The CEESI Iowa Quality Control program is made up of three parts. The first part addresses management issues as described in the ISO 9000 series of standards. It consists of the documented procedures and policies that govern the day to day operations. The second part addresses technical issues as described in the ISO 17025 standard. Examples include uncertainty analyses, calibration records and software verification. The Measurement Assurance Program (MAP) is the third part of the CEESI Iowa Quality Control program. This paper discusses the components of the CEESI Iowa MAP.
The main component of the MAP is the use of check standards. Each test section includes an ultrasonic meter check standard that is present during each calibration. Over time historical data have been accumulated on each check standard and typical performance has been quantified. At the conclusion of a customer calibration the consistent performance of the check standard provides assurance that the entire calibration process is also operating consistently. The formal tool used to monitor the check standards is the control chart.
While the check standards monitor the entire calibration, several programs are in place to monitor the individual components. The turbine substitution test identifies the performance of individual turbine meters relative to each other. The critical pressure and temperature measurements are made with redundant instruments. Control charts are used to monitor the transducer pair differences. Finally, the weekly calibration results for the gas chromatograph are monitored using control charts.
There are two overall objectives in the CEESI Iowa MAP, the first is to assure that the measurement process is operating consistently. The resulting benefits have been understood in the manufacturing community for many years, it is only more recently that the measurement community has adopted similar techniques.
The second objective of the MAP is to provide data for the uncertainty analysis, this results in several benefits. The first results from obtaining uncertainty estimates based on data rather than other methods. Data based estimates improve credibility and the likelihood of inadvertently excluding any components is reduced. The second benefit is the general improvement in uncertainty resulting from using historical calibration data instead of manufacturer’s specifications. A manufacturer may includes operating constraints not present in a particular application. A set of specifications may reflect the performance for an entire production batch, the performance of a single unit may be better. Finally, the use of historical data allows for the continuous maintenance of traceability, an important part of measurement uncertainty.

Industrial needs for measurements of low air velocity can be classified in three categories :
- Evaluation of comfort in private or collective building (houses, offices, hospitals, schools, stores, libraries, …) and in vehicles (cars, trucks, trains, planes, …). Actually, the fundamental parameters to qualify comfort are air velocity, temperature and humidity.
- Control of products quality in industrial processes (clean rooms for microelectronics industries, climatic chambers for aging tests, drying chambers for food industries, …)
- Control of equipment to ensure safety of people in hospitals, in pharmaceutical industries, in painting processes, …
These applications require a minimum uncertainty in air velocity measurements which lead to the following evolution in air velocity metrology :
- A calibration facility which ensure the smallest calibration uncertainty as possible : The reduction of this calibration uncertainty will lead to reduce the global measurement uncertainty of process and allow to qualify industrial applications conforming to European and American standards such as EN ISO Standard 7730 « Specifications for thermal comfort conditions », 1995), ASHRAE Standard 55 (« Thermal environmental conditions for human occupancy », 1992), Federal Standard 209E (« Airborne particulate cleanliness in clean rooms and clean zones »)
- A calibration facility which can work at different temperatures, different relative humidities and with different direction of flow.
Currently, anemometers calibrations are carried out at ambient conditions (around atmospheric pressure, 20°C and ambient humidity) in a horizontal flow. Depending on their working principle, anemometers can be very sensitive to the air flow temperature in which they are supposed to measure velocity, especially at low velocity. As working laws are complex, it is often difficult to take into account the real temperature influence on sensors in view to correct the measured value. It would be far more easy to be able to calibrate anemometers at their working temperature.

Turbine meters and orifice plates are designed to operate in ideal conditions, downstream of straight pipe lengths and therefore turbine meters are calibrated in this configuration. The metering accuracy strongly depends on the flow conditions encountered at the meter inlet. Turbine meters are very sensitive to installation effects inducing flow perturbations like jet flow or swirling effects, generated by pressure regulators or pipe configuration in city gate stations. The error due to bad installation effects can reach more than 3%.
Consequently, in order to maintain a good level of accuracy, either the bad installation configuration has to be removed, or the meter has to be isolated from flow perturbations. However, the first solution is not suitable because other constraints like urbanization require a higher compactness of flow measurement systems. In addition it is not economically viable to modify the geometrical configuration of current delivery stations. So the second solution (which consists of making the meter less sensitive to bad configurations) is more suitable, and flow conditioners fulfill this goal. Flow conditioners (FCs) reduce flow perturbations like swirl or asymmetry in a much shorter pipe length than that usually necessary to a natural attenuation. Flow conditioners are more and more used on gas networks. As a proof, a certain number of FCs are quoted in international standards such as the ISO 5167 on differential pressure metering, acknowledging the efficiency of flow conditioners.
The International Organization of the Legal Metrology has a project of recommendations concerning flow measurement systems of combustible gas. This text defines three categories of users and a given level of permissible metering error for each category. The future national laws based upon these recommendations will make the requirements concerning the metering even more drastic, especially for category A meters which will be the biggest systems. It is more than probable that the use of flow conditioners will be necessary for existing delivery stations to match the new requirements. A certain number of flow conditioners are available on the market. Their efficiency but also their limits are well known. Gaz de France proposes a new version of its patented flow conditioner SMM10.
Different experimental studies using hot wire-velocimetry and LDA measurement were carried out to assess the efficiency of the conditioner SMM. These results were the subject of papers presented in another congress. In addition, validation tests have been carried out under real operating conditions, on delivery station configurations of the Gaz de France network. This poster described results obtained.

In order to meet the requirement of rapid development of natural gas industry, and to calibrate natural gas flowmeter used in the project of west-east natural gas transportation in China, a natural gas flow calibration station (facility) with high pressure and big diameter of pipe will be designed and built in Nanjing city. So far, the location of the calibration station, the design scheme and the process flow has been decided. The conceptual design for the facility has been completed. The main specifications of the facility are as follows: the maximum operating pressure is 5.5 MPa, the maximum flowrate under actual working condition is 12000 m³ / h, the uncertainty of measurement is 0.5% and the maximum diameter of the test flowmeter is 400 mm.
The facility is composed of the primary standard, transfer standard, working standard, check standard, calibration-test section, steady pressure and flow systems. The primary standard is mass (gravimetric)-time (Mt) primary standard. The transferring standard is sonic venturi nozzles. The high accuracy of turbine flowmeters in parallel is used as for working standard. The ultrasonic flow meters are used as check standard.
This paper describes and discusses particularly the location of the calibration station, design scheme, function, specification, components, process flow, transfer standard schematic diagram etc.
When the facility is built, its capability is the biggest in china, with features of bigger construction scale, multifunction, advanced equipment, higher pressure-stage, wider flowrate range, higher accuracy and steady performance.

In the context of the gas market opening up to competition, the number of participants in the gas chain is increasing, exchanges are intensifying and the gas supply sources are multiplying for some parts of the world, notably in Europe where the networks are more and more interconnected. Therefore, it is crucial to be able to better determine the quantities of energy exchanged and the variations in the gas quality, with the view to having more accurate and more equitable billing. The variation over time in the calorific value at a given point in the grid can be as high as a few percent and can have important economic effects. Information on the Wobbe index or the density of the gas is also very useful for some industrial process controls: the Wobbe index variation may have strong effects on the products quality for industries like glassmakers. So important customers are more and more interested in a device able to continuously monitor gas quality variations, as well as the calorific value and the Wobbe index.