国内温湿度检定箱选用情况分析

一、温湿度检定箱概述目前,我国温湿度检定箱的性能指标主要有降温时间、温度及湿度偏差、均匀度等。具体指标为:温湿度范围为(5～50)℃/(20～90)%RH;温度波动度≤±0.2℃;温度均匀性≤0.3℃;湿度波动度≤±0.8%RH(20℃);湿度均匀性≤1%RH(20℃)。温湿度检定箱选用时,温湿度均匀度和波动度是判定温湿度检定箱性能的重要参数。此外,温湿度检定箱的连续无故障运行时间也是考量温湿度检定箱技术性能和可靠性的重要依据。为确保温湿度检定箱的性能达到需要的指标,用户可以请有资质的第三方验收。第三方验收时,首次验收费用一般由用户承担;第一次验收不合格时厂家要进行再调试或设计变更,验收费用由生产厂家负责。     

负温环境相对湿度发生器的不确定度分析

介绍了由我所自行研制的负温环境相对湿度发生器装置,该发生器产生的相对湿度范围为10%RH~95%RH（-60℃~40℃）。本文详细分析了发生器的相对湿度的不确定度大小。设计上精心的考虑以及采用的高精度的传感器均对相对湿度的不确定度的减小起到了很大的作用。负温环境相对湿度发生器的扩展不确定度在-60℃时为2.8%RH,在40℃时为0.8%RH。     

高温精密湿度发生装置

通过采用双温双压法原理，我们研制了一套高温精密湿度发生装置。该装置的测试室变温范围为50～150℃，变压范围为100～1000kPa，相对湿度发生范围为5％～95％RH，它的三倍标准偏差的最大不确定度为10％RH。该装置可用于校正高温湿度传感器及变送器。为了对该装置进行比对测试，我们还研制了一套重量法湿度计。     

双温双压法低露点标准湿度发生器

通过采用双温双压法原理 ,研制了一套微量水分发生装置。该装置能发生露点范围为 2 0～ - 74℃D .P的恒定含水量的气体 ,其测试室的变温范围为 2 0～ - 6 0℃ ,变压范围为 10 0～ 10 0 0kPa(绝对压力 ) ,其三倍标准偏差最大不确定度为± 0 .15℃D .P。装置适合于各类露点仪和水分分析仪器的计量校正。本装置中设计制作了能耐受 1MPa压力并且既适用于水面又适用于冰面的叠盘迷宫式饱和器 ,该饱和器由12个内有螺旋式气流通道的不锈钢圆盘组成 ,总的传质通道长度超过 6 0米 ,保证了其在低温和压力条件下的饱和度接近 10 0 %。     

冷镜式露点仪计量标准检定或校准结果的测量不确定度评定

本文以冷镜式露点仪作为标准器具,在温湿度检定箱中检定机械式温湿度计,在检定点为(20℃时):40%RH、60%RH、80%RH,对冷镜式露点仪计量标准检定/校准结果进行测量不确定度评定。冷镜式露点仪就是先测量露点温度T_d和环境温度T,然后通过温度与饱和水蒸气压的方程或者查。     

高露点湿度标准装置的研制

目前我国湿度计量基准中露点温度溯源的最高上限为80 ℃,为满足更高露点温度下的湿度参数溯源需求,研制了一套基于双温双压法原理的高露点湿度标准装置。该装置由恒温系统、预饱和系统、饱和系统、测量室和温度、压力测量与控制系统等部分组成,能够产生的露点温度范围为80～150 ℃,对应测量室的温度范围为80～200 ℃,绝对压力范围为0～1 MPa,扩展不确定度为0.34～0.80 ℃（k=2）。该装置准确性好、操作方便,弥补了国内在露点温度高于100 ℃时,温度计校准的不足。     

现场真空校准装置性能研究

研制了一台校准范围为10~(-5)~10~5Pa的现场真空校准装置。将不同种类单一成分的校准气体引入装置上游室,通过几何尺寸为微米量级激光小孔的衰减,建立校准用标准压力p_(std)。上游室压力变化范围为1~10~3Pa,相应地,校准室内对应的标准压力范围10~(-5)~10~(-2)Pa(N2),测量不确定度为2.4%。另外,该装置可采用与标准真空计直接比较进行动态或静态校准,其极限真空度为10~(-6)Pa量级。对装置暴露大气后的抽气性能、静态压升及其主要计量特性进行了实验研究。实验结果表明,该装置外形尺寸以及质量分别为475 mm×420 mm×800 mm、37.8 kg,校准范围为1.9×10~(-5)~1.0×10~5Pa,相对合成标准不确定度为2.8%~0.40%。     

