外文翻译 气体传感器.doc

英 文 翻 译系 别专 业班 级学生姓名学 号指导教师 Gas sensor Gas sensor is a gas volume fraction will be a corresponding electrical signal into the converter. The first sensor to detect the gas through the gas sample conditioning, usually including interference filter out impurities and gases, drying or cooling to deal with instrument display Gas sensor is a component of the gas concentration and other information can be converted into personnel, instrumentation, computers and other devices that use the information! Gas sensors are generally classified as a class of chemical sensors, although this classification does not necessarily science. "Gas sensor", including: semiconductor gas sensors, electrochemical gas sensors, catalytic combustion gas sensor, thermal conductivity gas sensors, infrared gas sensors. The application of gas sensors mainly include: carbon monoxide gas detection, gas detection, gas detection, freon11, R12 greasewood alcohol detection in the detection, exhale, human oral bad breath test and so on.Its species and information related to the concentration of the gas is converted into electrical signals according to the strength of these electrical signals can gain associated with the presence of gas under test in the environment of information which can detect, monitor, alarm, can also through the interface circuit and the computer automatic detection, control and alarm system.Different in nature, because there are so many types of gas can not use a sensor to detect all kinds of gas so can realize gas electricity transformation has a variety of sensors according to form gas sensor materials can be divided into two categories, semiconductor and semiconductor.Actually use at present most is the semiconductor gas sensor, therefore this article mainly tells about the principle and application of semiconductor gas sensitive element.Semiconductor gas sensor is used for measuring gas in contact with the surface of the semiconductor, changes in physical properties such as conductivity to detect gas.According to the interaction between semiconductor and gas changes limited to the semiconductor surface or internal, go deep into the semiconductor surface can be divided into the control model and control model, the former occur between semiconductor surface adsorption of gases and semiconductor electronic acceptance, the result makes the conductivity of the semiconductor and other physical properties to change, but the internal chemical composition is constant, the semiconductor and the reaction of the gas, the semiconductor of internal change and make the conductivity changes.According to the change of semiconductor physics and can be divided into resistance and resistance, resistance type semiconductor gas sensitive element is to use when contacting gas sensitive material, its resistance changes to test the composition or concentration of the gas plant type semiconductor gas sensor is based on gas adsorption and reaction, make its some relations characteristics of directly or indirectly change the corrosive gas detection, such as diode volt-ampere characteristics and the change of threshold voltage of the mosfet to detect the gas being measured. The harmful gas alarm to prevent gas leakage as a powerful weapon, it has, however, does not seem to have attracted the attention it deserves. This security and household fire extinguishers can be placed on a par, or even more than the fire extinguisher into the family of the little things that most families do not see it as one thing, do not even know there can be such a fundamental solution to gas poisoning and gas explosion, "the protection of God" exists. Shanghai as an example, last