Pinless moisture meter for boards and beams — MERLIN HM9 WS25

The MERLIN HM9 WS25 is a pinless timber moisture meter for boards and beams from 25 mm thick, with a published scanning depth of 40 mm.

Check thicker boards on arrival, compare timber within a stack and track drying before machining or assembly. The WS25 is intended for sawmills, timber yards and woodworking shops handling flat sawn timber, planks and beams. Its sensor takes a reading without puncturing the material, so you can revisit several positions while keeping the surface intact.

Choose the WS25 when the workpiece is at least 25 mm thick and you need the deeper HM9 sensor field. Its published scanning depth is 40 mm, compared with 20 mm for the WS13. The meter does not measure all the way through an arbitrarily thick beam, and one surface reading cannot establish that a large slab has dried evenly to its core.

The capacitive / dielectric sensor responds to the moisture-dependent electrical properties of wood. Choose from 21 calibration groups across a dry-density range of 175–1075 kg/m³. Automatic temperature compensation and a self-calibration function support routine checks; the illuminated display shows moisture, wood group, dry density and minimum wood thickness.

Select the wood group using the species and its actual dry density. Place the entire sensor surface against a clean, flat area of wood and keep the meter still while taking the reading. Check several positions on each piece and compare them before making a processing decision. The workpiece must cover the sensor and meet the minimum thickness for the selected model.

Rough surfaces, incomplete contact, unsuitable density settings and material beneath a thin workpiece can affect the reading. The stated scanning depth is not proof of moisture uniformity through a thicker board or beam. Follow the supplied instructions; near or above fibre saturation, treat high readings as an indication rather than a precise drying endpoint.

• Minimum wood thickness: 25 mm
• Published scanning depth: 40 mm
• Supplier-stated minimum workpiece face: 108 × 68 mm
• Measurement principle: pinless, capacitive / dielectric
• Wood groups: 21 selectable calibration groups
• Dry-density setting range: 175–1075 kg/m³
• Published display range: 2–99% wood moisture
• Display resolution: 0.1%; resolution is not measurement accuracy
• Automatic temperature compensation and self-calibration function
• Backlit display, battery indication and automatic switch-off
• Power: 4 × 1.5 V AA alkaline batteries
• Operating temperature: 0 to +40 °C
• Storage temperature: −20 to +60 °C
• Instrument dimensions: 150 × 73 × 23 mm
• Manufacturer-stated weight with batteries: 215 g
• Manufacturer: MERLIN Technology, Austria

MERLIN HM9 WS25 meter, soft case, batteries and operating instructions. Bioevibul also lists a calibration certificate for this model.

Choose HM9 WS13 for furniture stock from 13 mm thick, HM9 WS25 for timber from 25 mm thick, or HM9 DUO when your work includes both flooring from 5 mm and thicker boards or beams from 25 mm.