小议压力式温度计回差及重复性的检定

压力式温度计检定规程规定：“温度计在正反行程示值的检定中，在各检定点上分别进行多次(至少3次)示值检定，计算出各点同一行程示值之间最大差的绝对值。即为温度计的重复性。”根据规程的规定，结合以往工作经验，在检定中最好同时使用两个恒温槽，一个作为主检恒温槽．一个作为辅助恒温槽。主检恒温槽用于检定测试。辅助槽用于改变被检表在被检点的温度。     

工作用辐射温度计检定装置自动瞄准系统的探讨

检定工作用辐射测温仪时,应按照规程和产品说明书要求,在适当的距离上瞄准黑体源腔体的中心点,否则,会对检定准确性产生一定影响。常规手动的瞄准方法,瞄准的准确性和重复性都差。本文提出了一种工作用辐射温度计检定装置自动瞄准系统,不仅可以提高工作效率,更能降低辐射温度计的辐射源尺寸效应,提高检定准确度。     

工作用辐射温度计示值误差测量结果的不确定度评定

文章探讨了用辐射温度计检定装置测量工作用辐射温度计方法,分析工作用辐射温度计测量结果的不确定度来源,并对工作用辐射温度计示值误差测量结果的不确定度进行评定。     

JJG744-2004中关于摄片机检定的建议

JJG744—2004《医用诊断X射线辐射源》检定规程中关于摄片机的检定主要有辐射输出的质，辐射输出的线性、重复性，辐射野与光野一致性，X射线管的电压、电流、焦点及加载时间8个检定项目，其中X射线管的电流与加载时间两项指标要求首次检定时检．后续检定可不检。一般影响X射线摄片质量的主要因素有X射线管的有效焦点、辐射输出的质、辐射输出的重复性及线性等。     

辐射温度计检定方法的浅谈

本文对检定辐射温度计所使用的标准器和检定装置的技术条件做了归纳和比较。详细介绍了检定前的准备工作、检定项目和检定步骤,总结了检定固有误差的方法和数据处理。     

对恒温槽温场的测试

恒温槽主要用于玻璃液体温度计、压力温度计、工业用热电阻和铜-康铜、镍铬-铐铜热电偶的检定。通过比较这几种检定规程可知,检定工业用热电阻时对恒温槽的温场要求最高,要求各插孔之间的水平温差不大于0.0l℃,温度变化每10分钟应不超过0.04℃,工作区域内的垂直温差不大于0.02℃。目前,已有很多单位开展了热电阻的检定工作,并对标准仪器和电测仪器很重视,然而却忽略了恒温装置温场的测试,若标准和被检温度计不是处于同一温场,即温场温度不均匀时,将直接影响到检定结果的准确性。本文对恒温槽的温场测试方法作一介绍,以供参考。 一、温度均匀…     

在线气相色谱仪标准装置的建立

一、建标准备工作 1.工作原理及组成 在线气相色谱仪标准装置由C1~C6天然气标准物质、数字温度计、气体流量计等组成。气体流量计用于检定仪器载气流量的稳定性;数字温度计用于检定仪器柱箱温度的稳定性;天然气标准物质用于检测色谱柱的分离度、监测器的灵敏度、检测限和整机的定性、定量重复性。     

500℃以下工作用辐射温度计校准结果示值修正方法探讨

我国对工作用辐射温度计的校准使用《500℃以下工作用辐射温度计检定规程》和《工作用辐射温度计检定规程》,两本规程分别适用于温度范围在500℃以下和300～2200℃的工作用辐射温度计的检定。两本规程都规定,在检定过程中,对于温度计有发射率修正和调节功能的,应将发射率设置为1或将发射率设置为与辐射源靶面的有效发射率相同的数值。在实际工作中,很多工作用辐射温度计的发射率没有调节功能,恒为0．95,有的甚至没有标明发射率是多少,而一般计量部门的标准辐射源的发射率都为1．00。     

环境辐射对辐射温度计测量结果的影响

在辐射温度计响应波长一定情况下,主要通过计算环境辐射对黑体辐射温度、发射率不为1辐射温度计的修正值,分析和讨论了在计量检定工作中环境辐射对辐射温度计测量结果的影响大小,并阐述了在结果计算中对它们进行修正的必要性和重要性。     

观测角度对玻璃液体温度计读数的影响

检测玻璃液体温度计时,观测角度是影响温度计准确读数的一个主要问题.检定中需用读数放大装置观测温度计示值,并要求测量时读数装置与被检温度计垂直,否则会因视线不垂直于温度计造成温度测量读数误差.针对这一问题,分析了观测角度对读数的影响,并对不同观测角度进行了相关实验,对观测角度对玻璃液体温度计不确定度的影响进行了分析.     