year, due to poisoning and cooking gas water heater overflow out, piece of rubber hose off the aging caused by gas leakage and poisoning caused by a total of 86 deaths, accounting for all the gas data of accidents were 84%. However, according to an authoritative department to another survey released shows that in Shanghai, about three million gas users, the installation of domestic gas leakage alarm of less than 10%. In their daily lives, whether it is gas poisoning or gas explosion, because of gas leak into the sky. Home life, no one is inseparable from the use of gas, no matter what you do more preventive measures, but a hundred secret inevitably very careful, not to mention of any fire safety measures are not taken on even more dangerous family. Therefore it is necessary to prepare a The harmful gas alarm at home at any time for the owner guardian of the gas appliances, a gas alert to this invisible killer slipped quietly out to help the owner of the elimination of family problems in the bud, the domestic security of the good housekeeper, so that family members with the use of gas, the use of hearts at ease. For example, there are many families of fire gas explosion, do not know in the room full of gas leaking out, the blind use of electrical switches and tragedy in an instant, if there is an alarm, a tragedy like this can be greatly avoided. For the production of all kinds of different occasions and testing requirements, select the appropriate gas detector is every personnel engaged in the work of safety and health must be very attention.Here we will discuss some specific situation to do a introduction, for your reference. 1.confirm the types and to detect the gas concentration range: Each production unit of gas species are different.When choosing gas detector will consider all possible situation.If the methane and other lower toxicity of alkane, choose LEL detector is undoubtedly the most appropriate.This not only because the LEL detector principle is simple, widely used, at the same time it also has a convenient maintenance and calibration.If the toxic gases such as carbon monoxide, hydrogen sulfide, will give preference to a particular gas detector can ensure the safety of the workers.If more is organic toxic or harmful gases, considering its personnel may cause poisoning concentration is low, such as aromatic hydrocarbon, halogenated hydrocarbon, ammonia (amine), ether, alcohol, fat, etc., should choose the light of the previous chapter ionization detector, and never use LEL detector to deal with, because this may lead to loss of life. If gas species covered above a few kinds of gas, choosing a composite gas detector could reach twice the result with half the effort. 2.determine the occasions of use:Industrial environment different, choose different types of gas detector.a.fixed gas detector: This is in the industrial device and detector used in production.It can be installed on the specific testing point of specific gas leak detection.Fixed detector for two postures, commonly consists of sensor and transmitting test head for installation in test site, the integrated circuit, power supply and display alarm device of secondary instrument for installation in a safe place, easy to monitor.Its detection principle with former mentioned in section, just on the process and technology is more suitable for fixed testing required by the continuous and stable for a long time, etc.They also want to choose, and according to the types of the gas concentration at the same time also notice them installed in a certain gas is most likely to leak parts, such as to choose according to the proportion of the gas sensors installed the height