Absolute moisture meter
Absolute moisture determiners are measuring devices for determining the material moisture of a solid.
construction
An absolute humidity analyzer consists of a drying chamber with an integrated precision balance . The devices on the market differ in the type of heat input into the sample and in the number of samples that can be measured at the same time. There are devices with heating rods, infrared radiators (incandescent lamps) and surface radiators.
Procedure
Several (at least 7) representative samples are taken from the material to be measured ( solid matter ), the mass of which is determined before drying (depending on the design of the device, a certain mass may be prescribed, usually a few grams). These samples are then heated in the drying chamber (usually with a turntable for sample dishes). The free water contained in the samples is driven off.
The air inside the drying chamber is pre-dried by a drying cartridge (e.g. with silica gel or similar) to a dew point temperature of approx. −40 ° C and then heated. The desiccant cartridge absorbs the water released by the samples, which is released back into the environment the next time it is pre-dried.
The drying temperature depends on the material to be dried and on whether water of crystallization should also be expelled or not, often 105 ° C. The duration of drying is determined empirically by weighing whether there has been any weight loss; if two consecutive weighings (24 hours apart) show a difference of less than 0.01% (constant mass), drying is terminated.
The variables relevant to the material moisture are calculated from the difference between the last and the first measured value .
Libra
The integrated balance can be designed as a beam balance or as an electronic balance and normally has a resolution of 0.01 g to 0.001 g.
swell
K. Kupfer: Material moisture measurement - fundamentals, measuring methods, applications, standards , Renningen-Malmsheim: expert-Verlag, 1997
Individual evidence
- ↑ Committee 207: B 3355 Drainage of damp masonry . In: Austrian Standards Institute / Österreichisches Normungsinstitut (Ed.): B 3355 . January 15, 2011 edition. Part 1: Building diagnosis and planning principles, ÖNORM B 3355-1: 2011. Austrian Standards plus GmbH, Vienna, p. 19 .