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	Terms
	SCFM, standard cubic feet per minute Anguil:  70°F, 14.7 PSIA, dry Others: 60°F, 14.7 PSIA, dry             68°F, 14.7 PSIA, 67% R.H.             70°F, 14.4 PSIA, 67% R.H.    ^ Back To Menu ACFM, actual cubic feet per minute 1. Actual cubic feet that a scf occupies, at non standard conditions 2. Formula (assumes no humidity or pressure correction) acfm = scfm x  (460 + T1) (460 + 70) likewise scfm = acfm x  (460 + 70) (460 + T1) where T1 = non standard temperature, °F For example, if process discharge is 10,000 acfm at 250°F, what is scfm? scfm = 10,000 x    (460 + 70) (460 + 250) scfm = 7,465           ^ Back To Menu LEL, lower explosive limit This is the concentration needed to have an explosive mixture.     Rule of Thumb: Each 1% LEL results in 25°F temperature rise across the catalyst, likewise, Each 25°F temperature rise across the catalyst means the stream is at 1% LEL.    ^ Back To Menu Percent (%) by volume A 1% by volume mixture is equivalent to 10,000 parts/million (ppmv).    ^ Back To Menu

	Formulas
	Temperature rise across catalyst, due to exothermic oxidation of VOCs Temp rise, F =   (VOC, lbs/hour) x (VOC latent heat, btu/lb) (1.08) x (airflow, scf/min)    ^ Back To Menu Amount of VOCs that an oxidizer can handle VOCs, lbs/hr =   (permit temp rise, F) x (1.08) X (airflow, scf/min) (VOC latent heat, btu/lb)    ^ Back To Menu Concentration of VOCs in airstream, given lbs/hr flow of VOCs ppmv =   (VOC, lbs/hour) x (387 scf/mole) x 1,000,000 (airflow, scf/min) x (mol. wt. VOC, lbs/mole) x (60 min/hr)    ^ Back To Menu Pounds per hour of VOCs in an airstream, given the concentration in ppmv  lbs/hr =   (conc, ppmv) x airflow, scf/min (MW, lbs/mole x 60 min/hr (1,000,000) (387 scf/mole)    ^ Back To Menu Calculate % of LEL, given concentration in ppmv **Be careful, for this formula to work, LEL must be entered into the formula as whole percentage, ie if LEL = 2.3% enter the value 2.3 % LEL =   (conc. ppmv) (VOC LEL, %) x 100    ^ Back To Menu Energy required to heat an airstream btu/hr = (airflow, scf/min) x (1.08) x (temp rise required, F)    ^ Back To Menu Energy released by oxidation (assumes 100% reaction) btu = (VOCs, lbs) x (VOC latent heat, btu/lb)    ^ Back To Menu