Uncertainty Modelling of the Reference Pressure Generating with OIML and ASTM Weights in Pressure Balances

A pressure balance is a combined with a piston-cylinder unit and a system for the application of a vertical load on the piston. Pressure balances are primary measuring systems those measure pressure in terms of force per unit area. Reference pressure can be generated by a pressure balance. There are many parameters to calculate reference pressure, such as piston’s area, linear deformation of piston and cylinder, measuring temperature, mass, local gravity, surface tension of measuring liquid… All of these parameters have got measurement uncertainty, effects of these uncertainty components must be added to the uncertainty budget of reference pressure. In this study, the uncertainty model function of reference pressure is derived. And the uncertainty model function is rearranged. If the masses of pressure balance are calibrated according to the OIML R-111 or ASTM E-617 guides, the uncertainty model function that is given in the study can be used directly to calculate uncertainty of reference pressure.     

500 MPa活塞式压力计活塞系统关键参数设计

针对500MPa活塞式压力计活塞系统设计的要求,对其参数进行理论计算,确定了活塞杆截面直径,活塞杆伸出活塞筒最大长度,活塞筒外径及其与固定套之间的间隙。通过有限元分析软件对设计结果进行分析,结果表明活塞系统设计结果强度可靠。按设计结果制造活塞系统,在研制的500MPa活塞式压力计样机上进行了验证试验,500次加减压试验证明活塞系统运行稳定。对活塞进行不确定度校准,扩展不确定度为0.0038%。说明活塞系统结构设计合理,能够满足实际应用要求。     

压力计量技术的近期进展

近十年来压力计量技术有了明显的进展。本文介绍了我国微压、中压和高压方面国家基准的改进和我国动态压力校准技术的进展情况。对于活塞式压力计的性能改进以及新型的强制平衡式活塞式压力计和数字式活塞式压力计的研制成功作了不少描述。还介绍了数字式压力控制器的迅速发展及其对压力计量工作的影响。     

Dependence of the Characteristics of a High-Pressure Piston Pair on the Properties of PES-3 Working Fluid and the Pressure Distribution in the Piston-Cylinder Gap

Measurement Techniques - The use of the liquid PES-3 in a high-pressure piston pair is modeled and the parameters of the piston pair are determined. Equations are derived for a mathematical model...     

Failure Analysis of the Hydraulic Primary Standard Pressure Balance Piston

Journal of Failure Analysis and Prevention - In this study, failure analysis of piston which belongs to primary standard pressure balance unit is investigated. The strength analyses of the piston...     

The Reduction of Uncertainties for Absolute Piston Gage Pressure Measurements in the Atmospheric Pressure Range

NIST pressure calibration services with nitrogen are now based on two transfer standard piston gages for which the effective areas have been determined by calibration with the manometer developed at NIST for gas thermometry. Root-sum-squared three sigma uncertainties for the areas for the two gages are 3.05 ppm and 4.18 ppm.     

液压钳的液压系统工作压力

阐述了使用液压销压接电缆或导线接头的基本原理，分析了压缩接头所需的力、活塞弹簧处于不同变形状态下的弹力、液压钳工作时活塞和油缸之间的摩擦阻力及其它阻力，提出了计算上述各种阻力和液压钳的液压系统必要的工作压力的计算公式。     

磁力传动联轴器在数字气体活塞压力计上的应用

介绍了磁力传动联轴器的结构、工作原理以及在数字气体活塞压力计上的应用.磁力传动联轴器解决了数字气体活塞压力计绝压工作模式的传动密封问题,为数字气体活塞压力计的成功研制提供了密封保证.     

A Gas Pressure Scale Based on Primary Standard Piston Gauges

The National Institute of Standards and Technology (NIST) has redefined its gas pressure scale, up to 17 MPa, based on two primary standard piston gauges. The primary standard piston gauges are 35.8 mm in diameter and operate from 20 kPa to 1 MPa. Ten secondary standard piston gauges, two each of five series of the Ruska 2465 type, with successively smaller diameters form the scale extending up to 17 MPa. Six of the piston gauges were directly compared to the primary standards to determine their effective area and expanded (k = 2) uncertainty. Two piston gauges operating to 7 MPa were compared to the 1.4 MPa gauges, and two piston gauges operating to 17 MPa were compared to the 7 MPa gauges. Distortion in the 7 MPa piston gauges was determined by comparing those gauges to a DH Instruments PG7601 type piston gauge, whose distortion was calculated using elasticity theory. The relative standard uncertainties achieved by the primary standards range from 3.0 × 10⁻⁶ to 3.2 × 10⁻⁶. The relative standard uncertainty of the secondary standards is as low as 4.2 × 10⁻⁶ at 300 kPa. The effective areas and uncertainties were validated by comparison to standards of other National Metrology Institutes (NMIs). Results show agreement in all cases to better than the expanded (k = 2) uncertainty of the difference between NIST and the other NMIs, and in most cases to better than the standard (k = 1) uncertainty of the difference.     