中温区真空标准黑体辐射源研制

介绍了中国计量科学研究院研制的中温区真空标准黑体辐射源的结构设计,工作原理,测试结果和不确定度评定。黑体辐射源工作温度范围为320～500K,黑体空腔开口直径为50mm,空腔深度为260mm,表面喷涂了耐高温漆,空腔发射率优于0.999。真空环境下测试了黑体在335～500K温度范围内的轴向温度均匀性,温度稳定性及黑体辐射源亮度温度等性能指标,结果显示黑体温度均匀性优于0.15K,40min内温度稳定性优于0.03K。分析了黑体辐射源的不确定度来源,黑体辐射源的合成标准不确定度优于0.04K。     

动态流量法超高真空标准装置

研制成功的动态流量法超高真空标准装置是一台用来校准真空规的绝对真空计量标准。装置由校准系统、微流量计系统、抽气系统和计算机控制系统组成。校准系统采用四球结构 ,校准球室直径为50 0mm。极限真空度为 6 5× 10 - 9Pa ,校准范围为 10 - 2 ～ 10 - 7Pa ,不确定度为 3% (10 - 2 ～ 10 - 6 Pa)和10 % (10 - 7Pa)。     

数字式温湿度计的校准及测量不确定度评定

基于温湿度测量的原理,介绍一种采用冷镜式精密露点仪校准数字式温湿度计的方法.着重叙述了温湿度箱的有效工作区域选取及校准结果的测量不确定度评定,其扩展不确定度U95温度为0.4℃、相对湿度为1.0%RH,满足校准要求.该方法不仅解决了该类计量器具的校准问题,还提高了工作效率,节省了设备的投入.     

Characterization of KIM LIPI’s Relative Humidity Standard

At present, KIM LIPI is able to provide self-traceability in the scope of hygrometer calibrations in the range of 10–95 %RH using commercial two-pressure humidity generator as the standard which, previously, was traceable to SI unit through another NMI. In order to examine the calibration system, uncertainty of the calibration results was evaluated by performing characterization including measurement of saturator efficiency and chamber temperature distribution. A mini chamber was used to improve the chamber temperature uniformity. The validity of the RH calculation was evaluated by comparing our RH calculation with commercially available softwares. As a result, saturator efficiency gives the uncertainty 0.064 and 0.07 %RH at 20 and 27 °C. The contribution of uncertainty due to temperature non-uniformity is 0.014–0.14 %RH. The difference calculation with the commercial software is less than 0.01 %RH.     

Miniaturized Two-Pressure Generator for Relative Humidity

The concept and design of a miniaturized two-pressure humidity generator are presented. The generator is suitable for achieving relative humidity ranging from 10% to 95% with uncertainties of under 1% at ambient temperature and can be used for the calibration of relative humidity instruments in the laboratory and on site. By virtue of the concept, the relative humidity achieved is traced to only two pressure measurements. Further references are not necessary. A special adjustment algorithm enables standard industrial pressure sensors to be used. The two pressure sensors are synchronized by aligning their readings at ambient pressure. The resulting correlation of the uncertainties leads to very small systematic errors in the humidity display. Each humidity generator can still be individually adjusted through comparison with a chilled-mirror hygrometer, the total uncertainty of the generator being largely determined by the uncertainty of this hygrometer. Any drift of the pressure sensors that occurs can be compensated at any time by performing an alignment at ambient pressure without changing the individual adjustment of the generator. It can be demonstrated that the uncertainty of the displayed humidity remains practically unchanged over the course of a year by virtue of this alignment process.     

A Humidity Generator for Temperatures up to 200?°C and Pressures up to 1.6?MPa

A new humidity generator that produces gas streams of known moisture content at temperatures from 85?°C to 200?°C, absolute pressures from 0.2?MPa to 1.6?MPa, and relative humidities from 10 % to 90 % has been developed. The generator produces a moist gas stream by injecting fixed-rate streams of dry gas and liquid water into a vaporizer, where the water evaporates into the gas. The gas stream passes into a re-entrant radio-frequency (RF) cavity, which serves as our reference hygrometer, and then a test chamber. The present standard uncertainty of the RF hygrometer is 0.6 %, limited by the uncertainty of literature values for the polarizability of water. Dry nitrogen gas purging the pressure transducer line also combines with the moist gas stream downstream of the test chamber and flows through one of a set of capillaries. Modulation of gas flow through the fixed flow impedance of the capillary gives a simple method for controlling pressure. Individual insulated, temperature-controlled aluminum ovens enclose each major component. A larger oven encloses these ovens and their connecting tubing. To minimize corrosion, critical components are constructed of high-nickel alloys. The small total volume (<1?L) and small flow rate (<0.5 L·min^?1) reduce operational hazards from steam scalding or from gas explosion.     

