实验室振动式液体密度仪

本规程适用于密度范围(650～3000)kg/m³的实验室振动式液体密度仪(包括台式振动管密度仪和手持式振动管密度仪，以下简称密度仪)的首次检定、后续检定和使用中检验。JJF1002—1998国家计量检定规程编写规则JJF1001—1998通用计量术语及定义JJF1059—1999测量不确定度与表示ISO15212-1振动型密度仪第一部分：实验室仪器GB/T6682—2008分析实验室用水规格说明和试验方法使用本规程时应注意使用上述引用文献的现行有效版本。3概述密度仪主要是由U形玻璃振动管、电磁振荡器、温度控制器以及显示单元和数据处理单元组成。其结构见图1。当一定体积的液体充满U形玻璃振动管后，由于管内物质的质量发生变化，使得振动管的固有振动频率或特征频率也发生变化。体积一定时，振动管的频率是管内所充物质质量的函数。当质量增加时密度增加，频率降低，振动周期增大。反之，当质量减小时密度减小，振动周期减小。二者之间的关系式简单描述进样管U进样管U形玻璃振动管显示器排放管24计量性能要求密度仪的计量性能要求见表1和表2。工作级最大允差士0.15士1.55通用技术要求密度仪外观要求如下：密度仪应具有下列标志、标识：仪器名称、型号、编号、制造厂厂名和出厂日期；其标志、标识应清晰。密度仪外表不应有影响工作性能的机械损伤；显示屏表面平整、洁净、无划痕，读数清晰、完整；各调节器应能正常调节，各开关及按键接触良好，能正常工作，各紧固件无松动。6计量器具控制计量器具控制包括：首次检定、后续检定和使用中检验。6.1检定设备6.1.1检定用标准器按“密度计量器具检定系统”的规定配置。见表3。测量范围测量范围U=3×10-^kg/m²台式振动管密度标3表3(续)测量范围测量范围工作级6.1.1.1密度标准液体选取3个或4个密度标准液体，该液体必须是单一物质，且具有稳定的物理和化学性质。其运动粘度应不大于100mm²/s。标准液体的选取。尽可能在仪器测量范围内考密度仪的测量范围为(650～2000)kg/m³时，应选择如下3种密度标准液体：(3)(1450～1650)kg/m³:溴苯或四氯乙烯；密度仪的测量范围为(650～3.000)kg/m³时，可根据用户需要增加一个检定点，并选取如下密度标准液体：(4)(2200～2400)kg/m³:1.2,3-三溴丙烷。6.1.1.2振动管台式密度标准装置：测量范围为(650～3000)kg/m²,标准等级为0.01级的标准密度仪一台。6.1.1.3一等密度计标准装置：测量范围(650～2000)kg/m²的连续型一等密度计6.1.1.4温度计；范围为(0～50)℃的二等标准水银温度计或准确度不低于二等标准水银温度计的其他温度计。6.1.1.5空盒气压表(检定精密级和工作级用);范围(80～106)kPa,最大允许误差土0.25kPa,水银气压表(检定标准级用):范围(80～106)kPa,最大允许误差±0.03kPa。6.1.1.6相对湿度表：范围20%～85%,最大允许误差±5%。6.1.1.7清洗液：无水乙醇、蒸馏水、溶剂汽油、丙酮、石油醚、重铬酸钾洗液、甲苯、洗涤剂等。6.1.1.8注射器：(5～10)mL。6.1.1.9空气干燥装置：对于没有空气干燥泵的密度仪，可以外加一个微量空气泵。空气量以能够吹干U形管为宜；或者使用干燥的洗耳球，将U形管吹干。6.1.1.10实验室恒温装置：实验室内应有恒温装置，以保证室内温度、湿度能够达到46.1,2.1环境温度要求在(20±2)℃范围内，相对湿度20%～80%。度标准液体通常使用的溶解液见表4。清洗过后，用干燥空气将其油醚(30～60沸程)等。然后再用于燥空气将其吹出，并且净化。壬烷四氧乙炳1.2,3-三溴丙烷(1)空气自校将测量系统的温度设定为20℃,并将干燥空气充满U形振动管，待温度稳定后，记录空气密度值m和温度值，同时记录检定环境的相对湿度及大气压力值，并计5气密度示值进行修正。(2)用除气蒸馏水自校将测量系统的温度设定为20℃,用新鲜的除气蒸馏水充满U形振动管，并确保振动管内无气泡，待温度稳定后，记录水的密度值pxm和温度值。按记录的温度值查附录C中对应的纯水密度值pk。当|px-Pxm|超出仪器说明书所规定的要求时，需对水的密度示值进行修正6.2.3.2工作级的密度仪可以不进行空气自校.对于具有自动校准功能的仪器，按说明出要求设置好程序进行自动校准。蒸馏水应符合GB/T668220M的更求，水质新鲜。先过滤后蒸馏。除去空气的水应谨慎保存，减步是动，以尽量减少至一何为容入其中。6.2.4密度示值误差和重复性的检定6.2.4.1密度标准能体检定法将选定的密度标混液体注入并充病测属指，待密度仪温度已会后。记录密度和温度值。每个密度检起这独立测量3次十算平写值3在测量1050)kg/m²的密度点时，用基审水重复6次，并家下式计算单次测量标准偏卷乙印重复性：注入密度标准做体时，应仔细规在U形管内有无气泡，如公现有气泡，应将气泡排出，直至无气池手动进样时，注无容应继续保持在样品入口处。以免空地人U形管内。对于具有自动进样物能的仪器，按说明书要求设置好程产进行自动测量，记录密度和温度值。6.2.4.2台式振动管密度标准发费值定些门将被检密度仪与标准装置放置在工作台工，设定温度均为20℃,恒温后，根据被检仪器的测量范围选取6.1.1.1中的4种或前3种密度标准液体，分别注入被检密度仪与标准装置中，观察二者有无气泡，如果有气泡，需将气泡排出，待温度稳定后，分别记录标准装置和被检密度仪的密度和温度值。每种液体独立测量3次。按式(2)计算按下式计算密度示值误差式中：Pm——标准装置3次示值的平均值。6在测量(950～1050)kg/m²的密度点时，被检仪器重复6次，按式(4)计算单次测量标准偏差，即重复性。6.2.4.3用一等密度标准装置进行检定选取6.1.1.1中的前3种密度标准液体。分别将一等标准密度计放入温度为(20±0.1)℃的盛有密度标准液体的检定玻璃简中，用一等标准密度计对其进行测量。同时，用被检仪器也对其进行测量。待温度稳定后，分别记录一等密度计和被检密度仪的密度和温度值。每种液体独立测量3次。按式(2)计算各自的密度平均值并计算密度示值误差：式中：Pm——标准密度计3次示值的平均值修正后的实际密度值(包括证书修正值或毛细修正值等)。在测量(950～1050)kg/m²密度点时，被检仪器重复6次，按式(4)计算单次测量标准偏差，即重复性。如果检定液体和一等密度计证书上给出的工作液不同时，需要进行毛细常数作用修正。