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EH08: Hydrofluoric Acid

Safety Lecture

Environmental Health and Life Safety Department (EHLS)

713-743-5858

http://www.uh.edu/ehls/

Environmental Health & Life Safety

PowerPoint template 2 – begin entering text and images here.

Disclaimer


• This Hydrofluoric Acid Safety Training is NOT a substitute for hands-ontraining provided by your Principal Investigator or Designee.

• Laboratory Personnel who directly use hydrofluoric acid must be givenhands-on training for procedures/experiments involving hydrofluoric acidbefore beginning work.

• Hands-on training on the specific procedures must be performed by the PIor knowledgeable designee for all personnel working with HF, and must bedocumented (topics covered, date, employee names and signatures). Allpersonnel shall read and fully adhere to the lab-specific StandardOperating Procedures (SOPs) for HF, and shall document that they haveread it by signing and dating the SOP.

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Properties & Uses of Hydrofluoric Acid

Hazards Associated with Hydrofluoric Acid

Handling and Storage

Proper Personal Protective Equipment

Spills and Accidents

HF Training Outline


Properties of Hydrofluoric Acid (HF)“Weak” acid, e.g. low dissociation constant

Ionizes in aqueous solution but H3O+ and F‐ ions

are strongly attracted to each other and form the strongly bound pair, H3O

+ ∙ F‐. Because the hydroxonium ion is attached to the fluoride ion, it isn't free to function as an acid, thus limiting the strength of HF in water.

HIGHLY toxic & corrosive

Hydrogen & fluorine have a polar covalent bond.


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Common Uses of Hydrofluoric Acid (HF)Widely used in preparation of fluorine compounds,

such as Teflon (PTFE plastic), Freon (refrigerant), fluorocarbons, and many medications such as fluoxetine (Prozac).

Also used for industrial purposes such as glass etching, metal cleaning, and rust removal. Used in the semiconductor industry to clean silicon wafers.

Exposure usually unintentional and often due to inadequate use of protective measures.


Has a pungent, very unpleasant odor at less than 1 part per million (ppm).

It is irritating to the nose and throat at 3 ppm.

What should you do?

Hydrofluoric Acid has a strong, unpleasant odor. Exposure to the vapor at 3 ppm is likely to cause irritation to the nose and throat.


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OSHA Permissible Exposure Limit (PEL) = 3 ppm (Average over an 8 hour shift)

OSHA Short Term Exposure Limit (STEL) = 6 ppm (15 min)

Immediately Dangerous to Life and Health (IDLH) =30 ppm

Nonflammable, soluble in water

Vapor density = 0.7 (air = 1)


Hazards Associated with HFThere are two mechanisms of injury from Hydrofluoric Acid exposure:

1) A corrosive burn occurs from exposure to the free Hydrogen ions.

2) A toxicological effect occurs from tissue penetration of the Fluoride ions.

• Fluoride ions affect tissue integrity by liquefaction. • Fluoride ions cause decalcification/destruction of bone.• Fluoride ions form insoluble salts with calcium and

magnesium (Toxic). Also, toxic to CNS.• Without Calcium, many metabolic pathways breakdown.


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Fatality Statistics As little as 7 milliliters of anhydrous HF in contact with the

skin, left untreated, can bind all the free calcium in an average size adult male.

Fluoride ion poisoning, exposure involving greater than 25 square inches may cause fatal hypocalcemia and hypomagnesemia.

Exposure of 1% of Body Surface Area (BSA) to 50% HF solution may be fatal.

(1% BSA = palm of hand)

Exposure of 5% of BSA to HF solution at any concentration….may be fatal!


Lethal Exposure Incident - DERMALIncident 37YOM lab tech performing acid digestion of core samples w/70% HF in a

FH, knocked over <230 ml of HF, splashing both thighs. PPE–2 pairs of wrist length rubber gloves & pair of PVC sleeve protectors. Since the tech was working alone, it is unclear whether the spill was from

the digestion cup or the 2 LT bulk acid container. Sustained burns to 9% of BSA after washing legs in makeshift shower

supplying 6LTPM. ANSI standard is 75LTPM. No calcium gluconate gel wasapplied & contaminated clothing was not removed.

