原文：
石油化学工业在国民经济中占据非常重要的位置，化工流程泵作为关键配套设备也越来越受到人们的关注。由于化工介质的特性错综复杂，加之用户的要求不断提高，作为生产厂家，我们应如何选型？应重点注意哪些方面？…等等显得尤为重要。现结合公司相关产品特点以及个人的肤浅认识对常用化工泵的选型做一点简要评述，希望能有益于同仁在该领域更好地开展工作。 　　耐腐蚀问题 　　一直以来，腐蚀就是化工设备最xx的危害之一，稍有不慎，轻则损坏设备，重则造成事故甚至引发灾难。据有关统计，化工设备的破坏约有60%是由于腐蚀引起的，因此在化工泵选型时首先要注意选材的科学性。通常有一种误区，认为不锈钢是“{wn}材料”，不论什么介质和环境条件都捧出不锈钢，这是很危险的。下面针对一些常用化工介质谈谈选材的要点： 　　1.硫酸 　　作为强腐蚀介质之一，硫酸是用途非常广泛的重要工业原料。 不同浓度和温度的硫酸对材料的腐蚀差别较大，对于浓度在80%以上、温度小于80℃的浓硫酸，碳钢和铸铁有较好的耐蚀性，但它不适合高速流动的硫酸,不适用作泵阀的材料；普通不锈钢如304（0Cr18Ni9）、316（0Cr18Ni12Mo2Ti）对硫酸介质也用途有限。因此输送硫酸的泵阀通常采用高硅铸铁（铸造及加工难度大）、高合金不锈钢（20号合金）制造。氟塑料具有较好的耐硫酸性能，采用衬氟泵（F46）是一种更为经济的选择。公司适用产品有：IHF衬氟泵、PF(FS)强耐腐蚀离心泵、CQB-F氟塑料磁力泵等。 　　2.盐酸 　　决大多数金属材料都不耐盐酸腐蚀（包括各种不锈钢材料），含钼高硅铁也仅可用于50℃、30%以下盐酸。和金属材料相反，绝大多数非金属材料对盐酸都有良好的耐腐蚀性，所以内衬橡胶泵和塑料泵（如聚丙烯、氟塑料等）是输送盐酸的{zh0}选择。公司适用产品有：IHF衬氟泵、PF(FS)强耐腐蚀离心泵、CQ聚丙烯磁力泵（或氟塑料磁力泵）等。 　　3.硝酸 　　一般金属大多在硝酸中被迅速腐蚀破坏，不锈钢是应用最广的耐硝酸材料，对常温下一切浓度的硝酸都有良好的耐蚀性，值得一提的是含钼的不锈钢（如316、316L）对硝酸的耐蚀性不仅不优于普通不锈钢（如304、321），有时甚至不如。而对于高温硝酸，通常采用钛及钛合金材料。公司适用产品有：DFL(W)H化工泵、DFL(W)PH屏蔽化工泵、DFCZ流程泵、DFLZP自吸化工泵、IH化工泵、CQB磁力泵等，材料为304。 　　4.醋酸 　　它是有机酸中腐蚀性最强的物质之一，普通钢铁在一切浓度和温度的醋酸中都会严重腐蚀，不锈钢是优良的耐醋酸材料，含钼的316不锈钢还能适用于高温和稀醋酸蒸汽。对于高温高浓醋酸或含有其它腐蚀介质等苛刻要求时，可选用高合金不锈钢或氟塑料泵。 　　5.碱（氢氧化钠） 　　钢铁广泛应用于80℃以下、30%浓度内的氢氧化钠溶液，也有许多工厂在100℃、75%以下时仍采用普通钢铁，虽然腐蚀增加，但经济性好。普通不锈钢对碱液的耐蚀性与铸铁相比没有明显优点，只要介质中容许少量铁份掺入不推荐采用不锈钢。对于高温碱液多采用钛及钛合金或者高合金不锈钢。公司一般铸铁泵均可用于常温低浓度碱液，特殊要求时可采用各类不锈钢泵或氟塑料泵。 　　6.氨（氢氧化氨） 　　大多数金属和非金属在液氨及氨水（氢氧化氨）中的腐蚀都很轻微，只有铜和铜合金不宜使用。公司产品大多适用于氨及氨水的输送。 　　7.盐水（海水） 　　普通钢铁在氯化钠溶液和海水、咸水中腐蚀率不太高，一般须采用涂料保护；各类不锈钢也有很低的均匀腐蚀率，但可能因氯离子而引起局部性腐蚀，通常采用316不锈钢较好。公司各类化工泵都有316材料配置。 　　8.醇类、酮类、酯类、醚类 　　常见的醇类介质有甲醇、乙醇、乙二醇、丙醇等，酮类介质有丙酮、丁酮等，酯类介质有各种甲酯、乙酯等，醚类介质有甲醚、乙醚、丁醚等，它们基本没有腐蚀性，常用材料均可适用，具体选用时还应根据介质的属性和相关要求做出合理选择。另外值得注意的是酮、酯、醚对多种橡胶有溶解性，在选择密封材料时避免出错。 　　还有许多其它介质不能在此一一介绍，总之在选材时切不可随意和盲目，应多查阅相关资料或借鉴成熟经验。 冷却问题 　　高温介质的输送对泵的结构、材料以及辅助系统提出了更高要求，下面谈一谈不同的温度变化对冷却的要求以及公司适用泵型： 　　1.对于温度低于120℃的介质，通常不设置专门的冷却系统，多采用本身介质来润滑和冷却。像DFL(W)H化工泵、DFL(W)PH屏蔽化工泵(超过90℃时屏蔽电机的防护等级应采用H级)；而DFCZ普通型和IH化工泵由于采用了悬架结构可使温度上限达到140℃~160℃；IHF衬氟泵{zg}使用温度可达200℃；只有CQB普通磁力泵使用温度不超过100℃。值得一提是对于易结晶或含有颗粒的介质应配有密封面冲洗管路（设计时均留有接口）。 　　2.对于120℃以上、300℃以内的介质，一般在泵盖上须设有冷却腔，密封室也应接通冷却液（须配双端面机械密封），当不允许冷却液渗入介质中时，应采取将本身介质冷却后接入（可通过简易热交换器实现）。目前公司有DFCZ型化工流程泵、GRG高温管道泵以及HPK热水循环泵（正在开发）可供选用，另外CQB-G高温型磁力泵可用于280℃以内的高温介质。 　　3.对于300℃以上的高温介质，不仅 泵头部分需要冷却，悬架轴承室也应设有冷却系统，泵结构一般为中心支承形式，机械密封{zh0}采用金属波纹管型，但价格高（价格是普通机封的10多倍）。目前公司只有DFAY离心油泵使用温度能够达到420℃（正在开发）。 密封问题 　　无泄漏是化工设备的永远追求，正是这种要求促成了磁力泵和屏蔽泵的应用日益扩展。然而真正做到无泄漏还有很长的路要走，比如磁力泵隔离套和屏蔽泵屏蔽套的寿命问题、材料的孔蚀问题、静密封的可靠性问题等等。现就密封方面的一些基本情况简单介绍如下： 　　1.密封形式 　　对于静密封来说，通常只有密封垫和密封圈两种形式，而密封圈又以O型圈应用最广；对于动密封，化工泵很少采用填料密封，以机械密封为主，机械密封又有单端面和双端面、平衡型和非平衡型之分，平衡型适用于高压介质的密封（通常指压力大于1.0MPa），双端面机封主要用于高温、易结晶、有粘度、含颗粒以及有毒挥发的介质，双端面机封应向密封腔中注入隔离液，其压力一般高于介质压力0.07~0.1MPa。 　　2.密封材料 　　化工泵静密封的材料一般采用氟橡胶，特殊情况才采用聚四氟材料；机械密封动静环的材料配置较为关键，并不是硬质合金对硬质合金就{zh0}， 价格高是一方面，两者没有硬度差也并不合理，所以{zh0}根据介质特点区别对待。 　　（注：美国石油学会API 610第八版对机械密封和管路系统的典型配置在附录D中有比较详尽的规定） 粘度问题 　　介质的粘度对泵的性能影响是很大的，当粘度增加时，泵的扬程曲线下降，{zj0}工况的扬程和流量均随之下降，而功率则随之上升，因而效率降低。一般样本上的参数均为输送清水时的性能，当输送粘性介质时应进行换算（不同粘度的修正系数可查阅相关换算图表）。对于粘度较高的浆类、膏类及粘稠液的输送，建议选用螺杆泵，公司DFGG单螺杆泵适用介质粘度可达1000000cst。

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译文：
