# Hydrofluoric acid

Hydrofluoric Acid is classed as a hazardous substance, therefore the Control of Substances Hazardous to Health Regulations 2005 must be complied with.

You are required by the Regulations to undertake a risk assessment of the activity in which HF will be used, before the activity commences. You are also required to obtain a Materials Safety Data Sheet for the product from the supplier; this will provide you with hazard and other safety information, relevant to the specific product, which you will need to undertake the risk assessment.

You must consider the availability of a safer alternative and if a safer alternative is available you must use it.

If there is no safer alternative available you must ensure that the risk assessment results in suitable measures being taken to reduce risk of inhalation and skin contact, to the lowest level reasonably practical, this in both normal use and in emergency situations. Such measures should include the implementing of appropriate Safe Systems of Work that include the supply and mandatory use of suitable risk control measures, these may be a combination of management controls, mechanical controls (e.g. fume cupboard) and Personal Protective Equipment (e.g. gloves/face shield).

The significant findings of the risk assessment should be recorded, either in paper format or electronically. It is good practice to communicate details of the chemical's hazards and the requirements of the SSW in written form and a to obtain signatures from the users to verify that they have read and understood the requirements of the SSW.

Employers/managers are required, by the Regulations, to ensure that adequate information and training is given to the user as regards the hazards that hydrofluoric acid poses to health and the precautions that must be taken.

## Guidance and good practice

• Never work alone, ensure someone else knows that you are about to work with HF
• Ensure others in the area know the steps to be taken, in case of emergency, not only to help the user, but also to protect themselves and others in the vicinity
• Make sure that local first aiders know that HF is used in the laboratory
• Make sure that calcium gluconate gel is available in the first aid kit held within the laboratory
• Always store HF within a plastic secondary containment, in a suitable chemical cupboard with a drip tray
• Do not store in glass containers, or with incompatible chemicals
• Always open container, decant and use within a fume cupboard
• Only use a fume cupboard that is suitable for HF use (e.g. has water scrub facilities on the extract system)
• Always decant only sufficient quantity for immediate use
• Never store, or leave unattended, open containers of HF
• If HF is being used as part of a process within a fume cupboard and the process is to be left unattended, always close the sash window and ensure that a notice informing that HF is being used is attached to the sash window
• Never store other chemicals in a fume cupboard that is used for HF work
• Always wear a lab coat with the sleeves at full length
• Consider a Teflon coated lab coat, or the wearing of an impervious apron
• Always wear gauntlet protective gloves (nitrile or neoprene material is good)
• Always wash gloves before removing them
• If gloves are re-usable periodically use a recognised method to check for pinholes
• If HF is used outwith the confines of a fume cupboard a suitable half or full-face respirator with E (acid gas) filters fitted should be worn. If a half-face respirator is used also wear chemical resistant, gas tight goggles. The use of a full-face respirator is recommended as this affords face protection as well as eye protection and it should be noted that there are often fit compatibility problems when persons wear half-face respirators and goggles together
• If the SSW requires the use of half or full-face respirators the user must have been quantitatively face-fit tested on the particular respirator type (make and model) and a pass certificate obtained before commencing work with HF

## Emergency procedures

• Ensure that there is a stocked first aid kit available either in the laboratory where HF is used or immediately outside; also ensure that the kit contains calcium gluconate gel. Detailed first aid guidance is available in HSE's guidance leaflet Hydrofluoric Acid Poisoning'(2), it may be prudent to ensure that a copy of this leaflet is also held in the first aid kit
• Ensure all relevant personnel are aware of the procedures to take in case of emergency
• At time of incident clear all non-emergency response people from area
• Always protect yourself when administering aid
• If first aid is required remove the injured party from the hazard area and call nearest first aider
• If the area of skin contamination is large it may be prudent to also immediately call an ambulance using the University's 2222 emergency system
• In all cases the casualty should be sent to hospital as soon as possible, even if only as a precautionary measure. It is extremely important to inform the hospital that the cause of the injury is specifically an HF acid burn, rather than just an acid burn'. A hazard data sheet for HF should accompany the casualty, if possible
• Contact the Accident and Emergency (A&E) Department of the hospital to alert them that the casualty is on the way and specify the injury as an HF acid burn. If the injury is to the eye the injured person should be taken directly to the Princess Alexandra Eye Pavilion, Chalmers Street, A&E direct dial (0131 536 3753) for all other injuries the injured person should be taken to the Accident and Emergency Department of the Edinburgh Royal Infirmary, now at Little France, A&E direct dial (0131 242 1300)

## Spillage clean up

### Significant spillage

• If spillage is significant do not attempt to clean up as inhalation risk may be high and the use of breathing apparatus may be indicated, contact the emergency services via the University 2222 number and secure the area until their arrival, or
• If the significant spillage has occurred in a laboratory situated within the KB Campus telephone the School of Chemistry, advise of the spill and ask for the attendance of their BA team. Secure the area until their arrival.

### Smaller scale spillages

• For all other spills; don respirator, face protection, gloves and apron, as above.
• Spread soda ash liberally over the spillage and mop up cautiously with water - run this to waste diluting greatly with copious amounts of running water (Hazards in the Chemical Laboratory, 4th edition, Royal Society of Chemistry), or
• If spill is of dilute HF, soak up with HF compatible spill pillow or neutralise with lime, transfer to polyethylene container and dispose of through the School of Chemistry's hazardous waste disposal system