5y19QD9zo12zD83Qy6eGoK

FILE NAME: Koppers/Beazer East (KBE) DATE: 1944 DOC#: KBE017 DOCUMENT DESCRIPTION: Excerpt - HVAC Guide - Resistance of System HEATING VENTILATING AIR CONDITIONING GUIDE 1944 For additional information on dust and cinders, see Chapter 29, Air Cleaning Devices. RESISTANCE OF SYSTEM The maintained resistance of the exhaust system is composed of three factors: (1) loss through the hoods, (2) collector drop, and (3) friction drop in the duct system. The loss through the hoods is usually assumed to be equal to the suction maintained at the hoods. Where possible the resistance of the particular collector to be used should be ascertained from the manufacturer. Friction drop in the pipes must be computed for each section where there is a change in area or in velocity. Find the velocities in each section of pipe starting with the branch most remote from the fan. The friction drop for these sections can be determined by reference to Table 6 and Fig. 2, Chapter 32. Total friction loss in the piping system is the friction drop in the most remote branch plus the drop in the various sections of the main, plus the drop in the discharge pipe. T abus 7. Accepted Standards for T oxic Concentration of F umes, D usts and M ists* F umes Cadmium oxide._______________ Chiorodiphenyi________ _________ Lead or oxides o lead__________ Mercury or mercury compounds-- Pentacli1oronaphth alene._______ Trichloronaphthaiene___________ Zinc oxide___ ________________ D usts ___ _____ _____ ___ _____ _____ ____ Cement________________________ ______________ -- Gypsum.---------------------- --------------------------------------Lead or compounds of lead_________________ _____ Manganese..____ _____________________________ Silica (more than 70 per cent free silicon-dioxide)__ ._ Silica (more than 10 per cent free silicon-dioxide).____ Silica (less than 10 per cent free silicon-dioxide).______ M ists Chromic add ____ ________________________ ____ Sulphuric acid_____ __________________________ MILLIGRAMS PER Ousrc Meter 0.1 1.0 0.15 0.1 0.5 5.0 15.0 MiU-ION PARTC2 LL Cubic Foorb 5 100 100 0.15c 100 5 10 100 M illigrams per C ubic M eter 0.1 5.0 aAdapted from Safe Concentrations of Certain Common Toxic Substances Used in Industry, by M . Bowditch, C. FI. Drinker. P. Drinker. H. A. Haggard, and H. Hamilton (Journal c f Industrial Hygiene and Toxicology, Vol, 22, No. 6, June, 1940). Industrial Code Bulletin No. 35 (New York State Labor Depart ment). Study of Asbestos in Asbestos Textile Industry {U, S . Public Heallk Bulletin. No. 241, 1938). Chronic Manganese Poisoning in a a Ore Crushing MiU (U. S . Public Health BuUelm No. 247, 1940). bDetermined by light field o r equivalent technique. cMiUigrams per cubic meter 730 CHAPTER 4 0 . INDUSTRIAL EXHAUST SYSTEMS T a b l e 8 . C o r r o s io n R e s is t in g M a t e r ia l s f o r E x h a u s t S y st em s3- M A T E R IA L A CLD b A c e t ic C hrom ic H ydro c h l o r ic H ydro fl u o r ic N rrs ic P hos ph o r ic S u l phurous S e tP H O B IC M eta ls D il. JC o n o . D il.j C o n e . D iL C c n c . D i L C o n e . D t l JC o n e .* D ilj C o n e . D il.JC o n a D il C o n e . A lu m in u m - - - - - - - - - - G o o d F a ir P o o r N o D a ta P o o rj G o o d P o o r P o o r P o o r M a g n e siu m a c A t!o y 3_ . N o D a ta G o o d P o o r N o D a ta P o o rj G o o d N o D a ta N o D a ta N o D a ta N o D a ta Le a d an d Le a d -C o ste d _ _ P o o r G o o d P o o r P o o r P o o r P o o r G ood G ood P o o r M c ly -20 FAe Bo )_ y _ _(6_0_ N_ i-- __ 2_0_M _o Good N o D a ta F a rr N o D a ta Poet P o o r N o D a ta G ood M o n e l M e ta l_ _ _ _ _ _ _ F a ir P o o r F a ir P o o r G o o d * F a trj P o o r F a ir P o o r G oo d sp o o r B ram a- - - - - - - - - Poor Good S ilic o n Ir o n , F a ir | G o o d N o D a ta F a ir P o o r G o o d G oo d N o D a ta G oo d S ta$inNlei)s s S te e l_ (13. C r_- _ E n a m e le d S te e L M tSC B U A K SQ U S A sb esto s C cm p *. . Good N o -D ata Good N o D a ta P o o r N o D a ta G ood P o o r Good Poor Good Poor , G o o d e x c e p t a g a in s t stro n g a c id s a n d a lk a lie s G ood P o o rLo o d e N o D a ta G ood W o o d ._ _ _ _ _ _ _ _ _ _ _ _ _ R u b b e r.,_ _ _ _ _ _ . _ _ _ _ P la s tic s ^ TM ._ _ _ _ _ _ _ _ _ So m e w o o d s a re d eco m p o sed o r so fte n e d fa ste r th a n o th e rs. j ! ' F oot | j Poor , In g e n e ra l p la s tic s re s is t w e a k a c id s a n d a re d eco m p o sed b y c o n c e n tra te d a d d . Standard Practice Sheet No* 115 (Division of Industrial Hygiene, New York State Labor Department). Add mists in air are more corrosive than as liquid in storage tank. Galvanised iron not resistant to add. CSfcainless steel of <34 Or--10 N i) fairly resistant a t low temperature, for UCX and E i PQ*. Under most conditions. eA t room temperatures. EFFICIENCY OF EXHAUST SYSTEMS The efficiency of an exhaust system depends upon its effectiveness in reducing the concentration of dusts, fumes, vapors and gases below the safe or threshold limits10. Too much emphasis cannot be placed on the necessity of testing exhaust systems frequently by determining the concentration of atmospheric con tamination a t the worker's breathing level. Commonly accepted values of threshold limits for usual atmospheric contaminants, such as fumes, dusts and mists are given in Table 7* Similar data covering gases and vapor wpl be found in Chapter 28. TYPES OF FANS Manufacturers generally provide special fans for the collection of various industrial wastes. These are available for the collection of coal Criteria for Industrial Exhaust Systems, by J. J. Bloomfield (A.S.H.V.E. T ransactions, Vol. 40, 1934, p. 353). 731