# NIOSH Pocket Guide to Chemical Hazards
2-Butanone | CAS 78-93-3
CH3COCH2CH3 | RTECS EL6475000
Synonyms & Trade Names Ethyl methyl ketone, MEK, Methyl acetone, Methyl ethyl ketone | DOT ID & Guide 1193 127 1232 127
Exposure Limits | NIOSH REL: TWA 200 ppm (590 mg/m3) ST 300 ppm (885 mg/m3)
OSHA PEL†: TWA 200 ppm (590 mg/m3)
IDLH 3000 ppm | Conversion 1 ppm = 2.95 mg/m3
Physical Description Colorless liquid with a moderately sharp, fragrant, mint- or acetone-like odor.
MW: 72.1 | BP: 175°F | FRZ: -123°F | Sol: 28%
VP: 78 mmHg | IP: 9.54 eV |  | Sp.Gr: 0.81
Fl.P: 16°F | UEL(200°F): 11.4% | LEL(200°F): 1.4% |
Class IB Flammable Liquid: Fl.P. below 73°F and BP at or above 100°F.
Incompatibilities & Reactivities Strong oxidizers, amines, ammonia, inorganic acids, caustics, isocyanates, pyridines
Measurement Methods NIOSH 2500, 3800; OSHA 16, 84
Personal Protection & Sanitation Skin: Prevent skin contact Eyes: Prevent eye contact Wash skin: When contaminated Remove: When wet (flammable) Change: No recommendation Provide: Eyewash | First Aid (See procedures) Eye: Irrigate immediately Skin: Water wash immediately Breathing: Fresh air Swallow: Medical attention immediately
Respirator Recommendations NIOSH/OSHA Up to 3000 ppm: (APF = 25) Any supplied-air respirator operated in a continuous-flow mode£/(APF = 25) Any powered, air-purifying respirator with organic vapor cartridge(s)£/(APF = 50) Any chemical cartridge respirator with a full facepiece and organic vapor cartridge(s)/(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister/(APF = 50) Any self-contained breathing apparatus with a full facepiece/(APF = 50) Any supplied-air respirator with a full facepiece Emergency or planned entry into unknown concentrations or IDLH conditions: (APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode/(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus Escape: (APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, ingestion, skin and/or eye contact
Symptoms Irritation eyes, skin, nose; headache; dizziness; vomiting; dermatitis
Target Organs Eyes, skin, respiratory system, central nervous system
See also: INTRODUCTION