testo 405i Thermal Anemometer with Smartphone Operation

Overview

The testo 405i is a compact hot-wire (thermal) anemometer from the Testo Smart Probes series, operated through a smartphone or tablet via Bluetooth and the testo Smart App. It measures air flow velocity from 0 to 30 m/s and air temperature from −20 to +60 °C, and it calculates volume flow once the duct cross-section has been configured in the app. A telescopic shaft that extends up to 400 mm lets the probe reach into ducts and ceiling outlets, while the instrument itself measures only 200 × 30 × 41 mm, so it fits easily into a technician’s tool bag.

Seven Star LLC supplies the testo 405i to HVAC contractors, building maintenance teams and commissioning engineers in the Sultanate of Oman and across the GCC. With engineering support in Muscat, we can supply the probe together with the testo Smart Case and ISO calibration certificates listed by the manufacturer.

Measurement Principle

A thermal anemometer measures velocity through heat transfer. In the testo 405i, a heated hot-wire sensor sits at the tip of the telescopic shaft; moving air carries heat away from the sensor, and the electronics relate the cooling effect to the flow velocity. As general engineering guidance, hot-wire sensors are especially suited to low velocities and to measurements inside ducts through small test holes, where a vane anemometer would be too large or would lose sensitivity. An NTC temperature sensor at the probe head measures air temperature at the same time, which is useful when supply-air temperature and velocity are both needed at a diffuser or in a duct.

Volume flow is calculated by the testo Smart App from the measured velocity and the duct geometry. The user configures the dimensions and shape of the duct cross-section in the app, and the measured values are combined to give volume flow. The app also determines timed and multi-point mean values, which is the standard way to obtain a reliable average across a duct profile. According to Testo, the testo 405i can be combined with the testo 605i thermal hygrometer to determine cooling or heating performance of an air-handling system.

Engineering Design of the testo 405i

The instrument has no display of its own. The smartphone or tablet becomes the display, communicating over Bluetooth with a mobile device that supports Bluetooth 4.0 and runs iOS 11.0 or newer or Android 6.0 or newer. This keeps the probe small and light, and it means readings can be followed on the phone while the probe is positioned in a duct or above a ceiling. Measurement reports can be created in the app, enriched with photos and comments, and sent directly by e-mail as PDF or Excel files.

Power is supplied by three AAA micro batteries with a stated battery life of 15 hours. The operating temperature range is −20 to +50 °C and the storage range −20 to +60 °C. The housing measures 200 × 30 × 41 mm with a telescope extendable to 400 mm. The delivery scope listed in the datasheet for order no. 0560 1405 includes the probe, batteries and a calibration protocol.

Key Features

The main practical features of the testo 405i for HVAC testing are summarized below.

• Hot-wire velocity measurement from 0 to 30 m/s with 0.01 m/s resolution.
• NTC air temperature measurement from −20 to +60 °C with ±0.5 °C accuracy and 0.1 °C resolution.
• Volume flow calculation in the testo Smart App after entering duct dimensions and geometry.
• Timed and multi-point mean values for accurate averaging across a duct profile.
• Telescopic shaft extendable to 400 mm for access to ducts and outlets.
• Bluetooth operation with iOS and Android devices, removing the need for a separate meter.
• Reports with photos and comments sent directly as PDF or Excel files from the app.
• Compact 200 × 30 × 41 mm body powered by three AAA batteries for about 15 hours of use.

Industrial Applications

In Oman and the GCC the testo 405i is used for airflow checks in commercial buildings, hotels, hospitals, malls and residential towers, where HVAC systems run almost year-round and correct air balance directly affects comfort and energy use. Technicians use it to measure velocity in ducts through small test holes, to check supply and extract volumes at outlets, and to verify fresh-air rates after maintenance. Combined with a thermal hygrometer, it helps estimate the cooling performance of fan coil units and air-handling units. In industrial plants in the Sohar and Salalah free zones, at power and desalination sites and in oil and gas administration buildings, it supports ventilation checks for control rooms, switch rooms and battery rooms.

This probe complements other portable instruments supplied by Seven Star LLC. For combustion and emissions work on boilers and burners, the testo 350 portable industrial flue gas analyzer and the testo 340 industrial flue gas analyzer are available, and the FLIR E96 advanced thermal imaging camera helps locate duct leaks and poorly performing coils. Our team in Muscat supports customers across the region in choosing the right combination of tools.

Technical Specifications

The data below for the testo 405i is taken from the Testo data sheet for the testo 405i (order no. 0560 1405).

Accessories and Calibration for the testo 405i

Testo lists the testo Smart Case (VAC), order no. 0516 0260, for storing and transporting the testo 405i together with other Smart Probes such as the testo 410i, 510i, 605i, 805i and 905i; the case measures 270 × 190 × 60 mm. For quality systems that require documented traceability, an ISO calibration certificate for flow velocity with calibration points at 5 and 10 m/s (order no. 0520 0094) and a certificate with points at 1, 2, 5 and 10 m/s (order no. 0520 0004) are available. As general practice, calibration intervals should follow the user’s own quality procedures.

How to Order

To request a formal quotation for the testo 405i, contact the Seven Star LLC test and measurement team with your quantity and any case or calibration certificate you require. We provide engineering support in Muscat, can share the manufacturer data sheet, and support HVAC and facility teams throughout Oman and the GCC.