Objective
The only primary method for measuring humidity that is currently recognised is the gravimetric method, which involves the determination of the water/air mass ratio. Unfortunately, the gravimetric method is difficult to use and requires long sampling times, particularly when dealing with low levels of humidity. Many laboratories therefore use the measurement of dew-point temperature in a humid air generator as a less costly and less complicated means to calibrate transfer standards or industrial hygrometers.
Several types of humid air generators are currently in use in Europe. The methods of humidification may involve single stage, multiple stage or recirculating processes, and may be carried out at either atmospheric or elevated pressures. This project aims to demonstrate which approach, if any, offers superior metrological properties. By applying comparable tests to each of the different types of humidity generator, unique information will be gained about the repeatability and the hysteresis of each method. If the metrological quality of the different types of humidity generators can be demonstrated, it will be possible to use dew-point generation as a reference method for humidity.
Two reference condensation hygrometers with chilled mirrors circulate since June 1995 in 8 national laboratories.
Topic(s)
Data not availableCall for proposal
Data not availableFunding Scheme
CSC - Cost-sharing contractsCoordinator
VILLEURBANNE
France