How to choose a chemical pump needs to consider the following aspects:
Corrosion resistance problem
Sulfuric acid, one of the strong corrosive media, is an important industrial raw material with a wide range of uses. Different concentrations and temperatures of sulfuric acid have a great difference in corrosion of materials. For concentrated sulfuric acid carbon steel and cast iron with a concentration above 80 and a temperature of less than 80 °C, it has good corrosion resistance, but it is not suitable for high-speed flow of sulfuric acid. The ordinary stainless steel materials such as 3040Crl18Ni9 and 3160Cr18Ni12Mo2Ti are also limited in their use for sulfuric acid media. Therefore, the pump valve for conveying sulfuric acid is usually made of high-silicon cast iron and difficult to process, high-alloy stainless steel No. 20 alloy. Fluoroplastics have better resistance to sulfuric acid. Fluorine-lined pump F46 is a more economical option. The company's products are fluorine plastic alloy pump series fluoroplastic alloy magnetic pump CQBF fluorine alloy magnetic pump VYF fluoroplastic reinforced alloy liquid pump VFS fluoroplastic reinforced alloy centrifugal pump VFS fluorocarbon pump IHF fluoroplastic reinforced alloy centrifugal pump
Most of the metal materials of hydrochloric acid are not resistant to hydrochloric acid corrosion, including various stainless steel materials containing molybdenum and high silicon iron, and can also be used only for hydrochloric acid at 50 ° C or lower. Contrary to metal materials, most non-metallic materials have good corrosion resistance to hydrochloric acid. Therefore, rubber pumps and plastic pumps such as polypropylene and fluoroplastics are the best choice for transporting hydrochloric acid.
Most of the nitric acid metals are quickly corroded in nitric acid. Stainless steel is the most widely used nitric acid resistant material. It has good corrosion resistance to all concentrations of nitric acid at normal temperature. It is worth mentioning that molybdenum-containing stainless steel such as 316, 316L is suitable for nitric acid. Corrosion resistance is not only not superior to ordinary stainless steel such as 304, 321 and sometimes even worse. For high-temperature nitric acid, titanium and titanium alloy materials and fluoroplastic alloy pump series are generally used.
Acetic acid It is one of the most corrosive substances in organic acids. Ordinary steel is severely corroded in acetic acid of all concentrations and temperatures. Stainless steel is excellent resistance to acetic acid. Molybdenum-containing 316 stainless steel is also suitable for high temperature and dilute acetic acid vapor. High-alloy stainless steel or fluoroplastic pumps are available for high temperature, high concentration acetic acid or other corrosive media.
Alkali sodium hydroxide steel is widely used in sodium hydroxide solution below 30 ° C and 30 concentrations. Many factories still use ordinary steel at 100 ° C and below 75, although the corrosion is increased but the economy is good. The corrosion resistance of ordinary stainless steel to lye has no obvious advantages compared with cast iron. As long as a small amount of iron is allowed in the medium, it is recommended to use stainless steel. For high-temperature alkaline liquids, titanium and titanium alloys or both high-alloy stainless steels are used. Generally, cast iron pumps can be used for various types of stainless steel pumps or fluoroplastic pumps when used at room temperature and low concentration alkali.
Most of the metals and non-metals in ammonia ammonia are slightly corrosive in liquid ammonia and ammonia ammonia. Only copper and copper alloys should not be used. Many of our corrosion-resistant chemical pumps are suitable for use.
Salt water seawater ordinary steel in the sodium chloride solution and seawater, salt water corrosion rate is not high generally need to use paint to protect all types of stainless steel also has a low uniform corrosion rate but may cause local corrosion due to chloride ions. Usually 316 stainless steel is better.
Alcohols, ketones, esters, and ethers are commonly used in alcohols such as methanol, ethanol, ethylene glycol, and propanol. There are various esters such as acetone and methyl ethyl ketone, and various methyl esters and ethyl esters. Ether media such as methyl ether, ether, dibutyl ether, etc., which are basically free of corrosive materials, can be used for specific selection, and should be made according to the properties of the medium and related requirements. It is also worth noting that ketones and ester ethers have solubility in a variety of rubbers. Avoid mistakes when selecting sealing materials.
Sealing problem
Sealing form For static sealing, there are usually only two types of gaskets and sealing rings, and the sealing ring is the most widely used. For dynamic sealing, chemical pumps rarely use packing seals, mechanical seals, mechanical seals, single-end and double-end, balance. Type and non-equilibrium type flat and thin type Suitable for high pressure medium sealing Generally refers to pressure greater than 1.0MPa double end machine seal is mainly used for high temperature, easy to crystallize, have viscosity, contain particles and toxic volatilized medium double end machine seal should be oriented The pressure of the insulating liquid injected into the sealed chamber is generally higher than the medium pressure of 0.07-0.1MPa.
Sealing material chemical pump static sealing material is generally used in the special case of fluoro rubber. The material configuration of the mechanical seal of the PTFE is the key. The harder alloy is the best price for the hard alloy. On the one hand, there is no hardness. The difference is not reasonable, so it is best to treat it differently according to the characteristics of the medium.
Viscosity problem The viscosity of the medium has a great influence on the performance of the pump. When the viscosity increases, the lift curve of the pump drops. The optimum head and flow rate decrease, and the power increases, so the efficiency decreases. The parameter on the general sample is the performance when conveying clean water. When the viscous medium is transported, the correction coefficient of different viscosity should be converted. Refer to the relevant conversion chart. Screw pump rotor pumps are recommended for the transport of higher viscosity pulps, pastes and viscous liquids. The petroleum and chemical industries occupy a very important position in the national economy. Chemical process pumps are also receiving more and more attention as key supporting equipment. Due to the intricate nature of chemical media and the increasing requirements for environmental protection and equipment energy consumption, as a chemical manufacturer, Zhonglian Pump Industry should focus on which aspects of chemical pump selection should be focused on, etc. It is particularly important. Now combined with the characteristics of most chemical companies, a brief review of the selection of common chemical pumps hopes to benefit our customers in this field.
