A corrosion-resistant issues: 1. Sulfuric acid: As a strong corrosive medium, sulfuric acid is an important use of a wide range of industrial raw materials. Different concentrations and temperatures of sulfuric acid on the corrosion of materials vary greatly, for the concentration of more than 80%, the temperature is less than 80 ℃ of concentrated sulfuric acid, carbon steel and cast iron has good corrosion resistance, but it is not suitable for high-speed flow of sulfuric acid, Not suitable for pump valve material; ordinary stainless steel such as 304 (0Crl18Ni9), 316 (0Cr18Ni12Mo2Ti) sulfuric acid medium is also limited use. Therefore, the delivery of sulfuric acid pump valve usually adopts high silicon cast iron (casting and processing difficult), high alloy stainless steel (20 alloy) manufacturing. Fluoroplastic has good resistance to sulfuric acid, the use of fluorine pump (F46) is a more economical choice. The applicable products of the company include Fluorine plastic alloy pump series: CQBF type fluorine plastic alloy magnetic pump (CQBF fluorine alloy magnetic pump), VYF type fluoroplastic reinforced alloy submerged pump (VYF pump), VFS type fluorine plastic reinforced alloy centrifugal pump (VFS fluorine Alloy pump), IHF fluorine plastic alloy centrifugal pump (IHF pump). 2. Hydrochloric acid: Most of the metal materials are not resistant to hydrochloric acid corrosion (including a variety of stainless steel materials), molybdenum high ferrosilicon can only be used for 50 ℃, hydrochloric acid below 30%. In contrast to metallic materials, the vast majority of non-metallic materials have good corrosion resistance to hydrochloric acid, so lined rubber pumps and plastic pumps (such as polypropylene, fluoroplastic, etc.) is the best choice for the delivery of hydrochloric acid. 3. Fluorine plastic alloy pump series 3. Nitric acid: most of the general metal nitric acid is rapidly corrosive damage, stainless steel is the most widely used nitric acid-resistant materials, all concentrations of nitric acid at room temperature have good corrosion resistance, it is worth mentioning Mo-containing stainless steel (such as 316,316 L) corrosion resistance of nitric acid is not only not superior to ordinary stainless steel (such as 304,321), and sometimes even worse. For high-temperature nitric acid, usually titanium and titanium alloy materials, and fluorine plastic alloy pump series applicable. 4. Acetic acid: It is one of the most corrosive substances in organic acids. Ordinary steel will seriously corrode in all concentrations and temperatures of acetic acid. Stainless steel is an excellent acetic acid-resistant material. Molybdenum-containing 316 stainless steel is also suitable for high temperature And dilute acetic acid steam. For high temperature and high concentrations of acetic acid or other corrosive media containing the East when the harsh requirements of high-alloy stainless steel or fluorine plastic pump can be used. 5. Alkali (sodium hydroxide): Steel is widely used in sodium hydroxide solution below 80 ℃ and 30% concentration. Many factories use common steel even under 100 ℃ and 75%. Although the corrosion is increased, the economy it is good. Ordinary stainless steel lye corrosion resistance and cast iron compared with no obvious advantages, as long as the medium allows a small amount of iron mixed with the recommended use of stainless steel. For high temperature alkaline use of titanium and titanium alloy or high alloy stainless steel. General cast iron pump can be used for low concentration of alkali at room temperature, special requirements can be used when all kinds of stainless steel pump or fluorine plastic pump. 6. Ammonia (ammonia hydroxide): Most mostly and non-metals in liquid ammonia and ammonia (ammonia hydroxide) corrosion is very slight, only copper and copper alloy should not be used. The company a lot of corrosion-resistant chemical pump 7. Saltwater (sea water): ordinary steel in sodium chloride solution and seawater, salt water corrosion rate is not high, the general shall be used paint protection; all kinds of stainless steel also have a low uniform corrosion rate, but May cause localized corrosion due to chloride ions, usually 316 stainless steel is better. 8. Alcohols, ketones, esters, ethers: Common alcohol medium with methanol, ethanol, ethylene glycol, propanol, ketone medium with acetone, butanone and so on, ester medium has a variety of methyl ester , Ethyl ester and the like. Ethers medium ether, ether, butyl ether, etc., they are basically non-corrosive, common materials are applicable, the specific selection should be based on the media properties and related requirements to make a reasonable choice. It is also noteworthy that ketones and ester ethers are soluble in a wide variety of rubbers and avoid mistakes when selecting sealing materials. Second, the sealing problem: 1 sealed form: For the static seal, usually only two forms of seals and seals, and seals the most widely used; for the dynamic seal, chemical pumps rarely use packing seal to mechanical seal Mainly mechanical seal and single-sided and double-sided, balanced and unbalanced type, flat and thin type for high pressure medium seal (usually refers to the pressure greater than 1.0MPa), double-sided machine seal is mainly used for high temperature, easy Crystallization, viscosity, containing particles and toxic volatile medium, double-ended machine seal should be injected into the sealed chamber isolation fluid, the pressure is generally higher than the media pressure 0.07-0.1MPa. 2. Sealing material: Chemical pump static sealing material generally use fluorine rubber, special circumstances only use PTFE material; mechanical seal ring static material configuration is more critical, not cemented carbide is the best on the cemented carbide, the price is high On the one hand, the difference between the two hardness is not reasonable, so it is best to distinguish between media characteristics. Third, the viscosity of the problem: the viscosity of the medium on the performance of the pump is great, when the viscosity increases, the pump head curve down, the best conditions of the head and flow are decreased, while the power is then increased, and thus Reduced efficiency. The parameters of the general sample hail is the performance when delivering fresh water. When the viscous medium is transported, the conversion should be performed. (Correction factors of different viscosities can be found in the relevant conversion charts). For the viscosity of the pulp, paste and viscous fluid delivery, the proposed selection of screw pump, rotor pump. Nitric acid / sulfuric acid / hydrochloric acid / phosphoric acid / hydrofluoric acid / caustic soda / soda ash Petrochemical pump optional material Nitric acid (HNO3) General characteristics: Is an oxidizing medium. Concentrated HNO 3 working temperature is generally below 40 ℃, element Cr, Si is oxidation resistance, stainless steel containing Cr, Si and other materials is the ideal corrosion resistant HNO 3 material. Therefore, the general choice of nitric acid pump material: high silicon cast iron (STSi15R): temperature below 93% of all temperatures; high chromium cast iron (Cr28): temperature below 80% of all temperatures; stainless steel (SUS304, SUS316, SUS316L): temperature 80 % Below all the temperature.
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