PRODUCTS

HYDROFLUORIC ACID

Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colourless, acidic and highly corrosive. Hydrofluoric acid is used to make most fluorine-containing compounds; examples include the commonly used pharmaceutical antidepressant medication fluoxetine (Prozac) and the material PTFE (Teflon). Elemental fluorine is produced from it. It is commonly used to etch glass and silicon wafers. When hydrofluoric acid comes into contact with human skin it causes deep burns.

CAS No. : 7664-39-3
EC No. : 231-634-8

Synonyms:
Fluorane; Fluorhydric acid; Hydronium fluoride; HF; hydrogen fluoride; HYDROFLUORIC ACID; Hydrogen fluoride; hidroflorik asit; hidrofluorik asit; 7664-39-3; Fluorhydric acid; fluorane; Hydrofluoride; Rubigine; Fluorwasserstoff; Hydrogen-fluoride; Antisal 2B; Fluorowodor [Polish]; Caswell No. 484; Fluorwaterstof [Dutch]; Hydrogen fluoride (HF); hydrofluoric asit; Fluorwasserstoff [German]; UNII-RGL5YE86CZ; UN 1790 (solution); UN 1052 (anhydrous); RCRA waste number U134; Acido fluoridrico [Italian]; Acide fluorhydrique [French]; Acido fluorhidrico [Spanish]; Fluorure d'hydrogene anhydre [French]; RCRA waste no. U134; EPA Pesticide Chemical Code 045601; Hydrogen fluoride, anhydrous; Fluoruro de hidrogeno anhidro [Spanish]; Fluohydric Acid; Hydrofluoric acid 70% by weight or more HF; HFA; Hydrofluoric Acid; Hydrogen fluoride/Hydrofluoric acid (conc 50% or greater); Hydrogenfluorid; Fluorowodor; Fluorwaterstof; hydrogenfluoride; Acido fluoridrico; Hydrofluoric acid, ACS reagent, 48%; Acido fluorhidrico; Acide fluorhydrique; Hydrofluoricum acidum; Fluorure d'hydrogene anhydre; fluorum; Hydrofluoric acid, ACS reagent, 48-51% solution in water; Fluoruro de hidrogeno anhidro; Hydridofluorine; fluoridohydrogen; Hydrofluoric acid, for analysis, 48 to 51% solution in water; Fluoro radical; hyrofluoric acid; Fluorohydric acid; fluorure d'hydrogene; ACMC-1BAS6; Hydrogen fluoride,anhydrous; EC 231-634-8; KSC207Q2H; Hydrofluoric acid, 55%, CP; [HF]; 60% HF/DMF; Hydrofluoric acid, AR, >=40%; Hydrofluoric acid, LR, 39-43%; Hydrofluoric acid, SAJ first grade; BDBM50499187; Hydrofluoric acid, 48% ACS reagent; Hydrofluoric acid, JIS special grade; HYDROFLUORIC ACID ANTIDOTE GEL; Hydrofluoric acid, technical, 40-45%; FLUORINE, ISOTOPE OFMASS 18, AT.; Hydrofluoric acid, technical grade, 68.0%; hf; Hydrofluoric acid, with more than 60% strength; Hydrofluoric acid, with not more than 60% strength; Hydrogen fluoride, anhydrous [UN1052] [Corrosive]; Hydrogen fluoride, anhydrous [UN1052] [Corrosive]; Hydrofluoric acid, for ultratrace analysis, 47-51% (T); Hydrofluoric acid, Environmental Grade, (47-51 wt% in water); Hydrofluoric acid, 48 wt. % in H2O, >=99.99% trace metals basis; Hydrofluoric acid, Environmental Grade Plus, (47-51wt % in water); Hydrofluoric acid, electronic grade,49wt. % in H2O,99.99998%metals basis; Hydrofluoric acid, puriss. p.a., reag. ISO, reag. Ph. Eur., >=40%; Hydrofluoric Acid; Hydrogen fluoride/Hydrofluoric acid; Hydrofluoric acid, semiconductor grade VLSI PURANAL(TM) (Honeywell 17601); Hydrofluoric acid, p.a., ACS reagent, reag. ISO, reag. Ph. Eur., 48.0-51.0%; Hydrofluoric acid, puriss. p.a., ACS reagent, reag. ISO, reag. Ph. Eur., >=48%; Cytoreg (r) is pharmacologically active solution composed by 6 acids in an aqueous medium. The Active ingredient is Hydrofluoric Acid.

Hydrofluoric Acid

Uses of Hydrofluoric acid
Production of organofluorine compounds
The principal use of hydrofluoric acid is in organofluorine chemistry. Many organofluorine compounds are prepared using HF as the fluorine source, including Teflon, fluoropolymers, fluorocarbons, and refrigerants such as freon. Many pharmaceuticals contain fluorine.

Production of inorganic fluorides of Hydrofluoric acid
Most high-volume inorganic fluoride compounds are prepared from hydrofluoric acid. Foremost are Na3AlF6, cryolite, and AlF3, aluminium trifluoride. A molten mixture of these solids serves as a high-temperature solvent for the production of metallic aluminium. Other inorganic fluorides prepared from hydrofluoric acid include sodium fluoride and uranium hexafluoride.

