CRDConcept: measurement: moisture content

"The only indisputable method for measuring MC is to weigh the member, then dry it in an oven (OD) in accordance with published standards, and then find the MC based on OD weight (the amount of glue solids may alter this a bit, but not enough to make a practical difference). " -- Source (www.tjm.com/tin/mst1.cfm)

D.C. RESISTANCE MOISTURE METERS FOR WOOD-PART II. H. F. VERMAAS, South African Forestry Journal, 122: 70-81

moisture contents measurement methods:

Gravimetry: slice-dry-weigh method (For wood drying, see Drying hardwood lumber for in depth info.

Electrical methods: Resistance, Capacity

Gamma ray attenuation: Rucker, P., Holm, A. and Krus, M., 2000, Determination of moisture and salt content distributions by combining NMR and gamma ray measurements

Neutron radiography

nuclear magnetic resonance, NMR: Rucker, P., Holm, A. and Krus, M., 2000, Determination of moisture and salt content distributions by combining NMR and gamma ray measurements

TDR: Time Domain Reflectometry (Hansen, E. J. d. P. and Hansen, M. H., 2002, TDR measurement of moisture content in aerated concrete))

CT: computed tomography (CT) with X-ray Lindgren, O, 1992

X-ray attenuation,

¦Ă-ray (Y-ray) attenuation,

capacitance,

microwave,

Surface wetness

The ECC (electrochemical cell) "(also called Sereda) sensors are small (approx. 18 mm x 10 mm (11/16 in. x 3/8 in.)) and light (few grams) [see ASTM standard G 84-89]. They contain two different metals, copper and gold, in an interlaced pattern plated onto an insulating substrate. When moisture condenses on the sensor it activates the cell, producing a small voltage (0 to 100 mV) across a 10 MW resistor."-- Sa?d, M. N. A., Brown, W. C. and Walker, I. S., 1997, Long-Term field monitoring of an EIFS clad wall

Moisture content measurement by resistive and capacitive method

Quarles, S. L., Physical Limitations of Moisture Meters

The electrical resistance meter to measure the moisture content of wood and other materials is very handy tool for moisture contents upto fiber saturation. The probe is simple two metal pins. These pins can be made or consist of many choice and styles: the stainless steel nail with insulated shaft comes from the manufacture (about $25 to 40 per pair) is the most durable and can work for long time and under rough conditions. Custom made pins (or pin substitutes) are perfectly fit for many special conditions, such as use conductive clue to form two parallel electrodes on the material surface for MC close to surface; use gold plate connector (sub-D) pins for small installation footage, esp. suitable for thin panels.

See reviews:

Janz, M., 1997, Methods of measuring the moisture diffusivity at high moisture levels

Derome, D., Teasdale-St-Hilaire, A. and Fazio, P., 2001, Methods for the assessment of moisture content of envelope assemblies

Also see: Moisture Detection Equipment-Manufacturers

Electric Moisture Meters at PATH

Moisture Content of Timber a good article on gravimetry and meters.

Detailed info: at FPL

An article on Limitation

What is your electrical moisture meter telling your?

Balance for weighing gravimetry samples

Reference;

Norberg, 1999, Electrical measurement of moisture content in porous building materials

Grahn, J (1997) Electrical measurement of moisture content in wood. Influence of specimen geometry and electrode configuration. M.Sc Thesis, TRITA-BYMA 1997:6 E, Royal Instit ute of Technology, Stockholm.

James, WL (1994) Fundamentals of hand held moisture meters: An outline. Proc ASTM Hand Held Moisture Meter Workshop, Madison, WI, Forest Products Society, 5 May 199 3, pp 13-16.

Lin, RT (1967) Review of the electrical properties of wood and cellulose. For Prod J, Vol 17, N o 7, pp 54-60.

VerMaas, Hf (1982) D.c. Resistance Moisture Meters for Wood, Part I: Review of Some Fundamental Considerations. South Afr for J, No121, pp 88-92.

Tidbits

A great intro/basic about Dielectric Method and can be found at sensorteh.com.

http://www.woodweb.com/knowledge_base/Electric_Moisture_Meters.html A guide for using portable electric moisture meters on lumber. May 3, 2001, by R. S. Boone and E. M. Wengert

Web Links (4):

Notes

Jersey Balances: "supplier of Analytical, Precision, Top-Loading, Moisture & Industrial Balances and scales - for weighing to the nearest 0.00001g up to several hundred metric tons"
Moisture Content Measurement: An excellent, practical article on practical MC measurement.
Moisture detection equipment list at Xatta: List of more than a douzen sites that are either web resources pages (such as a page on this site) of industry directories (some are ad sites)
Wood movement as it effects joinery: Effect of moisture, isothermal, shrinkage of various wood specias

Related References (47)