Petrochemical industry in the national economy occupies a very important position as a key chemical process pumps, ancillary equipment is also more and more attention. Because the characteristics of complex chemical medium, coupled with higher requirements of users as producers, how should we type selection? Attention should be focused on what? ... And so it is particularly important. Features are combined with the company related products, and superficial understanding of the individual selection of commonly used chemical pump do some brief comments, hoping to benefit colleagues in the field work better. Corrosion-resistant All along, the corrosion of chemical equipment is one of the most troublesome damage, a little careless, at worst damage to the device, while in the accident or even lead to disaster. According to statistics, chemical equipment, about 60% of the damage caused by erosion, so when the first selection in the chemical pump to pay attention to the scientific selection. Usually there is a misunderstanding, that steel is the "Universal", no matter what medium and environmental conditions are endorse steel, this is very dangerous. The following media to talk about for some commonly used chemicals Selection points: 1. Sulfuric acid As one of the strong corrosive medium, sulfuric acid is to use a very wide range of important industrial raw materials. Sulfuric acid concentration and temperature corrosion of materials vary greatly, for more than 80% concentration, the temperature below 80 ℃ of concentrated sulfuric acid, carbon steel and cast iron has better corrosion resistance, but it is not suitable for high-speed flow of sulfuric acid , not used as a valve material; ordinary stainless steel such as 304 (0Cr18Ni9), 316 (0Cr18Ni12Mo2Ti) have limited use of the sulfuric acid. Therefore, the valve is usually sulfuric acid delivery using high silicon cast iron (casting and machining difficult), high alloy stainless steel (Alloy 20) manufacturing. Fluorine plastic has good resistance to sulfuric acid properties, using fluorine pump (F46) is a more economical choice. Company applies to products: IHF fluorine pump, PF (FS) Strong corrosion-resistant centrifugal pumps, CQB-F fluorine plastic magnetic pumps. 2. Hydrochloride Most decisions are tiring of hydrochloric acid corrosion of metallic materials (including stainless), molybdenum is also only for high-ferrosilicon 50 ℃, 30% less hydrochloric acid. And metal materials contrary, the vast majority of non-metallic materials have good resistance to hydrochloric acid corrosion, the pump liner of rubber and plastic pumps (such as polypropylene, fluorine plastic, etc.) is the best choice for hydrochloric acid transport. Company applies to products: IHF fluorine pump, PF (FS) Strong corrosion-resistant centrifugal pump, CQ polypropylene magnetic pump (or fluorine plastic magnetic pumps) and so on. 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, all concentrations of nitric acid at room temperature have good corrosion resistance, it is worth mentioning that the molybdenum containing stainless steel (such as 316,316 L ) on the nitric acid corrosion resistance not only superior to ordinary stainless steel (eg 304,321), and sometimes even better. For high-temperature nitric acid, usually titanium and titanium alloy materials. Company applies to products: DFL (W) H chemical pump, DFL (W) PH shield chemical pump, DFCZ flow pump, DFLZP self-priming chemical pump, IH chemical pump, CQB magnetic pumps, material 304. 