Influence of Non-ideal Blackbody Radiator Emissivity and a Method for its Correction

Demands for accurate temperature measurement and calibration are increasing along with the wider use of radiation thermometry in industry. However, the deviation of a ‘blackbody’ radiator emissivity from the emissivity of an ideal blackbody remains one of the main uncertainty contributions in the calibration of radiation thermometers, although the performance of blackbody radiators has been continually improving. Nevertheless, the influence of this deviation was often ignored due to the complexity of the correction. In this paper, general methods to evaluate the influence of the emissivity deviation of a blackbody radiator from unity for typical radiation thermometer models are described. An approximate practical method for wide-band radiation thermometers is proposed. Moreover, the concept of equivalent wavelength and the corresponding calculation method are introduced to simplify the mathematical model. The calculation result and a mathematical expression for the equivalent wavelength applicable to most popular radiation thermometers with a spectral range of 8–14 μm are given. The analysis and calculation show that the influence of blackbody radiator emissivity on longer working-wavelength radiation thermometer calibrations at mid or high temperatures cannot be ignored.     

提高辐射温度计检定结果准确度的方法研究

现行的辐射温度计检定规程,概念不够清晰,具体操作步骤描述过于简单,造成检定的实际测量条件有明显的差异,由此导致检定结果的差异。本文从技术角度出发,提出了一种可行的操作方法,力图提高辐射温度计检定结果的准确度。     

基于LabVIEW实现固定发射率辐射温度计校准的温度修正

在辐射温度计检定中,根据规程要求,需要将辐射温度计的发射率设置为1,而在实际校准辐射温度计的过程中发现大量发射率固定且不为1的情况,同样有用户要求校准后给出不同发射率下的辐射温度计修正值,为实现宽波段任意固定发射率辐射温度计在校准过程中的修正值计算,文章使用LabVIEW的两分法迭代实现Plank公式的积分算法,有效提高校准过程的自动化程度,文章用实例说明了两分法与普通步进算法的效率区别,从而高效的实现了任意波段、任意发射率、任意温度点的温度修正值计算。     

Using a CCD camera for the determination of the target size in radiation thermometry

The objective of this paper is to present the new objective method for the determination of the target size in radiation thermometry using a charge-coupled device (CCD) camera and the custom-made software. The target size is one of the essential components needed for the proper calibration of a radiation thermometer, as well as for everyday measurements. In practice, most of the radiation thermometers have a small black ring engraved on the ocular, and the interior of the ring defines the target area. Usually, manufacturers state how much radiation is gathered from the target area. Typical values stated are from 90% to 99%. The existing method was very subjective. A person determining the target size looked through the radiation thermometer and tried to read the target size of the thermometer from the millimeter grid paper. In our case, three different people in our laboratory, using this existing method, determined different target sizes. The new method uses a predefined mask of known dimensions, printed on millimeter grid paper and positioned in front of the radiation thermometer. Instead of a person looking through the ocular, a CCD camera and the custom-made image processing software are used. This target size can be used as an indication of target size in cases when other information is unavailable or to check manufacturer's data.     

Propagation of Uncertainty Due to Non-linearity in Radiation Thermometers

The measurement of the non-linearity of radiation thermometers is important in the realization of ITS-90 above the silver point and in the calibration of primary or secondary radiation thermometers using multiple fixed points both above and below the silver point. A non-linearity function is usually derived, enabling correction of the measured signals. Uncertainties in this non-linearity function propagate to the uncertainty in the determination of an unknown temperature. Since the same non-linearity function is used both during calibration and in subsequent use of the thermometer, there is a high degree of correlation between the uncertainties in the corrected calibration signals and the corrected in-use signals. While these correlations obviously lead to zero uncertainty at the calibration points, it is difficult to determine the correlation coefficients for temperatures away from these points. This article sets out a mathematical framework, based on interpolation theory, for propagating the uncertainty due to non-linearity in which correlation is easily included. The method is illustrated for a thermometer realizing ITS-90 up to 3,000°C based on one fixed point (silver, gold, or copper), and also for alternative realization schemes based on two or more fixed points. The total non-linearity uncertainty for the multipoint schemes is considerably lower than for the ITS-90 method. The mathematical framework can also be applied to secondary calibrations below the silver point, where non-linearity is typically more problematic for the detectors used in this temperature range.     