Properties of Hydrofluoric acid
Chemical formula HF (aq)
Appearance Colorless liquid
Density 1.15 g/mL (for 48% soln.)
Acidity (pKa) 3.17

Wet etching tanks
It is used in the semiconductor industry as a major component of Wright Etch and buffered oxide etch, which are used to clean silicon wafers. In a similar manner it is also used to etch glass by treatment with silicon dioxide to form gaseous or water-soluble silicon fluorides. Hydrofluoric acid can also be used to polish and frost glass.

SiO2 + 4 HF → SiF4(g) + 2 H2O
SiO2 + 6 HF → H2SiF6 + 2 H2O
A 5% to 9% hydrofluoric acid gel is also commonly used to etch all ceramic dental restorations to improve bonding. For similar reasons, dilute hydrofluoric acid is a component of household rust stain remover, in car washes in "wheel cleaner" compounds, in ceramic and fabric rust inhibitors, and in water spot removers. Because of its ability to dissolve iron oxides as well as silica-based contaminants, hydrofluoric acid is used in pre-commissioning boilers that produce high-pressure steam. Hydrofluoric acid is also useful for dissolving rock samples (usually powdered) prior to analysis. In similar manner, this acid is used in acid macerations to extract organic fossils from silicate rocks. Fossiliferous rock may be immersed directly into the acid, or a cellulose nitrate film may be applied (dissolved in amyl acetate), which adheres to the organic component and allows the rock to be dissolved around it.

Oil refining
In a standard oil refinery process known as alkylation, isobutane is alkylated with low-molecular-weight alkenes (primarily a mixture of propylene and butylene) in the presence of an acid catalyst derived from hydrofluoric acid. The catalyst protonates the alkenes (propylene, butylene) to produce reactive carbocations, which alkylate isobutane. The reaction is carried out at mild temperatures (0 and 30 °C) in a two-phase reaction.

Production of Hydrofluoric acid
Hydrofluoric acid was first prepared in 1771, by Carl Wilhelm Scheele. It is now mainly produced by treatment of the mineral fluorite, CaF2, with concentrated sulfuric acid at ca. 265 °C.

CaF2 + H2SO4 → 2 HF + CaSO4
The acid is also a by-product of the production of phosphoric acid from apatite/fluoroapatite. Digestion of the mineral with sulfuric acid at elevated temperatures releases a mixture of gases, including hydrogen fluoride, which may be recovered.

Because of its high reactivity toward glass, hydrofluoric acid is stored in plastic containers.

Hydrofluoric acid can be found in nature; it is released in volcanic eruptions.

Properties of Hydrofluoric acid
In dilute aqueous solution hydrogen fluoride behaves as a weak acid, Infrared spectroscopy has been used to show that, in solution, dissociation is accompanied by formation of the ion pair H3O+·F−.

H2O + 2HF ⇌ H+ + F− + H3O+⋅F−, pKa = 3.17
This ion pair has been characterized in the crystalline state at very low temperature. Further association has been characterized both in solution and in the solid state.

HF + F− ⇌ HF2− log K = 0.6
It is assumed that polymerization occurs as the concentration increases. This assumption is supported by the isolation of a salt of a tetrameric anion H3F4− and by low-temperature X-ray crystallography. The species that are present in concentrated aqueous solutions of hydrogen fluoride have not all been characterized; in addition to HF2− which is known the formation of other polymeric species, Hn-1Fn−, is highly likely.

The Hammett acidity function, H0, for 100% HF is estimated to be between −10.2 and −11. which is comparable to the value −12 for sulfuric acid.

Solutions of hydrofluoric acid attack glass, so they are stored and used in vessels made of teflon. They attack human skin, so must be handled with great care: see #Health and Safety, below.

Acidity of Hydrofluoric acid
Unlike other hydrohalic acids, such as hydrochloric acid, hydrogen fluoride is only a weak acid in dilute aqueous solution. This is in part a result of the strength of the hydrogen–fluorine bond, but also of other factors such as the tendency of hydrofluoric acid, H2O, and F− anions to form clusters. At high concentrations, hydrofluoric acid molecules undergo homoassociation to form polyatomic ions (such as bifluoride, HF−2) and protons, thus greatly increasing the acidity. This leads to protonation of very strong acids like hydrochloric, sulfuric, or nitric when using concentrated hydrofluoric acid solutions. Although hydrofluoric acid is regarded as a weak acid, it is very corrosive, even attacking glass when hydrated.

The acidity of hydrofluoric acid solutions varies with concentration owing to hydrogen-bond interactions of the fluoride ion. Dilute solutions are weakly acidic with an acid ionization constant Ka = 6.6×10−4 (or pKa = 3.18), in contrast to corresponding solutions of the other hydrogen halides, which are strong acids (pKa < 0). Concentrated solutions of hydrogen fluoride are much more strongly acidic than implied by this value, as shown by measurements of the Hammett acidity function H0(or "effective pH"). The H0 for 100% hydrofluoric acid is estimated to be between −10.2 and −11, comparable to the value −12 for sulfuric acid.