capacitive probe: A capacitance probe for measurement of moisture content in open pore thermal insulations, by Motakef, S., and L.R. Glicksman, 1989
--------: A comparison of different techniques to quantify moisture content profiles in porous building materials, by Roels, S., Carmeliet, J., Hens, H., Brocken, H., Cerny, R., Pavlik, Z., Ellis, A. T., Hall, C., Kumaran, K., Pel, L., Plagge, R., 2004
--------: A comparison of various techniques for determination of moisture diffusivity from moisture profiles, by Drchalova, J., Pavlik, Z. and Cerny, R., 2002
--------: A review of testing for moisture in building elements, by Dill, M.J., 2000
--------: Accuracy and functionality of hand held wood moisture content meters, by Fors¨¦n H., Tarvainen V., 2000
MC sensor for RH. +-10% error: Accuracy of wood resistance sensors for measurement of humidity, by Carll, C. and TenWolde, A., Carll, C., 1996
gamma-ray spectroscopy: Application of gamma-ray spectroscopy for determination of moisture distribution in insulating materials, by Kumaran, M. K., 1991
RH in tubes in material (concrete): Automatic structural moisture measurement system in inhabited dwellings, by Niemi, S., 2000
gypsum sensor: Comparison of empirical equations for temperature correction of gypsum sensors, by Aggelides, S. M. and Londra, P. A., 1998
--------: Contactless investigation of porous materials with the aid of He-Ne laser radiation , by Drobnik, A., Rozniakowski, K. and Wojtatowicz, T. W., 1995
ASTM standard D4442: D4442-92(1997)e1 standard test methods for direct moisture content measurement of wood and wood-base materials, by ASTM, 1997
oven dry: D4444-92e1 standard test methods for use and calibration of hand-held moisture meters, by ASTM, 1998
NMR and gamma ray: Determination of moisture and salt content distributions by combining NMR and gamma ray measurements, by Rucker, P., Holm, A. and Krus, M., 2000
--------: Determination of moisture properties for materials exposed to the indoor air, by Svennberg, K., 2003
--------: Drying hardwood lumber, by Denig, J., Wengert, E. M. and Simpson, W.T., 2000
--------: Electric field probes for quantitative moisture measurements in building materials, by Courville, G. E., Hylton, J. O., Murray, W. P., Blalock, A., and Remenyik, C. J., 1996
--------: Electric moisture meters for wood, by James, W. L., 2000
electrical resistance: Electrical measurement of moisture content in porous building materials, by Norberg, P., 1999
--------: G84-89(1999)e1 standard practice for measurement of time-of-wetness on surfaces exposed to wetting conditions as in atmospheric corrosion testing, by ASTM, 2002
--------: Identification of free and bound water content in wood by means of NMR relaxometry, by Ryszard, G., Olek, W. and Baranowska, H. M., 2000
--------: Identification of free and bound water content in wood by means of NMR relaxometry, by Ryszard, G., Olek, W. and Baranowska, H. M., 2000
--------: Long-Term field monitoring of an EIFS clad wall, by Sa?d, M. N. A., Brown, W. C. and Walker, I. S., 1997
--------: Measurement of moisture gradient in wood by Electrode Scanning Moisture Analysis ESMA, by Sobue, N., 2000
in soil: Measurement of soil moisture using gypsum blocks, by Nielsen, J., 2001
--------: Measurement system for long-term recording of wood moisture content with internal conductively glued electrodes, by Brischke, C., Rapp, A.O. and Baye, R., 2008
--------: Measuring moisture content in wood with built in probes 20+ years experience, by Brandt, E. and M. H. Hansen, 1999
computed tomography (CT) with X-ray: Medical CT-scanners for non-destructive wood density and moisture content measurements, by Lindgren, O., 1992
survey: Methods for the assessment of moisture content of envelope assemblies, by Derome, D., Teasdale-St-Hilaire, A. and Fazio, P., 2001
moisture diffusivity at high moisture levels: Methods of measuring the moisture diffusivity at high moisture levels, by Janz, M., 1997
--------: Moisture Gradient Measurement During Kiln Drying of Red Oak, by Gu, H., 1997
microwave: Moisture measurements in building materials with microwaves, by Kaariainen, H., M. Rudolph, Schaurich, D., Tulla, K., and Wiggenhauser, H., 2001
gamma-ray: Moisture migration in building walls - analysis of the interface phenomena, by De Freitas, V. P. Abrantes, V. Crausset, P., 1996
survey with large photos of setups: Moisture transport in porous building materials, by Pel, L., 1995
Neutron radiography: Neutron radiography: An excellent method of measuring water penetration and moisture distribution in cementitious materials, by Justnes, H., Bryhn-ingebrigtsen, K. and Rosvold, G. O., 1994
--------: Non-contact methods of measuring moisture concentration in external layers of building partitions. I--The influence of geometrical microstructure on the kinetics of moisture condensation on glass surfaces, by Klemm, A. J., Klemm, P., Rozniakowski, K. and Galbraith, G., 2002
TDR: Numerical and experimental investigation of coupled heat and moisture transport problems, by Grunewald, J., Plagge, R. and H?upl, P., 2001
--------: Physical Limitations of Moisture Meters, by Quarles, S. L., 0
--------: Predicting moisture content and density distribution of Scots pine by microwave scanning of sawn timber II: evaluation of models generated on a pixel level, by Lundgren, N. L. C., Hagman, O. and Johansson, J., 2006
soil: Preliminary evaluation of soil moisture probe for use with Arcillite, by Yendler, B., 1999
--------: Quantitative NMR imaging study of mass transport in porous solids during drying, by Koptyug, I. V., Kabanikhin, S. I., Iskakov, K. T., Fenelonov, V. B., Khitrina, L. Y., Sagdeev, R. Z. and Parmon, V. N., 2000
--------: Sampling and analysis of natural isotopes in moisture transport from porous materials: applications to capillary suction, by Koniorczyk, M., Gudmundsson, K., Johannesson , G., 2009
conductance-type, resistive: Standarization of conductance-type timber moisture meters, by Ahmet, K. and Jazayeri, S., 1996
TDR: TDR measurement of moisture content in aerated concrete, by Hansen, E. and Hansen, M. H., 2002
survey: Technique for measuring moisture storage capacity at high moisture levels, by Janz, M., 2001
--------: The independent core method----A new technique for the determination of moisture content, by Newmana, A. J., 1974
--------: What is the moisture meter trying to tell us?, by Burkinshaw, R., 0
Chapter 3, 12: Wood handbook - wood as an engineering material, by Forest Products Laboratory, 1999

CRDBER, at CBS, BCEE, ENCS, Concordia, June 2014