无线温湿度记录仪的校准方法研究

无线温湿度记录仪或无线温度记录仪是目前医疗行业验证药品储存箱、冰箱、灭菌器及生化培养箱等设备的温度、湿度参数性能的重要仪器,其准确性直接影响了实验或生产设备的性能判断.所以,对无线温湿度记录仪进行周期性校准必不可少.本文参考温度采集仪校准规范和湿度传感器校准规范,提供了一种校准方法,利用标准铂电阻和冷镜式露点仪作为标准器,实现了无线温湿度记录仪的量值溯源.对实验结果进行分析,验证了此实验方法的可行性.     

数字信号温湿度记录仪的校准及组网工程应用

本文介绍了数字信号温湿度记录仪的基本结构、工作原理以及其计量性能的校准方法,利用高精度温湿度校验箱或发生器、精密露点仪可以较好地实现对数字信号温湿度记录仪的计量校准.在工程应用中利用有线或无线的方式组网并进行终端分析、报警、控制、记录等.     

数字温湿度表的校准方法探讨及测量不确定度的评定

数字温湿度表广泛地应用于实验室、工业生产、仓库等环境温湿度测量。目前,数字温湿度表尚无国家和地方的校准规范。基于数字温湿度表实际使用情况,介绍了一种校准方法,即采用精密露点仪和温湿度检定箱组成校准系统,对数字温湿度表进行校准,并对该校准方法的不确定度进行了分析。     

温湿度检定箱校准方法研究

通过对几种常用温湿度检定箱的稳定时间、温湿度波动、温湿度分布、箱内风速等参数的测试研究,结合现行温湿度仪器的检定规程和校准规范以及校准的实际情况,提出了温湿度检定箱的主要校准项目、基本技术要求和对应的校准方法。     

多参数控制系统温湿度现场校准技术

本文介绍了温湿度现场校准技术的国内外发展现状,论述了多参数控制系统温湿度现场校准技术的研究环境、基本原理与校准方法,分析了多参数控制系统温湿度现场校准装置的工作原理、组成部分及其各部分装置的基本工作原理与预期达成目标,并阐述了该技术相对于现阶段国内外温湿度现场校准技术的主要技术难点与优点比较。     

温湿度场试验设备校准技术的研究

温湿度场试验设备是环境试验设备的一种。目前我国还没有针对温湿度场试验设备专门的校准方法。本文在简要介绍温湿度场试验设备的工作性能的基础上,提出了校准方法 ,可指导解决温湿度场试验设备的日常校准工作。     

嵌入温场型温度记录仪的校准方法研究

为完善嵌入温场型温度记录仪相关的实验室校准方法,针对目前其校准方法存在的问题,分析它的测量原理和实际工作环境,按照使用手册和现有检定规程,提出将记录仪置于可接受的不同的工作环境温度下进行校准的方法,并且按照提出的校准方法完成了实验和数据分析。实验结论证明了所提出的嵌入温场型温度记录仪校准方法的正确性和必要性。     

基于ZigBee技术的无线环境温湿度校准系统

本文介绍了一种基于Zig Bee技术的无线传感器在环境温湿度校准系统中的应用。按照JJF1101-2003《环境温湿度校准规范要求布置温湿度传感器》,温湿度传感器通过射频收发器将数据发送到Zig Bee网关。Zig Bee网关通过以太网网络将数据传输给电脑校准系统。本文并且考虑到了数据通信的可靠性。该系统稳定性好,可用于较大空间的环境温湿度校准。     

温湿度表校准误差产生的原因分析及对策

本文从温湿度表校准过程中三个主要部分即标准器、温湿度源和被校准温湿度表,探讨了各部分有可能产生校准误差的原因,并结合工作实际,提出相应的解决方法及注意事项,能够有效地提高对温湿度表的校准准确度.     

