Chemical pump selection points

Large selection of chemical pumps, many people both in the media and environmental conditions are made of stainless steel, it is not precise. The choice of overcurrent material is not only based on the nature of the medium, but also the effect of medium temperature and concentration on the corrosion of the material, as well as the choice of material with good cost performance, so the material selection is complicated. Following a brief summary of some of the commonly used chemical media on pump selection points. 1 Sulfuric acid General carbon steel and cast iron materials have better corrosion resistance of concentrated sulfuric acid, iron and concentrated sulfuric acid on the surface to generate ferric sulfate protective film and should not be dissolved, so at room temperature for concentrated sulfuric acid (concentration of 90% or more) in general Manufacturers from the economic point of view to use more cast iron materials. Strictly speaking, carbon steel and cast iron are not suitable for high-speed flowing sulfuric acid and therefore are not suitable for use as a pump material; stainless steel 304 (OCrl8Ni9), 316 (OCrl7Nil2M02) and 316L (OCrl8Nil2M02Ti) are also not ideal materials. From the material, the delivery of sulfuric acid should be used nickel cast iron (STNiCr202), Hastelloy (nickel-chromium-titanium molybdenum alloy) and other materials, but the casting and processing of nickel cast iron and other difficult. In contrast, fluoroplastics have better sulfuric acid resistance, therefore, the use of fluorine-fluorine pump (F46) is an economical choice. When using small flow head, we generally choose IHF lining fluorine pump, CQF fluorine plastic (F46) magnetic pump, etc. For large flow head, we require IH, SLZA and SLCZ chemical pump head material made of nickel cast iron, nickel cast iron material The price is 4 to 5 times the ordinary cast iron. Hastelloy higher prices, generally not recommended. For media containing larger particles of fluid, we generally use SLZAO pump. The power of the motor should be the product of the normal power and the relative water density ratio of concentrated sulfuric acid to prevent the motor from overloading. Hydrochloric acid Most metal materials (including stainless steel materials) are not resistant to hydrochloric acid corrosion. The vast majority of non-metallic materials have good hydrochloric acid corrosion resistance, such as lined with rubber pumps and plastic pumps (such as polypropylene, fluoroplastic, etc.) are the best choice for the delivery of hydrochloric acid. Therefore, we generally use: IHF lining pump, CQF fluorine plastic magnetic pump, CQ enhanced polypropylene (PP) magnetic pump. 3 Nitric acid Most metals are mostly corrosive in nitric acid, but stainless steel has good corrosion resistance to all concentrations of nitric acid at 80 ° C. It is the most widely used nitric acid resistant material so long as the overcurrent unit is a 304 pump Selection, such as: IH pump, I pump SLZA pump, SLOW stainless steel pumps. 4 phosphoric acid over-current components generally use 316L material. Because 904 or 904L price is too high, high silicon cast iron (STSil5R), high chromium cast iron (Cr28) processing more difficult, so do not use. If the media has larger particles, it is advisable to use a 316L SLZAO pump. 316L material price is 304 1.6 times, SLOW 316L price is 304 2.5 times. 5 hydrofluoric acid has great toxicity, requires no leakage, so we can only choose non-sealed structure, magnetic drive pump is the most economical choice, but over-current part can not choose F46 or ceramic, because of susceptibility to HF corrosion , Generally we use 304 material. 6 acetic acid It is one of the most corrosive substances in organic acids, ordinary steel will be corroded in acetic acid, stainless steel is an excellent acetic acid-resistant material, 316 stainless steel can also be suitable for high temperature and dilute acetic acid vapor, the price of 316 is 304 Of 1.5 times; for high temperature and high concentration of acetic acid or other corrosive media containing harsh requirements, the choice of IHF, CQF fluorine plastic pump or 316L pump material. 7 Strong bases (sodium hydroxide, potassium hydroxide, etc.) Stainless steel and cast iron are widely used in sodium hydroxide solution below 80 ℃ and 30% concentration. Many factories use common steel at below 100 ℃ and 75% Corrosion increases but economy is good. Selection, the general cast iron pump can be used for low temperature and low concentration of lye, special requirements can be used various types of stainless steel pump or IHF, CQF and other fluorine plastic pump. 8 Ammonia (ammonia hydroxide) is a weak base. Most metals and non-metals are slightly corroded in liquid ammonia and ammonia (ammonia hydroxide). Only copper and copper alloys should not be used. 9 Saline (seawater) Ordinary steel corrosion rate in sodium chloride solution and seawater, salt water is not too high, all kinds of stainless steel has a very low rate of uniform corrosion, sometimes using nickel-chromium cast iron (containing 2 to 3% nickel) as Flow components, the more commonly used is 304 stainless steel, but some users stress may be due to chloride ions caused by localized corrosion, so conservative, we will use 316 material. 