Document Byn4YQ8xXNDvYk0zVn4Q1MRRk

TOPIC: MAimipra PLAtT IPSUIATIOW Lessen #11 Page 1 As ve. have- already lec.rr.ed, prst rh-iir.il insulation depends upon finely divided s4v .-pc-d. - retard th* flow of heat. All the data on 1r.su". r.tira iriviriei s. * .vi her me re. aif bns*d on new materials, ur.affecied c-y str-h ;? ccr.ditipus. Hr-v. ^r, frcfe+fte day of instal lation, insulation Is s r ,'e c-, to the. d ?..?>'lor a* leg effect of moisture, and vcsr and tear_. which net c.ilv effe.ts the heat transfer qualities of ir.suletic-r, but.its useiul life as veil. ' An attempt win fs mad* hares t: cutline some cf the things that nay be done on the plant to overcome the natural enemies of insu lation. 1. The Moist ure i>..: 1 - a. General The unseer, mcn-rvxe in the sir plays havoc vith insulated construction. To- illustrate the uacnitude cf this single 'tern, cor.;ider the following: (l) Co, 4he a'--,rare day, if ti:_ 4>e ncisttrs in the air atove Kanr. attar. 1.-.1 art vf re tc fall to the earth as water, it would aa-v.-nt tv V-nvilV-r Being in `he air, this mcist-'O; can go wherever air can go, ar.i B' ccnrcn building muteri .il oar, withstand the fl. v of atr IOC#. Two fcrcih ^ci.r; each other ir. *.ie moisture attack: (1) Vker. the `-mper&tirrf- \thtv an insulated area is lowered, t-he chilled air gives up its moisture. The difference J*u nisi :r*. c.-stent between the lrildc act *he outride sir -cs vp a vapor pressure, which may be jo-'erf,1 enough to force over a quart of V'.te: a eeK 'hoc.igh a 2M re. it. area of a 13" thick brick vail. (2) !" p-pytr e.oar-pie, ve meruicted that when air ir. ar. ir.su'. ate i area is chilled in gives up moisture. Dev join', temperature is 1 ho temperature at which the nuis' -re ir. the e.ir will ocnieree tc form "dew." Ft ejner/ly, the tempera4 cre vnere `his nak-s place will le within the insulating materiel. Thus the insulation nay absorb water and lose its "heat blocking" values. This water will rapidly deteriorate the insulation, partic.larly if it .-.he .id tu~n to ice. DlJp 0900045 tW