Body
Title
Standard Operating Procedure for Hydrofluoric Acid
EHS SOP #: 008
Version No.: 2.0
Supercedes: 1.0
Purpose
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 because fluoride ions readily penetrate the skin causing destruction and damage to the deeper tissues layers. This process may continue for days if left untreated. Large burns may deplete the body of calcium or induce other toxic effects which may be fatal.
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. Dilute (20% or less) solutions may be delayed up to 24 hours, 20% ‐ 50% from 1 ‐ 8 hours, and solutions greater than 50% concentration will be immediately apparent. Delayed symptoms may include pain, redness of skin, and possible tissue destruction. HF can also cause bone and joint damage.
Eye exposure
Liquid and vapor can cause irritation or corneal burns. Blindness results from severe or untreated exposures.
Inhalation exposure
Mild
Nose, throat, and respiratory irritation. Onset may be delayed for several hours and symptoms of exposure are coughing, choking, chest tightness, chill, fever, and blue skin.
Severe
Nose/throat burns, lung inflammation and pulmonary edema. Other toxic effects such as hypocalcemia may result in death without proper treatment.
Ingestion
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.
Requirements
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, Ch 6 of the Laboratory Safety Manual, and the attached Safety Data Sheet (SDS) prior to work. HF should not be used when working alone.
- A calcium gluconate gel (brand name Calgonate) must be on hand prior to work being done. Calgonate has an expiration date and should be replaced prior to its expiration. Calgonate should be kept near the work being completed, but not within the chemical fume hood or near other hazards.
- Storage areas must be separated and clearly marked. HF reacts with glass, which should never be used to store or transfer it. Do not store HF containers next to other glass containers.
- Ensure all containers of HF are clearly labeled for "Hydrofluoric acid - Danger - Corrosive."
- Compatible chemical containers include polyethylene and Teflon.
- Always work with a chemically compatible secondary containment tray.
- Ensure HF containing flasks or vials are secured and cannot tip over.
- Keep all containers closed to minimize exposure.
- An HF spill kits should be kept near the location of use and stoarge of HF.
- All work areas of HF should be clearly marked and labeled with a sign stating "Danger, Hydrofluoric Acid use in this Area"
- This SOP or laboratory specific SOP should be posted or readily available near the designated area.
- Check all PPE fo integrity prior to donning and starting work. Reusable butyl or neoprene gloves break down over time and should be replaced frequently or when damaged.
Engineering Controls
- Hydrofluoric acid must be used in a properly functioning specifically designated chemical fume hood. Do not use HF in a general shared chemical fume hood.
- The sash opening should be minimized (below 18 inches) to prevent splashes.
- HF should be used in an area equipped with an eyewash and safety shower.
Personal Protective Equipment (PPE)
- Goggles
- Face shield (plastic)
- Acid resistant apron
- Long pants and sleeves
- Closed toe shoes
- Gloves: Depending on the elgnth of time and concentration of solutions, identify appropriate chemical resistant gloves.
- For brief use of dilute solutions: Thin disposable gloves (such as 4, 6, or 8 mil blue nitrile gloves) can be used in laboratory operations and provide a contact barrier only. Double gloving is required and should be disposed immediately when contamination is suspected. It is recommended that thicker chemical resistant gloves are used for handling of all solutions of HF.
- For use of concentrated solutions or large volumes: (10‐20 mil) butyl rubber or neoprene gloves should be used that cover the hands, wrists, and forearms.
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. Provide the concentration and SDS to first responders or physician and detail date, time of exposure, duration of exposure, body parts affected or exposed, and summary of first aid measures taken. Follow first-aid procedures outline below for exposed areas until medical treatment is given.
- Eye exposure: Rinse eyes for at least 15 minutes or until medical assistance is provided.
- 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. Prevent cross contamination: the victim of HF exposure shoudl perform the following actions on themselves whenever possible. Anyone who provides assistance should use the proper gloves and other PPE mentioned in this SOP in order to prevent contaminating themselves. Immediately after rinsing, apply calcium gluconate gel into the affected site (gel can be applied as soon as washing is done, area does not need to be dried). Calcium gluconate should be re-applied every 10-15 minutes until first responders arrive or a physician/EMT provide medical treatment.
- If calcium gluconate is not available, continue to rinse the area until medical treatment is given.
- 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