Selection of pumps for acids

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Acid-resistant pumps, in a broad sense, refer to pumps used for transporting acidic media. Among the acid-resistant pumps designed for transporting liquid substances, there are corrosion-resistant centrifugal pumps, corrosion-resistant gear pumps, and corrosion-resistant screw pumps. As for pumps used for transporting gases, there are acid-resistant vacuum pumps, acid-resistant diaphragm pumps, and corrosion-resistant jet pumps, among others. Among them, they are further classified into pumps resistant to strong acids (such as pumps for concentrated sulfuric acid) and ordinary acid-resistant pumps (such as pumps for dilute acids), based on the strength of the acidic corrosive medium being transported. Selecting a pump for acids is not complicated; by considering the properties of various acids and taking into account one’s financial capabilities, it is easy to find an acid-resistant pump that meets one’s needs. 1. For salt acid pumps, the highest concentration of salt acid that is commonly used is 38%; therefore, for such pumps it is sufficient that the materials of the flow-through components be plastic. However, considering factors such as service life and cost-effectiveness, FSB fluoroplastic alloy pumps can be chosen, as these pumps offer satisfactory prices and performance. 2. Sulfuric acid: Pumps for sulfuric acid are divided into pumps for dilute sulfuric acid and pumps for concentrated sulfuric acid. There is a wider range of options for pumps used with dilute sulfuric acid; these can be engineering plastic pumps, ceramic pumps, or F46/F26 pumps. For pumps used with concentrated sulfuric acid, only fluoroplastic (F46) pumps can be used, as concentrated sulfuric acid corrodes ordinary engineering plastics, whereas fluoroplastic does not get corroded. It should also be noted that concentrated sulfuric acid has a high density; therefore, when selecting a pump, it is necessary to choose one with an appropriately high motor power. A simple formula for calculating this is “shaft power” * 1.84, which gives the shaft power required for transporting concentrated sulfuric acid. 3. Hydrofluoric acid: Hydrofluoric acid is highly corrosive; it is recommended to use fluoroplastic magnetic pumps (and the ceramic components of such pumps must be replaced with materials resistant to hydrofluoric acid). 4. *AO acid: For pumping *AO acid, fluoroplastic magnetic pumps are also recommended, and the rubber seals should be replaced with those made of PTFE. 5. Acetic acid: It is one of the most corrosive organic acids; ordinary steel is severely corroded by acetic acid at all concentrations and temperatures. Stainless steel is an excellent material resistant to acetic acid, and 316 stainless steel containing molybdenum can also be used in high-temperature environments as well as with dilute acetic acid vapor. For demanding applications such as high-temperature, high-concentration acetic acid or environments containing other corrosive agents, high-alloy stainless steel or fluoroplastic magnetic pumps can be used. Such as CQB magnetic pumps, CQ316L stainless steel magnetic pumps. 6. Brine (seawater): Ordinary steel exhibits a low corrosion rate in sodium chloride solutions, as well as in seawater and brine; coating protection is generally required ； Various types of stainless steel also have very low rates of uniform corrosion, but local corrosion may occur due to chloride ions. 316 stainless steel is generally a good choice, although it is more expensive; it is recommended to use fluoroplastic centrifugal pumps, such as IHF chemical centrifugal pumps. 7. Sealing: Magnetic pumps utilize a static sealing mechanism, so there is no need to concern oneself with sealing performance. Centrifugal pumps generally employ external bellows-type mechanical seals, which offer good resistance to corrosion and wear; if the medium being transported contains particles, a hard-to-hard mechanical seal can be used.