Effects of humidity and temperature on the fatigue behaviour of an extruded AZ61 magnesium alloy

Load‐controlled fatigue tests were performed at 20 and 50 °C using two relative humidity levels of 55 and 80% to characterize the influence of humidity and temperature on the fatigue behaviour of an extruded AZ61 magnesium alloy. Fatigue tests were also conducted at 150 °C. No significant variation in fatigue properties was noticed with respect to temperature over the range from 20 to 50 °C for both the humidity levels. Fatigue limits in the range 140–150 MPa were observed for relative humidity of 55%. Fatigue strength decreased significantly with increase in temperature to 150 °C. Further, a significant reduction in fatigue strength with a fatigue limit of ～110 MPa was observed with increase in relative humidity to 80% at 20 and 50 °C. The crack initiation and propagation remained transgranular under all test conditions. The fatigue fracture at low stress amplitudes and high relative humidity of 80% results from the formation of corrosion pits at the surface and their growth to a critical size for fatigue‐crack initiation and propagation. The observed reduction in fatigue strength at high humidity is ascribed to the effects associated with fatigue–environment interaction.     

数字温湿度计相对湿度校准结果的扩展不确定度评定

本文以分辨力为0.1%RH的数字温湿度计为例,进行了相对湿度校准结果的扩展不确定度分析。     

一种双温法温湿度检定箱的探讨

阐述了我单位使用的一种双温法温湿度检定箱的原理,分析了其饱和器温度与露点值的不一致原因,并做了大量的实验重新定义其饱和器温度与相对湿度的函数关系,再次通过实验反向验证新的函数关系结果可靠。     

湿度对玻璃微珠增强硬质聚氨酯复合泡沫塑料黏弹力学性能影响

实验研究了温度与湿度因素对玻璃微珠增强硬质聚氨酯复合泡沫塑料(玻璃微珠/RPUF)黏弹力学性能的影响。结果表明, 湿度对黏弹力学性能有显著的影响, 随着湿度的增加, 玻璃微珠/RPUF的储能模量减小, 刚度下降, 力学损耗因子值增加, 蠕变柔量增大, 柔韧性增强。湿度对玻璃微珠/RPUF弯曲蠕变性能的影响具有类似于时间-温度等效原理的等效关系, 并给出了60 ℃/50%RH参考温湿度下玻璃微珠/RPUF的蠕变主曲线和平移因子。     

温湿度检定箱的湿度均匀度与波动度的测试方法

在温湿度检定箱的湿度均匀度与波动度测试中,针对现有湿度传感器准确度难以满足要求的情况,提出将同种型号规格的湿度传感器在同一台湿度标准装置上进行校准、并加修正值使用的测量方法,减小了测量不确定度,满足湿度均匀度和波动度的测量要求。精密露点仪测量结果验证了该方法的有效性。     

Realization of relative humidity scale from 10% to 98% at 25°C

The accurate measurements of relative humidity are increasingly needed in most of the Egyptian industries. The relative humidity has its own effect in the manufacturing of medicine, steel, metals, textile and is of great importance for controlling the environmental conditions in the factories. As a result of the above facts, it was found that the realization of Egyptian humidity scale is of prime importance for National Institute for Standards (NIS). The scale was realized using two-pressure humidity generator and humidity chamber as a medium, chilled mirror hygrometer to measure dewpoint and RTD to measure air temperature. The relative humidity scale was realized in the range from 10% to 92% using two-pressure humidity generator [1] and from 92% to 98% using humidity chamber at 25°C. All points of results were stable for more than 6 hours with stability range from 0.18% to 0.28%. The uncertainty was evaluated at a confidence level of 95% within 1.1% to 1.8% in the range from 10% to 92% and from 92% to 98%, respectively. The present measurement system is suitable for accurate calibration of different digital or chart hygrometers.     

电影胶片贮存温度湿度探讨

电影是人类重要的文化遗产之一,然而记录电影的载体电影胶片由于受自身构成材料和保存环境等因素的影响,面临巨大威胁。其中保存环境的温度、湿度是影响电影胶片长期保存的关键因素之一,实践证明低温低湿有利于胶片的长期保存,但温度、湿度过低会导致胶片变脆、变形,降低其机械性能,同时也会增加保存运行成本,增加档案管理工作的复杂性。结合我国的具体国情,我们初步认为电影胶片较为适宜的保存温度范围为-5℃～5℃,相对湿度范围为30％RH-50％RH。