修正公式如下：ay——证书上给出工作液的毛细常数，mm²;a₂——所选液体的毛细常数，mm²;D———等密度计的干管平均直径，mm;M———等密度计质量，mg;π——圆周率，取3.14,密度标准液体检定法作为仲裁的方法。6.3检定结果处理按本规程要求检定合格的密度仪发给检定证书。不合格的密度仪发给检定结果通知书。并注明不合格项目。当密度仪不符合本级计量性能要求，但符合低一级别的计量性能要求时，可发给检定证书，但要注明其合格的等级。6.4检定周期检定周期不超过1年。7检定记录格式受检器示值受检器误差123231234568检定证书和结果通知书内页格式外观外附录C999.099064999.097557999.996045909.094534999.093022999.091508999,089994999.A⁸47999.083923999.08280A999.080881999.079358999.077834999.07630999.068665999.09+999999.053290999.174999.050999.037298999.4999.0346859.999.042.458999.006463999.6%999.0039972200099998.974663998.973A8,971457098.969853998.968247998.966640998.965032980423998.96181998.958589998.9569756360998.953744998.952127998.950509998.948867269998.942400998.9407749988937520998.935812998.9342629982298.930999998.9293659098.909676998.908028998.906183-998.219.541.208-RM2G16257998.914614998.912969998.911323OLSEo7998.899769098.898114998,896458998.891801998.893142998.891482998.889821998.888159998.886406998.884832998.883167998.881500998.87983998.876494998.874822998.873150998.871477998.869802998.858127998.866450998.864772998,863093998.861412998.859731998.858049998.856365998.854680998.852994998.851307998.849619998.847930998,84623998842855998841161998839466998837770998836072998834374998832674998830974998,8292729台表(续)998.825865998.824160998.822453998,820746998.819037998.817327998.815616998.813904998.81219998.808762998.807045998.805327998.803609998.801889998.800168998.798445998.796722998.794998998.793272998.791545998.789817998.788088998.786358998.784627998.782895998.781161998.779427998.777691998.775954998.774216998.772477998.770737998.768995998.767253998.765509998.763765998.762019.998.760272998.756774998.755024998,753273998.751520998.749766998.748011998,746256998.744498998.74274998.739220998.737459998.735696998.733932998.732167998,730401998.728634998.726866998.72509998.721554998.719782908.718008998,716233098,714457998.712680998.710901998.709122998.70734998.703777998.701993998,700208998.698422998.696634998.694846998,693056998.691266998.689474998.687681998.685887998.684092998.682296998.680499998.678700998.676901998.675100998.673299998.671496998.669692998.667887998.666081998.664273998.662465998.660655998.658845998.657033998.655220998.653406998.651591998.649775998.647958998.646139998.644320998.642499998.640678998.638855998.637031998.635206998.633380998.631553998.629724998.627895998.626064998.624233998.622400998.620566998.618731998.616895998.615058998.613220998.611380998.609540998.607698998.605856998.604012998.602167998.600321998.598474998.596626998.594776998.592926998.591075998.589222998.587368998.585513998.583658998.581801998,579943998.578083998.576223998,574362998.572499998,570636998.568.771998.566905998.565038998.563170998.56130998.557560998.555688998.553814998.551940998.550064998.548187998.546310998.544431998.542551998.538787998.536904998.535020998,533134998.531