Health and Safety
ISRS DE provides Health and Safety for hazardous solvents, cleaning chemicals health & safety tips. Your friendly site for understanding hazardous solvents, chemicals, and toxic solvents.
Safe Handling of Solvents depends on:
(1) understanding the hazards, and
(2) being careful and prepared.
The flammability and/or toxicity of solvents are commonly the most talked about hazards. But many solvents are also extremely irritating to the skin and mucous membranes. In addition, one consideration that is of particular concern to chemists is pressure buildup. This is (due to the exothermicity of rxn in a volatile solvent) in reaction vessels with limited gas outlet capability.
Information table
below is information on the properties of several common solvents as regards their boiling, igniting, exploding, and poisoning:
| Values are Approximate |
bp, ?C |
Flash Point, ?C |
Explosive Limits% v/v |
PEL |
Fire Class |
NFPA HFR |
Odor Threshold |
Other Special |
| Acetone | 56 | -18 | 2 – 13 | 1000 | IB | – | 2 | – |
| Hexane | 69 | -7 | 1 – 8 | 500 | IB | – | 65 | – |
| Pentane | 36 | -40 | 1 – 8 | 1000 | IA | – | – | – |
| Heptane | 98.4 | -4 | 1 – 7 | 500 | IB | – | – | – |
| Acetonitrile | 82 | 2 | 3 – 16 | 40 | IB | – | 170 | – |
| Methylene Chloride | 40 | none | 12 – 23 (>100? C) | 12.5 | none | – | 160 or 250 | Yes |
| Chloroform | 62 | none | none | 50 (C) | none | – | 192 | Yes |
| Ethyl Ether | 35 | -45 | 1 – 49 | 400 | IA | – | – | – |
| Ethanol (Absolute) | 78 | 12 | 3 – 19 | 1000 | IB | – | 1000 or 49-716 | – |
| Ethanol (95%) | – | 17 | – | – | IB | – | – | – |
| Methanol | 65 | 11 | 6 – 36 | 200 | IB | – | 4 | – |
| Isopropyl Alcohol | 82 | 12 | 2 – 13 | 400 | IB | – | 50 or 22 | – |
| Tetrahydrofuran | 66 | -21 | 2 – 12 | 200 | IB | – | 2 | – |
| P-Dioxane | 101 | 12 | 2 – 23 | 100 | IB | – | 24 | Yes |
| Ethyl Acetate | 77 | -4 | 2 – 12 | 400 | IB | – | 7 | – |
| Toluene | 112 | 4 | 3 – 19 | 200 | IB | – | 2.9 | – |
| Xylenes | 140 | 25 | 1 – 7 | 200 | IB | – | 1.1 | – |
| Benzene | 80 | -11 | 1 – 8 | 1 | IB | – | 12 or 4.68 | Yes |
| Dimethylformamide | 158 | 58 | 2 – 15 at 100o C | 10 | II | – | 100 | – |
| Methyl Ethyl Ketone | 80 | -7 | 2 – 12 | 200 | IB | – | 2 | – |
Additionally, the Flashpoint of a material is defined as the temperature at which an ignition source 1 cm from the surface of the liquid will cause ignition. With that being said, the standard method is defined by ASTM. Most flash points are measured in a “closed cup” flashpoint tester. Finally, discrepancies/disagreements are found in the literature for some substances, but the values are usually fairly close.
Understanding Limits
Combustible and lower explosion limits! While generally regarded as non-flammable, and although no flashpoint can be measured by the standard method, dichloromethane (methylene chloride) has known explosive limits in air mixtures at 100 C and above. Similarly, it is also known by firefighters to give flammable/explosive mixtures with air if there is a high energy ignition source or an enriched oxygen content.
In other words, flammable solvents are an explosion hazard when the solvent vapor concentration in the air is greater than the lower explosive limit (LEL) and less than the upper explosive limit (UEL). Below the LEL, the mixture is too lean to burn. For example, the LEL of ethyl alcohol is 3.3%. Note that this is 33,000 ppm for comparison with the permissible exposure level of 1000 ppm.
OSHA Regulations on Health and Safety
In conclusion, the OSHA Permissible Exposure Limit is a regulatory limit for the concentration of a contaminant in workplace air. For instance, the values shown refer to the level as an 8h-TWA (8-hour time-weighted average) unless otherwise noted, given in ppm (parts per million in contaminated air) unless otherwise noted. See OSHA Z-1 and Z-2 tables.
Above all, the flash point increases as ethanol is diluted with water, but not really fast. Also, the flash point of 80% ethanol/water is about 24C, and for 70% EtOH/water, it’s 29C (according to the Aldrich catalog).
IA, IB, IC, II, IIIA, and IIIB classes are defined by NFPA (National Fire Protection Association) depending on flash points and boiling points.
NFPA
Finally, Health and Safety recommends the National Fire Protection Association’s health, flammability, and reactivity ratings. Furthermore, the symbol is usually referred to as the “NFPA 704 diamond.” A rating of 4 is the most dangerous in any category, and 0 is the least dangerous. In addition, the values shown in the table above were taken from various MSDSs and other references. They were not directly from the NFPA standard (there may be discrepancies).
Disclaimer: This web page is for general informational purposes only. Since every situation is unique, and these products are hazardous if not handled appropriately, you must consult qualified technical and engineering personnel to evaluate your specific situation and answer any specific questions you may have. Also, SRS disclaims all warranties, either expressed or implied, and assumes no responsibility for the accuracy or completeness of the data contained herein. SRS will not be liable for any personal injury, property damage, or environmental harm. We are also not liable for legal non-compliance that may result from reliance upon this document or your management of the product.
