Phosphoric acid is a colorless, clear and odorless liquid. It is a strong inorganic acid with the chemical formula H3PO4. It can be produced by absorbing phosphorous pentoxide directly in water or through the digestion of phosphate rock with sulfuric acid. The most common form of phosphoric acid is an 85 percent aqueous solution. Phosphoric acid has a wide range of uses, including as a food additive, rust inhibitor, fertilizers, electrolyte, dispersing agent, dental and orthopedic etchant and many more.
What Are Some Industry Applications of Phosphoric Acid?
- Agriculture: About 90 percent of phosphoric acid production is used to produce fertilizers. To produce phosphate salts, the phosphoric acid is reacted with the minerals available in phosphate rock.
- Food Industry: Food-grade phosphoric acid created through the thermal creation process is used to acidify beverage and foods. For instance, the acidity of most sodas is created through the use of phosphoric acid.
- Rust Removal: For rust treatment, phosphoric acid solutions are created as a gel or dipping bath to be applied to rusted areas.
- Medical Industry: Phosphoric acid is used in an assortment of teeth whiteners for removing plaque. It is also widely used as an etching solution in orthodontics and dentistry to roughen and clean surfaces of teeth before fillings or dental appliances are placed.
What Properties of Phosphoric Acid Will Affect the Pump Material Selected?
The specific gravity of phosphoric acid ranges from 1.3 to 1.95 depending on the concentration. At a concentration of 85 percent, which happens to be an industry standard, phosphoric acid tends to be very corrosive and extremely damaging to skin and eyes. Since the S.G. can vary greatly, it is paramount to plan ahead and consider this in the pump you’ll use.
Figure 1: Phosphoric Acid Concentrations and Pump Materials
A single or collection of material/s may be rated for a higher temperature/s then the pump as a whole is capable of. It is important to contact a March representative to determine if the pump as a complete unit is suitable for the concentration and temperature of any chemical.
What Materials Handle Phosphoric Acid the Best?
While some metals may have short working lives, they can be used in phosphoric acid pumps. Stainless steel, for instance, suffers a high rate of corrosion when coming in contact with phosphoric acid, but some grades are usable, although they suffer from a short working life. For better chemical resistance a non-metallic build, using materials such as polypropylene and kynar, are recommended. Viton, PTFE and Kalrez elastomers are very resistant to phosphoric acid corrosion, but for higher concentrations, natural rubber should be avoided.
Choosing the Right Phosphoric Acid Chemical Pump
March Pumps offers a wide range of chemical pumps that cover virtually any industry and special use case. The type of the pump you choose greatly depends on the concentration of the acid you plan to use, the acid temperature, its special gravity along with a host of other factors.
For more information on selecting an appropriate chemical pump we encourage you to contact our friendly team of pump experts. Please contact us online or call as at 847-729-5300.