Standard Operating Procedure for Hydrofluoric Acid


Standard Operating Procedure for Hydrofluoric Acid

EHS SOP #: 004

Version No.: 1.0

Supercedes: N/A

Hydrofluoric Acid Formula



Hydrofluoric acid is extremely corrosive and highly toxic by inhalation, ingestion, and skin absorption. It differs from other acids because it readily penetrates the skin and dissociates into fluoride ions, causing destruction of deep tissue layers, including bone. Hydrofluoric acid vapors are also an inhalation hazard and can cause ocular irritation. This document establishes procedures for the safe handling and use of hydrofluoric acid (CAS# 7664‐39‐3), also known as HF.

Health Effects

Hydrofluoric acid is a clear, colorless, corrosive fuming liquid with an extremely acrid odor and forms dense white vapor clouds if released. Both liquid and vapor can cause severe burns to all parts of the body. Specialized medical treatment is required for all exposures.

Skin exposure

Hydrofluoric acid liquid and vapors can cause severe burns. The skin will be penetrated and the deeper tissues will be attacked. Large burns may deplete the body of calcium or induce other toxic effects which may be fatal.

Eye exposure

Liquid and vapor can cause irritation or corneal burns.

Inhalation exposure


Nose, throat, and respiratory irritation. Onset may be delayed for several hours.


Nose/throat burns, lung inflammation and pulmonary edema. Other toxic effects such as hypocalcemia may result in death without proper treatment.


Severe mouth, throat, and stomach burns and may be fatal if swallowed. Hypocalcemia and systematic toxicity is likely without prompt medical treatment.

Delayed effects

Hydrofluoric acid can interact with nerves, causing a delay in pain from burns. Contact with dilute HF solutions or vapors may be delayed. 0%‐20% solutions may be delayed up to 24 hours, 20%‐50% from 1‐8 hours, and solutions >50% will be immediately apparent. Delayed symptoms may include pain, redness of skin, and possible tissue destruction. HF can also cause bone and joint damage.

Regulatory Limits

The Federal Occupational Safety and Health Administration (OSHA) have set a Permissible Exposure Limit (PEL) for hydrofluoric acid of 3 ppm as an 8 hour Time Weighted Average (TWA). The National Institute of Occupational Safety and Health (NIOSH) have established a ceiling limit value of 6 ppm over 15 minutes, and an Immediately Dangerous to Life or Health (IDLH) concentration of 30 ppm over 30 minutes.


Based on the risk associated with the use of hydrofluoric acid the safety procedures outlined below are required by all research staff when working with HF.

Administrative Controls

  • Anyone who handles hydrofluoric acid is required to review this SOP and the attached Safety Data Sheet (SDS) prior to work. Do not work with HF alone.
  • The antidote must be on hand prior to work being done.
  • Storage areas must be separated and clearly marked.

Engineering Controls

  • Hydrofluoric acid must be used in a properly functioning laboratory hood and in an area equipped with an eyewash and safety shower. The sash opening should be minimized to prevent splashes.

Personal Protective Equipment (PPE)

  • Goggles
  • Face shield (plastic)
  • Acid resistant apron
  • Long pants and sleeves
  • Closed toe shoes
  • Gloves: Thin disposable gloves (such as 4, 6, or 8 mil blue nitrile gloves) used in laboratory operations provide a contact barrier only and should be disposed immediately when contamination is suspected. Thicker (10‐20 mil) PVC or neoprene gloves provide better resistance but do not provide the necessary dexterity for many lab procedures. Thinner PVC or poly gloves can provide some resistance to HF, but require immediate changing at the first sign of contamination. Do not wear disposable gloves without double gloving because of the potential for exposure through pinholes.

Waste Disposal

  • Hydrofluoric acid waste will be disposed of as a hazardous material through EHS.

Accidents or Injuries

  • In the event of an exposure have someone call 911 immediately. Remove all exposed clothing and wash all exposed areas with copious amounts of water.
    • Eye exposure: Rinse eyes for at least 15 minutes.
    • Skin exposure: Skin should be flushed for 5 minutes followed by treatment with a calcium source. Calcium gluconate is preferred, but calcium carbonate may be used. DO NOT USE CALCIUM CHLORIDE - this may cause further injury.
    • Inhalation: Move person into fresh air. Provide artificial respiration if they are not breathing.
    • Ingestion: Do NOT induce vomiting. Rinse mouth with water.

Spill Procedures

  • Do not attempt to clean‐up if you feel unsure of your ability to do so or if you perceive the risk to be greater than normal laboratory operations.
  • Small spills (<100mL) can be neutralized with dry magnesium sulfate and absorbed with absorbent materials or spill control pads. Sodium bicarbonate or magnesium oxide should be added to any absorbent and placed in a plastic container for disposal. Wash the spill site with sodium bicarbonate solution.
  • Do not use sorbents that contain silicon like vermiculite or sand. This can produce silicon tetrafluoride, which is an odorless toxic gas.
  • If there is a large spill or a spill in a confined area, notify others in the area and evacuate the room immediately. Contact EHS (919‐962‐5507) during working hours and 911 if after hours.

Contact Information

Policy Contact

Environment, Health & Safety
1120 Estes Drive
Campus Box #1650
Chapel Hill, NC 27599-1650
Phone: 919-962-5507

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Article ID: 132072
Thu 4/8/21 9:23 PM
Tue 10/18/22 10:45 AM
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