SR161 The influence of timber treatment preservative systems on performance of commercial moisture meters (2006)
- Valid from
- Information provider
- BRANZ Limited
- G. Kear
- Information type
- Study report
In this report, three conductivity-based moisture meters have been used to measure the moisture content of 10 timber specimens - treated or untreated and all based on the wood species Pinus radiata. The moisture meters and the timber specimens used within this work are all commercially available in New Zealand. Moisture content data is measured and presented as a function of atmospheric equilibration at 65%, 75% and 98% relative humidity at 21±2˚C. Verification was provided by the standard oven-dry method as specified by AS/NZS 1080.1.
The aim of the research was to quantify the applicability of using all commercial resistance-based meters (available in New Zealand) with a single table of correction figures. With an examination of the results presented in this report, however, such an approach does not appear to be feasible without more thorough standardisation of meter use in New Zealand. Two of the three meters examined in this work were produced overseas but are also instruments that are commonly sold in New Zealand. In some instances, the internationally produced meters did not reproduce the behaviour of one commercial meter, which, it is reported, was manufactured and calibrated to the specifications and the correction figures laid out in AS/NZS 1080.1.
When the individual moisture meter correction figures (as supplied with each meter type) were introduced to the directly measured resistance data, all of the meters were able to accurately determine the moisture content of untreated Pinus radiata to within ±1% moisture meter units. In many cases, however, the introduction of treated timbers significantly lowered the accuracy of all of the meters to a degree that was dependent on the timber preservative type and the mode of meter operation. Of particular concern was the inability of some meters at 65% and 75% relative humidity to accurately determine the moisture content of ACQ, LOSP and boron-treated timbers within at least ±2% moisture meter percentage units.