The oil and chemical industry occupies a very important position in the national economy, and the chemical process pump, as a key supporting equipment, has attracted more and more attention. Due to the complex characteristics of chemical mediators and the continuous improvement of environmental protection requirements, as chemical manufacturers, how should we choose the chemical pumps and focus on what aspects should be paid attention to is particularly important. Combined with the characteristics of most chemical companies, we briefly review the selection of commonly used chemical pumps, hoping to benefit our customers in this field.
Corrosion resistance
All the time, corrosion is one of the most headache of chemical equipment, a little inadvertent, light damage equipment, heavy cause accident even cause disaster. According to the relevant statistics, about 60% of the damage of chemical equipment are caused by corrosion. Therefore, the scientific nature of material selection should be paid attention to in selecting chemical pumps. There is usually a misconception that stainless steel is a universal material. It is dangerous to hold stainless steel in any medium and environment. The following points for some commonly used chemical media to talk about the selection of materials:
As one of the strong corrosion medium, 1. sulfuric acid is an important industrial raw material which is very widely used. Corrosion difference of different concentration and temperature of sulfuric acid material is large, the sulfuric acid concentration is above 80%, the temperature less than 80 DEG C, carbon steel and cast iron has good corrosion resistance, but it is not suitable for high-speed flow of sulfuric acid, not suitable for ordinary stainless steel valve materials; such as 304 (0Cr18Ni9), 316 (0Cr18Ni12Mo2Ti) the sulfuric acid also of limited use. Therefore, the valve for transporting sulphuric acid is usually made of high silicon cast iron (hard casting and processing) and high alloy stainless steel (No. 20 alloy), but its processing is difficult and expensive, so it is not valued by people. Fluorine plastic alloy with good resistance to sulfuric acid good performance, it is Chinese Academy of Sciences, Shanghai Institute of organic chemistry, the patent materials, my company in 1985 the introduction of patented technology, first with the development and production of corrosion-resistant chemical pumps, proved by the Chinese Academy of Sciences, yet which can react with the chemical medium, so using fluorine pump (F46) is a more economical choice. The products are: IHF fluorine pump, FSB strong corrosion resistant centrifugal pump, IMD fluoroplastic magnetic pump, and so on.
2. hydrochloric acid in the majority of metal materials is not resistant to hydrochloric acid corrosion (including all kinds of stainless steel), and molybdenum high ferrosilicon can also be used only for hydrochloric acid below 50 C and 30%. Contrary to metal materials, most non-metallic materials have good corrosion resistance to hydrochloric acid, so lining rubber pumps and plastic pumps, such as engineering plastics, fluoroplastics, etc., is the best choice for transporting hydrochloric acid. The products are: CQB fluoroplastics leakage resistant acid pump, CQF engineering plastic magnetic pump (or fluoroplastic magnetic pump), etc.
3. nitric acid most of the general metal corrosion in nitric acid was rapidly destroyed, stainless steel is the most widely used nitric acid resistant materials have good corrosion resistance, all concentrations of nitric acid at room temperature, it is worth mentioning that the stainless steel containing molybdenum (316, 316L) of nitric acid corrosion resistance is not only no better than ordinary stainless steel (as of 304, 321), sometimes even better. In the case of high temperature nitric acid, fluoroplastic alloy is usually used. The company's products are: CQB fluoroplastic alloy magnetic pump, FSB fluorine alloy centrifugal pump and so on.
4. acetic acid is one of the most corrosive substances in organic acids. Ordinary steel will seriously corrode in acetic acid at all concentrations and temperatures. Stainless steel is excellent acetic acid resistant material, and molybdenum containing 316 stainless steel can also be applied to high temperature and dilute acetic acid steam. High alloy stainless steel or fluoroplastic pump can be used for high temperature and high concentration acetic acid or other harsh requirements for corrosion medium. Such as CQB magnetic pump, CQ stainless steel magnetic pump.
5. alkali (sodium hydroxide) general corrosion is not very strong, but generally will have a crystalline alkali solution, FSB fluorine alloy pump so you can use the configuration of the silicified graphite mechanical seal material 169
6. the corrosion of most metals and nonmetals in the liquid ammonia and ammonia (hydrogen oxide ammonia) is very slight, only copper and copper alloys are not suitable for use. Most of the company's products are suitable for the transportation of ammonia and ammonia water. Such as CQF engineering plastic magnetic pump, FSB fluorine alloy centrifugal pump better
7. salt water (sea water) ordinary steel in Sodium Chloride Solution and sea water, salt water corrosion rate is not high, are generally required to use paint protection; all kinds of stainless steel has a very low corrosion rate, but may be due to localized corrosion caused by chloride ions, typically 316 stainless steel is better. All kinds of chemical pumps in the company have 316 materials, such as IH chemical centrifugal pump.
8. alcohols, ketones, esters, ethers common alcohols media are methanol, ethanol, ethylene glycol, alcohol, ketones medium with acetone and butanone, a variety of media methyl esters, ethyl ester, ether medium with ether, ethyl ether, butyl ether, etc., they basically do not corrosive, and therefore may use an ordinary stainless steel, also should make a reasonable choice according to the relevant requirements of the medium properties and specific use. It is also worth noting that ketones, esters, and ethers are soluble in many kinds of rubber, and avoid errors when choosing sealing materials. Recommending the selection of inorganic sealed fluoroplastic magnetic pump
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