My friend Jeff Biosmell just took a long look at OSHA (US industrial safety regulator) and other safety regulations regarding handling of methanol. Some scary stuff turned up that a lot of us didn't know, and that many are basing our biodiesel-making practice on. I feel especially responsible due to all of the people in the classes I've taught, since we focused strongly on organic vapor cartridge respirator safety and it turned out to be dangerously inaccurate information:
It turns out that organic vapor cartridge respirators are useless against methanol vapors. I imagine that this also means that such a respirator will not protect you from any vapors arising from the agitation and settling portion of the biodiesel making process, as methanol will vaporize during this process to some extent in an open processor (obviously many people use a completely enclosed processor to protect themselves from poisonous vapors). Methanol handling/methoxide mixing can be done in a completely enclosed environment as well, rather easily and inexpensively, so don't panic, but it's time to get rid of all our open-tank methoxide mixers (a la Tickell). I devised a decent carboy-based non-mechanically-agitated system to minimise methoxide handling here (look at journeytoforever.org for the 'methoxide the easy way' description, it's the start of that carboy system I've got) which can then be plumbed into a closed processor easily. there are many other ways that others have accomplished this as well. I have copied some info below (I believe it might be from the 3M site, but what I saw from more 'neutral' sources was very similar to 3M's recommendation not to use organic vapor cartridges for longer than a few hours max) OSHA and the other safety regulators all had the same answer when we called them: no organic vapor cartridge respirator will protect against methanol vapors, only a supplied-air system will do so. Here's some more info, I don't remember which source it's from: Q. Can chemical cartridges be used for more than one shift? Organic vapors are removed by the process of adsorption. Weak physical forces hold the organic vapor on the activated carbon. Since these forces are weak, the process can be reversed and the organic vapor can be desorbed. Desorption during storage or nonuse periods can result in the migration of the chemical through the cartridge. Migration is mainly a concern only for organic vapor cartridges. Organic vapors adsorbed on an organic vapor cartridge can migrate through the carbon bed without airflow. Desorption of very volatile contaminants can occur after a short period (hours) without use (e.g., overnight). Partial use of the chemical cartridge and subsequent reuse could potentially expose the user to the contaminant. This is most significant for the most volatile and poorly retained organic vapors (e.g., boiling point < 65‰Ãõ C). For organic vapors with a boiling point less than 65‰Ãõ C, it is recommended that the organic vapor cartridge never be used longer than one shift even if the estimated service life is greater than 8 hours and the cartridge is used for only a short time during the shift. However, a boiling point of 65 oC is not a fine line between chemicals that migrate and those that do not. Chemicals with boiling points greater than 65 oC can still migrate, but the nonuse period of concern may be longer than above. For chemicals with boiling points greater than 65 oC, nonuse or storage periods of a few days, like over a weekend, may be the concern. For these chemicals, (e.g., ethyl acetate, boiling point 77oC), reuse should not be allowed after two days of nonuse even if the service life estimate would suggest it. As the volatility decreases migration will become less of a concern. Your reuse pattern should still be carefully evaluated even for these less volatile chemicals. Chemicals with low volatility will give long service lives, but even in these situations use should probably not extend beyond a week or two even if the service life estimate is