10 alcohols, ketones, esters, ethers common alcohol medium with methanol, ethanol, ethylene glycol, propanol, ketone medium with acetone, butanone and so on, esters of various methyl ester media, B Esters, ethers medium ether, ether, butyl ether, etc. They are basically non-corrosive, common materials are applicable, the specific selection should also be based on the media properties and related requirements to make a reasonable choice. It is also noteworthy that ketones, esters, ethers are soluble in a wide variety of rubbers and avoid mistakes when selecting sealing materials. 11 oil products SLZA, SLCZ and other chemical process pump is mainly used for petroleum products. The type selection needs to consider the viscosity, density and temperature of such media. For some mediums which are cold and condense into blocks, the heating device and the thermal insulation jacket need to be used. The power of the motor should be the product of the relative power density and the relative water density ratio , To prevent overloading motor overload. The use of insulation jacket need to go up 20%. For medium containing larger particles of fluid, we generally use SLZAO pump, because it is semi-open impeller, over-flow ability, note that: As the semi-open impeller pump efficiency is slightly lower than the closed impeller pump, so you need Need to increase the power when the motor with a file. In addition, for the viscosity of the media, we recommend the selection of G-type screw pump, (K) CB gear pump. In addition, there is a simple selection method, that is, according to the material of the pipe selection pump material. If the pipe is made of cast iron, we can directly select the cast iron pump, without having to consider in depth the corrosiveness of the medium. With the improvement of production environment, modern enterprises require no leakage of production sites. Chemical pumps are used mechanical seal, chemical pump mechanical seal in the use of the process, due to the special nature of the media and diversity, the need for regular maintenance and repair. According to different conditions of use to install a different mechanical seal. Such as built-in single-end balanced and unbalanced, double-ended balanced and unbalanced, external mechanical seal. Chemical pump mechanical seal in the selection, methods of use and precautions are also different: General mechanical seal is generally suitable for use in clean, non-suspended particles in the media, therefore, the newly installed piping systems and storage irrigation should be Seriously clean, prevent solid impurities from entering the mechanical seal face and seal failure. In the crystallization of the medium (such as salt) the use of mechanical seal should be noted that regular washing. Before restarting the parking, the mechanical seal should be cleaned; the mechanical seal should be carefully removed, not allowed to hammer with hand hammer, iron, etc., so as not to damage the sealing surface of the moving and static ring; if the dirt can not be removed, should Try to remove dirt, rinse clean and then disassemble, so as not to damage the sealing components; installation of mechanical seals, should check all sealing components are invalid or damaged, if any, should be re-repair or replacement; should be strictly check the moving ring and the static ring Relative friction sealing surface, does not allow any minor scratches, bumps and other defects. All parts, including the pump body, impeller, sealed chamber, etc. should be washed before assembly, especially moving and stationary ring end surface, carefully clean with a clean, soft cloth or cotton yarn, then apply a layer of clean grease Or oil; attention should be paid to eliminate deviations in the assembly, tighten the screws should be evenly tightened to avoid deflection, the seal failure; the correct amount of compression spring, the pump installed after the hand to move [Procurement] Relay [Procurement 】 【Tool】 【Procurement】 fire pump 【Purchase】 Pump 【Purchase】 Proportional Amplifier 【Purchase】 Level Transmitter 【Procurement】 Regulating Valve 【Purchase】 Automated Staking Machine 【Purchase】 No Negative Pressure Frequency Conversion Water Supply Unit