With the development of the national economy, the status of the petroleum, chemical industry, more and more significant as the key equipment of chemical pumps more and more people's attention. Due to corrosion and chemical medium stringent environmental requirements, how to correct chemical pump selection becomes a potential problem customers, following by professional chemical resistant pump manufacturers in Wenzhou Valve Co., Ltd. for you to solve some common chemical pump selection type problems.

          Corrosion problems

          All along, the corrosion is one of the most headache hazards of chemical equipment, the slightest mistake, ranging from damage to equipment, while causing the accident and even lead to disaster. According to statistics, the destruction of chemical equipment, about 60% is due to corrosion caused by chemical pump selection so when first pay attention to the selection of scientific. Usually there is a misunderstanding that the stainless steel is universal, no matter what the media and environmental conditions are ushering in an era of stainless steel, which is very dangerous. Here to talk about for some commonly used chemical medium selection of key points:

          1. As one of the highly corrosive sulfuric acid medium, sulfuric acid is the use of very wide range of important industrial raw materials. Different concentrations and temperatures of sulfuric acid corrosion of materials vary greatly, for concentrations above 80% and a temperature of 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 valve materials; ordinary stainless steel such as 304 (0Cr18Ni9), 316 (0Cr18Ni12Mo2Ti) limited use of sulfuric acid medium. Therefore transport sulfuric valve usually high silicon cast iron (casting and machining difficult), high-alloy stainless steel (Alloy 20) manufacturing, but its processing difficulty Japan is expensive, so people are not optimistic. Fluorine plastic alloy has good performance good resistance to sulfuric acid, which is the Shanghai Institute of Organic Chemistry, Chinese Academy of patented materials, the company introduced in 1985, patented technology, first with its development and production of corrosion-resistant chemical pumps, proved by the Chinese Academy of Sciences, What is not yet able to respond to their chemical medium, so the use of fluorine pump (F46) is a more economical choice. The company applies to products: IHF fluorine pump, FSB strong corrosion-resistant centrifugal pumps, IMD fluorine plastic magnetic pumps.

          2. HCl overwhelming majority are intolerant of hydrochloric acid corrosion of metallic materials (including stainless steel), containing molybdenum high ferrosilicon is only available for 50 ℃, 30% less hydrochloric acid. And metal materials contrary, most non-metallic materials of hydrochloric acid has good corrosion resistance, so the rubber lined pumps and plastic pump (such as plastic, fluorine plastic, etc.) is the best choice for transporting hydrochloric acid. The company applies to products: CQB-F fluorine plastic leak acid pump, CQF engineering plastic magnetic pump (or fluorine plastic magnetic pump) and so on.

          3. It is one of acetic acids in the most corrosive substances, ordinary steel in all the acetic acid concentration and temperature will be severe corrosion, acid-resistant stainless steel is an excellent material, 316 stainless steel containing molybdenum also suitable for high temperature and dilute acetic acid vapor. For when demanding high temperature and high concentration of acetic acid or contain other corrosive media, etc., can use high-alloy stainless steel or fluorine plastic pump. As CQB magnetic pump, CQ stainless steel magnetic pump.

          4. Most of the general metal nitrate in nitric acid was rapidly corrosion 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 that the molybdenum-containing stainless steel (such as 316,316L) nitric acid corrosion resistance is not only no better than ordinary stainless steel (eg 304,321), and sometimes even better. For hot nitric acid, usually fluorine plastic alloy material. The company applies to products: CQB-F fluorine plastic alloy magnetic pump, FSB fluorine alloy pump and so on.

          5. alkali (sodium hydroxide) is generally not very strong corrosive, but generally will produce crystalline alkali solution, so you can choose to configure silicified material graphite mechanical seal 169 FSB fluorine alloy base pump.

          6. ammonia (ammonium hydroxide) to most metals and non-metallic corrosion in liquid ammonia and ammonia (ammonium hydroxide) in a very small, only copper and copper alloys should not be used. Most of the company's products suitable for ammonia and ammonia transport. CQF engineering plastics such as magnetic pump, FSB fluorine alloy pump better.

          7. saline (seawater) ordinary steel in sodium chloride solution and water, salt water corrosion rate is not too high, generally shall paint protection; all kinds of stainless steel also has a very low uniform corrosion rate, but may be due to chloride ions and cause localized corrosion, usually 316 stainless steel is better. The company has 316 kinds of chemical materials pump configurations, such as IH chemical centrifugal pump.