After flushing, tech immersed himself in a chlorinated swimming pool atthe rear of the workplace, where he remained for approximately 35‐40min before ambulance help arrived.

Died 15 days later from multi-organ failure.


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Contributing Factors Amount of fluoride ion absorbed.

BSA area exposure.

Inadequate PPE. Duration of exposure. No proper safety shower.

Calcium gluconate not available.

Possible inhalation of HF vapors.

Improper workspace design. SafetyLine Institute


How Corrosive is it?The initial extent of the burn depends on the concentration, temperature, duration of contact, and quantity.

Concentration Time of Pain onset 0-20% Up to 24 hours20-50% 1-8 hours>50% <1 hour99% immediate


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Routes of Entry

Skin

Eyes

Respiratory System

Ingestion

Most HF Acid Exposures Occur by: Inhalation of the

gas/vapor

Dermal (skin) contact

Dermal exposure to Hydrofluoric Acid. The material moved through the chemical protective gloves


Dermal Exposure Hazards At low concentrations, symptoms of exposure to Hydrofluoric Acid

may not be immediately evident.

HF interferes with nerve function, meaning that burns may not initially be painful.

Accidental exposures can go unnoticed, delaying treatment and increasing the extent and seriousness of the injury.


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The surface area of the burn does NOTpredict the total effects of the exposure.

Skin exposure to high concentrations produces immediate necrosis (tissue death) and severe pain with whitish tissue discoloration.


The eyes can be severely damaged from either vapor or liquid exposure.

Potentially permanent corneal damage may develop immediately, or after several days.

Eye Exposure Hazards

Exposure to HF Acid can cause permanent blindness


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Inhalation Exposure Hazards Due to the solubility of HF in water, the extent of the damage

to the lungs will depend on the DOSE from inhalation. Acute inhalation exposure symptoms include:

– Chills – Fever – Tightness in the chest – Coughing– Bluish colored lips & fingernails– Injury to lining of lungs – Pulmonary Edema– Death

Inhaling Hydrofluoric Acid will damage the

lungs.


Ingestion Exposure HazardsPoor laboratory practices, coupled with inadequatepersonal hygiene is the most common route ofingestion exposure.

These drinks are NOT properly stored outside

of the laboratory.

Always wash your hands after working in

the laboratory.


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Direct and Indirect Exposure

Liquid exposure (skin, eye, ingestion)

Gas/Vapor exposure (inhalation, skin & eyes)

Indirect• Victims exposed to HF vapors only, do not pose a

significant risk of secondary contamination, i.e. you will not be harmed helping them.

• Victims whose clothing or skin is contaminated with HF solution, will secondarily contaminate response personnel by direct contact or off-gassing vapors.

Direct


Assessments prior to using HF HF safety training

HF SOP completed and approved by PI

Functional/inspected safety shower and eye wash station

Functional/inspected fume hood. Recommended to have an HF designed chemical fume hood.

Readily available method for contacting emergency services/posted emergency contacts

Proper labeling for HF containing vessels

HF acid spill kit and first aid kit

Required personal protective equipment

Proper storage for HF containing vessels, e.g. Designated HF Work Area.


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Handling & Storage of Hydrofluoric Acid Prevent contamination of the work surfaces by placing plastic trays

or Teflon paper then neutralize unknown spills of HF with HF acid neutralizer.

If possible, substitute a less hazardous substance for Hydrofluoric Acid.

Always use the most dilute solution and smallest amount of Hydrofluoric Acid possible.

ALWAYS work inside a properly operating chemical fume hood, in designated HF Work Area, working at least 6” from the edge.

LABEL every container with the chemical name, percentage & hazards. Recommend adding user’s name as well.

Study the chemical operating procedure!


Safe Handling of Hydrofluoric Acid Review SDS & use the proper Personal Protective

Equipment (PPE).

Implement the buddy system and never work alone.

Use the buddy system! Remember that only one individual should be using the fume hood at a time. Individuals do not have to be performing the same work to enact the buddy system, but they do need to be in the same laboratory.


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Safe Handling of Hydrofluoric Acid Order the smallest quantity possible.

Cap all bottles when not in use, even during the actual experiment.

Use a bottle carrier when transporting HF (never transport open containers).