248998.529360998.527471998.525582998.52369998.519905998.518011998.516116998.514220998.512322998,510424998.508524998.506623998.504721998.502818998.500914998.499009998.497103998.495196998.493288998.491378998.489468998.487556998.485643998.483730998.481815998.479899998,477982998.476.064998.474144998.472224998.470303998,468380998,46645998.462606998.460679998.458752998.456823998.454893998.452961998.451029998.449096998.447161998.445226998.443289998.441352998.439413998.437473998.435532998.433591998.431648998.429703998.427758998.425812998.423865998.421916998.419967998.418016998.416064998.414112998.412158998.410.203998.40824998.404332998.402373998.400412998.398451998.396489998.394525998.392561998.390595998.388628表(续)二998.384691998.382722998.380751998.378778998.376805998.374831998.372856998,370879998.36890998.364944998.362963998.360981998.358998998.357015998.355030998.353044998.351056998.349068998.347079998,345089998.343097998.341105998.339111998,337117998.335121998.333124998.331127998.32912998.325127998.323125998.321122998.319117998.317112998.315106998.313099998.311090998.309081998.307.070998.305058998.303046998.301032998,299017998.297001998.294984998.292966998.290947998.288927998.286906998.284883998.282860998.280835998.278810998.276783998.274756998.272727998,270697998.26866998.264602998.262568998.260533998.258497998.256460998.254421998.252382998.250342998.248301998.244215998.242170998.240124998.238078998.236030998,233981998.231931998.229880998.22782998.223721998.221666998.219610998.217553998.215495998.213435998.211375.998.209313998.207251998.205187998.203123998.201057998.198990998.196923998.194854998.192784998.190713998.188641998.186568998.184494998.182419998.180343998.178265998.176187998.174108998.172027998.169946998.167863998.165780998.161610998.159523998.157435998.155346998.153256998.151166998.149074998.146981998.144887998.140695998.138598998.136500998.134401998.132301998.130199998.128.097998.125993998.12388998.119677998.117569998.115460998.113351998.111240998.109128998.107015998.104901998.102787998.100671998,098554998.096436998,094316998,092196998.090075998,087953998.085830998.083705998.08158998.077326998.075198998.073068998.070938998.068806998.066673998,064540998.062405998.060269998.058133998.055995998.053856998.051716998.049575998.047433998,045290998.043.146998.011001998.038855998.036708998.034560998,032410998.030260998.028109998.025956998.023803998.021649998.019493998.01733998.013021998,010861998.008701998.006539998.004376998.002213998.000048997.997882997.995715997.993547997.991379997,989209997.987038997.984866997.982693997.980519997,978344997.976168997,97399997.969633997.967453997.965272997.963.090997.960906997.958722997.956537997,954350997.95216997.947785997.945595997.943403997.941211997.939017997.936822997.934627997.932430997.930233997.928034