          8. alcohols, ketones, esters, ethers common alcoholic medium methanol, ethanol, ethylene glycol, propanol, etc., ketones media acetone, methyl ethyl ketone, etc., esters of methyl various media, ethyl ester, ether media have ether, ethyl ether, butyl ether, etc., which basically is not strong corrosive, so can use an ordinary stainless steel, but also to make a rational choice based on media properties and related requirements specific choice. Also worth noting is that ketones, esters, ethers, for a variety of rubber have solubility, in the choice of the sealing material to avoid making mistakes. Recommended to choose inorganic fluorine plastic magnetic pump seal.

There are many other media can not introduce them all here, in short, must not be arbitrary and blind, should be more access to relevant information or learn mature experience in the selection.

          Sealing problems

          No leakage is always the pursuit of chemical equipment, it is this requirement led to expanding the application of magnetic pump. But truly no leakage is still a long way to go, such as magnetic pump isolation sets life issues, pitting the issue of materials, static sealing reliability problems and so on. Now on some basic aspects of the seal briefly as follows:

          1. Seal form for static seal, it is usually only two forms of gaskets and seals, O-rings and seals again the most widely used; for dynamic sealing, chemical pumps rarely used packing seals, mechanical seals primarily Mechanical seals have a single face and double face, balanced and unbalanced type of points, balanced for high pressure sealing medium (usually refers to a pressure greater than 1.0MPa), double-end mechanical seal is mainly used for high temperature, easy to crystallize, there viscosity, containing particles and toxic volatile media, double-end mechanical seal should seal spacer fluid injected into the cavity, the pressure is generally higher than the medium pressure 0.07 ~ 0.1MPa.

          2. sealant chemical magnetic pump static sealing materials commonly used fluorine rubber, special circumstances the use of PTFE material; material configured mechanical seal ring movement is more critical, it is best not carbide cemented carbide, high prices on the one hand, there is no difference in hardness between the two is also unreasonable, so it is best to treat the difference according to the media characteristics.

Viscosity problems

Affect the viscosity of the medium on pump performance is great, when the increase in viscosity, the pump head curve down the best condition of head and flow all fall, and the power will rise, thus reducing efficiency. Samples are general parameters on the performance of water during transport, when pumping viscous media should be scaled (different viscosity correction factor can be found in the relevant conversion chart). For transporting high viscosity slurries, pastes and viscous fluids, suggested the use of mortar pump, suitable for medium with viscosity or with particles.

          Pump selection principle

          1, so that the type and performance to meet the requirements of the selected pump unit flow, head, pressure, temperature, NPSH, suction and other process parameters.

          2, must meet the requirements of the transport properties of the medium flammable, explosive and toxic or expensive media pump, requiring reliable or pump seal leak-free, such as magnetic drive pump (no seal, the use of isolated magnetic indirect drive) for delivery pump corrosive media, require the use of corrosion-resistant material convection components, such as fluorine plastic corrosion resistant pumps for conveying media containing solids pumps require convective component wear-resistant material, if necessary, by the use of clean 
          liquid seal flushing.

          3, the mechanical requirements of high reliability, low noise, small vibration.

          4, the correct calculation of purchasing pump input costs, see: How to correctly calculate the cost of procurement of inputs pump.

          5, when transporting corrosive medium (such as concentrated sulfuric acid, concentrated nitric acid), when transporting explosive media, the use of the environment without any contamination: the choice of magnetic pump, such as CQB series magnetic pump, IMD series magnetic pump, such as need self-absorption, the choice FZB fluorine plastic pump.

          6, when the medium is liquid at the bottom of the pump installation location: FZB fluorine plastic pump should be used, such as the need to meet the characteristics of magnetic pump, the choice of ZMD fluorine plastic self-priming magnetic pump.

          7, when the transport medium containing solid particles of chemical pumps, require convection member with wear-resistant materials: UHB mortar pump is the best choice of the object, UHB corrosion resistant materials for high-strength mortar pump new engineering plastics UHBWPE, it is a change of ultra-high molecular weight (over 5 million) polyethylene. In plastics, it has excellent wear resistance, experimental comparison, it is much higher than the wear resistance of stainless steel, and impact resistance, creep resistance and excellent corrosion resistance (and quite F4), and no Unique properties of adhesion and the like.

          8, IHF and FSB centrifugal pump centrifugal pump with high speed, small size, light weight, high efficiency, large flow, simple structure, no pulse infusion, steady performance, easy operation and maintenance of convenient features, such as the use conditions without special requirements , the choice of a centrifugal pump better.