SOP for hydrofluoric acid (and HF-based solutions)
 

General Notice
 
These are not authorized official regulations for general use of HF and HF-based solutions. But, these are valuable rules to protect your safety and everyone should follow these rules whenever using HF in the LAMP cleanroom.
  1.  Before you start, read the Material Safety Data Sheet for hydrofluoric acid carefully as well as of solutions containing HF such as Buffered Oxide Etch (BOE) (http://www.enma.umd.edu/LAMP/lamp_msds.htm).
    More details about medical treatment for HF exposure available here (pdf format)
    Additional safety information is also listed in the Lab Safety section of this web site.

  2. Hydrofluoric acid is not like any other acids. It is considered as extremely hazardous either as a liquid or vapor. HF can cause severe burns which can take up to 24 hours before being visible or painful. However it will readily be absorbed into the skin and bind with calcium and magnesium to form insoluble salts. These insoluble salts will interfere with cellular metabolism, causing cellular necrosis and death.

  3.  You must know that BOE is not a dilute HF. The ratio given on the BOE container is buffer to HF, so the fluorine content is the same as in HF for any ratio

  4. Any LAMP users who want to use HF or HF-based solution such as BOE must be qualified and authorized by the lab manager prior to do any work.

  5.  During the qualification process, the lab manager will insure that the Materials Safety Data Sheets for HF-based chemicals have been carefully read and understood, and that the procedures detailed in this SOP are thoroughly followed.

  6. The list of the authorized users is published on this web site. If your name is not on this list, you are not allowed to use HF or HF-based solutions at any time.

  7. Any accident regarding the use of HF must be reported without delay to the lab manager.
 

Protection equipment
 
  1. The handling of HF solutions require special protection equipment in addition to the regular clean room protection outfit (see Lab Safety page) .

  2. The additional protective equipment include: a full face shield, PVC or neoprene gloves (regular Nitrile gloves used in LAMP will not provide sufficient protection), as well as a PVC acid apron to wear on top of the lab coat.
    Gloves are located in the acid cabinet, apron and mask are available in the fitting room.

  3. As a reminder, open-toed shoes are not allowed when working in the lab and bare legs must be covered by wearing a full size bunny suit.
 

HF handling
 
  1. HF solutions, as well as any corrosive or hazardous substances, can only be used in LAMP during operational hours (9 am to 6 pm, Monday to Friday) and requires at all time the presence of a second knowledgeable user (buddy system).

  2. HF vapors are extremely hazardous. Therefore HF solutions can be only handled  under the flow hood dedicated to work with chemicals.

  3. Whenever handling HF, all containers used during the experiment must be very clearly labeled and a warning sign, visible by any user working under the flow hood, must be posted at all time to indicate that the solutions contains HF.

  4. After completion of the work, the user will insure that all surfaces in contact with HF have been carefully rinsed with DI water and blown dry. The user must also insure that the HF bottle is perfectly dry before being stored in the acid cabinet.
 

HF waste disposal
 
  1. You must know that BOE is not a dilute HF. The ratio given on the BOE container is buffer to HF, so the fluorine content is the same as in HF for any ratio. For this reason, the same amount of Calcium Chloride must be used when neutralizing BOE as when neutralizing HF.

  2. HF solutions or BOE must be collected in the dedicated plastic containers, located on the tray next to the flow hood

  3. Do not completely fill up the waste container with HF solution.

  4. The waste containers will be discarded by the student in charge of the waste management according to DES waste management procedure.
 

Emmergency procedure
 
  1. As stipulated earlier HF solutions are considered extremely hazardous because their effects are not immediate and the fluoride ion will penetrate the skin causing destruction of the deep tissue layers and even bone. It has been reported that as little as 7 ml of anhydrous HF in contact with the skin untreated can bind on the calcium in a normal size adult.

  2.  In case of large exposure, the victim should be removed from the contaminated area, placed under a safety shower while emergency personal is contacted (911)
    In any case, even if the burn appear initially minor, you must seek immediate medical attention. A copy of the MSDS that contains a note to the physician should be brought with you.

  3. All contaminated clothing should be removed immediately with appropriate gloves and safely discarded.

  4. In case of contact with the skin, the affected area must be immediately rinsed with large amounts of water for at least 15 min. However washing off the skin will not be sufficient. A calcium gluconate gel contained in a white tube is available in the LAMP facility (in the First Aid box located to the right of the lab entrance door). The gel should be massaged over the affected area. When applying the gel, the washing with water can be reduced from 15 to 5 min. The gel should be reapplied at regular intervals.

  5. In case of contact with the eye, irrigate the eye for at least 30 minutes, keeping the eyelids apart and away from eyeballs during irrigation. Place ice pack on eyes until reaching emergency room.
 

Supply and storage
 
  1. In order to limit the number of HF containers in the lab,  all solutions containing HF are supplied by the lab. If for specific research purposes, you need your dedicated source of hydrofluoric acid, you must request the authorization from the lab manager first.

  2. Supplied HF solutions are typically diluted to 37%. If you need to adjust this concentration, you will supply your own container for storage, a polyethylene bottle with a positive closure (never store in a glass container since HF attacks glass and other silicon containing compounds)

  3. All HF-containing solutions will be stored in the acid cabinet located under the flow hood. It is not allowed to leave the lab with a HF solution left on the bench top under the flow hood.

  4. If you notice that the supply of HF or BOE is running out, contact the person responsible of chemicals inventory (do not wait the last minute though since it can take up to 4 weeks to renew the supply)
 

 

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Laboratory for Advanced Materials Processing, University of Maryland - 2009