利用超高压力国家基准对返压活塞式压力计校准的试验研究

原超高压力国家基准准确度仅为0.1级，无法对0.05～0.1级的活塞压力计进行检定。现在新的1500MPa国家基准准确度达到了0.02级，为超高压活塞压力计的检定打好了基础。2005年利用新的国家基准对南京理工大学0．05级的1000MPa返压式活塞压力计和国营9319厂0.1级6000kgf／cm^2返压式活塞压力计作了校准。本文报告了校准时两台活塞压力计的压力平衡判断原则，介绍了一种较为成功的锰铜压力计间接比较法。     

基于活塞式压力计和数字压力计的微小压力测量新方法

提出了一种微小表压力（差压）测量的新方法。采用1台活塞式压力计和1台精密的数字压力计,通过关断阀连接高低压端的特殊连接方式实现微小表压力（差压）测量,解决了活塞式压力计由于受其下限值的限制而不能实现微小压力测量的问题。利用数字压力计较好的短期稳定性以及活塞式压力计较低的不确定度,可以实现1~10kPa微小表压（差压）的校准,其校准结果的扩展不确定度为U=2.2Pa（k=2）。     

空气声高声压的激光活塞法溯源技术研究

目前空气声高声压的溯源存在空白,本文基于激光-活塞发声器法,研究采用激光直接测量高声压下活塞振速的方式,实现了180 dB下高声压的溯源,并通过实验验证了理论公式和结果的一致性,为高声压的绝对溯源提供了技术方法,保障了高声压量值的准确可靠。     

Influences of Casting Pressure Conditions on the Quality and Properties of a Magnesium Cylinder Head Cover Die Casting

Casting pressure conditions have great influences on the casting defects, such as gas porosity, shrinkage porosity and gas holes. A Mg cylinder head cover die casting was used to experimentally study the influences of casting pressure, the loading time and the piston position of pressure intensification on the variation of pressure and the quality of casting. The results show that casting pressure, the loading time and the piston position of pressure intensification have great influences on the pressure variations in the mold, the quality and performance of casting. The external quality, the density and the tensile strength of casting were improved with the increase of casting pressure and the piston position of pressure intensification and the decrease of the loading time of pressure intensification.     

空气声高声压校准技术现状和趋势

一些传声器需要工作在160～190 d B的高声压下。本文介绍了用于高声压传声器校准的驻波管法、声流调制法、活塞发生器法、脉冲方法和激波管法的工作原理,比较了上述方法的优点和缺点,并根据国内外空气声计量发展的现状分析了空气声高声压校准技术的发展趋势,为高声压传声器的量值溯源和校准提供参考。     

高静压差压校准方法分析比较

高静压差压测量的准确度、可靠性对于提高压力测量装置研制质量有很大影响。本文介绍了差压传感器基本原理及其校准过程中存在的主要问题,分析比较了几种高静压差压校准方法,重点介绍了双活塞方式差压校准及分压方式高静压差压校准方法,并结合试验数据对高静压差压传感器静压影响进行了分析。     

基于高压级活塞排量的双级压缩制冷循环制冷量计算式

为了研究双级压缩制冷循环制冷量简化计算方法，分析了高低压级压缩机活塞排量比、容积效率及指示效率等参数对制冷量的影响，以活塞排量比与中间温度的关系式为基础，作一定的简化处理，理论推导出基于高压级活塞排量的双级压缩制冷循环制冷量简化计算式，并通过实例进行了验证。实例计算结果表明：根据简化计算式以及常规方法计算的结果误差较小，吻合度高，推出的双级压缩制冷循环制冷量计算式是准确的。     

自动标准压力发生器动态控制准确度分析

自动标准压力发生器(以下简称发生器)性能的一个重要指标是准确度。当发生器处于动态控制模式及使用面板显示时需要考虑附加控制准确度。本文通过对PACE6000系列的发生器进行比对实验,以活塞式压力计为标准器,高准确度数字压力计为参考对象,得出了其控制准确度,最后给出了以0.01级数字压力发生器为标准器、0.05级数字压力计示值误差的测量不确定度分析,其内置压力传感器的最大允许误差须为±0.008%。     

Deviation of deformation of piston and cylinder of high-pressure piston pair from deformation as calculated with the use of a solution of the Lamé problem

The deviations of the deformation of a piston and cylinder from the deformation as calculated from formulas in the solution of the Lamé problem as well as the influence of the pressure distribution in the working channel of a piston pair on these deviations are considered. Conclusions regarding certain aspects of the design of high-pressure piston pairs are presented.     

滑阀泵不平衡力的分析

滑阀真空泵是一种容积式真空泵,在工业领域中广泛应用。该泵的旋转活塞平衡长期以来无精确的计算方法,其旋转活塞产生的离心力引起泵的大振动。因此降低该泵的振动长期以来是各国设计者们追寻的目标。文章在分析滑阀泵旋转活塞惯性力的基础上,从理论上分析比较了H－150A,H－150型国产单缸泵及英国GENERAL公司的GKT－300AB型三缸结构滑阀泵的平衡效果。在滑阀泵动平衡的发展方向上提出了自己的看法。     

一等标准活塞式压力计有效面积的测量不确定度评定

从测量过程分析，给出了一等标准活塞式压力计有效面积的测量不确定度分析实例。