# NIOSH Pocket Guide to Chemical Hazards
Tetrahydrofuran | CAS 109-99-9
C4H8O | RTECS LU5950000
Synonyms & Trade Names Diethylene oxide; 1,4-Epoxybutane; Tetramethylene oxide; THF | DOT ID & Guide 2056 127
Exposure Limits | NIOSH REL: TWA 200 ppm (590 mg/m3) ST 250 ppm (735 mg/m3)
OSHA PEL†: TWA 200 ppm (590 mg/m3)
IDLH 2000 ppm [10%LEL] | Conversion 1 ppm = 2.95 mg/m3
Physical Description Colorless liquid with an ether-like odor.
MW: 72.1 | BP: 151°F | FRZ: -163°F | Sol: Miscible
VP: 132 mmHg | IP: 9.45 eV |  | Sp.Gr: 0.89
Fl.P: 6°F | UEL: 11.8% | LEL: 2% |
Class IB Flammable Liquid: Fl.P. below 73°F and BP at or above 100°F.
Incompatibilities & Reactivities Strong oxidizers, lithium-aluminum alloys [Note: Peroxides may accumulate upon prolonged storage in presence of air.]
Measurement Methods NIOSH 1609, 3800; OSHA 7
Personal Protection & Sanitation Skin: Prevent skin contact Eyes: Prevent eye contact Wash skin: When contaminated Remove: When wet (flammable) Change: No recommendation | First Aid (See procedures) Eye: Irrigate immediately Skin: Water flush promptly Breathing: Respiratory support Swallow: Medical attention immediately
Respirator Recommendations NIOSH/OSHA Up to 2000 ppm: (APF = 25) Any supplied-air respirator operated in a continuous-flow mode£/(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 = 25) Any powered, air-purifying respirator with organic vapor cartridge(s)£/(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, upper respiratory system; nausea, dizziness, headache, central nervous system depression
Target Organs Eyes, respiratory system, central nervous system
See also: INTRODUCTION