Transporting chemicals with a bottle carrier helps to minimize the risk of dropping a container.


Conduct a dry run before the actual experiment (Very Important).

Check your spill kit contents and location before you start working.

Check expiration date of the calcium gluconate BEFORE you start the experiment or procedure. If expired, suspend use until a new tube is received.

Be sure to check the expiration date on the calcium gluconate BEFORE working with hydrofluoric acid.


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Additional Safety Considerations

When using for etching applications with metal, the process may generate hydrogen gas.– Ensure that all ignition sources are extinguished.

– Always work in a properly functioning chemical fume hood.


Storing Hydrofluoric Acid HF reacts with many materials, therefore, never store

hydrofluoric acid in glass, ceramic, concrete or other silicon containing materials.

Use secondary containment

Store away from incompatibles

– Ammonia

– Bases

– Flammables/combustibles

– Other materials readily decomposed by acids (cyanides, sulfides, carbonates and metal oxides)

– Oxidizers, Reducers, Alkalis, Organics


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Storing Hydrofluoric Acid Recommend to store in ventilated acid

cabinet vice “standard” fume hood.

Always store below eye level.

Always cap when not in use.

Never use in a squirt bottle.

Store HF in containers made of polyethylene or fluorocarbon plastic, lead, or platinum. Place storage bottles in polyethylene secondary containment trays.


Additional Safety ConsiderationsWhile working with HF and the fume hood malfunctions or stops working, please follow these general steps:

If safe, close any opened chemical containers

Fully close sash

Notify lab workers, hood is not working and cannot be used

Put “Danger Fume Hood not Working” sign on fume hood

Put “Danger Fume Hood not Working” sign on entrance door

Notify PI or lab manager of fume hood failure

PI or lab manager will make decision to evacuate laboratory

When in doubt about personal safety…evacuate the laboratory


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Proper PPEEyes, Face and Neck Always use ANSI approved

indirectly vented or non-vented splash goggles. Indirect vents on the top and bottom protect against liquids while permitting indirect ventilation.

Full face shield


Proper PPEGlovesUse neoprene or nitrile gloves (22 mil thickness, 14

inch length), or other HF resistant gloves. Review glove manufacturer’s rating chart carefully.

Remember the breakthrough time! This is the time it takes for a substance to pass through the protective material of the glove.


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Proper PPE

Always wear a lab coat.

Wear an Acid resistant apron.

No shorts, sandals (open toed or perforated shoes), short skirts


Accidents and Spills

HF First Aid and Spill Kit


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General Procedures for Exposures

Do not panic! Think, Think, Think

Activate buddy system response –– The buddy should:

1. Alert others in the area.

2. Help the victim to the safety shower/eyewash. DO NOT CONTAMINATE YOURSELF (secondary contamination risk). Wear PPE!

3. Call 911 - Let the University Police know:

– You have an Hydrofluoric Acid exposure.

– Give the exact location.

– Instruct them to send emergency personnel.

4. Get the spill/exposure kit


First Aid – Skin

Help individual to

eyewash/safety shower– Time limit is 15 minutes in the safety

shower.

– Victim should remove all contaminated clothing, shoes and jewelry while under the shower.

– Remove goggles last, face water and pull over head.


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General Procedures Exposures The buddy should get spill/exposure kit.

– Wear the proper PPE.

– Puncture the calcium gluconate tube.

– Get the calcium carbonate tablets (TUMS®) out.

– Provide both to the victim when appropriate.


Calcium Gluconate Treatment

– Neutralizes HF.

– Binds the Fluoride ion to prevent deep tissue destruction and systemic absorption.

– Easy to use.

– Treatment fast and effective.

– Treatment can be started immediately.

http://www.calgonate.com/


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First Aid – Skin Victim should self administer calcium gluconate

immediately after decontamination. Rub the gel onto the burn/exposure site and any other areas that may have been exposed.

– NOTE THE TIME OF INITIAL APPLICATION

Ingest 6 calcium carbonate tablets (TUMS).

Buddy should bag all contaminated clothing and supplies if safe, use correct PPE.


First Aid – Eyes

Flush eyes in eyewash for 15 minutes –holding lids open (both lower and upper) for irrigation.