INRIM–NMC Comparison of Pt/Pd Calibration Above the Ag Point

A comparison of a Pt/Pd calibration above the Ag point between the INRIM and NMC was arranged with the aims of evaluating measurement systems and exploiting the potential of the Pt/Pd thermocouples. Two commercial Pt/Pd thermocouples were used as transfer thermometers. A calibration method using a blackbody cavity as a transfer source and a radiation thermometer as a reference thermometer was adopted in both institutes. The T ₉₀ carried by the radiation thermometers is established by an extrapolation technique for INRIM and by scale realization according to ITS-90 definition for NMC and, therefore, this exercise is also a useful comparison of different approaches to disseminate T ₉₀ above the Ag point. The comparison results are presented and analyzed.     

Monochromator-Based Absolute Calibration of Radiation Thermometers

A monochromator integrating-sphere-based spectral comparator facility has been developed to calibrate standard radiation thermometers in terms of the absolute spectral radiance responsivity, traceable to the PTB cryogenic radiometer. The absolute responsivity calibration has been improved using a 75 W xenon lamp with a reflective mirror and imaging optics to a relative standard uncertainty at the peak wavelength of approximately 0.17 % (k = 1). Via a relative measurement of the out-of-band responsivity, the spectral responsivity of radiation thermometers can be fully characterized. To verify the calibration accuracy, the absolutely calibrated radiation thermometer is used to measure Au and Cu freezing-point temperatures and then to compare the obtained results with the values obtained by absolute methods, resulting in T ? T ₉₀ values of +52 mK and ?50 mK for the gold and copper fixed points, respectively.     

Calibration of Thermocouples and Infrared Radiation Thermometers by Comparison to Radiation Thermometry

The National Metrology Institute of Spain (CEM) has designed, characterized, and set-up its new system to calibrate thermocouples and infrared radiation thermometers up to 1600 °C by comparison to radiation thermometry. This system is based on a MoSi₂ three-zone furnace with a graphite blackbody comparator. Two interchangeable alumina tubes with different structures are used for thermocouples and radiation thermometer calibrations. The reference temperature of the calibration is determined by a standard radiation thermometer. Normally, this is used at CEM to disseminate the International Temperature Scale of 1990 (ITS-90) in the radiation range, and it refers to the Cu fixed point. Several noble metal thermocouples and infrared radiation thermometers with a central wavelength near 900 nm have been calibrated, and their uncertainty budgets have been obtained.     

红外辐射温度计专用数字表的研制及评价

日本CHINO公司生产的IR-RST系列标准辐射温度计由于没有设计温度显示装置,无法实时显示温度,针对此类型温度计设计了一款专用的电压测量和温度显示,同时可提供24V直流电压的电测显示仪表。利用高等级的电压源和数字电压表,修正了本专用数字表的误差系数,并考核了稳定性,得到其最大相对误差不超过0.03%。与一款名义波长为0.65 μm的IR-RST辐射温度计配合使用,通过TG HT-9500型高温炉对其组合进行内插分度,实验结果证实分度后校准准确度优于0.03%,1 300 ℃时系统测量结果的扩展不确定度为0.62 ℃。     

New PTB Setup for the Absolute Calibration of the Spectral Responsivity of Radiation Thermometers

The paper describes the new experimental setup assembled at the PTB for the absolute spectral responsivity measurement of radiation thermometers. The concept of this setup is to measure the relative spectral responsivity of the radiation thermometer using the conventional monochromator-based spectral comparator facility also used for the calibration of filter radiometers. The absolute spectral responsivity is subsequently measured at one wavelength, supplied by the radiation of a diode laser, using the new setup. The radiation of the diode laser is guided with an optical fiber into an integrating sphere source that is equipped with an aperture of absolutely known area. The spectral radiance of this integrating sphere source is determined via the spectral irradiance measured by a trap detector with an absolutely calibrated spectral responsivity traceable to the primary detector standard of the PTB, the cryogenic radiometer. First results of the spectral responsivity calibration of the radiation thermometer LP3 are presented, and a provisional uncertainty budget of the absolute spectral responsivity is given.