建筑门窗保温性能检测设备自动校准系统研究

为保证建筑门窗保温性能检测设备测试结果的准确可靠,设计开发了一种基于LoRa网络的无线远程校准系统。本文采用高精度数字式温湿度传感器结合LoRa无线模块,开发无线温湿度标准仪表,基于云服务器远程采集无线标准温湿度信号,根据相关校准规范,实现了远程校准功能,使数字温湿度仪表精度满足校准需求。该系统现场安装方便、不用布线,可通过云服务器及手机App远程操作,可用于计量部门实现建筑门窗保温性能检测设备的远程校准。     

Improving the Traceability of Meteorological Measurements at Automatic Weather Stations in Thailand

A joint project between the National Institute of Metrology Thailand (NIMT) and the Thai Meteorology Department (TMD) was established for improving the traceability of meteorology measurements at automatic weather stations (AWSs) in Thailand. The project aimed to improve traceability of air temperature, relative humidity and atmospheric pressure by implementing on-site calibration facilities and developing of new calibration procedures. First, new portable calibration facilities for air temperature, humidity and pressure were set up as working standard of the TMD. A portable humidity calibrator was applied as a uniform and stable source for calibration of thermo-hygrometers. A dew-point hygrometer was employed as reference hygrometer and a platinum resistance thermometer (PRT) traceable to NIMT was used as reference thermometer. The uniformity and stability in both temperature and relative humidity were characterized at NIMT. A transportable pressure calibrator was used for calibration of air pressure sensor. The estimate overall uncertainty of the calibration setup is 0.2 K for air temperature, 1.0 % for relative humidity and 0.2 hPa for atmospheric pressure, respectively. Second, on-site calibration procedures were developed and four AWSs in the central part and the northern of Thailand were chosen as pilot stations for on-site calibration using the new calibration setups and developed calibration procedures. At each station, the calibration was done at the minimum temperature, average temperature and maximum temperature of the year, for air temperature, 20 %, 55 % and 90 % for relative humidity at the average air temperature of that station and at a one-year statistics pressure range for atmospheric pressure at ambient temperature. Additional in-field uncertainty contributions such as the temperature dependence on relative humidity measurement were evaluated and included in the overall uncertainty budget. Preliminary calibration results showed that using a separate PRT probe at these AWSs would be recommended for improving the accuracy of air temperature measurement. In case of relative humidity measurement, the data logger software is needed to be upgraded for achieving higher accuracy of less than 3 %. For atmospheric pressure measurement, a higher accuracy barometer traceable to NIMT could be used to reduce the calibration uncertainty to below 0.2 hPa.     

Method for Effective Calibration of Temperature Loggers with Automated Data Sampling and Evaluation

A highly automated calibration method for temperature loggers is presented. By using an automated procedure, a time- and cost-efficient calibration of temperature loggers is made possible. The method is directed at loggers that lack the function/property of direct reading from a display. This type of logger has to be connected to a computer for the setting-up of the measurement and again for collection of the measurement results. During the calibration, the loggers are offline. This method has been developed for temperature loggers from Gemini Data loggers, but the software and method could be modified to suit other types of loggers as well. Calibration is performed by comparison to a reference thermometer in liquid baths; and for loggers which have external sensors, only the sensor is normally placed in the bath. Loggers with internal sensors are protected from the liquid by placing them in an exterior plastic or metallic cover, and thereafter the entire loggers are placed in the bath. A digital thermometer measures the reference temperature of the bath and transmits it to a computer by way of Bluetooth. The developed calibration software, SPTempLogger, controls the logger software, and thus the communication protocol of the logger software does not need to be known. The previous method, with manual handling of the start and termination of every measuring sequence, evaluation of the resulting data and its corresponding uncertainty components, can be replaced by this automated method. Both the logger and reference measurement data are automatically downloaded once the logger has been connected to a computer after the calibration, and the calibration software started. The data are then evaluated automatically, and by statistical analysis of the confidence coefficient and standard deviation, the temperature plateaus that the calibration includes are identified. If a number of control parameters comply with the requirements, then the correction, resolution, and short-term stability are calculated for each calibration temperature. The calculated values are saved in a database, along with information about the instruments used during the calibration, after which calibration certificates and measurement uncertainty calculations can be generated. Up to ten loggers can be connected at the same time and are then evaluated in sequence. The paper will show that the system can correctly analyze different types of measurement sequences and what measurement uncertainties are associated with this.     

