Assessment of drug delivery devices working at microflow rates.

Almost every medical department in hospitals around the world uses infusion devices to administer fluids, nutrition, and medications to patients to treat many different diseases and ailments. There have been several reports on adverse incidents caused by medication errors associated with infusion equipment. Such errors can result from malfunction or improper use, or even inaccuracy of the equipment, and can cause harm to patients' health. Depending on the intended use of the equipment, e.g. if it is used for anaesthesia of adults or for medical treatment of premature infants, the accuracy of the equipment may be more or less important. A well-defined metrological infrastructure can help to ensure that infusion devices function properly and are as accurate as needed for their use. However, establishing a metrological infrastructure requires adequate knowledge of the performance of infusion devices in use. This paper presents the results of various tests conducted with two types of devices.

Narrow stack emissions: Errors in flow rate measurement due to disturbances and swirl.

European legislation continues to drive down emission limit values, making the emission measurement of narrow stacks of increasing importance. However, the applicable standards (EN ISO 16911-1 and EN 15259) are poorly validated for narrow stacks, and the effect of flow disturbances on the described methods are largely unknown. In this article, measurement errors are investigated in narrow stacks with flow disturbances and swirl, both experimentally and through computational fluid dynamics (CFD) simulations. The results indicate that measurement errors due to misalignment of the flow with typical measuring probes (pitot tubes) are small compared to errors resulting from the positioning of these probes in the measurement plane. Errors up to 15% are reported using the standardized methods, while the measurement error is both smaller and more predictable when using additional measurement points. Implications: Current international standards provide methods to measure emissions from industrial stacks. With increasingly small emission limit values, the accuracy of these measurements is becoming considerably more important. The data from this study can be used to inform revisions of these standards, in particular with respect to flow disturbances in narrow stacks, and can help law- and policy-makers to obtain insight into the uncertainties of emission measurements in these specific situations.