Remove contacts as necessary, assure the fingers are free of contamination.


Apply calcium gluconate gel to the effected skin areas. DO NOT apply the gel directly to the eyes. If Calgonate®

eyewash is available, flush eyes as directed.

Conduct this process for both liquid or vapor contamination.


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First Aid – Inhalation

Immediately remove the victim to clean air.

Utilize the safety shower or eyewash for decontamination based on the type of vapor exposure.


Apply calcium gluconate gel to the effected skin areas.


First Aid – IngestionDo not induce vomiting.


Apply calcium gluconate gel to the effected skin areas.

For additional HF exposure utilize the safety shower or eyewash for decontamination and follow skin/eye/inhalation decontamination procedures.


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General Procedure to Follow After the Victim has Completed the Decontamination Process

1) The victim must be thoroughly decontaminated prior to being transported to the hospital.

2) The victim must be escorted to the hospital by the responding person or assisting laboratory personnel.

3) Take the calcium gluconate gel with you to the hospital, re-apply every 20 minutes until the pain subsides.

4) Provide EMS with the calcium gluconate gel administration time, and also let them know 6 calcium carbonate tablets (TUMS®) have been ingested.


General Procedure to Follow After the Victim has Completed the Decontamination Process

The Following must go to hospital with the victim:– SDS

– Recommended Medical Treatment

– Calcium gluconate gel

– Calcium carbonate tablets


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Hydrofluoric Acid Spill/Exposure KitThe Spill/Exposure Kit Contains the Following:

1) Calcium gluconate gel.2) Copy of the HF SOP, SDS, and Recommended Treatment

Guide.3) 1 roll of calcium carbonate tablets (TUMS®).4) Clean-up materials:

– HF specific absorbent pads– HF acid neutralizer– 2 pair of 22 mil nitrile or neoprene gloves – 1 heavy duty polyethylene bag/bucket– 1 waste label

http://www.hfacidsafety.com/


Spill Kit Materials3M's Universal Sorbent is recommended,

as it does not react with HF. Organic spill kits that contain Floor-Dri, Kitty Litter, Vermiculite or Sand should not be usedbecause HF reacts with Silica to produce Silicon Tetrafluoride, a toxic gas.


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Small HF SpillsHF Chemical Spill Kit must be readily

available during HF work. http://www.hfacidsafety.com/

For small spills:

1) Follow the HF chemical spill procedure. For example, alert others in the area and contain the spill if it is safe to do so. Keep in mind you must wear all HF PPE.

2) Neutralize small spills with available HF neutralizer and apply control pads or other absorbent materials from HF spill kit.

3) Call EHLS (3-5858) to dispose of spill clean-up materials. All spill clean-up materials must be placed and sealed in a plastic container.


Large HF Spills

If the spill is large (> 5 gallons), please follow general guidelines:

1) Alert others in the area and evacuate the room.

2) Immediately report the spill to EHLS (3-5858) or after hours call 911.

3) Post a DO NOT ENTER - HF SPILL

sign.

1) Wait for responders to arrive.


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Summary The Principal Investigator (PI) must have a completed Standard

Operating Procedures on file with EHLS.

Every individual working directly with HF or in the same laboratory must be trained annually.

Every Principal Investigator must authorize students or workers to use Hydrofluoric Acid.

Every lab must have a HF Spill/Exposure kit, proper PPE, written chemical spill procedures.

Each lab is responsible for inspecting the

spill/exposure kit before each use.

Check Safety Equipment (shower, eye

wash, PPE) before HF use.


Summary

The BUDDY SYSTEM applies during ALL HF use.

No after hours work with HF, only work with the material between 8:00 am and 4:30 p.m.


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BE PROACTIVE! Attend EH08: HF Acid Safety Lecture & EH06: General

Lab Safety Orientation. Read and Follow the Standard Operating Procedure. Assure that a trained buddy is available. Check the operation of your Engineering Controls (fume

hoods). Check the Emergency Equipment (Safety

Shower/Eyewash Stations). Wear all Personal Protective Equipment. Label all containers. Post signs in your area while working. Assure that your Spill kits are inspected and current.


Please take the survey at the web address below.

• https://baseline.campuslabs.com/uoh/ehsendofcoursesurvey2019

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