工业热电阻温度计的选型探索

热电阻温度计是工业生产测温系统建造中最常用的温度传感器之一,但在不同的测温工况下选择什么样的热电阻产品,是技术人员需要了解的内容.选用错误或不合适类型的热电阻可能会造成系统测温不准,使用寿命缩短等问题,甚至可能对生产场所带来安全隐患.本文从测量准确性、经济性、使用环境限制、安装空间限制等角度,考察目前已有的热电阻温度计...     

温度仪表的选型与应用

温度仪表是工业生产过程中温度测量的重要仪表,主要有热电阻、热电偶、工业双金属温度计和温度变送器等几大类。本文主要介绍了热电阻和热电偶的精度、测量范围、和产品结构,详细介绍了不同部件的功能、不同类型保护管的适用工况、法兰安装时压力等级规格选定的注意事项,使用户能更好地完成选型,确保订货的正确性。     

釉瓷铂热电阻元件试制总结

近年来,在我国工业部门中广泛地应用BA_1、BA_2分度的云母和玻璃支架的工业铂热电阻元件,在-200℃～+500℃温度范围内,进行温度测量和调节。这两种类型的元件制造工艺比较复杂,支架材料来源也不易。有些工业部门又特别注意铂热电阻元件机械性能的稳定性和可靠性。1968年国际实用温标(IPTS—68)中规定13.81K到630.74℃温度区间标准铂电阻温度计是实现温标的标准仪器,工业铂热电阻元件也将从现行规定的使用温度上限500℃延申到650℃。综上所述,云母和玻璃支架的铂热电阻元件要达到这些要求会有一定的困难,为此,寻找新的支架材料制造铂热电阻元件就很有必要。我们经过几年来的试制,     

工业热电阻检定软件的研究与实现

依据JJG229-2010《工业铂、铜热电阻检定规程》,详细阐述工业热电阻0℃冰点槽和100℃恒温槽的检定计算过程,通过两个检定点测量数据和α计算值对热电阻符合性进行判断,结合规程中的工业热电阻通用函数公式,提出了一种系数A、B和C值的修正方法,提高了热电阻的测量准确度,并针对上述应用开发出了工业热电阻(工业铂电阻PRT和工业铜电阻CRT)的热工检定软件。同时依据JJG160-2007《标准铂电阻温度计检定规程》,开发出了0℃～660.323℃和-189.3442℃～0.01℃两温区的标准铂电阻计算软件。检定软件可以稳定高效的实现工业热电阻检定计算和标准铂电阻系数计算,提高了检定效率和操作准确度达到了预期的设计效果。     

温度测量仪表第一讲 概论

温度测量仪表是使用最广泛的一类仪表,为了使读者系统了解该类仪表的基本原理,结构及发展趋势,我们请杨兴易高级工程师等三人作全面介绍.讲座共分四讲,第一讲概论;第二讲热电偶热电阻温度计;第三讲双金属和压力式温度计;第四讲温度变送器及其应用.     

铂电阻温度计及其使用中的误差分析

主要介绍铂电阻温度计的产生发展、结构、用途、分类、技术性能等基本内容,对铂电阻温度计在检定和使用过程中出现的不同种误差做了分析,并提出不同误差的解决方法。     

工业热电阻检定中产生偏差的原因分析

工业热电阻广泛应用在许多领域的生产之中。就目前来看,在工业热电阻中依然存在着检定偏差率较高等问题,严重影响到了工业热电阻在运行期间的稳定性与效率。本文就基于以上因素,对工业热电阻检定产生偏差的原因进行相关论述,旨在实际生产过程中充分发挥出工业热电阻的积极作用。     

几种温度传感器的误差

本文叙述了在温度控制中,除了考虑基型传感器一些显而易见的特性外,还必须考虑到的谐因素。要想控制温度,就必须精确地检测温度,如热电偶和热电阻温度计有许多可能会产生误差的因素。为了精确地控制温度,不仅要考虑基型传感器的特性,而且还要考虑:污染的影响、导线的长度、浸入液体、热传导及控制器     

秦一厂循泵热电阻温度信号异常波动原因分析及处理

针对秦一厂海水厂房循泵热电阻温度信号频繁异常波动的问题,从元器件本身、热电阻三线制接法、仪表测量回路构成、DCS接收侧组态设置等方面分析对热电阻温度测量过程中产生波动的原因,并介绍了几种现场消除或降低干扰的一些实用措施,供同行参考。     

沈阳市仪器仪表工业公司产品简介

我公司有关企业的产品简介如下。沈阳市测温仪表厂:主要产品为铜、铂热电阻、镍铬——考铜、镍铬——镍硅、铂铑——铂、铂铑——铂铑、铠缆、标准铂铑——铂、钢水快速热电偶。厂址:沈阳市沈河区小南街五段2号,电话:482389 沈阳市测温仪表二厂:主要产品为WSS双金属温度计WSSX、电接点双金属温度计、300—3000W电炉丝、LMK、LQG电流互感器。厂址:沈阳市沈河区中央路二段25号,电话:442971     

Automatic measurement of temperature in a nuclear reactor

A circuit has been developed to display the temperatures measured using platinum resistance thermometers. The thermometer number and the temperature are displayed sequentially together with the highest temperature and the number of the corresponding thermometer.     

