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Since most analytical instrumentation is comparative, it requires a sample of known composition (reference material) for accurate calibration. These reference materials are produced under stringent manufacturing procedures and differ from laboratory reagents in their certification and the traceability of the data provided.
The formal definition of calibration by the International Bureau of Weights and Measures (BIPM) is the following: "Operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties (of the calibrated instrument or ...
According to the dynamic Leeb principle, the hardness value is derived from the energy loss of a defined impact body after impacting on a metal sample, similar to the Shore scleroscope. The Leeb quotient ( v i , v r ) is taken as a measure of the energy loss by plastic deformation: the impact body rebounds faster from harder test samples than ...
The technicians who work in the PMEL will often specialize in one of these sections. The K-Sections are derived from the primary function of the TMDE. This is based upon the calibration authority. Most labs have three calibration sections divided into K1/K8, K5/K6 and K3/K4 that specialize in like test equipment.
The isotopic scales for sulfur and nitrogen are both defined for only a single anchoring reference material. For sulfur the scale is defined by IAEA-S-1 and is reported relative to VCDT, while for nitrogen the scale is both defined by and reported relative to AIR. Figure 1: The development of modern stable isotope reference materials.
The reading is taken from the scale marked next to the grooves, in dimensionless "Hegman units" (or National Standard units; NS) and/or mils or micrometres. [5] Hegman units are defined in terms of an inverted size scale as shown below: [6] Hegman Grind Gage and doctor blade Paint sample at top of Hegman Hegman after paint drawdown
All analytical procedures should be validated. Identification tests are conducted to ensure the identity of an analyte in a sample through comparison of the sample to a reference standard through methods such as spectrum, chromatographic behavior, and chemical reactivity. [5] Impurity testing can either be a quantitative test or a limit test.
Although "International Temperature Scale of 1990" has the word "scale" in its title, this is a misnomer that can be misleading. The ITS-90 is not a scale; it is an equipment calibration standard. Temperatures measured with equipment calibrated per ITS-90 may be expressed using any temperature scale such as Celsius, Kelvin, Fahrenheit, or Rankine.