Bunded Sulphuric Acid Tanks are required for storage of a widely produced, corrosive inorganic acid that is used across a range of industries. The chemical formula for the acid is H2SO4. H2SO4 is a diprotic, strong mineral acid that is considered “weighty” due to its high density. Chemical solutions of sulfuric acid are very reactive and express true hazards that must be considered whenever handling and storing.

Sulfuric acid is an odourless, semi-oily liquid that ranges in appearance from clear to yellow depending upon solution purity, where solutions are colourless. H2SO4 has a viscosity greater than water, which contributes to its characterization as an oily solution.  Viscosity has an indirect correlation with temperature: as temperatures increase, viscosity decreases. The increased viscosity of H2SO4 can be attributed to its internal resistance to flow based upon the molecular, three-dimensional structural orientation and the electrical attraction of its atomic constituents; that is, polar dipole moments and increased hydrogen bonding.

Commonly characterized as a “heavy” chemical solution because of its high density, which is dependent upon a specific solution’s concentration. Density can range from 1.07 to 1.84 g/cm3, (where water = 1.0 g/cm3), making H2SO4 on its most dense side almost twice as heavy as water when occupying the same volume.  Sulfuric acid is a mineral acid with sulphur as its parent atom – (mineral meaning inorganic, inorganic meaning non-carbon-based). Comparatively, acetic acid, CH2COOH, is an organic, carbon-based acid. H2SO4 can result from dissolving sulphur trioxide gas in water. A visual representation of the reaction and sulfuric acid molecular structure:

H2O(l) + SO3(g) = H2SO4(aq) Sulfuric acid is capable of dangerous reactions and is hazardous to human health. The chemical is a strong acid due to the high dissociation constant of the first hydrogen released in reactions. Sulfuric acid is a potent oxidizer capable of oxidizing certain chemicals and materials, such as some metals, and has great affinity and reactivity with water. The reactivity between sulfuric acid and water is exothermic (heat-generating) and is so great that the reaction can be incredibly violent and consequently hazardous, especially with strengths greater than 80% H?SO?. This exothermic reaction warrants important consideration in storage applications as the diluting or mixing of sulfuric acid with water or other chemicals can generate sizeable amounts of heat and can potentially warm the solution to levels hazardous to the storage container or associated equipment.

The most common containers used for storing sulfuric acid solution quantities are high-density polyethene (HDPE) tanks. Due to the increased density of H?SO? solutions, only tanks with specific gravity ratings of 1.9 or higher are recommended for sulfuric acid storage for the tank to adequately withstand the chemical weight. A benefit of using plastics such as poly tanks for sulfuric acid storage is that such materials are not reactive with H2SO4.

The maximum service temperature of HDPE tanks peaks around 130?F. This is important in H2SO4 applications as diluting or mixing of concentrated acid can drive temperatures up to and beyond this range. Due to these concerns with elevated temperatures, diluting concentrated sulfuric acid in plastic storage tanks is not generally recommended except under stringent engineering controls, methods, and mechanisms that allow it to be performed successfully. It is recommended to buy pre-diluted H?SO? if less-concentrated solutions are required.

Tank Configuration For Storing Sulfuric Acid

Secondary containment is recommended when storing sulfuric acid. If your storage tank leaks, secondary containment can capture the leak before it causes a risk to your staff or facility.

Polyethene tanks for outdoor H2SO4 storage are recommended to be formulated with UV-stabilizers or insulated to aid in tank integrity and service life. Request a quote for a Bunded Sulfuric Acid Tanks or contact us for more information on 01778 562810

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