The constant close control on Temperature ins the base for dimensional emtrology as declared by the international standard ISO1.
Branca Idealair offers quality solutions for precision air conditioning of Metrology laboratories.
Environmental control is not difficult if it is correctly planned and installed but is a nightmare to fix if you try to patch it up after the main installation is complete. Most of the laboraotries will require a temperature control of 23°C +/- 2°C for high level work and +/-5°C for general purpose work. Traditionally, the dimentional laboratories have worked at 20°C and sometimes require a tighter specification of +/-1°C. It is, however, better to have a good stable temperature than the ideal set point. What is of equale importance is the temperature profile of the Whole laboratory. The correct use of diffusers will spread the conditioned air evenly around the alboratory so that there are no direct draughts over any specific work space. Humidity control is of less importance but needs to be maintained at around 45% +/- 10% RH.
Normally, environmental control requires two stages with an interlocked system to maintain these conditions well. The first stage is that the general building air conditioning provides a comfortable working environment, and the second is that the laboratory is controlled within that zone. this means that the laboratory conditioning unit only has to contend with the small variances of the building environmental system and not the full flunctuaitons of the external weather conditions. In this case it gerally not necessary to have an airlock between the general building and the laboratory. The laboratory should also have a small amount of positive pressure (through a dust filter system) to keep the outside air and dust out of the laboratory itself.
The electrical supply and lighting is frequently overlooked when establishing a laboratory. The lighting in the laboratory needs to be >500 Lux over the work surfaces and about 300 Lux in the storage areas. Some laboratories like to have a combination of fluorescent and incandescent lights sot that, if they are doing an electrical noise sensitive measurement, they can turn off the fluorescent lighs (they generate a great deal of electrical noise).
The instruments required to measure the barometric air pressure, air temperature and relative humidity
The laboratory maintains documented uncertainty measurements results
Using air conditioners and de-humidifiers.
The barometric pressure in the laboratory should be recorded.
The value of local acceleration due to gravity (g) local should be measured /known to the best possible measurement uncertainty.