In thermodynamic terms, hydrofluoric acid solutions are highly non-ideal, with the activity of hydrofluoric acid increasing much more rapidly than its concentration. The weak acidity in dilute solution is sometimes attributed to the high H—F bond strength, which combines with the high dissolution enthalpy of hydrofluoric acid to outweigh the more negative enthalpy of hydration of the fluoride ion. Paul Giguère and Sylvia Turrell have shown by infrared spectroscopy that the predominant solute species in dilute solution is the hydrogen-bonded ion pair H3O+·F−.

H2O + HF ⇌ H3O+⋅F−
With increasing concentration of hydrofluoric acid the concentration of the hydrogen difluoride ion also increases. The reaction
3 HF HF2− + H2F+ is an example of homoconjugation.

Health and safety of Hydrofluoric acid
In addition to being a highly corrosive liquid, hydrofluoric acid is also a powerful contact poison. Because of the ability of hydrofluoric acid to penetrate tissue, poisoning can occur readily through exposure of skin or eyes, or when inhaled or swallowed. Symptoms of exposure to hydrofluoric acid may not be immediately evident, and this can provide false reassurance to victims, causing them to delay medical treatment. Despite having an irritating odor, hydrofluoric acid may reach dangerous levels without an obvious odor. Hydrofluoric acid 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. Symptoms of hydrofluoric acid exposure include irritation of the eyes, skin, nose, and throat, eye and skin burns, rhinitis, bronchitis, pulmonary edema (fluid buildup in the lungs), and bone damage.

Popular culture of Hydrofluoric acid
In the series 4 episode 'Chain reaction' of the British medical drama Casualty a road traffic collision results in a spillage of hydrofluoric acid testing the resources of the department and resulting in the death of a police officer and severe burns to other motorists. This episode realistically depicts the fire service response to a chemical spillage

In an episode of Breaking Bad titled "Cat's in the Bag...", Jesse Pinkman uses hydrofluoric acid to dissolve the body of Emilio Koyama. In another episode, "Box Cutter", Walter White and Jesse Pinkman use hydrofluoric acid to dissolve the body of Victor.

In the film Saw VI, hydrofluoric acid is used for killing William Easton. In the film Jigsaw, Carly is killed by hydrofluoric acid injected into her bloodstream.

In an episode of Titans titled "Jason Todd", a young Dick Grayson claims that his parents' murderer used hydrofluoric acid to burn their trapeze ropes.

In a trio of segments of the videogame Zero Time Dilemma titled "First Come, First Saved", each of the three teams of participants are given the option to press a button that activates a hydrofluoric acid shower that pours over the other two teams. The corrosion process of the acid is both described and depicted as being fast enough to melt everything from metal and glass to the entire body of a sizable adult male in a matter of seconds, leaving only small amounts of tissue behind.

Hydrofluoric Acid: What You Need to Know
Incidents involving hydrogen fluoride, or hydrofluoric acid, are not common, but the consequences of exposure to this compound by any means can be devastating. This little-known acid has unique properties that make it extremely dangerous to emergency personnel and others. Frequently mistaken for or confused with hydrochloric acid, HF should be referred to as Hydrofluoric acid.

I became interested in Hydrofluoric acid while working in an oil refinery that uses it as a catalyst to make high-octane gasoline. As a paramedic, I found the effects of Hydrofluoric acid on the human body fascinating. I learned what I could about it and began teaching Hydrofluoric acid safety to my coworkers.

Then, in 2001, I was involved in an Hydrofluoric acid incident in which I was seriously exposed. I had been sprayed with anhydrous Hydrofluoric acid at approximately 150 pounds of pressure when a ¾" pipe broke at an ell as I was preparing to remove a plug. The Hydrofluoric acid had eaten the threads inside the ell and the weight of my pipe wrench caused the damaged pipe to give way, spraying both my legs just below my groin, and my right forearm. That exposure began a battle for my life that continues today.

Luckily, our local EMS and emergency facility had been trained on the dangers of this acid and proper treatment. Many EMS and ER personnel have probably never heard of this dangerous compound, but all emergency services, fire or law enforcement personnel who operate near and may be called to respond to any facility that uses or manufactures a form of Hydrofluoric acid should receive yearly training on treatment for Hydrofluoric acid exposure. This information should be available from your county LEPC.

Anhydrous hydrogen fluoride (Hydrofluoric acid) is an inorganic, corrosive compound with many industrial and commercial uses. It is manufactured by heating purified fluorspar (calcium fluoride) with concentrated sulfuric acid to produce the gas, which is then condensed by cooling or dissolving in water. It can also be refined as a by-product of the production of phosphoric acid, which is derived from the mineral apatite. Apatite sources typically contain a small amount of fluorite. The acid hydrolysis of fluorite-containing minerals generates an impure gas stream consisting of sulfur dioxide, water and Hydrofluoric acid. Separating gases from solids and treating them with sulfuric acid and oleum produces anhydrous Hydrofluoric acid. Hydrofluoric acid can also be released when other fluoride-containing compounds, such as ammonium fluoride, are combined with water or when certain plastics are exposed to fire conditions, creating carbonyl fluoride (the fluorine analog of phosgene).

