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Chemical Datasheet

HYDROFLUORIC ACID AND SULFURIC ACID MIXTURE

8 - Corrosive 6.1 - Poison

Chemical Identifiers

CAS Number UN/NA Number DOT Hazard Label USCG CHRIS Code
  • 7664-39-3   (HYDROGEN FLUORIDE)
  • 7664-93-9
  • 1786
  • Corrosive
  • Poison
none
NIOSH Pocket Guide International Chem Safety Card
Hydrogen fluoride
  • HYDROFLUORIC ACID (70% AQUEOUS SOLUTION)
  • HYDROGEN FLUORIDE
  • SULFURIC ACID
NFPA 704
Diamond Hazard Value Description
0
4 2
W
Blue Health 4 Can be lethal.
Red Flammability 0 Will not burn under typical fire conditions.
Yellow Instability 2 Readily undergoes violent chemical changes at elevated temperatures and pressures.
White Special W Reacts violently or explosively with water.
Note: NFPA ratings shown are for sulfuric acid, CAS number 7664-93-9
(NFPA, 2010)
General Description
A clear colorless liquid with a pungent odor. Corrosive to metals and tissue. Exposure to the fumes or brief contact can cause severe burns as mixture penetrates to cause deep-seated ulceration that is sometimes complicated by gangrene.

Hazards

Reactivity Alerts
Air & Water Reactions
Soluble in water with evolution of heat spattering of acid fumes.
Fire Hazard
Excerpt from 157 Polymerizable warning [Substances - Toxic and/or Corrosive (Non-Combustible / Water-Sensitive)]:

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. UN1796, UN1802, UN1826, UN2032, UN3084, UN3085, and, at concentrations above 65%, UN2031 may act as oxidizers. Also consult 140 Polymerizable warning. Vapors may accumulate in confined areas (basement, tanks, hopper/tank cars, etc.). Substance may react with water (some violently), releasing corrosive and/or toxic gases and runoff. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water. (ERG, 2020)
Health Hazard
Excerpt from 157 Polymerizable warning [Substances - Toxic and/or Corrosive (Non-Combustible / Water-Sensitive)]:

TOXIC; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance may cause severe injury, burns or death. Reaction with water or moist air may release toxic, corrosive or flammable gases. Reaction with water may generate much heat that will increase the concentration of fumes in the air. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental contamination. (ERG, 2020)
Reactivity Profile
HYDROFLUORIC ACID AND SULFURIC ACID MIXTURE reacts exothermically with bases of all kinds, both organic (amines, amides) and inorganic (oxides and hydroxides of metals). If diluted with water (below 65%) reacts with many metals (aluminum, zinc, iron, steel) to generate hydrogen gas with the possibility of explosion. May react explosively with cyanogen fluoride, methanesulfonic acid or glycerol mixed with nitric acid. May react violently with arsenic trioxide, phosphorus pentachloride, acetic anhydride, ammonium hydroxide, chlorosulfonic acid, ethylenediamine, fluorine, potassium permanganate, oleum, propylene oxide, vinyl acetate, mercury(II) oxide. Emits highly corrosive fumes of hydrogen fluoride gas when heated [Sax, 9th ed., 1996, p. 1839]. Contact with silicon compounds, especially metal silicides, may cause evolution, often violent, of toxic silicon tetrafluoride gas [Mellor, 1956, Vol. 2, suppl. 1, p. 121].

For Sulfuric Acid look at the Sulfuric Acid datasheet.
Belongs to the Following Reactive Group(s)
Potentially Incompatible Absorbents

Use caution: Liquids with this reactive group classification have been known to react with the absorbents listed below.

Response Recommendations

Isolation and Evacuation
Excerpt from 157 Polymerizable warning [Substances - Toxic and/or Corrosive (Non-Combustible / Water-Sensitive)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.

SPILL: Increase the immediate precautionary measure distance, in the downwind direction, as necessary.

FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2020)
Firefighting
Excerpt from 157 Polymerizable warning [Substances - Toxic and/or Corrosive (Non-Combustible / Water-Sensitive)]:

Note: Some foams will react with the material and release corrosive/toxic gases.

SMALL FIRE: CO2 (except for Cyanides), dry chemical, dry sand, alcohol-resistant foam.

LARGE FIRE: Water spray, fog or alcohol-resistant foam. If it can be done safely, move undamaged containers away from the area around the fire. Avoid aiming straight or solid streams directly onto the product. Dike runoff from fire control for later disposal.

