In this paper, the flow measurement performance of the ambient air sampler is studied, which is widely used in environmental monitoring, health care and mining enterprises. The paper develops the flow rate performance test device of ambient air sampler, which consists of the high-low temperature test device, the load performance test device, the flow standard device and the pressure measurement device. For various types of ambient air samplers and its calibrators, the device can carry out flow performance tests with the flow range of 10 mL/min ~ 265 L/min, with flow indication error no more than ±2%, the high-low temperature tests with the range of (-20 ~ 40)℃, and the load performance tests in the range (-50 ~ 0)kPa. The uneven capability of temperature adaption of different types of samplers or from various manufacture is found through experiments research, but the flow metering performance of samplers is significantly improved compensated by temperature in this paper. In the load test, the sampler load condition of different ranges or manufacturers are different, which meets the requirement of more than 50 % the air extraction capacity.

As part of the Metrology for Drug Delivery ("MeDD II") European joint research project, a primary method for the measurement of liquid flow rates at the nanolitre per minute scale has been developed. This primary standard allows the calibration of flow meters and flow generators such as infusion pumps, pressure controllers and syringe pumps, for flow rates ranging from 10 nL/min to 1500 nL/min with relative expanded uncertainties (k = 2 ) of 12 % and 0.15 %, respectively. The system is based on the measurement of the displacements over time of a liquid/air interface moving inside a cylindrical glass capillary tube. The flow rate is obtained by multiplying the resulting flow velocity by the cross-sectional area of the tube which depends on the square of the capillary’s inner radius. In order to ensure the traceability of flow rate measurements to International System of Units, camera and frame rate calibration procedures have been established. However, the measured flow rates depend on the local value of the inner diameter which must also be traceable. In this paper, we present a method to measure the inner diameter of cylindrical thin-walled capillaries by confocal microscopy. The method allows visualizing the inside of a tube by filling it with a fluorescent solution and acquiring -stacked images along its full height. The mean inner diameter is deduced from the widths of the fluorescent signal in the obtained images which are measured by image processing. The method was applied on capillaries with different inner diameters and the results were compared with the values given by manufacturers. The relative expanded uncertainties (k = 2 ) were estimated to a maximum of 4 %, which is two times lower than the one provided by manufacturers.

According to the JJG 1113-2015 “Verification Facility for Water Meters” calibration regulations, when testing the verification facility for water meters of Piston, the indication error and repeatability of the main standard implement are determined by two parameters, namely the verification volume and flow rate. Experiments show that the setting of two parameters affects the verification results, when the flow rate is set to 25 L/h and the verification volume is 2 L, the indication error and repeatability of the main standard implement meet the requirements of the verification regulation; while when the flow rate increases to 50 L/h, or even larger, the test results do not meet the requirements, i.e. the test results produce a misjudgment of the piston cylinder's metering performance. The main purpose of this paper is to verify the influence of the verification volume and flow rate settings on the piston cylinder's indication error and repeatability through testing.

The purpose of this paper is to explore the potential of calibration of ADCP discharge measurement in open channel, which conclusion can improve the traceability of ADCP. In this paper, the current velocity and discharge synthesis and other important issues are taken into consideration, and establishes a set of rectangular open channel standard discharge facility, and conducts experimental research on the flow measurement by using Workhorse. The moving boat ADCP measurement uncertainty source is analyzed, and the error situation introduced by the approximate solution is analyzed. By estimating the back scattering intensity, a new type of acoustic reflector is designed, so that the signal quality of ADCP can be kept in the best state in the process of towing calibration, so as to ensure the reliability of the WT measurement results. An experimental device for WT, BT, depth measurement is established to evaluate the basic performance of the instrument. At last an ultrasonic transit time flow-meter(UFM) is taken as reference in field situation, to calibrate the discharge directly, the results are close to laboratory calibration.

A gas flowmeter for measuring low flow rate has been widely used in the field of medical, health, environmental protection, energy industry, aerospace, etc. To against Covid-2019, the requirement on the low flow rate has been increasing dramatically. At present, the typical standard devices for calibrating low gas flowmeter mainly include standard bell provers of gas flow, standard piston provers of low gas flow and standard laminar of low gas flow. Different measuring principles are adopted among these typical standard devices. To ensure the consistency of these typical standard devices, a comparison test is performed. The standard devices used in the comparison are of the same accuracy grade, with an extended uncertainty of 0.2 %(k = 2). The piston-type gas flow calibrator of grade 1.0 is selected as the transfer standard, and three flow points with high flow rate, medium flow rate and low flow rate are selected for test. The consistency of measurement results is evaluated by normalized deviation En. The comparison results are acceptable which show that three typical standard devices are accurate and reliable.