4. Acetate It is the most corrosive substances in organic acids, one of ordinary steel in all the acetic acid concentration and temperature will be severe corrosion, acid-resistant stainless steel is an excellent material, but also 316 stainless steel containing molybdenum for high temperature and dilute acetic acid vapor . For the high temperature and high concentration of acetic acid, or contain other corrosive media such stringent requirements may make use of high alloy stainless steel or fluorine plastic pump. 5. Alkali (sodium hydroxide) Steel is widely used in less than 80 ℃, 30% of the concentration of the sodium hydroxide solution, there are many factories in the 100 ℃, 75% is still below the ordinary steel, although the corrosion increased, but the economy is good. General corrosion resistance of stainless steel on the lye no significant advantages compared with cast iron, as long as the medium to allow incorporation of small amount of iron were made of stainless steel is not recommended. For the high-temperature alkaline to use more titanium and titanium alloy or high alloy stainless steel. Companies are generally of cast iron pumps can be used for low concentration of alkali at room temperature, special requirements can use all kinds of stainless steel pumps or fluorine plastic pump. 6. Ammonia (ammonium hydroxide) Most of the metal and nonmetal in liquid ammonia and ammonia (ammonium hydroxide) in the corrosion were slight, not only the use of copper and copper alloys. Most of our products suitable for the delivery of ammonia and ammonia. 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, usually in 316 stainless steel better. The company has 316 kinds of chemical materials pump configuration. 8. Alcohols, ketones, esters, ethers Common alcohols media are methanol, ethanol, ethylene glycol, propanol, etc., ketones medium with acetone, methyl ethyl ketone, etc., a variety of media methyl esters, ethyl ester, ether medium with ether, ethyl ether, ether, etc., they basically did not corrosive materials can be used for the specific use of the property should also be under the media and related requirements to make reasonable choices. Also noteworthy was the ketone, ester, ether a variety of rubber has dissolved, the choice of sealing materials to avoid mistakes. There are many other media can not be introduced in the 11, when a word must not be arbitrary in the selection and blind, should be more access to relevant information or learn from mature experience. Cooling problem Heat transport medium of the pump structure, materials and support systems put a higher demand, the following talk about the different requirements of temperature change on cooling and the company for pump: 1. For the temperature below 120 ℃ in the media, usually does not set a special cooling system, multi-media to use their own lubrication and cooling. As DFL (W) H Chemical pump, DFL (W) PH chemical pump shield (over 90 ℃, shielded motor protection level should be H-level); and DFCZ common type and IH chemical pump As a result of suspension structure will allow the temperature limit to 140 ℃ ~ 160 ℃; IHF fluorine pump maximum service temperature of 200 ℃; only CQB Magnetic Pump ordinary temperature does not exceed 100 ℃. It is worth mentioning is the easy to medium crystal or contain particles should be flush with the sealing surface pipeline (design are left interface). 