When the chemical pump operates in many complex working conditions, the most prominent problem is the corrosion resistance of the chemical pump. In the face of various complex working conditions, the use of chemical pumps must be done with the manufacturer timely and comprehensive communication, in view of some commonly used chemical media,we simple introduce how to choose the chemical pump material, it hope can help customer choose suitable pumps.
1,Sulfuric acid. As one of the strong corrosive media, sulfuric acid is an important industrial raw material with a wide range of applications. Different concentrations and temperatures of sulfuric acid are different in the corrosion of materials. Carbon steel and cast iron have good corrosion resistance for concentrated sulfuric acid with concentration above 80% and temperature less than 80 ℃, but it is not suitable for high speed flowing sulfuric acid and is not suitable for the material of pump valve. Ordinary stainless steel such as 304 (0Cr18Ni9), 316 (0Cr18Ni12Mo2Ti) has limited use of sulfuric acid medium. Therefore, sulfuric acid pump valves are usually made of high silicon cast iron (difficult to cast and processing) and high alloy stainless steel (alloy 20). Fluorine plastics have better sulphuric acid resistance, so PTFE is a more economical choice.
2,Hydrochloric acid. Most metal materials are not resistant to hydrochloric acid corrosion (including various stainless steel materials), molybdenum containing high silicon iron can only be used at 50 ℃, less than 30% hydrochloric acid. Contrary to metallic materials, most nonmetallic materials have good corrosion resistance to hydrochloric acid, so lined rubber pumps and plastic pumps (such as polypropylene, fluoroplastics, etc.) are the best choice to transport hydrochloric acid.Nitric acid. Most metals are rapidly corroded in nitric acid, and stainless steel is the most widely used nitric acid resistant material. It is worth mentioning that the corrosion resistance of molybdenum containing stainless steel (such as 316 316L) to nitric acid is not better than that of ordinary stainless steel (such as 304, 321), and sometimes worse than that of common stainless steel (such as 304,321).For high temperature nitric acid, titanium and titanium alloy materials are usually used.
3,Acetic acid. It is one of the most corrosive substances in organic acids. Ordinary iron and steel can be seriously corroded in acetic acid of all concentrations and temperatures. Stainless steel is an excellent acetic acid resistant material. 316 stainless steel containing molybdenum can also be used in high temperature and dilute acetic acid vapor. High alloy stainless steel pump or fluoroplastic pump can be used for high-temperature high-concentration acetic acid or other corrosive medium and other demanding requirements.
4,Base (sodium hydroxide)Iron and steel are widely used in sodium hydroxide solution under 80 ℃ and 30% concentration.Many factories still use common steel at 100 ℃ and below 75%. Although corrosion is increased, but economy is good. The corrosion resistance of ordinary stainless steel to alkali solution has no obvious advantage compared with cast iron, so long as a small amount of iron is allowed in the medium, stainless steel is not recommended. For high-temperature lye, titanium and titanium alloys or high-alloy stainless steel.
5, Ammonia (ammonia hydroxide) The corrosion of most metals and nonmetals in liquid ammonia and ammonia (ammonia hydroxide) is mild, and only copper and copper alloys are not suitable for use.
6, Brine (seawater) The corrosion rate of common iron and steel in salt water and sodium chloride solution is not too high, so it is necessary to use paint to protect it. All kinds of stainless steel also have low uniform corrosion rate, but it may cause local corrosion due to chloride ions, usually 316 stainless steel is better.
7, Alcohols, ketones, esters, ethers, and the like, wherein the alcohol medium is methanol, ethanol, ethylene glycol, propanol and the like; the ketone medium is provided with acetone, butanone and the like; the ester medium is provided with various methyl esters, ethyl esters and the like; and the ether medium is methyl ether, ethyl ether, butyl ether and the like. They are basically not corrosive, common materials can be used, the specific selection should be based on the properties of the medium and relevant requirements to make a reasonable choice.
It is also worth noting that ketones, esters, and ethers are soluble in many kinds of rubber and avoid mistakes in selecting sealing materials.
If you have any problem in choose chemical pump material, please contact us.