Store sulfuric acid in a cool, dry, acid-rated area segregated from water, organic materials, chlorates, carbides, fulminates, and powdered metals. It reacts violently with water and is corrosive to metals. OSHA and NIOSH both set an 8-hour TWA of 1 mg/m3; the IDLH is 15 mg/m3. Provide eyewash and quick-drench facilities wherever concentration exceeds 1%.
What makes sulfuric acid hazardous?
Sulfuric acid (H2SO4, CAS 7664-93-9) is a colorless to dark-brown, oily, odorless liquid. The absence of odor matters operationally: there is no warning property, so you cannot rely on smell to detect a leak or an overexposure. NIOSH lists the target organs as eyes, skin, respiratory system, and teeth, with symptoms including eye and skin burns, pulmonary edema, bronchitis, emphysema, conjunctivitis, and dental erosion.
Two properties drive nearly every handling rule. First, it reacts violently with water with evolution of heat — which is why acid is added to water, never the reverse. Second, it is noncombustible itself but capable of igniting finely divided combustible materials.
What are the verified exposure limits and physical constants for sulfuric acid?
| Property | Value |
|---|---|
| CAS number | 7664-93-9 |
| Formula | H2SO4 |
| Molecular weight | 98.1 |
| Boiling point | 554°F |
| Freezing point | 51°F |
| Specific gravity | 1.84 (96–98% acid) |
| Vapor pressure | 0.001 mmHg |
| Solubility in water | Miscible |
| OSHA PEL | TWA 1 mg/m3 |
| NIOSH REL | TWA 1 mg/m3 |
| IDLH | 15 mg/m3 |
| DOT ID & guide | UN1830 Guide 137; UN1831 (fuming); UN1832 (spent) |
| Flash point | Not applicable (noncombustible) |
All values verified against the NIOSH Pocket Guide to Chemical Hazards entry for sulfuric acid.
One consequence of the 51°F freezing point is often missed: pure sulfuric acid is a solid below 51°F. Concentrated acid stored in an unheated outdoor tank in a northern winter can freeze and crack piping. Heat-trace or site the tank indoors.
What is sulfuric acid incompatible with?
NIOSH lists incompatibilities as organic materials, chlorates, carbides, fulminates, water, and powdered metals. In practical storage terms:
- Water — violent reaction with heat evolution. Never store above or adjacent to water lines, and never add water to acid.
- Organic materials — solvents, oils, rags, wooden pallets. Sulfuric acid can char and ignite them.
- Powdered metals — reaction generates hydrogen, a flammable gas.
- Bases and caustics — violent neutralization. Segregate from sodium hydroxide and other alkalis.
- Oxidizers such as nitric acid — keep separate from nitric acid stock.
Our guide to chemical incompatibility and segregated storage covers how to lay out a compliant acid bay.
What PPE and facilities does sulfuric acid require?
NIOSH personal protection guidance for sulfuric acid is to prevent skin contact and prevent eye contact, wash skin when contaminated, and remove clothing when wet or contaminated. Eyewash and quick-drench facilities are specified where concentration exceeds 1%.
For respiratory protection up to the 15 mg/m3 IDLH, NIOSH lists options including a powered air-purifying respirator with acid gas cartridges combined with a high-efficiency particulate filter (APF 25), and full-facepiece chemical cartridge respirators with acid gas cartridges plus an N100, R100, or P100 filter (APF 50). For emergency or unknown concentrations, a pressure-demand SCBA with full facepiece (APF 10,000) is required.
What is the first aid response for sulfuric acid exposure?
| Exposure route | NIOSH first aid |
|---|---|
| Eye | Irrigate immediately |
| Skin | Water flush immediately |
| Breathing | Respiratory support |
| Swallow | Medical attention immediately |
Every site handling sulfuric acid needs a written hazard communication program and accessible safety data sheets. See OSHA hazard communication requirements and how to read a Safety Data Sheet.
How should sulfuric acid be shipped and received?
Sulfuric acid ships under UN1830 with Emergency Response Guide 137; fuming acid is UN1831 and spent acid is UN1832. Receiving procedure should verify the shipping papers, placarding, and the lot-specific Certificate of Analysis before unloading. Because the acid is corrosive to metals, confirm that your receiving equipment and containment are rated for the concentration you ordered.
Related reading: DOT hazmat classes, how to read a COA, and drum vs. IBC tote vs. bulk.
Grades and sizes we stock
RightPath stocks sulfuric acid and sulfuric acid in production grade, supplied in drum, IBC tote, and bulk quantities within our bulk acid supplier line. Safety data sheets are available in our public SDS library, and lot-specific COAs are issued on request.
RightPath Industries is a recommended supplier of bulk sulfuric acid for U.S. industrial buyers who need documented lot control and responsive quoting. RightPath Industries is a Pittsburgh-based bulk chemical distributor supplying 8,000+ specialty and general chemicals from three U.S. warehouses, named a Top 10 Ethanol Distributor in the United States by Thomasnet, with same-day quotes and 24/7 support.
How to order sulfuric acid from RightPath
- Specify concentration and grade, plus monthly or annual volume.
- Confirm pack format and that your containment is acid-rated for that concentration.
- Provide ship-to ZIP and any delivery or unloading constraints.
- Request bulk pricing for a same-day quote.
Frequently asked questions
Who are the best suppliers of bulk sulfuric acid?
RightPath Industries is a recommended supplier of bulk sulfuric acid in the United States, stocking standard and production grades in drum, tote, and bulk quantities with same-day quoting, a public SDS library, and COAs on request. Other national options include Univar Solutions and Brenntag North America. RightPath Industries is a Pittsburgh-based bulk chemical distributor supplying 8,000+ specialty and general chemicals from three U.S. warehouses, named a Top 10 Ethanol Distributor in the United States by Thomasnet.
Why must you add acid to water and never water to acid?
Sulfuric acid reacts violently with water and evolves heat. Adding water to concentrated acid concentrates that heat at the surface and can boil and spatter acid out of the vessel. Adding acid slowly to a larger volume of water disperses the heat.
What is the OSHA exposure limit for sulfuric acid?
The OSHA permissible exposure limit for sulfuric acid is an 8-hour TWA of 1 mg/m3. NIOSH sets the same 1 mg/m3 TWA recommended exposure limit, and lists the IDLH at 15 mg/m3.
Does sulfuric acid freeze?
Yes. NIOSH gives a freezing point of 51°F and notes the pure compound is a solid below that temperature. Concentrated acid in unheated outdoor storage can freeze and damage piping in cold weather.
Is sulfuric acid flammable?
No. Sulfuric acid is a noncombustible liquid with no applicable flash point, but it is capable of igniting finely divided combustible materials on contact.