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Hydrofluoric Acid


The following is the manual used to train cleanroom personnel about handling and storing Hydrofluoric acid:
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  1. Description of HF

    1. Physical Properties of HF:
    2. Vapor has an acrid, irritating odor
    3. Colorless, clear, fuming liquid
    4. Miscible with water
    5. Vapor pressure = 14 mmHG at 20 C
    6. Hydrofluoric acid (HF) is a weak acid as defined in chemestry - only partly ionizes in water.
  2. Prior to Performing Work

    1. Make sure all containers are labeled properly - remember HF is a clear liquid and can be mistaken for water. In addition to labeling containers, the laboratory needs to designate and assign a location for use of HF.
  3. Skin Exposure and Hazards

    1. Initial Signs of Exposure:

    2. Redness
    3. Blistering
    4. Edema, an Abnormal excess accumulation of serous fluid in connective tissue or in a body caviy
    5. Advanced Signs of Exposure:

    6. Painful deep seated burns that are slow to heal.
    7. Insert picture of skin exposure here
    8. HF burns pose unique dangers distinct from other inorganic acids such as HCl and sulfuric Acid. Some differences include:

    9. The fluoride ion readily penetrates the skin
    10. Deep tissue is damaged
    11. Note: If left untreated damage may continue for days
    12. De-mineralization of the body occurs
    13. Different Than Other Inorganic Acids

    14. Readily penetrates the skin and the onset of pain may be delayed.
    15. Insert pictures of fingers and of discoloration table--page 6
    16. Skin/Eye Exposure

    17. Severity of Skin Exposure is Dependent Upon at Least:
    18. Concentration
    19. Surface Area Exposed
    20. Duration fo Contact
    21. Temperature
    22. Note: All exposures require immediate first aid and medical attention
  4. How Toxic is Hydrofluoric Acid?

    1. Toxicity Comparison:

    2. Carbon Monoxide: LC50=1807ppm, 4 hours
    3. Hydrogen Fluoride: LC50=342ppm, 60 minutes
    4. Arsine, Arsenic Hydride: LC50=94ppm, 15 minutes
    5. Hydrogen Cyanide: LC50=63ppm, 40 minutes
    6. HF Vapor, Airborne Exposure Limits

    7. OSHA (based upon outdated information): Permissible Exposure Limit = 3ppm
    8. Note: An airborne permissible exposure limit (PEL) is the 8-hour tmie weighted average not to be exceeded.
    9. ACGIH 2006 (based upon recent health data):

    10. Threshold Limit Value TWA = .5 ppm
    11. Threshold Limit Value Ceiling Limit = 2 ppm
    12. Note: A TWA is the 8-hour time weighted average not to be exceeded. A ceiling limit is the airborne concentration that should never be exceeded.
    13. Airborne HF is especially dangerous because:

    14. · You can't rely upon sight to detect it's presence
    15. · The airborne limits are very close to the odor threshold (Odor Threshold: Less than 1 ppm)
    16. · Inhalation may cause pulmonary edema
    17. Exposure to Airborn HF

    18. It is impossible to distinguish between 1 & 2 ppm using your sense of smell
    19. When working with HF you should not be able to smell it.
    20. If you can smell HF (acrid, irritating odor) when working with it, stop work and speak with the lab manager. The controls being used may be inadequate or may have stopped functioning properly.
  5. Summary of Exposure

    1. Exposure Routes

    2. Eye/Skin Absorption
    3. Inhalation and Ingestion
    4. Individuals can be exposed to HF through any route of exposure. Reference your lab safety procedures to find out what controls to use, how to use them, and when.
    5. Exposure Control Heirarchy

    6. Most Preferred: Engineering Controls
    7. Less Preferred: Administrative Controls
    8. Least Preferred: Personal Protective Equipment
    9. In most situations it is necessary to us engineering controls in conjunction with other controls. OSHA requires implementation of engineering controls (if practical and feasible) prior to using the other controls.
  6. Exposure Controls

    1. The best treatment for exposure is prevention. Use a less toxic/dangerous chemical if possible. Controls that are used to control HF exposure must be designed for such use, and used in accordance with manufacturer recommendations.
    2. Some of the controls you may need to use include:
      1. Acid Digestion Hood with Polycarb Sash and Plastic Ducting
      2. Splash Goggles
      3. Gloves
      4. Face Shield
      5. Acid Smock

        Reference your lab safety procedures to find out what controls to use, how to use them, and when.
  7. Buddy System

    1. Never work alone when using HF. The extra person does not use HF, instead they are to summon emergency services, direct the victim, and prevent further damage.
    2. Role of the Buddy in the Event of Exposure

    3. Verbally direct the victim to use the emergency shower for a maximum of five minutes, and then to immediately apply calcium gluconate to the exposed skin.
    4. Immediately call 911 to summon emergency services.
    5. Note: Do not remain in an area of the lab where exposure may continue.
    6. Provide Material Safety Data Sheet (MSDS) and Calcium Gluconate to the emergency responders.
    7. Note: all the information needed is stored in an envelope next to the Calcium Gluconate.
    8. Cordon of the lab, or contaminated area, to prevent others from being exposed and spreading contamination.
    9. Contact the lab manager to find out how clean-up should proceed. Contact police if you are not prepared to clean-up HF.
  8. The Victim Does the Following as Soon as Possible

    1. · Use the emergency flushing facilities (eyewash/shower) for five minutes.
    2. · Disrobe while using the flushing facilities. Not doing so will hold acid against the skin. Do not bother to dry off.
    3. · Immediately apply Calcium Gluconate to all surface areas of the body that have been exposed to liquid HF. Use gloves.
    4. · Note: If Calcium Gluconate is not available rinse for 15 minutes.
    5. · Continue rubbing the calcium gluconate into the skin until redness or pain has disappeared.
    6. · Note: Emergency may be transporting you to the hospital by this point.
    7. · Be prepared to explain how you were exposed to HF (skin, inhalation, ingestion, injection), what concentration of HF was being used at the time of exposure, and what time the exposure occured.
  9. Other First Aid Information for HF Exposure

    1. · Eye Exposure - Rinse eyes out for 5 minutes.
    2. · Inhalation - Relocate to fresh air.
    3. · Ingestion - Drink two glasses of water the consume two glasses of milk or antacids.
    4. · Always seek immediate medical attention following first aid.
  10. HF Awareness Training Summary

    1. · When possible avoid using HF.
    2. · HF is extremely toxic and corrosive.
    3. · HF can enter the body through any root of exposure.
    4. · When using HF, you should not be able to smell it.
    5. · Never work alone when using HF.
    6. · Always use the exposure controls necessary to prevent exposure to HF (ventilation, etc.).
    7. · If your skin/eyes are exposed to HF, immediately use the emergency shower/eyeflush for five minutes (15 if there is no Calcium Gluconate).
    8. · Massage exposed area with Calcium Gluconate immediately after showering.
    9. · Always seek immediate medical attention following first aid.

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