- Certified Reference Materials (e.g. Primary Reference Gas Mixtures) produced by NPL under ISO Guide 34 will have an expiry date stated on the certificate.
- There should be no interference as the Wi-Fi transmit frequencies are so different from the MSF frequency.
- For the last 20 years there has been a considerable amount of work undertaken looking for an alternative, more fundamental, definition for the SI unit of mass - the kilogram.
- The length of time that it will take for the step gauge to reach ambient temperature in the laboratory will depend on both its mass and the temperature differential between the car boot and the laboratory.
- In Europe the weight classification system adopted is that produced by the International Organization of Legal Metrology (OIML), known as document OIML Recommendation R 111.
- Yes there is a difference.
- 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.
- Yes there are - some are listed here.
- 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.