997.925834997.923633997.921432997.919229997.917025997.914820997.912614997.910407997,908200997,905991997.903781997.901570997,899358997.897145997.894931997.892716997.890499997.888282997.88606河997.881625997.879404997.877182997.874958997.872734997.870509997.858282997.866055997.863827997.859367997.857136997.854903997.852670997.850435997.848200997.845963997.843726997.841487997.837007997.834766997.832523997.830280907.828.026407.825789997.823543997.821295997.819016897.814546997.812294997.769319997.767047992097.762500997.760225997.757949097.507297.753394997.751997.746554997.74427207.931989997.739705.997.737420997.735134997.732842<07N30558997.728997.723688997.72197.719103997.716809997.714513997.712217997.7099209000A622997.70532997.654487997.82166997.649842997.8751997.631220997.878997.626554997.62422997.607853997.856)997.603997.8008234598478997.66997.659129997.656808997.638.341997.635881997.610-8997.612534997.59hf997.589087997.562997.565541997.563181997.560820997.55862497.5560*0*553731MWEF766997.549066007F¹6E³3997.537155997.53419A532410997.530036997.527.661997.525285997.52290894,0530997.518997.513.390997.5110087:08.625997.506242997.503857997.501471997.499081-8096696997.4943997.489527997.4871359997.482349997.479954997.477558997.476002067.472764907.470365997.465565997.463163997.4606458352997,455953997.45307t997.441505997.439093997.436681971017S853615.27021997.424604997.422186997.419766997.417346997.414925997.412503997.410079907.707855997.405230997.402804997.400377997.397949997.393090997.390659997.388226997.385793997.383360997.380925997.378489997.376052997.373614997.371175997.368735997.366294997.363852997.361410997.358966997.356521997.354076997.351629997.349181997.346733997.344283997,341832997.339381997.336928997.334475997.332.020997.329565997.327108997.324651表(续)997.319733997.317273997.314812997.312349997.309886997.307422997.304957997.302491997.300024997.295086997.292.616997.290145997.287673997.285200997.282727997.280252997.277776997.275299997.272821997.270342997.267863997.265382997.262900997.260418997.257934997.255449997.252964997.250477997,247990997.245501997.243012997.240522997.238030997.235538997.233045997.230550997.228055997.225559997.220564997.218065997.215565997.213064997.210562997.208059997.205555997.203050997.200544997.195530997.193021997.190511997.188001997.185489997.182976997.180463997.177948997.175433997.170399997.167881997.165361997.162841997.160320997.157798997.155275997.152751997.150225997.147699997.145172997.142644997.140116997.137586997.135055997.132523997.129990997.127457997.124922997.122386997.119850997.117312997.114774997.112234997.109694997.107153997.104610997.102067997.099523997.096977997.094431997.091884997.089336997.086787997.084237997.081686997.079134997.076582997.074028997.071473997.068917997.066361997.063803997.061244997.05868