Using Smart Sensor Strings for Continuous Monitoring of Temperature Stratification in Large Water Bodies

A "smart" thermistor string for continuous long-term temperature profiling in large water bodies is described allowing highly matched yet low-cost spatial and temporal temperature measurements. The sensor uses the three-wire SDI-12 communications standard to enable a low-powered radio or data logger on supporting buoys to command measurements and retrieve high-resolution temperature data in digital form. Each "smart" temperature sensor integrates a thermistor element, measurement circuitry, power control, calibration coefficient storage, temperature computation, and data communications. Multiple addressable sensors at discrete vertical depths are deployed along a three-wire cable that provides power and allows data transfer at regular intervals. Circuit, manufacturing, and automated calibration techniques allow temperature measurements with a resolution of plusmn0.003degC, and with intersensor matching of plusmn0.006degC. The low cost of each sensor is achieved by using poor tolerance thermistor and circuit components in conjunction with a 15-bit charge-balance analog-to-digital converter. Sensor inaccuracies and temperature coefficients are corrected by a two-point calibration procedure made possible by a standard-curve generator within the sensor, based upon the method of finite differences. This two-point calibration process allows in-field sensor string calibration in stratified water bodies and provides a means to correct for long-term calibration drift without having to return the string to a laboratory     

环境试验设备温湿度校准系统的研制

介绍基于MSC1200的温湿度自动校准系统。以JJF 1101-2003《环境试验设备温度、湿度校准规范》为设计依据,硬件以美国TI公司的MSC1200作为测量、信号处理以及通信核心部件,组成一套多通道高精度温湿度采集仪。按照校准规范的要求设计专用的校准软件,通过RS232接口与温湿度采集仪通信,将测量数据进行显示、绘图、存储,计算并自动生成满足要求的原始记录及校准报告,从而实现校准过程程序化、规范化、自动化,满足计量部门对环境试验设备温湿度校准的需要。     

Characterization of the Humidity Calibration Chamber by Numerical Simulations

At the Centre for Metrology MIKES of VTT Technical Research Centre of Finland (VTT MIKES), we have been developing a humidity calibration apparatus for radiosondes within an EMRP Project Metrology for Essential Climate Variables. The minimum air temperature and absolute humidity are \(-80\,^{\circ }\hbox {C}\) and 2.576 \(\times \) \(10^{-4} \,\hbox {g}\cdot \hbox {m}^{-3}\) (corresponding the dew-point temperature \(-90\,^{\circ }\hbox {C}\)), respectively. Recent developments for the apparatus extend its pressure operation range down to 7 hPa (abs). When operating in such dry conditions, the efficiency in calibration is highly limited by the time of humidity stabilization in a measurement chamber: Because the water vapor pressure is very low, the adsorption and desorption of water molecules at the chamber walls have a significant effect on the spatial and temporal humidity differences in the chamber. Inhomogeneity in humidity field inside the calibration chamber increases calibration uncertainty. In order to understand how varying parameters such as pressure, temperature, inflow speed and geometry of chamber effect on stabilization time of humidity field, computational fluid dynamics simulations were developed using Comsol software. Velocity and pressure of fluid, water vapor diffusion, temperature as well as adsorption/desorption of water molecules on the chamber walls were included in the simulations. Adsorption and desorption constants for water on the measurement chamber wall were determined experimentally. The results show that the flow speed and the surface area are the dominant parameters affecting the stabilization time of a calibration chamber. It was also discovered that more homogenous water vapor concentration field is obtained at low pressures.     

A Low-Cost Wireless Sensor System and Its Application in Dental Retainers

In this paper, a wireless interrogable sensor device based on an ultra low-power microcontroller for data collection and a radio frequency identification (RFID) interface for data transmission is presented. Wireless sensor systems utilizing RFID transponders offer a new and exciting means of measurement and identification suitable for many biomedical applications. For the majority of these applications, small, inexpensive radio request sensor systems are desirable. In this paper, an ultra-low-power and low-cost wireless temperature data logger system is presented with its application in observing dental retainer use. For this purpose, the retainer's ambient temperature is measured by an integrated sensor and recorded using a microcontroller which acts like a temperature data logger storing the thermal history of several months. For a self powered wireless data transmission from the sensor to the interrogation unit a RFID transponder, operating in the 13.56 MHz ISM band, is used. The presented sensor system includes hard- and software power saving modes reducing the sensor idle current consumption to 1 $mu$ A. This allows a battery powered operation of the device for up to two years. For dental and biomedical applications, the device is hermetically sealed using a biocompatible polymeric encapsulation. Results of the first clinical trials observing the patient's dental retainer usage by a set of retainers equipped with the RFID temperature sensor/data logger device are presented. The stored temperature values are analyzed and a clear temperature characteristic indicating the retainer usage was found.      