FIRE INVOLVING TANKS OR CAR/TRAILER LOADS: Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles. Do not get water inside containers. Cool containers with flooding quantities of water until well after fire is out. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. (ERG, 2020)
Non-Fire Response
Excerpt from 157 Polymerizable warning [Substances - Toxic and/or Corrosive (Non-Combustible / Water-Sensitive)]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. All equipment used when handling the product must be grounded. Do not touch damaged containers or spilled material unless wearing appropriate protective clothing. Stop leak if you can do it without risk. A vapor-suppressing foam may be used to reduce vapors. DO NOT GET WATER INSIDE CONTAINERS. Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material. Prevent entry into waterways, sewers, basements or confined areas.

SMALL SPILL: Cover with DRY earth, DRY sand or other non-combustible material followed with plastic sheet to minimize spreading or contact with rain. Use clean, non-sparking tools to collect material and place it into loosely covered plastic containers for later disposal. (ERG, 2020)
Protective Clothing
Excerpt from ERG Guide 157 [Substances - Toxic and/or Corrosive (Non-Combustible / Water-Sensitive)]:

Wear positive pressure self-contained breathing apparatus (SCBA). Wear chemical protective clothing that is specifically recommended by the manufacturer when there is NO RISK OF FIRE. Structural firefighters' protective clothing provides thermal protection but only limited chemical protection. (ERG, 2020)
DuPont Tychem® Suit Fabrics
Normalized Breakthrough Times (in Minutes)
Chemical CAS Number State QS QC SL C3 TF TP RC TK RF
Hydrofluoric acid (48-51%) 7664-39-3 Liquid 400 446 >480 >480 >480 15 >480 >480 >480
Hydrofluoric acid (60%) 7664-39-3 Liquid 52
Hydrofluoric acid (70%) 7664-39-3 Liquid 143 126 35 >480 >480 >480
Hydrogen fluoride (20-27°C, gaseous) 7664-39-3 Vapor imm 93*/134 186 imm imm 130 >480 >480
Sulfuric acid (30%) 7664-93-9 Liquid >480
Sulfuric acid (50%) 7664-93-9 Liquid >480
Sulfuric acid (70%) 7664-93-9 Liquid >480
Sulfuric acid (98% at 50°C) 7664-93-9 Liquid >480
Sulfuric acid (>95%) 7664-93-9 Liquid >480 >480 >480 >480 >480 50 >480 >480 >480
> indicates greater than.
"imm" indicates immediate; having a normalized breakthrough time of 10 minutes or less.
* indicates based on lowest single value.

Special Warning from DuPont: Tychem® and Tyvek® fabrics should not be used around heat, flames, sparks or in potentially flammable or explosive environments. Only...

(DuPont, 2023)

First Aid
Excerpt from 157 Polymerizable warning [Substances - Toxic and/or Corrosive (Non-Combustible / Water-Sensitive)]:

Call 911 or emergency medical service. Ensure that medical personnel are aware of the material(s) involved and take precautions to protect themselves. Move victim to fresh air if it can be done safely. Give artificial respiration if victim is not breathing. Do not perform mouth-to-mouth resuscitation if victim ingested or inhaled the substance; wash face and mouth before giving artificial respiration. Use a pocket mask equipped with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult. Remove and isolate contaminated clothing and shoes. In case of contact with substance, immediately flush skin or eyes with running water for at least 20 minutes. In case of skin contact with Hydrofluoric acid (UN1790), if calcium gluconate gel is available, rinse 5 minutes, then apply gel. Otherwise, continue rinsing until medical treatment is available. For minor skin contact, avoid spreading material on unaffected skin. Keep victim calm and warm. Effects of exposure (inhalation, ingestion or skin contact) to substance may be delayed. (ERG, 2020)

Physical Properties

Chemical Formula:
  • HF (hydrofluoric acid)
  • H2SO4 (sulfuric acid)
Flash Point: data unavailable
Lower Explosive Limit (LEL): data unavailable
Upper Explosive Limit (UEL): data unavailable
Autoignition Temperature: data unavailable
Melting Point: data unavailable
Vapor Pressure: data unavailable
Vapor Density (Relative to Air): data unavailable
Specific Gravity: data unavailable
Boiling Point: data unavailable
Molecular Weight: data unavailable
Water Solubility: data unavailable
Ionization Energy/Potential: 15.98 eV [From NPG: Hydrogen fluoride] (NIOSH, 2023)
IDLH: 30 ppm [From NPG: Hydrogen fluoride] (NIOSH, 2023)

