- The purpose of this guidance note is to explain why it is not possible to claim formal traceability for the pressure measurements made by a pressure balance, at anywhere approaching state-of-the-art levels of measurement uncertainty, when such traceability is based on locally obtained dimensional measurements of individual pistons and cylinders.
- The best thermometer to use in a particular application is something that only you can decide. Your choice will depend on many factors and a selection of these is listed below.
- In 1790 the French National Assembly obtained Louis XVI's assent to commission the country's leading scientists to recommend a consistent system for weights and measures.
- Probably not. The figures should be interpreted with caution, especially if an instrument has not been independently calibrated for some time.
- Machines capable of undertaking force calibrations are known as force standard machines and they may be categorised as either primary or secondary.
- Some barometer measurement principles are listed below; there are bound to be others.
- The micrometre (0.001 mm) gauge should be taken first, followed by the hundredth, tenth and millimetre gauges.
- No, definitely not.
- Since 1995 October 22 there has been a permanent one-hour difference between British time (as broadcast by MSF) and Central European Time, as broadcast by DCF-77 in Germany.
- No, they are not. The internationally recognised SI unit for pressure is the pascal, abbreviated to Pa, and this is the unit realised by the primary measurement standards in the world's national metrology institutes to provide traceability for pressure measurements.
- The International Prototype Kilogram is not perfectly stable (its mass changes with time), the amount it changes cannot be known perfectly (there is no 'perfect' reference against which to judge it) and the values of the national copies cannot be monitored at the highest level of accuracy without being compared directly with it.
- The most accurate barometers are indeed the mercury primary barometers used at national measurement institutes. Most barometers, though, are secondary instruments rather than primary ones and when considering these it is not correct to say that those based on a mercury column are invariably more accurate than those that are based on an alternative principle.
- The time at which summer time begins and ends is given in the relevant EU Directive and UK Statutory Instrument as 1 a.m. Greenwich Mean Time (GMT).
- Up to a point yes, but unless a weight is of suitable design and material and in appropriate condition it will not be possible to give it a meaningful calibration and it would certainly be a waste of money.
- Give the weight a general inspection to check its construction, surface finish and the suitability of its magnetic properties.
- A number of factors need to be taken into account when considering sources for calibrating radiation thermometers.
- Yes - Saturated (or unsaturated) salt solutions, and certain other chemicals, can be used to generate an environment of a particular relative humidity in an enclosed space.
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