HYDROFLUORIC ACID FAST FACTS

Hydrogen fluoride is available commercially either in an anhydrous (water-free) state or in water solutions of various concentrations. At higher concentrations, Hydrofluoric acid is a colorless gas or a fuming liquid. Hydrofluoric acid may be known as Hydrogen fluoride (UN 1052), hydrofluoric acid (UN 1790) or fluorohydric acid. Identification numbers are CAS number 7664-39-3, UN: 1052 or RTECS: MW7875000. Main Manufacturers/main importers are DuPont (US), Allied (US) and Honeywell (US).

Its physical properties are:

Molecular weight: 10
Boiling point: Gas at temperatures above 19°C
Auto-ignition: Not relevant
Vapor pressure: 150mm (70% solution at 26.7°C); 70mm (70% solution at 20.0°C)
Solubility: Aqueous solutions to 70%
Explosive limits: Not applicable--non-flammable (BLEVE hazard if container subjected to fire conditions)
Shipping name: Hydrogen fluoride, anhydrous (1052), hydrofluoric acid, with not more than 60% strength (1790)
Identification number: 1052 (hydrogen fluoride, anhydrous) (Guide 125), 1790 (hydrofluoric acid) (Guide 157)
Hazardous class or division: 8 (1052)
Subsidiary hazardous class or division: 6.1, Inhalation hazard (1790)
Label: Corrosive, Poison (toxic) (1052), Corrosive, Poison (Toxic), Inhalation Hazard (1790)
Hydrogen fluoride is used in solution form in glass and metal etching, industrial and home cleaners and rust removers, and in manufacturing electronics. Full strength, it is used to manufacture high-octane fuels in oil refineries. Other major industrial uses of hydrogen fluoride include synthesis of fluorocarbons (e.g., freon and Teflon) and production of aluminum fluoride and synthetic cryolite for use in aluminum refining. It is also employed in refining uranium for use as a nuclear fuel, in manufacturing various organic chemicals, in producing stainless steel, and for various other applications such as:

Propellants and solvents
Insecticide and fertilizer production
Manufacture and reduction of chlorides
Brewery to control fermentation
Fabric industry for stain removal
Leather industry for tanning
Drug and dye production
Manufacture of semiconductors.
Present household uses include:

Rust remover
Aluminum brighteners
Heavy-duty cleansers.

Hydrofluoric acid is a colorless fuming liquid below 67°F (19.4°C), or a colorless gas. When hydrogen fluoride is combined with water it is known as hydrofluoric acid, a colorless liquid, which in low concentrations is visually indistinguishable from water. Hydrofluoric acid that is more than 40% hydrogen fluoride fumes in air.

Hydrofluoric acid can be used for intra-oral repair of restorations. Contamination of tooth substrate with hydrofluoric acid cannot always be avoided. /The study objective was/ to investigate the bonding effectiveness to hydrofluoric acid contaminated dentin by, micro-tensile bond strength testing, SEM and TEM. For this study, 15 molar teeth were used of which dentin surfaces were subjected to five, different etching procedures. Group A, 37.5% phosphoric acid (Kerr Gel) (control group); group B, 37.5% phosphoric acid followed by 3% hydrofluoric acid (DenMat); group C, 37.5% phosphoric acid, followed by 9.6% hydrofluoric acid (Pulpdent); group D, 3% hydrofluoric acid followed by 37.5%, phosphoric acid; group E, 9.6% hydrofluoric acid followed by 37.5% phosphoric acid. After the bonding procedure (OptiBond FL, Kerr) a composite resin build-up (Clearfil AP-X, Kuraray), was made. After 1 week storage, specimens were prepared for micro-tensile bond testing, SEM- and, TEM-analysis. Data were analyzed using ANOVA and post hoc Tukey's HSD (p<0.05). In the control group (solely phosphoric acid), the mean microTBS was 53.4+/-10.6 MPa, which was, significantly higher than any hydrofluoric acid prepared group (group A versus groups B-E, p<0.001). No, significant differences in microTBS were found between the 3% and 9.6% hydrofluoric acid groups: group B versus group C (13.5+/-5.5 MPa and 18.7+/-4.3 MPa, respectively) or group D versus group E (19.9+/-6.8 MPa and 20.3+/-4.1 MPa, respectively). Due to its adverse effect on the bond strength of composite to dentin, contact of hydrofluoric acid to dentin should be avoided.

Hydrogen fluoride is a colorless, fuming liquid or gas with a strong, irritating odor. Hydrofluoric acid is usually shipped in steel cylinders as a compressed gas. Hydrogen fluoride readily dissolves in water to form colorless hydrofluoric acid solutions; dilute solutions are visibly indistinguishable from water.