Improved 3-omega measurement of thermal conductivity in liquid, gases, and powders using a metal-coated optical fiber

A novel 3ω thermal conductivity measurement technique called metal-coated 3ω is introduced for use with liquids, gases, powders, and aerogels. This technique employs a micron-scale metal-coated glass fiber as a heater/thermometer that is suspended within the sample. Metal-coated 3ω exceeds alternate 3ω based fluid sensing techniques in a number of key metrics enabling rapid measurements of small samples of materials with very low thermal effusivity (gases), using smaller temperature oscillations with lower parasitic conduction losses. Its advantages relative to existing fluid measurement techniques, including transient hot-wire, steady-state methods, and solid-wire 3ω are discussed. A generalized n-layer concentric cylindrical periodic heating solution that accounts for thermal boundary resistance is presented. Improved sensitivity to boundary conductance is recognized through this model. Metal-coated 3ω was successfully validated through a benchmark study of gases and liquids spanning two-orders of magnitude in thermal conductivity.     

Effect of bushings in thermometric fixed-point cells

Bushings are tubular inserts that can be used with temperature fixed-point cells for the calibration of standard platinum resistance thermometers in accordance with the International Temperature Scale of 1990. They are made out of different materials such as glass and various metals with high thermal conductivities. Their function is to increase the thermal contact between the thermometer’s sensor and the phase boundary in the thermometer well of the cell. In the paper, the effect of bushings on the self-heating and on the immersion profiles of thermometers in fixed-point cells was researched. Three different thermometers were used: one fused silica sheathed and two Inconel sheathed. The self-heating was measured in the temperature range from the mercury triple-point to the zinc freezing-point with and without metal bushings: brass, aluminum and copper. The immersion profiles were measured in the zinc cell with and without an aluminum and a glass bushing. Besides experimental measurements, some qualitative results of numerical modeling are also presented. The bushings considerably lower the self-heating, in some cases even by more than 50%. But, on the other hand, bushings seem to increase the measured temperature, worsen the immersion profile and act as a radiation shield in the gap between the thermometer and the fixed-point cell at higher temperatures, where radiation is the dominant mode of heat transfer.     

Simple bridge detector for use with a low-temperature capacitance thermometer, and thermometer performance limits

A simple high-resolution bridge circuit for use with a glass-ceramic capacitance thermometer is described. This circuit allows a linear readout of capacitance changes and has better than 1 mK resolution and short-term stability. Performance limits of the thermometer itself are also reported. Irreproducibility of thermometer calibration upon thermal cycling can be as large as 0.3 K, and changes in the calibration slope dC/dT are also observed. The bridge circuit described partially compensates for these shifts in dC/dT.     

A pulsed ionizing radiation calorimeter

A calorimeter with a metallic radiation absorber for the pulsed bremsstrahlung dosimetry is described. The absorbed dose is recorded by a wire resistance thermometer or thermocouple, which is installed at one’s discretion into the device for measuring the wire resistance or thermal emf. The calorimeter is capable of recording the absorbed dose in metallic absorbers in a 10- to 10⁶-Gy range with a relative error of no more than several percent.     

Construction of a low-temperature thermodynamic measurement system for single crystal of molecular compounds under pressures

An apparatus to obtain low-temperature thermodynamic information under high pressures for a tiny single crystal of molecular compounds was developed based on the ac technique. To detect small temperature oscillation of a sample inside the cramp-type pressure cell, we have used a small ruthenium oxide chip sensor as a thermometer. The adoption of the four-terminal method by the ac resistance bridge has made high-resolution detection of thermal anomaly possible in the low-temperature region. The constructed high-pressure thermodynamic system was mounted on a 3He refrigerator and we have succeeded to detect the thermal anomaly in relevant to magnetic order of single crystal sample of Mn4-cluster complex up to 1.05 GPa. A distinct peak of the heat capacity and its upward shift with increasing pressures was observed using a tiny crystal of about 100 microg. The high-pressure behavior of the discontinuity of heat capacity at the superconductive transition of 6 mg of metal indium has also been detected by this apparatus. The details and performance of the technique are reported.     

网络化温度校准系统的研究与实现

针对传统校准的不足,提出了网络化远程温度校准系统的实施方案,分析了校准系统的硬件结构、测量仪器入网方式、软件开发技术及校准原理,在LabVIEW平台上,结合远程视频监控、远程控制技术及网络数据传输,实现了铂电阻温度计网络化校准.实验证明:网络化温度校准提高了校准效率,使得校准在异地随时随地进行成为可能,并且操作方便,网络通信实时可靠,实验及数据处理结果满足校准要求.     

激光测距仪中基于脉冲电流供电的高精度温度控制系统

半导体激光器及雪崩光电二极管作为激光测距仪中发射和接收系统中的关键器件,温度对其性能的影响限制激光测距仪的测量精度。而且二者均为小功率器件,精密测温电路中采用Pt电阻测温时,Pt电阻的自热效应产生的测温误差不能忽略。基于此,在对Pt电阻测温的误差产生机理做详细分析的基础上,提出了一种新的脉冲电流供电的方案,建立了脉冲电流供电电路及其自热升温过程的数学模型,给出了脉冲宽度和热量积累的关系,通过合理控制脉冲宽度大大减小了自热效应引起的测温误差;使用高阶正交多项式拟合的方法对Pt电阻的非线性进行了补偿,给出了该系统温度测量模块测量数据与一级标准铂电阻温度值的比较实验,在不同的温度点,该温度测量系统的最大误差为 0.0006度。系统稳定性测试结果表明,该系统在0度到15度 的温度范围内各温度点控制稳定度均优于±0.005度 。     

淬火温度对铬钨合金白口铸铁热疲劳行为的影响

用自约束试验方法研究了铬钨合金白求恩口铸铁的热疲劳抗力,用透射电镜观察了热循环前后材料组织的变化,在扫描电镜上观察了热疲劳断口。结果表明：在热循环过程中材料的基体组织发生回复和再结晶,产生循环软化;适当提高淬火温度可以提高热疲劳抗力,但淬火温度过高,反而使热疲劳抗力降低。