longer. For workers that use their respirators intermittently and perhaps in different environments, such as a maintenance worker or inspector, the organic vapor cartridges should never be reused. The user can conduct desorption studies, mimicking the work conditions of use and nonuse, to determine acceptable patterns of reuse. The ANSI Z88.2-1992 American National Standard for Respiratory Protection recommends that organic vapor cartridges be changed daily unless desorption studies support longer use. For more detail on chemical bed migration see: Reuse of Organic Vapor Chemical Cartridges (pdf - 50Kb) Chemical Sampling Information Methyl Alcohol å Chemical Sampling Information - Table of Contents å Field Definitions å Analytical Methods General Description ------------------------------------------------------------------------ NAME: Methyl Alcohol SYNONYM(s): Methanol; Wood alcohol; Columbian spirits; Carbinol IMIS: 1660 CAS: 67-56-1 NIOSH: RTECS PC1400000; 48518 DOT: UN1230 Flammable Liquid; Poison DESCRIPTION: Colorless liquid with a characteristic, pungent odor. MW: 32.04 BP: 148 F VP: 97 mm MP: -144 F INCOM: Strong oxidizers Exposure Limits ------------------------------------------------------------------------ OSHA GENERAL INDUSTRY PEL: 200 ppm, 260 mg/m3 OSHA CONSTRUCTION INDUSTRY PEL: 200 ppm, 260 mg/m3 TWA ACGIH TLV: 200 ppm TWA; 250 ppm STEL (Skin); (TLV listed under Methanol) NIOSH REL: 200 ppm TWA (Skin); 250 ppm STEL (Skin) Health Factors ------------------------------------------------------------------------ SYMPTOM(s): Eye irritation; headaches, drowsiness, lightheadedness; nausea, vomiting; visual disturbance, blindness HEALTH EFFECTS: Cumulative CNS effects (HE7); Narcosis (HE8) Irritation-Eye, Nose, Throat, Skin---Mild (HE16) ORGAN: Eyes, skin, CNS, GI tract Monitoring ------------------------------------------------------------------------ PRIMARY SAMPLING/ANALYTICAL METHOD (SLC1): MEDIA: Two Anasorb 747 Tubes in series(First tube 400mg, second tube 200 mg section) See note ANL SOLVENT: 50:50 Carbon Disulfide:Dimethylformamide MAX V: 3 Liters (RH<50% @ 25 C) å å MAX F: 0.05 L/min (TWA) MAX V: 5 Liters (RH>50% @ 25 C) å å MAX F: 0.05 L/min (TWA) MAX V: 0.75 Liters å å MAX F: 0.05 L/min (STEL) ANL 1: Gas Chromatography; GC/FID REF: 2 (OSHA 91) SAE: 0.09 CLASS: Fully Validated . NOTE: Separate tubes and seal each after sampling. MEDIA: Silica Gel Tube (520/260 mg sections, 20/40 mesh) ANL SOLVENT: 0.02 N H2SO4 MAX V: 6 Liters å å MAX F: 0.1 L/min (TWA) MAX V: 1.5 Liters å å MAX F: 0.1 L/min (STEL) ANL 1: Gas Chromatography; GC/FID REF: 1,2 (OSHA Modified NIOSH 2000) SAE: 0.16 CLASS: Fully Validated NOTE: The larger size tube is recommended due to low capacity of the 150/75 mg tubes at high humidities. SECONDARY SAMPLING/ANALYTICAL METHOD (SAM2): DEVICE: Detector Tube COMPANY: Gastec PART #: 111L RANGE: 25-1000 ppm CLASS: Mfg DEVICE: Detector Tube COMPANY: Draeger PART #: CH 29701 RANGE: 100-3,000 ppm CLASS: Mfg DEVICE: Detector Tube COMPANY: Draeger PART #: 67 28941 RANGE: 50-3,000 ppm CLASS: Mfg DEVICE: Detector Tube COMPANY: MSA PART #: 95097 RANGE: 100-10,000 ppm CLASS: Mfg DEVICE: Detector Tube COMPANY: Kitagawa PART #: 119U RANGE: 20-1000 ppm CLASS: Mfg DEVICE: Instrumentation COMPANY: Infrared Spectrophotometer PART #: MIRAN 1A & 1B RANGE: 0.3 ppm @ 9.7 um CLASS: Mfg DEVICE: Instrumentation COMPANY: Infrared Spectrophotometer PART #: MIRAN 103 RANGE: 0-300 ppm @ 9.9 um CLASS: Mfg DEVICE: Instrumentation COMPANY: Organic Vapor Analyzer PART #: Organic Vapor Analyzer CLASS: Mfg DEVICE: Instrumentation COMPANY: PID PART #: Photoionization Detector CLASS: Mfg å Chemical Sampling Information - Table of Contents Biofuels at Journey to Forever http://journeytoforever.org/biofuel.html Biofuel at WebConX http://webconx.green-trust.org/2000/biofuel/biofuel.htm List messages are archived at the Info-Archive at NNYTech: http://archive.nnytech.net/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! 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