Ocular tissues are extremely sensitive to hydrofluoric acid. Concentrations as low as 5 mg/L (5 ppm) may produce irritation to the eye. Although the protein aqueous precipitation of coagulation necrosis limits the penetration of other inorganic acids, hydrofluoric acid is able to penetrate the ocular tissues and produces severe damage to ocular structures. Lacrimation, pain, and conjunctival injection are early symptoms of hydrofluoric acid exposure. Corneal and conjunctival epithelium may be denuded, leading to edema and ischemia. Corneal vascularization and scarring may result. Toxicity may be delayed by up to 4 days after dilute exposures. Global perforation has also been reported.

Hydrofluoric acid is an irritant to the mucosa of the upper and lower portions of the respiratory tract. As in ocular tissues, concentrations as low as 5 mg/L (5 ppm) may produce irritation to the nasal mucosa. When hydrofluoric acid is present in concentrations greater than 48%, the solution fumes, adding to the volatile airborne fraction. Mucosal edema, bronchospasm, bronchorrhea, wheezing, atelectasis, and airways obstruction may result. A chemical tracheobronchitis or pneumonitis, either of which may be hemorrhagic, and pulmonary edema may follow. Onset of signs and symptoms may be immediate, with death reported in as little as 30 minutes after exposure, or they may not appear for several days. Symptoms in survivors may be sustained for greater than 1 year.

A waste containing hydrofluoric acid may (or may not) be characterized a hazardous waste following testing for corrosivity characteristics as prescribed by the Resource Conservation and Recovery Act (RCRA) regulations.

Hydrogen fluoride/hydrofluoric acid has not been classified as a carcinogen. It is not known whether chronic or repeated exposure to hydrogen fluoride/hydrofluoric acid increases the risk of reproductive toxicity or developmental toxicity. Chronic or repeated exposure to hydrogen fluoride/hydrofluoric acid has been associated with fluorosis, mottling of the teeth, weight loss, malaise, anemia, leukopenia, discoloration of teeth, osteosclerosis, skeletal changes such as increased bone density of the spine and pelvis, calcification of ligaments, hyperostosis, and liver or kidney damage.

A chemical polishing soln consisting of nitric acid and hydrofluoric acid (1 vol each) and glycerol (2 vols) generated enough pressure during storage for 4 hr to rupture the closed plastics container. This was caused by gas evolution from oxidation of glycerol by the strongly oxidizing mixture. A mixture of nitric acid (80 mL), hydrofluoric acid (80 mL) and glycerol (240 mL) was used immediately for etching metal, again the next day, and then stored in a stoppered flask. After some 2-3 days, the stopper was ejected and approx 300 mL was sprayed around the fume cupboard containing the flask. The metals dissolved during use further destabilize the mixture, which should not be stored under any circumstances.

Mixtures of the 3 acids /hydrofluoric acid, lactic acid, and nitric acid/, used as metal polishing solutions, are unstable and should not be stored. Lactic acid and nitric acid react autocatalytically after a quiescent period, attaining a temp of about 90 °C with vigorous gas evolution after about 12 hr.

A chemical polishing mixture /of hydrofluoric acid, propylene glycol, silver nitrate, and nitric acid/ was put into a closed glass bottle which burst 30 min later, and formation of silver fulminate was suggested. However, in absence of the silver salt such mixtures evolve gas and should not be stored in any event, especially after use for metal polishing, when the dissolved metal(s) tend to further destabilize the mixture.

The International Maritime Dangerous Goods Code lays down basic principles for transporting hazardous chemicals. Detailed recommendations for individual substances and a number of recommendations for good practice are included in the classes dealing with such substances. A general index of technical names has also been compiled. This index should always be consulted when attempting to locate the appropriate procedures to be used when shipping any substance or article. Hydrogen fluoride, anhydrous; hydrofluoric acid solution, with more than 60% hydrogen fluoride; and hydrofluoric acid solution, with not more than 60% hydrogen fluoride are included on the dangerous goods list.

Hydrofluoric acid is an indirect food additive for use only as a component of adhesives.

Hydrofluoric acid is a dangerous inorganic acid that can cause local corrosion and systemic effects by ongoing absorption via the skin, mucosae, respiratory tract and digestive system. Recently, a serious toxic leak of low-concentration hydrofluoric acid solution occurred in the Pujiang area of Zhejiang Province, China. This accident resulted in 253 cases of chemical injury due to hydrofluoric acid exposure. Despite an immediate response by the local and provincial health-care system, as well as the local government, three people died due to acute poisoning and related complications. This article describes the events that took place leading to casualties as well as presenting the first-aid experience and the lessons learnt from this kind of mass injury.

Hydrogen fluoride/hydrofluoric acid can be absorbed systemically into the body by ingestion, inhalation, or skin or eye contact. Eye exposure to hydrogen fluoride/hydrofluoric acid is highly unlikely to result in systemic toxicity. Inhalation is an important route of exposure.