AEGLs (Acute Exposure Guideline Levels)

Final AEGLs for Hydrogen fluoride (7664-39-3)
Exposure Period AEGL-1 AEGL-2 AEGL-3
10 minutes 1 ppm 95 ppm 170 ppm
30 minutes 1 ppm 34 ppm 62 ppm
60 minutes 1 ppm 24 ppm 44 ppm
4 hours 1 ppm 12 ppm 22 ppm
8 hours 1 ppm 12 ppm 22 ppm
(NAC/NRC, 2023)
Interim AEGLs for Sulfuric acid (7664-93-9)
Exposure Period AEGL-1 AEGL-2 AEGL-3
10 minutes 0.2 mg/m3 8.7 mg/m3 270 mg/m3
30 minutes 0.2 mg/m3 8.7 mg/m3 200 mg/m3
60 minutes 0.2 mg/m3 8.7 mg/m3 160 mg/m3
4 hours 0.2 mg/m3 8.7 mg/m3 110 mg/m3
8 hours 0.2 mg/m3 8.7 mg/m3 93 mg/m3
(NAC/NRC, 2023)

ERPGs (Emergency Response Planning Guidelines)

Chemical ERPG-1 ERPG-2 ERPG-3
Hydrogen Fluoride (7664-39-3) ** 2 ppm star-in-circle icon indicates that odor should be detectable near ERPG-1. 20 ppm 50 ppm
Sulfuric Acid (Oleum [8014-95-7], Sulfur Trioxide [7446-11-9], and Sulfuric Acid [7664-93-9]) 2 mg/m3 star-in-circle icon indicates that odor should be detectable near ERPG-1. 10 mg/m3 120 mg/m3
** Addendum published in 1999 with new 10-minute values (ERPG-1: 2 ppm; ERPG-2: 50 ppm; ERPG-3: 170 ppm).
star-in-circle icon indicates that odor should be detectable near ERPG-1.
(AIHA, 2022)

PACs (Protective Action Criteria)

Chemical PAC-1 PAC-2 PAC-3
Hydrogen fluoride; (Hydrofluoric acid) (7664-39-3) 1 ppm 24 ppm 44 ppm
Sulfuric acid (7664-93-9) 0.2 mg/m3 8.7 mg/m3 160 mg/m3
(DOE, 2018)

Regulatory Information

EPA Consolidated List of Lists

Regulatory Name CAS Number/
313 Category Code
EPCRA 302
EHS TPQ
EPCRA 304
EHS RQ
CERCLA RQ EPCRA 313
TRI
RCRA
Code
CAA 112(r)
RMP TQ
Hydrofluoric acid 7664-39-3 100 pounds 100 pounds 100 pounds X U134
Hydrofluoric acid (conc. 50% or greater) 7664-39-3 100 pounds 100 pounds 100 pounds X U134 1000 pounds
Hydrogen fluoride 7664-39-3 100 pounds 100 pounds 100 pounds 313 U134
Hydrogen fluoride (anhydrous) 7664-39-3 100 pounds 100 pounds 100 pounds X U134 1000 pounds
Sulfuric acid 7664-93-9 1000 pounds 1000 pounds 1000 pounds
Sulfuric acid (aerosol forms only) 7664-93-9 1000 pounds 1000 pounds 1000 pounds 313

(EPA List of Lists, 2022)

CISA Chemical Facility Anti-Terrorism Standards (CFATS)

RELEASE THEFT SABOTAGE
Chemical of Interest CAS Number Min Conc STQ Security
Issue
Min Conc STQ Security
Issue
Min Conc STQ Security
Issue
Hydrofluoric acid (conc. 50% or greater) 7664-39-3 50.00 % 1000 pounds toxic
Hydrogen fluoride (anhydrous) 7664-39-3 1.00 % 1000 pounds toxic 42.53 % 45 pounds WME

(CISA, 2007)

OSHA Process Safety Management (PSM) Standard List

Chemical Name CAS Number Threshold Quantity (TQ)
Hydrofluoric Acid, Anhydrous 7664-39-3 1000 pounds
Hydrogen Fluoride 7664-39-3 1000 pounds

(OSHA, 2019)

Alternate Chemical Names