Can't say I have design experience on local exhaust, but I'll bet the basic scrubbing concept is very similar to the first aid concept: bind the diss ociated fluorine ion with a group II cation. (In plainspeak, bring HF in c ontact with calcium salts or magnesium salts, and you end up with a very st able fluoride.) But choose your group II salt carefully! We have a Honeyw ell document that indicates Calcium Carbonate as a good selection - slow re action (meaning exotherm problems are reduced, slow gas evolution). The sa me document warns that limestone pebbles can become passivated (coated in r eaction product which inhibits further reaction). So either look to use in creased surface area (small particle sizes) or overbudget for limestone peb bles. Perhaps someone else can give higher confidence guidance on this... Hope this helps! -Nick -----Original Message----- From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**LIST.UVM.EDU] On Behalf Of Jo seph Passante Sent: Monday, November 30, 2009 8:41 AM To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU Subject: [DCHAS-L] HF digestion safety Does anyone on this list have experience with proper exhaust design for small scale digestion using 48% HF? The geochemistry researcher I am working with anticipates evaporating 2 liters of concentrated HF per month in a fume hood. I am interested in scrubbing technologies and if anyone has designed local exhaust systems that do not involve a fume hood. Thanks Joe Joseph R. Passante, CIH, CHO Associate Director Chemical Hygiene Officer Environmental Health & Radiation Safety University of Pennsylvania 215.746.6550
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