of the most effective and so on. b. portable gas detector: Because of the portable instrument is easy to operate, small size, can carry to different production area, electrochemical detector using alkaline batteries, can be used for 1000 hours;New LEL detector, PID, and compound instruments use rechargeable batteries (some nimh or lithium ion battery has no memory), that they can generally work almost 12 hours in a row, so, as this type of equipment in all kinds of plants and the application of the health sector is more and more widely. Be used to take their dispersive gas detector, continuous, real-time, because it can accurately show the scene of the concentration of poisonous and harmful gases.This kind of new instruments have equipped with vibration alert attachment - to avoid heard no sound alarm in a noisy environment, and install a computer chip to record peak, STEL short-term exposure levels (15 minutes) and TWA (statistical weighting average 8 hours) - provide specific guidance for worker health and safety. If it is to enter confined Spaces, such as reaction tank, storage tank or vessel, drains or other underground pipes, underground facilities, agricultural airtight Yun Huo Cang granary, railway tank car, ship, tunnel, such as workplace, before the personnel to enter, it is necessary to detect, and outside confined space for testing.At this point, you have to choose more gas detector with a built-in sampling pump.Because of different parts in confined Spaces (below), which the gas distribution and gas species are quite different.For example, a general sense of the proportion of combustible gas lighter, most of them distributed in the upper part of the closed space;The proportion of carbon monoxide and air, general distribution in the middle of enclosed Spaces;While the heavier gases, such as hydrogen sulfide, exist in the lower part of the confined space (as shown).At the same time, the oxygen concentration is must to test for a variety of.In addition, if considering the organic material tank may be volatile and leak, one can detect organic gas detector is needed.Therefore a complete airtight space gas detector should be the one who has a built-in pump suction function, so that you can not contact, parts detection;With multiple gas detection function, in order to detect the danger of the spatial distribution of different gas, including inorganic and organic gas;With oxygen detection function, prevent oxygen or oxygen enrichment;Small size, does not affect the workers of the portable instrument.Only in this way can ensure the employees entering the confined space is absolutely safe. In addition, after entering confined Spaces, but also on the gas content of continuous testing, in order to avoid because of the personnel to enter, sudden leakage, temperature changes, such as volatile organic compounds or other poisonous and harmful gas concentration changes. If used for emergency accidents, leak detection and tour, you should use the pump suction, short response time, high sensitivity and resolution of the instrument, so that we can easily determine the orientation of the leak.In the case of detection of industrial hygiene and health surveys, data records and statistics calculation and can join computer functions such as instrument application is very convenient. At present, with the development of manufacturing technology, more portable gas detector (compound) is one of our new options.Because of this detector can be equipped with the required in a host of multiple gas detection sensor (inorganic/organic), so it has small volume, light weight, fast accordingly, for the characteristics of gas concentration shows at the