1. OSHA Occupational Chemical Database
  2. 2-METHYLBUTANE (ISOPENTANE)
Label abbreviations descriptions

2-METHYLBUTANE (ISOPENTANE)†

Chemical Identification
Chemical Identification
CAS # 78-78-4
Formula

C₅H₁₂
Synonyms

isopentane; ethyldimethylethane; isoamylhydride
Physical Properties
Physical Properties
Physical description Watery colorless liquid with a gasoline-like odor.
Boiling point 82°F Molecular weight 72.17
Freezing point/melting point -255.8°F Vapor pressure 689 mmHg
Flash point -70°F Vapor density 2.48
Specific gravity 0.062 Ionization potential
Lower explosive limit (LEL) 1.4% Upper explosive limit (UEL) 7.6%
NFPA health rating 1 NFPA fire rating 4
NFPA reactivity rating 0 NFPA special instruction
Vapor hazard ratio (VHR)
Historical exceedance percentage
Target organs
Monitoring Methods Used by OSHA
Monitoring Methods Used by OSHA
Analyte code (IMIS no.) R228
Sampling group
Sampler/Sampling media CSC tube (100/50 mg) [SKC 226-01]
Sampling time*
Sampling volume (TWA)*

4 L
Sampling flow rate (TWA)*

0.2 L/min
Sampling volume (STEL/Peak/C)*
Sampling flow rate (STEL/Peak/C)*
Analytical method instruments GC-FID
Method reference NIOSH 1500 (partially validated)
Notes
Special requirements

* All sampling instructions above are recommended guidelines for OSHA Compliance Safety and Health Officers (CSHOs), please see the corresponding OSHA method reference for complete details.

Wipe Method
Wipe Method
Sampler/Sampling media
Bulk Method
Bulk Method
On-Site Screening Techniques
On-Site Screening Techniques
Device
Model/Type
Sampling information
(see manufacturer instructions)
Exposure Limits
Exposure Limits
OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
NIOSH REL
Up to 10-hour TWA
(ST) STEL
(C) Ceiling
ACGIH TLV©
8-hour TWA
(ST) STEL
(C) Ceiling
CAL/OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
PEL-TWA

1000 ppm (2950 mg/m³)

 REL-TWA
 

120 ppm (350 mg/m³)

 TLV-TWA
 

1000 ppm [2013]

 PEL-TWA
 

600 ppm (1800 mg/m³)
PEL-STEL REL-STEL
 

 

 TLV-STEL
 

 

 PEL-STEL
 

 
PEL-C REL-C
 

610 ppm (1800 mg/m³) [15 minutes]

 TLV-C
 

 

 PEL-C
 

 
Skin notation

N

 Skin notation
 

N

 Skin notation
 

N

 Skin notation
 

N
Notes:
 

As Pentane; there is no specific OSHA PEL for 2-Methylbutane. Construction and Maritime Industry PEL is 500 ppm (1500 mg/m³) as an 8 hr TWA for Pentane. See 29 CFR 1926.55 Appendix A and 29 CFR 1915.1000 Table Z-Shipyards.

 Notes:
 

as n-Pentane

 Notes:
 

as Pentane, all isomers

 Notes:
 

as Pentane
Health factors:  See NIH-NLM PubChem. IDLH
 

1500 ppm (as n-Pentane)
Carcinogenic classifications: Not listed Notes:
 

 
AIHA emergency response planning guidelines - ERPG-1/ERPG-2/ERPG-3:
 

 
Additional Resources and Literature References
Additional Resources and Literature References

NOAA: CAMEO Chemicals - Isopentane

NIOSH: Pocket Guide to Chemical Hazards - n-Pentane

Literature References

 
  • ACGIH: Documentation of the Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Pentane, all isomers. See annual publication for most recent information.
  • Chiba, S. and Oshida, S.: Metabolism and toxicity of n-pentane and isopentane [Japanese]. Nippon Hoigaku Zasshi 45(2): 128-137, 1991.
  • Galvin, J.B. and Marashi, F.: 2-Methylbutane (isopentane). CAS# 78-78-4. J. Toxicol. Environ. Health A 58(1-2): 23-33, 1999.
  • Pohanish, R.P. (editor): Isopentane. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 2. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1341-1342.

Last Updated Date : 11/01/2022