By Abdulaziz A. Al-Ghonamy, Mamdouh Halawa and Mohamed Aichouni
This paper presents a proposal for establishing a portable laboratory in hot, arid regions to provide the necessary maintenance services for equipment used in remote sites as on-site services. A portable, on-site metrology laboratory eliminates the need to ship instruments and reduces the calibration turnaround time, thus reducing downtime for the production equipment and lowering the cost of calibration. The proposal stresses the importance of the portable laboratory approach in hot, arid regions with typical applications such as electrical measurements and fluids flow metering. Technical requirements needed for the portable laboratory as well as the expected challenges and difficulties are also discussed.
Continue reading Technical Requirements for a Portable Metrology Laboratory in Hot, Arid Regions
By Sulan Zhang
This paper introduces a solution for high attenuation measurement of step attenuators. Fundamentally, this high attenuation measurement method is based on the cascaded 2-port network and S-parameter theory. This method is to compute the S-parameters of high attenuation (> 80 dB) using the measured S-parameters of lower attenuation (< = 80 dB) settings, the calculations of which depend on attenuator card sequence and physical structure of the step attenuator. Such a method can measure attenuation as low as 120 dB. This is not a straight dB addition; rather, this solution can offer considerable accuracy only using a VNA (Vector Network Analyzer) and T-matrix (as known as transmission parameter or cascade parameter) method which can make the calculations easier. Measurement uncertainties are derived from uncertainties of cascaded S-parameters, for example, measurement uncertainty for 80 dB @ 18 GHz is less than 0.8 dB and 110 dB @ 18 GHz is less than 1.0 dB.
Continue reading High Attenuation Measurement of Step Attenuators
By Mike Stears
Like many calibration laboratories, our laboratory provides calibrations for a wide range of instrumentation. For the most part, we calibrate the instrumentation to the manufacturer’s published specifications. As one of our services, we provide calibrations of electronic balances for customers within our company; the calibrations are performed at the customer’s location. In our experience, most of our customers are not using their balance as a comparator, but simply putting an unknown quantity on the balance and reading the displayed value. Manufacturer’s specifications for balances typically include specifications such as readability, repeatability, linearity, and sensitivity temperature drift; but, what does this all mean when the balance user simply reads the displayed mass value and accepts the reading as the true value? What is the uncertainty in the measurement? This paper discusses a method for assigning a direct-reading uncertainty to a balance based upon the observed calibration data and the environment where the balance is being used.
Continue reading Balance Calibration – A Method for Assigning a Direct-Reading Uncertainty to an Electronic Balance
By Ann Lenhardt
Training Objective: Enable the pipette user to assess the performance of a single channel adjustable volume pipette. The method used for the performance analysis is the gravimetric method.
Continue reading Metrology 101: How to Calibrate a Single Channel Adjustable Volume Pipette