Occupational injuries to digits due to hydrofluoric acid (HFA) are frequently encountered. They have distinctive features, including intense pain, progressive tissue necrosis, and possible bone erosion. To minimize tissue damage, it is of great importance to execute prudent preoperative assessment and determine the correct surgical modality to reconstruct and maintain the function of the hand. However, proper protocols for fingers have not been presented in previous studies. Eight cases with hydrofluoric acid burn to digits were presented to the emergency room. Wounds were immediately irrigated with saline, calcium gluconate was applied topically to block destructive effects of fluoride ions. Blisters that could lead to progressive tissue destruction were debrided. A fish-mouth fasciotomy was performed and prostaglandin was administered intravenously to maintain maximal distal circulation. Wounds were evaluated daily for apparent demarcation for 6 or 7 days. Digits were reconstructed with free sensate second toe pulp-free flap to provide sufficient padding for the fingertip. All patients showed excellent recovery with stable flaps with acceptable external contour, durable soft tissue padding, and full range of motion of affected joints. In conclusion, when a patient is admitted due to hydrofluoric acid (HFA) exposure to the finger, early treatment including irrigation, topical neutralizers, and fasciotomy are of great importance to minimize tissue damage. In addition, a physician should wait at least 7 days until the degree of damage to the tissue can be classified so that the physician can decide whether aggressive debridement should be proceeded. In case of deep layer injuries of weight bearing portions such as finger pulp, reconstruction techniques utilizing durable tissues such as partial second toe pulp free flap should be employed.

Hydrofluoric acid is increasingly used as a rust remover and detergent. Dermal contact with hydrofluoric acid results in a chemical burn characterized by severe pain and deep tissue necrosis. It may cause electrolyte imbalances with lethal consequences. It is important to identify high-risk patients. 'High risk' is defined as a total affected body area > 3% or exposure to hydrofluoric acid in a concentration > 50%. We present the cases of three male patients (26, 31, and 39 years old) with hydrofluoric acid burns of varying severity and describe the subsequent treatments. The application of calcium gluconate 2.5% gel to the skin is the cornerstone of the treatment, reducing pain as well as improving wound healing. Nails should be thoroughly inspected and possibly removed if the nail is involved, to ensure proper healing. In high-risk patients, plasma calcium levels should be evaluated and cardiac monitoring is indicated.

Hydrofluoric acid (HFA) is commonly used and many injuries occur on the upper extremities following exposure to HFA. The use of calcium gluconate (CG) -containing gel or local injections of CG are widely used for the initial treatment of Hydrofluoric acid (HFA) exposure. However, severe pain continues in some cases despite the treatment. There was a report that trans-arterial CG infusion could improve Hydrofluoric acid (HFA) burns, however, such treatment is not an established clinical procedure. A 30-year-old male presented at our hospital with severe pain in his left thumb. He had been cleaning tiles with an HFA-containing detergent. We diagnosed him with a chemical burn due to Hydrofluoric acid (HFA) exposure. Local CG injections were tried several times, but his terrible pain continued. Therefore, a direct arterial sphygmomanometry line was inserted from the left radial artery, and continuous transarterial CG injection was performed. His terrible pain dramatically improved. Direct arterial sphygmomanometry systems are widely used in the critical care field to monitor the hemodynamics and ICU staffs are used to dealing with it. Moreover, continuous saline infusion prevents the tube obstruction. Continuous CG infusion from a direct arterial sphygmomanometry line is simple and safe way to administer CG in Hydrofluoric acid (HFA) burns.

Hydrofluoric acid (HF) is a highly toxic poison that can be rapidly fatal. Death usually results from the many systemic effects of dissociated fluoride ions, including hypocalcemia, hypomagnesemia, hyperkalemia, and direct cardiotoxicity. A patient is described who accidentally ingested a hydrofluoric acid-containing substance and who likely benefited from hemodialysis. His fluoride level post-dialysis was reduced by approximately 70% from a level drawn three hours prior to the initiation of hemodialysis. However, the single treatment did not reduce the fluoride level to normal. A review of the pathophysiology of hydrofluoric acid intoxication and the outcomes of prior exposures suggests that hemodialysis could play a vital role in the management of poisonings with fluoride-containing substances. However, the initial hemodialysis treatment should be prolonged beyond the standard four-hour session.

Uses & Benefits of Hydrofluoric acid (HFA)
Industrial/Manufacturing Uses of Hydrofluoric acid (HFA)
Hydrofluoric acid (HFA) is used to make refrigerants, herbicides, pharmaceuticals, gasoline, stainless steel kitchen products, aluminum, plastics, electrical components and incandescent light bulbs (electric light with a wire filament, used in appliances, incubators, portable lighting). Sixty percent of the hydrogen fluoride used in manufacturing is for processes to make refrigerants used in refrigeration, freezer and air conditioning systems.

In laboratories and industrial settings, hydrofluoric acid can be used for etching glass and enamel, removing rust, and cleaning brass and crystal. It also is used in manufacturing silicon semiconductor chips. Hydrogen fluoride also is used as an alkylation catalyst in oil refineries to make high-octane gasoline as well as power nuclear reactors.

Cleaners and Rust Removers
Due to Hydrofluoric acid (HFA)s strong corrosive qualities, a diluted form of hydrofluoric acid is used in some commercial automotive cleaners, rust and stain removers and water-spot removers.

