Optimize The Wood Drying Process With Accurate Measurements

Relative humidity plays an essential role in wood drying, along with time and temperature. As a natural product, wood has a unique set of characteristics that can make drying a challenging and complex process. Accurate RH measurement helps to ensure that the wood does not crack due to too rapid drying, conversely, it’s not efficient to dry the wood too slow either. If conditions are too moist the wood can take a lot longer to dry than it should, and that means higher energy consumption and operating costs.

With robust and stable measurement equipment in place you can maximize both the energy efficiency of the drying process and the quality of the end product itself. The equipment has to be robust enough to cope with high humidity as well as contaminants such as resin fumes. Properly insulated sensor helps to reduce the risk of inaccurate measurement caused by condensate build-up. The probe itself also needs to be protected from condensation and horizontal airflow, which can lead to water and dirt accumulating on the sensor. Vaisala’s range of humidity, temperature, and dew point measurement sensors are built to withstand the tough conditions of wood drying processes – meaning they are highly accurate, robust, and easy to calibrate. An annual calibration check against a reference reading combined with regular maintenance activities such as probe cleaning and filter replacement will ensure the quality of your measurements in the long term.

Dpstar has the appropriate moisture measuring device for your requirements. At Dpstar, you will find a diverse range of measurement sensors used to determine the moisture contents of many different wood types. With the help of an accurate, easy-to-use, professional wood moisture sensors, the moisture contents of wood products such as hardwood flooring, cabinets, furniture, lumber, slats, beams, plywood, paneling, conglomerates, window frames, forestry wood, rolled products, building materials and more can be measured. With the moisture measuring devices from Dpstar you can quickly and reliably determine the humidity level in almost every material. Using the compact, precise devices even the degree of moisture in different types of wood can be measured.

How does moisture affect wood?

Wood and its reaction to moisture wood is characterized by its hygroscopic nature. Like all porous materials, this enables wood to take in water from the air and store it within the cell membrane and cell cavities. The hygroscopic behavior of wood describes the adsorption and desorption of moisture to maintain equilibrium depending on the surrounding climate in particular relative humidity and temperature.

Knowing the accurate amount of moisture in wood is extremely important in the production of various types of wood products. The amount of moisture at various stages of the production process is also important; as is knowing when and where to measure depending on how the wood is being processed. The moisture content of wood can impact subsequent machining, gluing, finishing, and product performance. It is the job of wood product producers to establish a moisture content in the wood that will be similar to what the wood will experience in service. To accomplish that, manufacturers must develop a standard procedure that will measure wood moisture content consistently and accurately.

If the relative humidity is inaccurately shown as too moist, wood may crack due to the overly dry conditions. Overdrying also wastes energy and ties up expensive facility capacity unnecessarily.
If the relative humidity is inaccurately shown as too dry, the overly moist conditions will slow the drying process, leading to longer drying times and reduced capacity.

Too high or too low humidity leads to undesired wood moisture content or unwanted fluctuations in the wood moisture balance. Wood-processing companies are often confronted with the resulting problems:

Increased dust generation

Electrostatic charging

Splitting of solid wood

Deformation of dimensionally accurate parts

How to maintain high measurement accuracy?

A wood drying facility is a very challenging measurement environment, combining high humidity with wood contaminants such as resin fumes. Insulating sensor cables to prevent condensation caused by temperature differences between the drying chamber and ambient conditions. The measurement probe is usually fed through the chamber’s roof – insufficient insulation can result in the formation of condensation, leading to faulty readings and corrosion. It is important to ensure that the measurement probe feedthrough is tight to prevent condensation inside the chamber. Moreover, the probe must be protected from water if it is hanging from the roof because water can run down the cable or sensor supports directly onto the probe, resulting in inaccurate measurements. Three main factors help to keep measurements accurate:

Vaisala’s patented warmed measurement technology

The warming function minimizes the risk of condensation in the probe, thereby enabling fast and accurate measurement results as soon as the drying chamber is loaded. The sensor material also plays an important role when it comes to long-term stability. In environments where chemicals are present, polymer-based humidity sensors can often indicate lower values than expected due to chemical contamination. The Vaisala HUMICAP®180R sensor can be supplied with an optional chemical purge feature to remove chemical vapor from the sensor. This is done by regularly heating the sensor to a high temperature.

Vaisala’s Patented Warmed Measurement Technology

Protect The Probe Against Drips & Splashes

The Vaisala HUMICAP® Humidity and Temperature Transmitter HMT337 can be equipped with a unique protective cover (HMT330WPA) to prevent any water splashing on the humidity sensor. A dry sensor minimizes measurement response times and eliminates ‘water spikes’, which can disturb measurements. The cover also protects the sensor filter from dirt, so the filter needs replacing less often. Overall, less maintenance is needed and measurements are more accurate.

