The present paper discusses an example of application of a method for the comparison of calibration curves. The method, presently in development, is expected to be an useful tool for the analysis of complex sets of data in several situations; two possible examples are the analysis of the drift of instrument with complex calibration curves or the analysis of data in Key Comparisons performed for quantities which require the use of measurement instruments as Transfer Standards. The proposed example is based on data from a Key Comparison. The paper discusses the merits of both the technique...
This study cooperated the KOH anisotropic etching with the laser machining to fabricate small sonic nozzles in the shape of a pyramidal convergent inlet followed by a conical diffuser with a divergent angle of 5°. Three different diffuser lengths were made for the nozzles. The throat diameters were around 100 µm. Experiments were performed to obtain discharge coefficients and critical back pressure ratios in Reynolds numbers ranging from 5.8 × 10² to 4.5 × 10³. The critical back pressure ratio for one of the nozzle type examined reached 0.486 at Re = 4.4 × 10³. Numerical simulations were...
RTA (Recovery Temperature Anemometry), which estimates the flow velocity field based on the recovery temperature measured by a very thin thermocouple wire without disturbing the flow field, is introduced in the paper. Measurements of flow fields in critical nozzles by RTA reveal very interesting phenomena such as interaction of oblique shock system fixed on the nozzle geometry and a strong shock moving along the nozzle axis depending on the pressure ratio, which is considered to have a relationship with the premature unchoking phenomenon. Possibility to estimate the flow velocity...
Because of the low uncertainty and very good long term stability the application of critical nozzles became very important especially for test rigs. The majority of nozzles are used in the so-called “suck mode” using atmospheric air as test medium. In order to use nozzles for the generation of different flow rates as well as to generate gas flows with different kinds of gases the application with increased input pressure became more important. An other field of extended application is the usage for small flow rates. Nozzles which have a shape in accordance to ISO 9300 are available with...
For over forty years CEESI has operated primary calibration standards to provide traceable flow measurement services. Critical flow venturies (CFVs) have always been used as transfer standards to directly calibrate customer meters. Over the past ten years CEESI has invested in the fabrication and calibration of additional CFVs to reduce calibration uncertainty. This paper discusses test programs based on two sets of critical flow venturies. The first set was calibrated by NIST and used to compare one of the CEESI primary standards to NIST. A second set allows for multiple CFVs to be...
In calibration technique validation, reliability and the traceability of all are very important issues during operation. According to the currently applied rules the traceability or Key Comparison (KC) usually takes place every three-six months. But it’s also obvious, that in the case of relocation KC needs to be performed immediately. For such KC the so-called Youden-Analysis was used, which made the collection of very acceptable results at this ambiance possible.
The National Institute of Standards and Technology (NIST) uses a bi-directional 20 L-displacement piston prover as its primary standard for measuring hydrocarbon liquid flows ranging from 1.86 × 10 -5 m 3 /s (0.3 gpm) to 2.6 × 10 -3 m 3 /s (40 gpm). Our analysis that shows that the prover’s uncertainty over this flow range is 0.074 % ( k = 2, corresponding to a 95 % confidence interval). Using a dual rotor turbine meter as the transfer standard, we compare the new 20 L piston prover standard with NIST’s other hydrocarbon liquid standards and NIST’s water flow standard. The results are...
Generally the construction costs of a calibration facility for hydrocarbons are very high and it is difficult to cover every kind of hydrocarbon and all flow rate ranges required at industry. So far, at the primary standard in Japan, the calibration liquids are limited to kerosene and light oil, in spite of the demands from the industry for other hydrocarbons such as gasoline and heavy oil. Therefore the expansion techniques from the present primary standard to other liquids such as gasoline and heavy oil using flowmeters have been developed. Furthermore the standard flow has expanded to...
A new calibration facility for small flow of hydrocarbon liquid has been established at National Metrology Institute of Japan (NMIJ). At present, the facility provides calibration service for hydrocarbon flowmeters in the mass flow range between 10 kg/h to 100 kg/h. The new primary standard adopts gravimetric calibration method with standing-start-and-finish using static weighing. Light oil is used as the working fluid.
This paper presents a laboratory facility for calibration and testing of flow meters and measurement systems components for oil and liquid petroleum derivatives newly built in Brazil. The laboratory is installed in a fully air-conditioned four floors building with a total area of 700 m². The set of flow meter working standards is composed of two five path ultrasonic meters and two Coriolis master meters, calibrated by the laboratory reference standard, an especially designed 6 tons diverting type gravimetric system. The measurement uncertainties attainable with the test facility lie between...