Hydrogen Fluoride & Hydrofluoric Acid Use

Best Practices

• Avoid contact with all solutions. Wear proper PPE (see below).
• Be prepared for an emergency, whether it be a spill or exposure. Pre-planning is essential before beginning any HF work. Know where eyewash and safety showers are located as well as the first aid materials such as calcium gluconate (see below).
• Only use compatible plastic or teflon-coated labwares for HF solutions and do not store in glass bottles.
• Make sure you are trained on any procedure involving HF.
  Read all the sections below carefully before beginning your work with HF.

Personal Protective Equipment (PPE)

Proper choice of Personal Protective Equipment (PPE) is imperative. A risk assessment should be
performed prior to beginning any operation involving HF to identify the appropriate PPE for the specific
operations.

Eye Protection
Always use chemical splash goggles together with a face shield when handling concentrated HF. Safety glasses, even those with side shields, do not provide adequate eye protection. At any concentration chemical splash goggles should be the minimum eye protection because of the ability of HF to cause
blindness.

Body Protection
Because of the hazards associated with skin exposure it is vital that PPE is worn to protect the entire
body. Long sleeve shirts, pants, and closed-toe shoes must be worn when working with HF. A laboratory
coat must also be worn. If working with concentrated HF an acid-resistant apron made out of natural
rubber, neoprene, or viton should be worn.

Gloves
Glove selection is very important. Viton, nitrile, or butyl gloves are typically worn when working with HF. However it is always important to consult the manufacturer’s glove selection guide when selecting a glove for HF. Always check for leaks prior to glove use. As an added precaution a second pair of nitrile
exam gloves can be worn under the gloves for protection against leaks. If gloves become contaminated with HF, remove them immediately, thoroughly wash your hands, and check your hands for any sign of
contamination

Exposures

Exposure to HF solutions requires immediate action. Delays can lead to more extensive injury and, in serious cases, can cause death. Remember also that effects are delayed so even exposure incidents which are not painful require proper attention, including a medical evaluation. In all emergencies call 911.

Access to eye wash and safety showers is necessary for any work involving HF. Additionally, a first aid kit containing 2.5% calcium gluconate gel should be readily available. Calcium gluconate is topically applied to areas where skin has been exposed. This works by forming insoluble calcium fluoride, preventing the fluoride from combining with the body’s calcium. Periodically check the calcium gluconate to ensure that it has not expired. Calcium gluconate solutions are also commercially available for eye exposures.

Skin Exposure
Immediately wash all the affected areas of skin. Using the sink may be
appropriate for exposures to the hands and forearms, but contamination of the
head, legs or torso should be handled with a safety shower. When using a safety
shower remove all affected clothing. Remember that your health is more
important than your modesty! However, unlike dermal exposures to other mineral acids, washing with water is not sufficient. If calcium gluconate is available and the contaminated area is accessible then washing can be reduced from the typical 15 minutes to 5 minutes followed by immediate application of the gluconate gel. This will minimize the migration of the HF. Contaminated clothing should be carefully put in a bag and placed in a fume hood or other safe location to prevent inadvertent exposure to other individuals.

Eye Exposure
Immediately irrigate eyes at eyewash for at least 15 minutes with copious quantities of water keeping eyelids apart and away from eyeballs followed by a washing with a calcium gluconate solution. Do not apply calcium gluconate gel to eyes. Seek prompt medical attention.

Inhalation
Move the exposed person to fresh air. In all cases of overexposure through inhalation seek prompt medical attention.

Ingestion (Swallowing)
If HF has been swallowed do not induce vomiting. Drink large amounts of water to dilute the acid. If available several glasses of milk or several ounces of milk of magnesia can be given. Antacids such as Tums or Rolaids may also be given. In all cases of ingestion seek prompt medical attention. Do not give any fluids to an unconscious victim.

Spill Clean-up and Decontamination

All spills of HF solution presents a hazard – even within a fume hood – and precautions must be taken including use of appropriate PPE. Small spills can usually be cleaned, with proper precautions, by the user. When using HF solutions spill kits should be readily available. Sodium carbonate (soda, ash), sodium bicarbonate, lime, or a spill absorbent material (specified for use with HF by the manufacturer) should be used for cleaning spills. Spill kits that contain kitty litter or sand should not be used because HF reacts with silica to produce silicon tetrafluoride, a toxic gas.

For large spills, especially those involving concentrated HF, the lab should be cleared, the door closed and a sign should be posted to prevent entry of others. Contact EH&S (265-5000) during working hours and 911 after hours. If the spill resulted in a personal exposure perform the decontamination procedures
described above.

Training

Before working with hydrofluoric acid, workers should be trained in:

• The properties and hazards associated with HF;
• General handling and storage techniques as well as the specific procedures involving HF (as outlined in
  SOPs);
• The appropriate personal protective equipment requirements;
• First aid procedures (including use of calcium gluconate gel) and emergency response;
• Spill control procedures.

Disposal of HF

Cylinders of anhydrous HF should be returned to the vendor. If you have old cylinders that you cannot send back then contact EH&S for assistance. Solutions of hydrofluoric acid can be neutralized and disposed of down a laboratory drain. Instructions for this can be found in the “Laboratory Safety Guide”. However, due to the health hazards of this chemical extreme care must be taken when performing this task and it is not recommended that this be performed with large quantities and/or high concentrations. Also, chemical suppliers will sell HF mixtures with various non-aqueous solvents such as HF-pyridine or HF-alcohol mixtures. It is not appropriate to neutralize these mixtures. EH&S will gladly pick up any HF solutions during its weekly rounds. Submit a request for a pickup online. Make sure you complete the Surplus Chemical Form and leave with the chemicals to be picked up. As with all materials for pickup, clearly label the container.