testo 405 Mini Hot-Wire Anemometer

Overview

The testo 405 Mini Hot-Wire Anemometer is a compact, handheld environmental measurement instrument engineered for precise air velocity and volumetric flow quantification in HVAC commissioning, indoor air quality (IAQ) assessments, and routine ventilation system diagnostics. Based on constant-temperature anemometry (CTA), the device employs a fine platinum-coated tungsten wire sensor that maintains thermal equilibrium with the surrounding airflow. As air passes over the heated element, convective heat loss is measured and converted into a linear velocity signal—enabling high-resolution real-time response even at low flow rates. Its miniature form factor (120 × 45 × 25 mm) and integrated telescopic probe make it uniquely suited for confined ductwork, grilles, diffusers, and laminar flow hoods where spatial constraints preclude use of bulkier instruments. Designed and manufactured in Germany, the testo 405 complies with fundamental metrological principles outlined in ISO/IEC 17025–accredited calibration practices and supports traceable verification against NIST-traceable standards.

Key Features

• Miniaturized hot-wire sensor with 0.01 m/s resolution for detecting subtle airflow variations in low-velocity environments (e.g., underfloor air distribution, cleanroom return vents)
• Auto-ranging dual-scale velocity measurement: optimized sensitivity in 0–2 m/s range (±0.1 m/s + 5 %) and extended capability up to 10 m/s (±0.3 m/s + 5 %)
• Integrated telescopic probe (extendable to 2.4 m) with precision-aligned sensor tip, enabling repeatable positioning within duct cross-sections per ISO 12599 and ASHRAE Guideline 12
• Standard-fit pipe mounting bracket (included) allows secure, vibration-damped installation during long-duration monitoring or multi-point traverse measurements
• IP54-rated housing ensures operational reliability in typical HVAC mechanical rooms and non-hazardous industrial environments
• Zero-point stability maintained across ambient temperatures from 0 °C to 50 °C without manual recalibration

Sample Compatibility & Compliance

The testo 405 is validated for use with clean, dry, non-corrosive air streams—making it appropriate for commercial building HVAC systems, laboratory exhaust verification, and pharmaceutical facility air change rate validation. It is not rated for particulate-laden, high-humidity (>80 % RH), or chemically aggressive airstreams. While the instrument itself does not carry CE marking for explosion-proof use, its electrical design conforms to EN 61010-1 for safety in measurement and control laboratories. For regulatory compliance workflows, raw velocity data may be manually logged in accordance with GLP documentation requirements; however, the device does not include built-in audit trail or electronic signature functionality required under FDA 21 CFR Part 11.

Software & Data Management

The testo 405 operates as a standalone field instrument with no embedded memory or Bluetooth/Wi-Fi connectivity. All measurements are displayed in real time on the high-contrast LCD screen with backlight. Users perform manual data recording using external logbooks or spreadsheet templates aligned with ISO 5167 or EN 12599 duct traverse protocols. Optional accessories—including the testo 405 calibration certificate (traceable to DKD/DAkkS-accredited labs) and magnetic mounting kit—facilitate integration into certified QA/QC programs. For automated reporting, third-party DAQ systems may interface via analog voltage output (0–1 V = 0–10 m/s), though this requires external signal conditioning and is not natively supported by testo’s firmware.

Applications

• Verification of supply/return air velocities in VAV boxes and terminal units per ASHRAE Standard 111
• Commissioning of displacement ventilation systems requiring sub-0.5 m/s resolution
• Validation of fume hood face velocity (EN 14175) and biosafety cabinet inflow uniformity
• Field calibration cross-checks against primary reference anemometers in metrology labs
• Energy audit support—estimating volumetric flow (m³/h) from duct geometry and point-velocity traverses
• Educational demonstrations of boundary layer development and turbulence intensity in fluid mechanics labs

FAQ

Does the testo 405 require periodic factory recalibration?
Yes—testo recommends annual recalibration against a certified reference standard to maintain stated accuracy, particularly when used in regulated environments.
Can the instrument measure air temperature simultaneously?
No—the testo 405 is dedicated solely to velocity and volumetric flow; it does not integrate a temperature sensor.
Is the telescopic probe removable or replaceable?
The probe is permanently affixed and not user-serviceable; replacement requires return to an authorized testo service center.
What is the maximum allowable particulate concentration for reliable operation?
Operation is limited to clean, filtered air; continuous exposure to dust concentrations exceeding 1 mg/m³ may degrade sensor longevity and repeatability.
Does the included pipe bracket meet ASHRAE duct traverse mounting guidelines?
The bracket enables stable, repeatable probe positioning but does not constitute full compliance with ASHRAE 111 traverse grid specifications—users must still apply proper grid spacing and dwell time protocols independently.