same time.And, more importantly, the price of pump suction compound gas detector is better than the single dispersive gas detector is cheaper, use rise more convenient also.It is important to note when choosing this type of detector, had better choose to have a separate switch function of each sensor equipment, in order to prevent the damage due to a sensor influence other sensors use.At the same time, in order to avoid jams getter pump situation such as water, choose to have stopped pump alarm intelligent pump design of instrument will be safer Harmful gas alarm into household and industrial production, will become the good assistant of production safety of life, it is indisputable fact.Product Description: Detection of gas: natural gas, liquefied petroleum gas, city gas (H2)Size: 115mm * 71mm * 43.3mm(1) add automatic sensor drift compensation, the real and omitted to prevent the false positives.(2) The failure prompted the police to enable the user to replace and repair, to prevent the non-reported.(3) MCU control the entire process, working temperature -40 degrees to 80 degrees. Operating voltage: 220VAC or 110VAC, 12VDC-20VDCAdditional features: linkage exhaust fan, the manipulator, the solenoid valveNetworking: wired networking functions: (NO, NC)Wireless networking: 315MHZ/433MHZ (2262 OR 1527) 气体传感器 气体传感器是一种将某种气体体积分数转化成对应电信号的转换器。探测头通过气体传感器对气体样品进行调理，通常包括滤除杂质和干扰气体、干燥或制冷处理仪表显示部分 气体传感器是一种将气体的成份、浓度等信息转换成可以被人员、仪器仪表、计算机等利用的信息的装置！气体传感器一般被归为化学传感器的一类，尽管这种归类不一定科学。 “气体传感器”包括：半导体气体传感器、电化学气体传感器、催化燃烧式气体传感器、热导式气体传感器、红外气体传感器等。气体传感器的应用主要有：一氧化碳气体的检测、瓦斯气体的检测、煤气的检测、氟利昂勠11、R12蓠检测、呼气中乙醇的检测、人体口腔口臭的检测等等。它将气体种类及其与浓度有关的信息转换成电信号根据这些电信号的强弱就可以获得与待测气体在环境中的存在情况有关的信息从而可以进行检测、监控、报警还可以通过接口电路与计算机组成自动检测、控制和报警系统。 由于气体种类繁多, 性质各不相同不可能用一种传感器检测所有类别的气体因此能实现气-电转换的传感器种类很多按构成气体传感器材料可分为半导体和非半导体两大类。目前实际使用最多的是半导体气体传感器因此本文主要讲述半导体气敏元件的有关原理及应用。半导体气体传感器是利用待测气体与半导体表面接触时，产生的电导率等物理性质变化来检测气体的。 按照半导体与气体相互作用时产生的变化只限于半导体表面或深入到半导体内部，可分为表面控制型和体控制型，前者半导体表面吸附的气体与半导体间发生电子接受，结果使半导体的电导率等物理性质发生变化，但内部化学组成不变，后者半导体与气体的反应，使半导体内部组成发生变化而使电导率变化。 按照半导体变化的物理特性，又可分为电阻型和非电阻型，电阻型半导体气敏元件是利用敏感材料接触气体时，其阻值变化来检测气体的成分或浓度厂半导体式气敏元件则是根据气体的吸附和反应，使其某些关系特性发生改变无对气体进行直接或间接的检测，如二极管伏安特性和场效应晶体管的阈值电压变化来检测被测气体的。 有害气体报警器作为预防燃气泄漏的有力武器，它的出现却似乎并没有引起人们应有的注意。这个在安全防护上可以和家用灭火器相提并论、甚至比灭火器更需要进入家庭的小东西，大多数家庭根本没有把它当一回事，甚至不知道还有这样一个可以从根本上解决煤气中毒和煤气爆炸的"保护神"存在。以上海为例，去年因热水器废气中毒及灶具溢熄、橡皮管老化脱落引起的燃气泄漏和造成中毒死亡的共86人，占全部燃气事故死亡人数据的84%。但据权威部门公布的另一项调查表明，在上海市300万左右的燃气用户中，安装家用燃气泄漏报警器的不足10%。 在日常生活中，无论是煤气中毒还是煤气爆炸事故，都因煤气泄漏而起。居家过日子，谁都离不开使用煤气，无论你的预防措施做得多好，但百密难免一疏，更何况对消防安全不采取任何措施的家庭就更加危险。因此很有必要在家里准备一个有害气体报警器，随时替主人守护着燃气用具，时刻警惕着燃气这个无形杀手悄悄溜出来，帮助主人将家庭隐患消灭在萌芽之际，成为家庭安全的好管家，让家人使用燃气具时，用得安心放心。例如有很多的家庭煤气爆炸火灾，都是在不知道房间里充满了泄露出来的煤气，盲目动用电器开关而在瞬间发生的悲剧，如果有一个报警器，类似这样的悲剧就可以大大避免。对于各类不同的生产场合和检测要求，选择合适的气体检测仪是每一个从事安全和卫生工作的人员都必须十分注意的。这里我们将就一些具体情况做一介绍，供大家参考。1.确认所要检测气体种类和浓度范围：每一个生产部门所遇到的气体种类都是不同的。在选择气体检测仪时就要考虑到所有可能发生的情况。如果甲烷和其它毒性较小的烷烃类居多，选择LEL检测仪无疑是最为合适的。这不仅是因为LEL检测仪原理简单，应用较广，同时它还具有维修、校准方便的特点。如果存在一氧化碳、硫化氢等有毒气体，就要优先选择一个特定气体检测仪才能保证工人的安全。如果更多的是有机有毒有害气体，考虑到其可能引起人员中毒的浓度较低，比如芳香烃、卤代烃、氨(胺)、醚、醇、脂等等，就应当选择前章介绍的光离子化检测仪，而绝对不要使用LEL检测器应付，因为这可能会导致人员伤亡。如果气体种类覆盖了以上几类气体，选择一个复合式气体检测仪可能会达到事半功倍的效果。2.确定使用场合：工业环境的不同，选择气体检测仪种类也不同。a.固定式气体检测器：这是在工业装置上和生产过程中使用较多的检测器。它可以安装在特定的检测点上对特定的气体泄漏进行检测。固定式检测器一般为两体式，有传感器和变送组成的检测头为一体安装在检测现场，有电路、电源和显示报警装置组成的二次仪表为一体安装在安全场所，便于监视。它的检测原理同前节所述，只是在工艺和技术上更适合于固定检测所要求的连续、长时间稳定等特点。它们同样要根据现场气体的种类和浓度加以选择，同时还要注意将它们安装在特定气体最可能泄漏的部位，比如要根据气体的比重选择传感器安装的最有效的高度等等。b.便携式气体检测器：由于便携式仪器操作方便，体积小巧，可以携带至不同的生产部位，电化学检测仪采用碱性电池供电,可连续使用1000小时;新型LEL检测仪、PID和复合式仪器采用可充电池(有些已采用无记忆的镍氢或锂离子电池)，使得它们一般可以连续工作近12小时，所以，作为这类仪器在各类工厂和卫生部门的应用越来越广。如果是在开放的场合，比如敞开的工作车间使用这类仪器作为安全报警，可以使用随身佩戴的扩散式气体检测仪，因为它可以连续、实时、准确地显示现场的有毒有害气体的浓度。这类的新型仪器有的还配有振动警报附件以避免在嘈杂环境中听不到声音报警，并安装计算机芯片来记录峰值、STEL(15分钟短期暴露水平)和TWA(8小时统计权重平均值)为工人健康和安全提供具体的指导。如果是进