The Testo 400 two-channel instrument is a multi-parameter handheld meter for conducting indoor air quality measurements including temperature, humidity, air velocity, pressure, carbon dioxide, and carbon monoxide. The unit can be used as a handheld instrument or as a complete logging system. The unit is capable of storing 500,000 readings which can be downloaded directly to a PC or to an optional infra-red printer.

Measurement parameters include:

1. Temperature with accuracy to <0.1 °C/°F Probes have calibration for adjustment capabilities.
2. Relative humidity and dewpoint, complete Mollier diagram values
3. Pressure, velocity and volume flow
4. Current and voltage
5. RPM
6. Carbon Monoxide (CO) & Carbon Dioxide (CO2)

• A comfort level probe corresponding to ASHRAE 55 can be connected when measuring ambient air velocity.
• Checks indoor air quality and air exchanger using a CO² probe
• Checks ventilation in parking garages with a CO probe
• Logs data with date, time and location over long periods of time
• Optional connection of external transmitters, such as particle counters and pressure transmitters.

Advantages at a glance

• Over 200 different probes available
• 2 easily accessed probe sockets are located at the bottom of the meter
• Clear graph display and user friendly operation via cursor
• 3 user assignable fast function buttons
• Power supply/quick battery recharge
• Optional printer module prints readings on location in the matter of seconds