Methyl mercaptan
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CAS
74-93-1
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CH3SH
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RTECS
PB4375000
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Synonyms & Trade Names
Mercaptomethane, Methanethiol, Methyl sulfhydrate
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DOT ID & Guide
1064 / 117
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Exposure
Limits
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NIOSH REL: C 0.5 ppm (1 mg/m3) [15-minute]
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OSHA PEL†: C 10 ppm (20 mg/m3)
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IDLH
150 ppm
See: 74931
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Conversion
1 ppm = 1.97 mg/m3
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Physical Description
Colorless gas with a disagreeable odor like garlic or rotten cabbage. [Note: A liquid below 43°F. Shipped as a liquefied compressed gas.]
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MW: 48.1
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BP: 43°F
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FRZ: -186°F
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Sol: 2%
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VP: 1.7 atm
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IP: 9.44 eV
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RGasD: 1.66
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Sp.Gr: 0.90 (Liquid at 32°F)
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Fl.P: NA (Gas) (oc) 0°F (Liquid)
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UEL: 21.8%
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LEL: 3.9%
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Flammable Gas
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Incompatibilities & Reactivities
Strong oxidizers, bleaches, copper, aluminum, nickel-copper alloys
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Measurement Methods
NIOSH 2542; OSHA 26
See: NMAM or OSHA Methods |
Personal Protection & Sanitation (See protection)
Skin: Prevent skin contact (liquid)/Frostbite
Eyes: Prevent eye contact (liquid)/Frostbite
Wash skin: No recommendation
Remove: When wet (flammable)
Change: No recommendation
Provide: Eyewash (liquid), Quick drench (liquid), Frostbite wash
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First Aid (See procedures)
Eye: Irrigate immediately (liquid)/Frostbite
Skin: Water flush immediately (liquid)/Frostbite
Breathing: Respiratory support
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Respirator Recommendations
NIOSH
Up to 5 ppm:
(APF = 10) Any chemical cartridge respirator with organic vapor cartridge(s)
(APF = 10) Any supplied-air respirator
Up to 12.5 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)
Up to 25 ppm:
(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 powered, air-purifying respirator with a tight-fitting facepiece and organic vapor cartridge(s)
(APF = 50) Any supplied-air respirator that has a tight-fitting facepiece and is operated in a continuous-flow mode
(APF = 50) Any self-contained breathing apparatus with a full facepiece
(APF = 50) Any supplied-air respirator with a full facepiece
Up to 150 ppm:
(APF = 1000) Any supplied-air respirator operated in a pressure-demand or other positive-pressure mode
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
Important additional information about respirator selection
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Exposure Routes
inhalation, skin and/or eye contact (liquid)
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Symptoms
Irritation eyes, skin, respiratory system; narcosis; cyanosis; convulsions; liquid: frostbite
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Target Organs
Eyes, skin, respiratory system, central nervous system, blood
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See also: INTRODUCTION
See ICSC CARD: 0299 See MEDICAL TESTS: 0144
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