Safety Information of Hydrofluoric acid (HFA)
Due to its strong corrosive qualities, a diluted form of hydrofluoric acid is used in some commercial automotive cleaners, and rust and stain removers. Care should be taken when using commercially available products containing hydrofluoric acid, and safety instructions on labels should always be followed. Skin contact or inhalation of hydrofluoric acid can cause moderate to severe health effects.

What Hydrofluoric acid is
Hydrofluoric acid is a chemical compound that contains fluorine. It can exist as a colorless gas or as a fuming liquid, or it can be dissolved in water.
When Hydrofluoric acid is dissolved in water, it may be called hydrofluoric acid.
Hydrofluoric acid can be released when other fluoride-containing compounds such as ammonium fluoride are combined with water.

Where Hydrofluoric acid is found and how it is used
Hydrofluoric acid is used to make refrigerants, herbicides, pharmaceuticals, high-octane gasoline, aluminum, plastics, electrical components, and fluorescent light bulbs. Sixty percent of the Hydrofluoric acid used in manufacturing is for processes to make refrigerants.
Hydrofluoric acid is also used for etching glass and metal.

How you could be exposed to Hydrofluoric acid
In a natural disaster, you could be exposed to high levels of Hydrofluoric acid when storage facilities or containers are damaged and the chemical is released. This release could occur at an industrial site or even a retail location.
You could be exposed to Hydrofluoric acid if it is used as a chemical terrorism agent.
If you work in an occupation that uses Hydrofluoric acid, you may be exposed to this chemical in the workplace.
You may be exposed to Hydrofluoric acid as part of a hobby.

How Hydrofluoric acid works
Hydrofluoric acid goes easily and quickly through the skin and into the tissues in the body. There it damages the cells and causes them to not work properly.
The seriousness of poisoning caused by Hydrofluoric acid depends on the amount, route, and length of time of exposure, as well as the age and preexisting medical condition of the person exposed.
Breathing Hydrofluoric acid can damage lung tissue and cause swelling and fluid accumulation in the lungs (pulmonary edema).
Skin contact with Hydrofluoric acid may cause severe burns that develop after several hours and form skin ulcers.

Immediate signs and symptoms of exposure to Hydrofluoric acid
Swallowing only a small amount of highly concentrated Hydrofluoric acid will affect major internal organs and may be fatal.
Hydrofluoric acid gas, even at low levels, can irritate the eyes, nose, and respiratory tract. Breathing in Hydrofluoric acid at high levels or in combination with skin contact can cause death from an irregular heartbeat or from fluid buildup in the lungs.
Even small splashes of high-concentration Hydrofluoric acid products on the skin can be fatal. Skin contact with Hydrofluoric acid may not cause immediate pain or visible skin damage(signs of exposure).
Often, patients exposed to low concentrations of Hydrofluoric acid on the skin do not show effects or experience pain immediately. And, severe pain at the exposure site may be the only symptom for several hours. Visible damage may not appear until 12 to 24 hours after the exposure.
Depending on the concentration of the chemical and the length of time of exposure, skin contact with Hydrofluoric acid may cause severe pain at the point of contact; a rash; and deep, slow-healing burns. Severe pain can occur even if no burns can be seen.
Showing these signs and symptoms does not necessarily mean that a person has been exposed to Hydrofluoric acid. Other chemicals also can cause these effects.
Exposure to Hydrofluoric acid can result in severe electrolyte problems.

Long-term health effects of acute exposure to Hydrofluoric acid
People who survive after being severely injured by breathing in Hydrofluoric acid may suffer lingering chronic lung disease.
Skin damage caused by concentrated Hydrofluoric acid may take a long time to heal and may result in severe scarring.
Fingertip injuries from Hydrofluoric acid may result in persistent pain, bone loss, and injury to the nail bed.
Eye exposure to Hydrofluoric acid may cause prolonged or permanent visual defects, blindness, or total destruction of the eye.
Swallowing Hydrofluoric acid can damage the esophagus and stomach. The damage may progress for several weeks, resulting in gradual and lingering narrowing of the esophagus.

How you can protect yourself, and what to do if you are exposed to Hydrofluoric acid
First, if the Hydrofluoric acid was released into the air, get fresh air by leaving the area where the chemical was released.
If the Hydrofluoric acid release was outside, move away from the area where the chemical was released.
If the Hydrofluoric acid release occurred indoors, get out of the building.

If you are near a release of fluorine or Hydrofluoric acid, emergency coordinators may tell you either to evacuate the area or “shelter in place” inside a building to avoid being exposed to the chemical. For more information on evacuation during a chemical emergency, see “Facts About Evacuation.” For more information on sheltering in place during a chemical emergency, see “Facts About Sheltering in Place.”
If you think you may have been exposed to Hydrofluoric acid, you should remove your clothing, rapidly wash your entire body with water, and get medical care as quickly as possible.

Removing your clothing
Quickly take off clothing that may have Hydrofluoric acid on it. Any clothing that has to be pulled over the head should be cut off the body.
If you are helping other people remove their clothing, try to avoid touching any contaminated areas, and remove the clothing as quickly as possible.

