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温度钱汇娱乐的使用方法及常见误差问题解决方案

作者: 来源: 日期:2018-9-26 10:11:01 人气:114

温度钱汇娱乐是指能感受温度并转换成可用输出信号的钱汇娱乐。温度钱汇娱乐是温度测量仪表的核心部分,品种繁多。按测量方式可分为接触式和非接触式两大类,按照钱汇娱乐材料及电子元件特性分为热电阻和热电偶两类。

温度钱汇娱乐在安装和使用时,应当注意以下事项:

1、安装不当引入的误差

如热电偶安装的位置及插入深度不能反映炉膛的真实温度等,换句话说,热电偶不应装在太靠近门和加热的地方,插入的深度至少应为保护管直径的8~10倍;热电偶的保护套管与壁间的间隔未填绝热物质致使炉内热溢出或冷空气侵入,因此热电偶保护管和炉壁孔之间的空隙应用耐火泥或石棉绳等绝热物质堵塞以免冷热空气对流而影响测温的准确性;热电偶冷端太靠近炉体使温度超过100℃;热电偶的安装应尽可能避开强磁场和强电场,所以不应把热电偶和动力电缆线装在同一根导管内以免引入干扰造成误差;热电偶不能安装在被测介质很少流动的区域内,当用热电偶测量管内气体温度时,必须使热电偶逆着流速方向安装,而且充分与气体接触。

2、绝缘变差而引入的误差

如热电偶绝缘了,保护管和拉线板污垢或盐渣过多致使热电偶极间与炉壁间绝缘不良,在高温下更为严重,这不仅会引起热电势的损耗而且还会引入干扰,由此引起的误差有时可达上百度。

3、热惰性引入的误差

由于热电偶的热惰性使仪表的指示值落后于被测温度的变化,在进行快速测量时这种影响尤为突出。所以应尽可能采用热电极较细、保护管直径较小的热电偶。测温环境许可时,甚至可将保护管取去。由于存在测量滞后,用热电偶检测出的温度波动的振幅较炉温波动的振幅小。测量滞后越大,热电偶波动的振幅就越小,与实际炉温的差别也就越大。当用时间常数大的热电偶测温或控温时,仪表显示的温度虽然波动很小,但实际炉温的波动可能很大。为了准确的测量温度,应当选择时间常数小的热电偶。时间常数与传热系数成反比,与热电偶热端的直径、材料的密度及比热成正比,如要减小时间常数,除增加传热系数以外,最有效的办法是尽量减小热端的尺寸。使用中,通常采用导热性能好的材料,管壁薄、内径小的保护套管。在较精密的温度测量中,使用无保护套管的裸丝热电偶,但热电偶容易损坏,应及时校正及更换。

温度钱汇娱乐在安装和使用时应注意哪些问题?

4、热阻误差

高温时,如保护管上有一层煤灰,尘埃附在上面,则热阻增加,阻碍热的传导,这时温度示值比被测温度的真值低。因此,应保持热电偶保护管外部的清洁,以减小误差。

当然,昆山丹瑞传感测控在温度钱汇娱乐上的行业应用案例较为丰富,在产品和行业中有着多年的实际操作经验,如果你对你目前遇到的钱汇娱乐问题无法解决,请咨询右侧在线客服或拨打客服热线,昆山丹瑞将免费提供解答。

A temperature sensor is a sensor that can sense temperature and convert it into usable output signal. Temperature sensor is the core part of the temperature measuring instrument. According to the characteristics of sensor materials and electronic components, it can be divided into two categories: contact type and non-contact type.

When installing and using temperature sensors, we should pay attention to the following matters:

1. Error caused by improper installation.

In other words, the thermocouple should not be installed too close to the door and the heating place, the insertion depth should be at least 8-10 times the diameter of the protective tube; the insulation between the protective sleeve and the wall of the thermocouple does not fill in the insulation material, resulting in heat overflow or cold air in the furnace. Therefore, the gap between the protective tube of thermocouple and the hole of furnace wall should be blocked by insulating material such as refractory mud or asbestos rope so as to avoid convection of cold and hot air affecting the accuracy of temperature measurement; the cold end of thermocouple is too close to the furnace body to make the temperature exceed 100 degrees Celsius; the installation of thermocouple should avoid the strong magnetic field and electric field as far as possible, so the thermocouple and the furnace should not be placed. The power cable is installed in the same duct to avoid interference, and the thermocouple can not be installed in the area where the medium under test is rarely flowing.

2. Error caused by insulation deterioration.

If the thermocouple is insulated, too much dirt or salt slag in the protective tube and the pull-wire board will lead to poor insulation between the thermocouple and the furnace wall, even more serious at high temperatures. This will not only cause the loss of thermoelectric power but also introduce interference, resulting in errors sometimes up to Baidu.

3. The error introduced by thermal inertia.

Because of the thermal inertia of the thermocouple, the indicator value of the instrument lags behind the change of the measured temperature, which is especially prominent in the rapid measurement. Therefore, the thermocouple with smaller diameter and smaller diameter should be used as far as possible. Protection can be taken even when the temperature is permitted. Because of the measurement lag, the amplitude of temperature fluctuation detected by thermocouple is smaller than that of furnace temperature fluctuation. The larger the measured lag, the smaller the amplitude of the thermocouple fluctuation, the greater the difference between the actual temperature and the actual furnace temperature. When the temperature is measured or controlled by a thermocouple with a large time constant, the temperature shown by the instrument fluctuates very little, but the actual furnace temperature may fluctuate greatly. In order to accurately measure the temperature, a thermocouple with small time constant should be chosen. The time constant is inversely proportional to the heat transfer coefficient, and is proportional to the diameter of the thermocouple hot end, the density of the material and the specific heat. If we want to reduce the time constant, the most effective way is to reduce the size of the thermocouple hot end as far as possible, in addition to increasing the heat transfer coefficient. Generally, the protective sleeve with good thermal conductivity, thin wall and small inner diameter is usually used. In more precise temperature measurement, bare-wire thermocouple without protective sleeve is used, but the thermocouple is easy to be damaged and should be corrected and replaced in time.

What problems should be noticed when installing and using temperature sensors?

4, thermal resistance error

At high temperatures, if there is a layer of coal ash on the protective pipe, dust attached to it, the thermal resistance increases, hindering the conduction of heat, at this time the temperature indication is lower than the true value of the temperature measured. Therefore, the external cleaning of the thermocouple protection tube should be kept to reduce the error.

Of course, Kunshan Than Shwe sensor monitoring and control in the temperature sensor industry more abundant applications, in the product and industry has many years of practical experience, if you are currently encountering sensor problems can not be solved, please consult the right online customer service or call the customer service hotline, Kunshan Than Shwe will provide free answers.

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