Protect The Probe Against Drips & Splashes

Annual Calibration Maintains Measurement Accuracy

Making sure your transmitter is correctly installed ensures reliable operation, while an annual check against a reference maintains high-quality measurements. Annual maintenance typically consists of cleaning the probe and replacing the dirty filter. Humidity transmitters are easy to calibrate on-site using the Vaisala Humidity Calibrator HMK15 (based on saturated salt solution). They can also be sent for calibration to the nearest Vaisala Service Center. On-site calibration has the advantage that the transmitter can stay on site, while laboratory calibration is more accurate and always carried out by an expert.

Annual Calibration Maintains Measurement Accuracy

Our Success Story

Optimize Timber Drying Conditions For Sawmill

Our client produces standard sawn timber and special sawn timber, mainly for big industrial end users in construction and the furniture and joinery industry. They are a global forest products group with core businesses in printing papers, specialty papers, label materials, and wood products.

Controlled Drying Chambers

After the timber is brought to the sawmill, it is typically sawn up into planks. The planks are then dried to reach the desired humidity level in a special chamber. The drying process takes over a week, depending on the type of timber. It is very important that the drying takes place evenly and under carefully controlled conditions, to ensure the high quality of the end product.

Our client relies on the Vaisala HUMICAP® Humidity and Temperature Transmitter Series HMT330 to achieve optimal timber drying conditions at their facilities. In order to run efficiently, our client seeks to minimize the drying time for timber goods. Therefore, the drying temperatures must be very high, which creates very specific requirements for the humidity conditions in the chambers. The correct temperature-humidity ratio is essential to ensure the timber doesn’t twist or crack.

The humidity and temperature transmitters’ measurement probes were installed inside the drying chambers, whereas the electronics and housing are outside the chambers. The information transmitted by the probes is sent to process control, which in turn controls the ventilation and temperature. Vaisala’s humidity and temperature measurement probes help the sawmill to minimize the drying time for timber goods.

Customer Benefits

Consistent and high-quality products

Increases profit – less waste of the raw material

Protection of wood during the entire production run

Dust reduction to protect both machinery and people

Uniform drying, maturation and ageing of products

Consistent and high-quality products

Increases profit – less waste of the raw material

Protection of wood during the entire production run

Dust reduction to protect both machinery and people

Uniform drying, maturation and ageing of products

Wood & Timber Drying Related Products

Vaisala HMP7 Relative Humidity & Temperature Probe

Vaisala HM70 Handheld Humidity & Temperature Meter

Vaisala Indigo200 Series Transmitters For Vaisala Smart Probes

Vaisala Indigo500 Series Transmitters For Vaisala Smart Probes

Vaisala DMT345 & DMT346 Dew Point Transmitters

Vaisala HMP7 Relative Humidity & Temperature Probe

Vaisala HM70 Handheld Humidity & Temperature Meter

Vaisala Indigo200 Series Transmitters For Vaisala Smart Probes

Vaisala Indigo500 Series Transmitters For Vaisala Smart Probes

Vaisala DMT345 & DMT346 Dew Point Transmitters

Your Trusted Partner For Innovative Measurement Control Solutions

Improve Your Wood Drying Process with Accurate Humidity Measurements

Wood drying is necessary because it helps reduce moisture, extending its lifespan and hardening it for construction purposes. No matter what your needs are, Dpstar has the right instruments for your purposes. Let us control your humidity level and optimize your lumber and milling operations. With Dpstar’s high precision, state-of-the-art sensors enable users to control and operate drying systems for wood with maximum energy efficiency. Humidity and temperature measurement devices from Dpstar make this possible and much more besides.

Your Trusted Partner For Innovative Measurement Control Solutions

Wood drying is necessary because it helps reduce moisture, extending its lifespan and hardening it for construction purposes. No matter what your needs, Dpstar has the right instruments for your purposes. Let us control your humidity level and optimize your lumber and milling operations. With Dpstar high precision, state-of-the-art sensors enable users to control and operate drying systems for wood with maximum energy efficiency. Humidity and temperature measurement devices from Dpstar make this possible and much more besides.

Get In Touch With Our Experts Today!

Dpstar Group
No 35, Jalan OP ½, Pusat Perdagangan One Puchong,
Off Jalan Puchong, 47160 Puchong,
Selangor Darul Ehsan, Malaysia.
Email: [email protected]