Hydrofluoric acid must not be used in any laboratory outside normal working hours. Complete rules for out of hours working can be found in Appendix 2.
Hydrofluoric acid (HF), a highly corrosive colourless fuming liquid, can produce very unpleasant and sometimes fatal injuries from skin and eye burns, inhalation and ingestion. This emphasises the need for special care when handling HF, even in laboratories where the quantities being handled are generally small.
Protocols for Working with HF
The 'First Rule' is: "THE BEST TREATMENT IS PREVENTION."
Any laboratory where HF is used should have the following: a working supply of clean water, a tube of calcium gluconate jelly, and access to an HF trained first aider with the “HF crash kit” containing additional emergency equipment for HF exposures.
1. Before working with HF: Contact an HF trained first aider to ensure help is available should an accident occur. You should give your name, location, and expected duration of use. Contact the same first aider again when you are finished working with HF.
2. Personal Protective Equipment (PPE) – required for all work with HF
Eye protection (goggles or a full face mask are preferred), a lab coat with a plastic apron and two pairs of gloves. A full Tyvek suit is acceptable, but be careful removing it if any acid splashes occur. Always check there are no gaps at the wrists, and wear gloves or coats that cover this area of skin.
The dressing sequence: apron - eye protection - inner gloves - outer gloves
The removal sequence: apron - outer gloves - eye protection - inner gloves
3. All HF work must be carried out in a fume cupboard approved for such work.
Any HF spillage should be neutralised with acid neutralising material such as slaked lime (calcium carbonate). If you are unsure what to do next, the Local Safety Officer or Chemical Safety Advisor will advise on how to further clean up the spill.
Wash your hands before leaving the work area. Smoking (which is illegal), drinking (no water bottles or coffee/tea cups) and eating are strictly forbidden in all laboratories to avoid internal exposures to chemicals, especially HF.
Disposal of HF waste
Small amounts of HF are usually evaporated and blown out fume cupboard extracts, so there is no waste. Large volumes of HF waste should be safely collected and stored in a plastic winchester bottle (with lid) and labelled as HF waste. The Department Chemical Safety Officer organises and oversees all waste chemical disposal, and will give advice on what should be done.
HF must not be poured down the drain, except for small quantities involved in rinsing residues from bottles, in which case a large excess of tap water should be used.
Small exposures can be dangerous, so if any doubt exists, the affected person should go to hospital, if possible with the HF first aider. The hospital personnel would need to know that the exposure was to hydrofluoric acid (HF), the concentration of the HF, the approximate quantity, the route of exposure -.e.g. inhalation, skin contact, when this took place, any treatment given, and any odd behaviour by the affected person.
Skin exposure: Remove any contaminated clothing. The affected area should be immediately flushed with copious quantities of water for five minutes. This is best done in a sink with the water flowing directly on the area affected. If a safety shower is used, the casualty should be closely monitored for hypothermia, and also be careful to avoid slipping on the wet floor. Calcium gluconate jelly should then be promptly applied to the area of the burn and rubbed continuously for 20 minutes into the exposed area (while wearing gloves). Small skin exposures can be effectively and successfully treated by prompt treatment such as this. But if in any doubt, or if pain persists, the person should be taken to A&E.
Eye exposure: Carefully flush the eye(s) with clean water for 15 minutes. If possible, it is best to hold the eye open with a clean gloved hand but without touching the eye. This should continue as long as it takes for suitable transport to be arranged to take the person to hospital. If possible continue the flushing on the way to hospital with a portable eye wash. Contact lenses should be removed if possible, though not at the expense of flushing with water.
Inhalation. HF vapour is very irritating to the eyes, nose, mouth and lungs. Atmospheric concentrations of vapour as low as 50 ppm are dangerous, even for brief exposure.
The casualty should move to fresh air as quickly as possible. An ambulance should be called if the casualty is overcome and becomes unconscious at any time after HF exposure, otherwise arrange for transport to hospital by other transport (e.g. taxi). After exposure to HF fumes, surveillance will be required for approximately 24 hours to rule out the possibility of pulmonary oedema developing.
Artificial ventilation should only be performed using the Ambu-bag – no mouth to mouth. Chest compressions may be necessary.
Ingestion. If any HF has been ingested, DO NOT INDUCE VOMITING. Rinse the mouth with water and call an ambulance or take immediately to hospital (1-999 any internal phone). This is a life-threatening situation.
HF Trained First Aiders
- Mr Charlie Aldous (33465)
- Dr Jason Day (65282)
- Mr Rob Theodore (33446)
Purchasing, Storage and Distribution
Analytical grade HF for general use is ordered by the Department Chemistry Officer and stored in the acid store (N. wing). Supplies for laboratory use may be obtained as required from the Chemistry Officer, who will keep records of all such movements. Ultra-pure ('Romil') HF is ordered by Hazel Chapman in single 500 ml bottles for use in the Isotope Geochemistry Laboratory (room S410).