Washing yourself
As quickly as possible, wash any Hydrofluoric acid from your skin with large amounts of water.
If your eyes are burning or your vision is blurred, rinse your eyes with plain water.
If you wear contacts, remove them after washing your hands and put them with the contaminated clothing. Do not put the contacts back in your eyes (even if they are not disposable contacts). If you wear eyeglasses, wash them with soap and water. You can put your eyeglasses back on after you wash them.

Disposing of your clothes
After you have washed yourself, place your clothing inside a plastic bag. Avoid touching contaminated areas of the clothing. If you can’t avoid touching contaminated areas, or you aren’t sure which areas are contaminated, put the clothing in the bag using tongs, tool handles, sticks, or similar objects. Anything that touches contaminated clothing should also be placed in the bag.
Seal the bag, and then seal that bag inside another plastic bag. Disposing of your clothing in this way will help protect you and other people from any chemicals that might be on your clothes.

Hydrogen fluoride is a colorless, corrosive liquid or gas and is composed of a hydrogen atom and a fluorine atom. It has a strong, irritating odor. Hydrogen fluoride readily dissolves in water and is referred to as hydrofluoric acid (HFA) in its dissolved form. It is present in a variety of over-the-counter products at concentrations of 6–12%. Although HFA is weak compared with most other mineral acids, it can produce serious health effects by any route of exposure. These effects are due to the fluoride ion’s aggressive, destructive penetration of tissues.

Hydrofluoric acid (HF) is formed when hydrogen fluoride is combined with water. Hydrogen fluoride can be a devastating eye, skin, and systemic toxin in both gaseous and liquid states (see Chapter 90). It has multiple industrial and household uses (Box 15-1).

The damage caused by HF is concentration dependent and largely related to the fluoride component rather than its corrosive hydrogen ion. Because HF is a relatively weak acid (pKa 3.8), it is largely nonionized and can penetrate cell membranes easily. During deep tissue penetration, the fluoride ion is released, and subsequently binds avidly to divalent cations to form insoluble salts (predominantly calcium and magnesium fluoride). This results in liquefaction necrosis and significantly decreased tissue concentrations of ionized calcium and magnesium concentrations. Alterations in calcium and magnesium concentrations result in an increase in cellular potassium permeability, which causes spontaneous neuronal depolarization and pain. The onset of pain is immediate following exposure to high-concentration liquids but may be delayed for several hours to days for less concentrated solutions.18 Despite its deep tissue penetration, systemic fluoride toxicity is highly unlikely following ocular exposure to HF-containing products.

Drug overdose
Dissociated fluoride ions cause systemic poisoning, owing to their high affinity for cellular enzymes and divalent cations, mainly calcium and magnesium.

A 65-year-old skilled worker was in the process of cleaning iron pipes associated with a cooling apparatus by using a high-pressure stream of water, in which hydrofluoric acid gas was liquefied into hydrofluoric acid [2]. About 5 minutes later, he was heard crying for help and was found crouching, his face gray in color. He complained of chest pain. At the time he was wearing a helmet, goggles, rubber gloves, and a raincoat. It was not clear whether during the accident he had been wearing a plastic face shield that was found nearby. When an ambulance arrived about 30 minutes after the accident, he was in cardiopulmonary arrest. Despite aggressive cardiopulmonary resuscitation and the intravenous administration of adrenaline, atropine, and sodium bicarbonate, he died about 1.5 hours after the accident. Subsequent police investigation showed that one of the iron pipes had been clogged with crystallized hydrofluoric acid. It was therefore surmised that a solution containing hydrofluoric acid and vapor was unexpectedly expelled on to his face from the pipe by the application of a high-pressure stream of water while it was being cleaned. At post-mortem there was a third-degree chemical burn to his face, extending to both ears. The affected area was greenish-gray in color, and the upper and lower lips had turned black. Both temporal bones were dyed greenish-gray. Both lungs were edematous, with diffuse parenchymatous hemorrhage. Although a frothy fluid containing blood was found inside the trachea and both of the main bronchi, there was no definite evidence of burning in the upper airway.

What is hydrofluoric acid?
Hydrofluoric acid is a highly corrosive, inorganic acid of elemental fluorine that is used in the production of plastics, semiconductors, pottery glazing, and rust removal and is a component of aluminum brighteners. Hydrofluoric acid injury is an occupational hazard for petroleum refinery workers and for those engaged in the cleaning of air conditioning equipment. It has been widely used since the discovery in the late seventeenth century of its ability to dissolve silica. Contact with hydrofluoric acid typically is initially pain-free, with subsequent localized pallor. This pallor progresses to penetrating tissue necrosis and severe tissue pain.

Hydrofluoric acid is a highly corrosive chemical primarily causing dermal injury to the hands. Hydrofluoric acid releases free hydrogen ions (H+) that penetrate and corrode the skin, potentially down to bone, producing bone demineralization and necrosis. The respiratory effects parallel those of the skin, except effects in the lungs have a rapid onset and patients present with acute respiratory distress. Hydrofluoric acid is water-soluble and thus predominantly exerts its effects on the upper airways, resulting in rapid onset of tissue damage and bronchoconstriction, in some cases even leading to chemical pneumonitis, delayed-onset pulmonary edema, and death.