2. For more than 120 ℃, 300 ℃ within the media, the general cooling in the pump chamber cover shall be provided with sealed room should also be connected to coolant (to be equipped with double mechanical seal), when not allowed when the cooling medium liquid infiltration should be taken to their cool media access (can be achieved by simple heat exchanger). The company has DFCZ type chemical process pump, GRG heat pumps and pipelines HPK hot water circulation pump (under development) are available for selection, another CQB-G High temperature magnetic pump can be used within 280 ℃ high temperature medium. 3. For more than 300 ℃ high temperature medium, not only the pump head part of the needs of the cooling, suspension bearings room should be a cooling system, pump structure supporting the general form for the center, preferably mechanical seals metal bellows type, but high price ( price is 10 times more common mechanical seal). The company only DFAY centrifugal pump temperature can reach 420 ℃ (under development). Seal of No leakage is always the pursuit of chemical equipment, it is this requirement led to shield pump magnetic pump and the application of ever-expanding. But really no leakage is still a long way to go, such as magnetic pump shield pump shield isolation kits and sets of life issues, pitting the material issues, and so the reliability of static sealing. The closed area are some basic brief is as follows: 1. Seal type For the static seal, usually only two types of gaskets and seals, and O-ring seals Youyi the most widely used; for dynamic sealing, chemical pump seal packing seldom used, mainly mechanical seals, mechanical seals it a single face and double-end, balanced and unbalanced type of points, balanced medium suitable for high pressure seal (usually a pressure greater than 1.0MPa), double-end machine is mainly used for high temperature sealing, easy to crystallize, with viscosity, with particles and toxic volatile media, double-face mechanical seal shall be sealed into the isolation chamber in the fluid, its pressure is generally higher than the medium pressure of 0.07 ~ 0.1MPa. 2. Sealing materials Chemical pump static sealing materials commonly used fluorine rubber, under special circumstances, use of PTFE material; mechanical seal ring material movement is more critical configuration is not the best of carbide carbide, high prices on the one hand, the two hardness difference between those who did not also unreasonable, so the best features of discrimination under the medium. (Note: American Petroleum Institute API 610 Eighth Edition of the mechanical seal and the pipe system typical configuration in more detail in Appendix D requirements) Viscosity problem Medium viscosity on pump performance impact is huge, as viscosity increases, the pump head curves down, the best conditions of the head and flow rate were decreased, while the power will rise, thus reducing efficiency. General samples are carrying water on the parameters of performance when, when handling viscous medium should be converted (different viscosity correction factor can be found related to conversion chart). The high viscosity slurries, pastes and viscous fluid type transmission, suggested the use of screw pump, screw pump for the company DFGG medium viscosity up to 1000000cst.