How should corrosion-resistant pumps be selected? Here is a brief explanation: Sulfuric acid As one of the highly corrosive media, sulfuric acid is an important industrial raw material with a wide range of uses. Sulfuric acid of different concentrations and temperatures has a large difference in the corrosion of materials. For concentrated sulfuric acid with a concentration of more than 80% and a temperature of less than 80°C, carbon steel and cast iron have good corrosion resistance, but it is not suitable for high-speed flow of sulfuric acid and is not suitable for use as pump valve materials; ordinary stainless steel such as 304 and 316 are also limited in use for sulfuric acid media. Hydrochloric acid: Most metal materials are not resistant to hydrochloric acid corrosion, and molybdenum-containing high-silicon iron can only be used for hydrochloric acid below 50°C and 30%. In contrast to metal materials, most non-metallic materials have good corrosion resistance to hydrochloric acid, so lined rubber pumps and plastic pumps are good choices for transporting hydrochloric acid.
Nitric acid: Most general metals are quickly corroded and destroyed in nitric acid. Stainless steel is a widely used nitric acid-resistant material with good corrosion resistance to nitric acid of all concentrations at room temperature. It is worth mentioning that the corrosion resistance of molybdenum-containing stainless steel to nitric acid is not only not better than that of ordinary stainless steel, but sometimes even worse. Acetic acid: It is one of the most corrosive substances in organic acids. Ordinary steel will be severely corroded in acetic acid of all concentrations and temperatures. Stainless steel is an excellent acetic acid resistant material. Molybdenum-containing 316 stainless steel can also be used for high temperature and dilute acetic acid vapor. For demanding requirements such as high temperature and high concentration acetic acid or other corrosive media, high alloy stainless steel or fluoroplastic pumps can be selected. Alkali is generally not very corrosive, but general alkaline solutions will produce crystals. Ammonia Most metals and non-metals are slightly corroded in liquid ammonia and ammonia water (ammonia hydroxide), only copper and copper alloys are not suitable for use.
The selection of corrosion-resistant pumps also needs to pay attention to: Salt water (seawater) Ordinary steel has a low corrosion rate in sodium chloride solution, seawater, and salt water, and generally needs to be protected by coatings; various types of stainless steel also have a very low uniform corrosion rate, but may cause local corrosion due to chloride ions, and 316 stainless steel is usually better. Alcohols, ketones, esters, ethers Common alcohol media include methanol, ethanol, ethylene glycol, propanol, etc., ketone media include acetone, butanone, etc., ester media include various methyl esters, ethyl esters, etc., ether media include methyl ether, ethyl ether, butyl ether, etc., they are basically not very corrosive, so ordinary stainless steel can be used. When selecting, reasonable choices should be made based on the properties of the media and related requirements. It is also worth noting that ketones, esters, and ethers are soluble in many types of rubber, so avoid mistakes when choosing sealing materials.