Handheld Instruments for Measuring Humidity & Temperature

Select a location for the measurement that is well representative of the ambient conditions. Make sure you are close enough to the device under test to avoid temperature fluctuations. Do not place humidity sensors near sources of heat or moisture. Avoid areas near air outlets, exterior doors and windows, and walls that are exposed to strong sunlight. Ensure that the air around the sensor can flow freely. Some wall-mounted sensors can emit heat. You should therefore carry out the measurement underneath these sensors. Avoid heating the hand-held measuring device with your hand or breath so as not to falsify the measured values. Give the temperature sufficient time to stabilize. Note that a temperature deviation of just 1 °C (1.8 °F) can cause a difference of 6 % in relative humidity. Graphical displays are helpful to monitor stabilization, the additional function with trend indicator helps to avoid situations where moisture or condensation could settle on the sensor or sample. A damp humidity sensor will not give correct readings.

The battery life depends on various factors, such as the operating temperature, selected logging interval or permanent backlighting. In general, the more the device is used, the faster it needs to be recharged. Depending on the quality of the rechargeable battery or battery used, 20% of the original capacity of the battery may be lost after just 500 charging cycles, which can lead to a short operating time. To extend the battery life, you should pay attention to energy-efficient use, switch off the device when not in use or put it into sleep mode, determine a consistent time interval when logging (do I really need a reading every second?) and pay attention to the ambient temperature.

Handheld measuring devices can be found for a number of applications and various industries. For example, a hand-held measuring device can be used for field calibrations (samples and transmitters in the field), as a calibrator with a reference sample. Another common application is spot checks, where the hand-held measuring device is placed as close as possible to the sensor being compared. Whether in incoming goods inspection, in the laboratory or in the field, a handheld enables a wide range of functionalities and applications.

This depends on how the hand-held measuring device is constructed. Battery-operated devices usually have a cover on the back of the device that can be opened to replace the battery. In the case of hand-held measuring devices with a rechargeable battery, it may not be possible to replace the battery when it is exhausted.

As humidity measurement is temperature-dependent, temperature fluctuations can lead to falsified humidity data. Therefore, the sensor of the hand-held measuring device should be connected and the device should be given sufficient time to adapt to the conditions. Other factors that can influence humidity include air currents, wind, heating and air conditioning systems. Mapping can help to create the right location for a representative measurement result. As the sensor is close to the operator, it is important to ensure that the operator does not touch the sensitive sensors or influence them with their breath. Finally, contamination (air pollution) such as chemical substances can also influence the humidity readings.

Hand-held measuring devices are usually easy to use and self-explanatory. A hand-held meter typically has a 1-point or multi-point adjustment function, where the reference values must be entered. Depending on requirements, calibration can be carried out using a calibration box and the salt solutions, or with a HygrogGen humidity and temperature generator up to ISO 17025 calibration in our own SCS laboratory. If the hand-held measuring device has two sample inputs, the values of the reference sample can also be overwritten by the other sample.

A distinction must be made here between the possible measuring ranges with the sensor connected and the operating temperature range of the power supply used. In the case of a lithium-polymer accumulator, the operating temperature is limited to -20... +60 °C, but the measuring range of the sensor is not affected by this. The industrial sensors from Rotronic AG are equipped with 2 or 5 meter cables so that the hand-held measuring device can be easily distanced from the heat source and the temperature range from -100 to +200 °C, 0...100 %rH can be covered.