Data Loggers - SensorLabs

Data logger “GetDew Go 350”

Humidity and temperature measurement at high process temperatures – special applications for which the mobile humidity meter GetDew Go 350 was developed.

Relative and absolute humidity as well as temperatures at up to 7 user-defined measuring points are measured exactly where it matters most – in the process at temperatures up to 350 °C – environmental conditions such as those commonly found in baking processes, drying plants, autoclaves and continuous furnaces.

The GetDew Go 350 can be used in industrial continuous and stationary furnaces where measurements must be taken directly in the furnace atmosphere, as well as in drying systems and autoclaves. You are sure to find your own specific application here too. Investments in several cost-intensive stationary devices are often unnecessary when using a mobile GetDew Go.

Special designs are available for additional requirements, such as a lower housing height, a larger number of temperature sensors, or other sensor types, for example for measuring flow velocity.

Measurement duration

The maximum measurement duration is limited by three factors: temperature resistance, battery capacity and measurement value storage capacity.

In self-sufficient measurement mode, the internal power supply guarantees a recording time of approx. 120 minutes. When the charger is connected, the recording time is only limited by the number of connected temperature sensors and the set measurement period (time interval between two measurement points).

The maximum possible measurement duration is also limited by the thermal stress in the process. A robust stainless steel housing and high-temperature-resistant insulating materials protect the high-quality electronics and the sensor from overheating. The adjacent graph shows the dwell time in the process at the corresponding ambient air temperatures.

After a measurement, an integrated cooling system allows the device to cool down quickly, enabling it to be reused quickly. All that is required is a standardised cold water connection.

Diagram: Measurement duration in the oven

Operation and visualisation

The connection to the device is established via a USB-C interface. The user interface can be accessed via standard web browsers. All the tools required to operate the device are available on the website. Recorded measurements can be displayed and exported in common formats (ods, xls, csv, xml, json).

Before the measurement, all necessary settings in GetDew Go, such as measurement rate and measurement duration, are easily made via the browser.

The device offers various start options: delayed, upon reaching a threshold temperature, or via a manual button.

During the measurement, the GetDew Go remains in the oven without any connections such as tow ropes, recording and storing humidity and temperature values completely independently. After a measurement, the GetDew Go is reconnected to the PC and the stored data is displayed in the web browser or transferred to the PC for further processing.

The adjacent diagram was recorded during a three-minute measurement in a continuous oven. The curves of relative humidity, dew point and oven temperature are displayed over time, which in continuous ovens corresponds to the length of the oven.

With seven additional external temperature sensors, temperature profiles can be measured not only over the length but also over the width of the continuous oven. By using very small sensors, the surface and internal temperatures of a process material can also be measured.

Measurement principle

Moisture sensor: The GetDew Go works according to the dew point principle. The surface of an electric stray field capacitance is cooled until dew condenses on it. The temperature of the surface at this moment is a direct measure of the absolute humidity (grams of water per cubic metre of air). Since this method reduces humidity measurement to a pure temperature measurement, the sensor technology achieves a high degree of measurement accuracy and dynamics.

Even rapid changes in humidity in the range of 1°C to 100°C dew point can be detected without any problems. The adjacent graph shows that a change in humidity from 17°C to 88°C dew point temperature is registered in just under 10 seconds. Such a change, equivalent to approximately 14g of water per cubic metre of air to 396 g/m³, occurs, for example, in the humidification zones of continuous ovens.

Diagram: Dynamics of the measuring principle

Temperature sensors: The GetDew Go works with NiCr-Ni thermocouples, type K. The temperature measuring range is between -100°C and 500°C. Other ranges can be offered as an option. Up to seven temperature sensors can be connected to the standard device; more are possible on request. All inputs are galvanically isolated from the measuring device and from each other. This prevents electrical interference between the sensors. Thermocouples have a very small mass and can therefore accurately measure the internal temperature of even small objects. In a flat design, they can be used to measure surface temperatures.

Other transducers: Additional transducer types are available as options, for example for voltage or current inputs, resistance temperature sensors (Pt100) or anemometers.

Technical specifications

max. operating temperature:	350° Celsius
residence time at ambient air temperature of 350° C:	max. 10 min
of 200° C:	max. 30 min
dew point temperature: (the minimum achievable dew point temperature is approx. 50 Kelvin below the intake duct temperature)	1° C – 100° C
external temperature sensors:	max. 7 NiCr-Ni thermocouples type K
measurement range of external temperature sensors:	-100° – +500°C
storage temperature:	-10° C – +45°C
relative error of external temperature sensors:	± 0.5%
relative error of dew point temperature:	± 1%
dew point dynamics:	max. 8 Kelvin/s
measurement frequency of all measuring points:	max. 10Hz (10 data points per second)
interface, battery charging, sensor heating:	USB-C
dimensions (LWH):	max. 350 x 260 x 50 mm³
housing:	stainless steel, polished
weight:	approx. 5 kg

brief description

Highly dynamic humidity and temperature measurement at high process temperatures according to the dew point principle with stray field capacitance,

Storage of measurement time, dew point, process temperature and relative humidity,

7 temperature measuring points for connecting external thermocouples,

Transducers for other physical quantities available as an option,

Communication and power supply via USB-C interface,

Measurement frequency and measurement time configurable via web browser,

Start of a measurement either manually on the device, via various trigger conditions (event-controlled) or via direct command from the operating computer.

Stopping a measurement using various trigger conditions (event-driven)

Self-sufficient power supply for up to 2.5 hours,

Fast charging of batteries via USB-C,

Overload protection,

Integrated aftercooling system, suitable for connection to water supply,

Device operation, reading and saving data via web browser,

Export data using common data formats.