温度变送器自动校准系统研究

目前,温度变送器在温度参数的测量与控制过程中广泛应用,定期对其校准是实现温度变送器量值准确传递的有效途径.手动校准不仅校准效率低,而且容易引入读数误差.本文深入研究了实现温度变送器自动校准的必要性,介绍了搭建温度变送器自动校准系统所需的硬件设备,参考了JJF 1183-2007《温度变送器校准规范》,并通过LabVIE...     

Calibration of Heat Stress Monitor and its Measurement Uncertainty

Wet-bulb globe temperature (WBGT) equation is a heat stress index that gives information for the workers in the industrial areas. WBGT equation is described in ISO Standard 7243 (ISO 7243 in Hot environments—estimation of the heat stress on working man, based on the WBGT index, ISO, Geneva, 1982). WBGT is the result of the combined quantitative effects of the natural wet-bulb temperature, dry-bulb temperature, and air temperature. WBGT is a calculated parameter. WBGT uses input estimates, and heat stress monitor measures these quantities. In this study, the calibration method of a heat stress monitor is described, and the model function for measurement uncertainty is given. Sensitivity coefficients were derived according to GUM. Two-pressure humidity generators were used to generate a controlled environment. Heat stress monitor was calibrated inside of the generator. Two-pressure humidity generator, which is located in Turkish Standard Institution, was used as the reference device. This device is traceable to national standards. Two-pressure humidity generator includes reference temperature Pt-100 sensors. The reference sensor was sheltered with a wet wick for the calibration of natural wet-bulb thermometer. The reference sensor was centred into a black globe that has got 150 mm diameter for the calibration of the black globe thermometer.     

An experimental verification of saturated salt solution-based humidity fixed points

The high instability and hysterisis of the relative humidity sensors currently available on the market render necessary simple and economic calibration methodologies that can be used as a secondary of working standards. The chemical equilibrium-type systems based on saturated aqueous salt solutions, even though simple and economical, are not always metrologically satisfactory for calibration. They can, in fact, be unreliable, when some fundamental requirements are neglected: also, unacceptable discrepancies continue to exist in the equilibrium relative humidity reference data of saturated aqueous salt solutions furnished by both literature and standards. To highlight the factors that increase the reliability of calibrations with saturated aqueous salt solutions, the authors of this paper have redetermined the equilibrium relative humidity reference data of 11 saturated aqueous salt solutions at ambient pressure and temperature. The solutions chosen were the ones generally used as fixed points to obtain a relative humidity calibration scale.     

Temperature and Heat Flow Rate Calibration of a Calvet Calorimeter from $$0\,{^{\circ }}\hbox {C}$$ to $$190 \,{^{\circ }}\hbox {C}$$19

This study describes the temperature and heat flow rate calibrations of a Calvet calorimeter (SETARAM, BT2.15) in the temperature range of 0–190 \({^{\circ }}\hbox {C}\). Temperature calibration is carried out using three reference materials, namely water, gallium, and indium, as specified in the International Temperature Scale of 1990 (ITS-90). The sample temperature of the Calvet calorimeter is corrected by the obtained mean value, \(-0.489 \,{^{\circ }}\hbox {C}\), of the measured extrapolated peak onset temperature (\(T_{e})\) when the heating rate (\(\upbeta )\) is zero (\(\Delta T_\mathrm{corr }(\upbeta ~=~0\))). The heat flow rate is calibrated using a reference material with a known heat capacity, namely SRM 720 \(\alpha \)-\(\hbox {Al}_{2}\hbox {O}_{3}\) (synthetic sapphire), which is traceable to the National Institute of Standards and Technology. From the heat flow rate measurements of the blank baseline and SRM 720, the proportional calibration factor, \(\hbox {K}_{\Phi }\), in the 0–190\( \,{^{\circ }}\hbox {C}\) temperature range was determined. The specific heat capacity of copper was measured with the obtained calibration values, and the measured data show consistency with the reference value.