Humidity transmitters – find manufacturers and suppliers

Humidity transmitters are devices that measure humidity or moisture in other materials and convert it into a standardized electrical signal that can then be used for further processing or monitoring.

They are important in numerous industries, such as building technology, the pharmaceutical industry, food production and the storage of sensitive products.

Below you will find information on how they work, the various measuring principles of humidity transmitters, their areas of application and information on installation and commissioning as well as maintenance and calibration:

How humidity transmitters work:

A humidity transmitter typically consists of a sensor that detects the humidity and a transducer that converts the measurement signal into a standardized electrical output signal.

1. The sensor in the humidity transducer measures the humidity. There are different measuring principles.
2. The transducer converts the signal from the sensor into a standardized electrical output signal, such as 4-20 mA, 0-10 V or a digital interface (e.g. Modbus, BACnet).
3. The signal can be further processed by control systems such as PLCs or data loggers.

Measuring principles of humidity transmitters:

1. Capacitive sensors measure humidity by measuring the capacitance between two electrodes that are coated with a hygroscopic layer (moisture-absorbing). When the humidity changes, the capacitance changes, which is then used as the measured variable. These sensors are widely used and offer good accuracy.
2. Resistive sensors measure the change in electrical resistance, which is influenced by the humidity of the surrounding medium. The resistance increases or decreases with increasing humidity and the humidity can be calculated from this.
3. Psychrometers measure according to an older principle in which humidity is measured by comparing the temperature of a wet and a dry thermometer. This principle is less common today, but can still be found in certain environments.
4. Dew point sensors measure the temperature at which moisture condenses (dew point) and thus calculate the relative humidity.

Areas of use and application of humidity transmitters:

Humidity transmitters are used in numerous applications where the monitoring and control of humidity is required:

1. Building and air conditioning technology:
In ventilation and air conditioning systems, humidity transmitters monitor the relative humidity to ensure a comfortable indoor climate and prevent the formation of mold.

2. Industrial process control:
In production, especially with hygroscopic materials (e.g. paper, textiles, food), humidity monitoring is crucial to ensure product quality and process stability.

3. Food industry:
When storing and processing food, precise humidity measurement ensures that products retain their quality and that no moisture damage, such as mold, occurs.

4. Pharmaceutical and medical sector:
Humidity must be strictly controlled in clean rooms and pharmaceutical storage rooms, as high humidity can affect the stability and effectiveness of medicines.

5. Storage and transportation monitoring:
For moisture-sensitive products, such as electronics, pharmaceuticals or works of art, humidity transmitters are useful to prevent damage caused by moisture.

Installation and commissioning:

• The humidity transmitter should be installed in a representative location where the humidity is typical for the environment. However, it should not be directly exposed to draughts, sunlight or heat sources, as these can distort the measurement.
• For applications in dusty or humid environments, the transmitter should be protected or housed in an enclosure with an appropriate protection class (e.g. IP54 or IP65).

Maintenance and calibration:

• Regular maintenance and calibration are important to maintain measurement accuracy. Especially in dusty or humid environments, the functionality of the sensor can be impaired.
• Most manufacturers offer calibration solutions or kits that allow easy on-site calibration.

Humidity transmitters are indispensable measuring devices for precisely monitoring humidity in various environments and ensuring a stable climate. Their selection depends on the application, the desired measurement accuracy, robustness and the available connection options. With the right selection and regular maintenance, they make a significant contribution to efficiency and quality assurance in many areas.

Here you will find an overview of the most important criteria that you should pay attention to when purchasing humidity transmitters:

When purchasing humidity transmitters, there are several important criteria to consider to ensure that the device meets the specific requirements. These selection criteria will help you find the right device for the application in question and avoid making the wrong purchase.

• Choose a transmitter that is suitable for the temperature range in which it will be used, especially for applications in cold stores, heating systems or in environments with large temperature fluctuations.
• Pay attention to the specified measurement accuracy, which is often given as a percentage of the relative humidity (% RH). For applications in industry or in laboratory and quality assurance, an accuracy of ±1-2 % RH should be aimed for.
• The humidity transmitter should cover the entire relevant measuring range. usual measuring ranges range from 0-100 % relative humidity (RH) or include certain dew point ranges for special applications.
• As humidity is temperature dependent, the humidity transmitter should have temperature compensation. This function corrects the measurements to provide accurate humidity readings even at fluctuating temperatures.
• Capacitive sensors usually offer higher accuracy and greater long-term stability and are therefore well suited for demanding measurements.
• Resistive sensors are often less expensive, but offer sufficient accuracy for less demanding applications.
• If the dew point is more important than the relative humidity, a dew point sensor should be preferred. This is well suited for applications in compressed air systems or for condensation monitoring.
• The most common analog output signals are 4-20 mA and 0-10 V, while digital interfaces such as Modbus, BACnet or RS485 are increasingly used for industrial applications.
• Make sure that the humidity transmitter has an interface that is compatible with existing control systems or data loggers.
• A good humidity transmitter should also measure stably and reliably over long periods of time, especially in industrial applications where frequent calibration would be time-consuming and expensive.
• As humidity sensors tend to drift over time, it is an advantage if the humidity transmitter can be easily calibrated. Many models offer an on-site calibration function or have removable sensors that can be calibrated externally.
• Depending on the location, the humidity transmitter should have a suitable protection class. For humid or dusty environments, at least IP54 or IP65 is recommended, while even higher protection may be required for outdoor applications.
• In the case of aggressive media (e.g. acids, solvents), the sensor should be resistant to the chemical load. Special housings and protective coatings are available for such environments.
• The faster the response time of the humidity transducer, the better it can react to rapid changes in humidity. A short response time is advantageous for fast processes or sensitive climate controls.
• A higher measuring frequency may be necessary for real-time applications, for example in processes with rapid humidity changes. However, it affects energy consumption and data processing.
• consider how the humidity transmitter is to be mounted (e.g. on the wall, in a ventilation system, on a duct). Some models offer different mounting options or mounting kits to make installation easier.
• Make sure there is sufficient cable length and flexible plug connections so that the transmitter can be easily attached in the desired position.
• In some industries, such as pharmaceuticals and food, a calibration certificate is required to prove compliance with quality standards. Manufacturers often offer factory calibration, which is documented.
• For certain industries and environments, it may be necessary for the humidity transmitter to be certified according to certain standards (e.g. ATEX for potentially explosive atmospheres).
• The investment in a high-quality humidity transmitter can quickly pay for itself through higher accuracy and long-term stability. It makes sense to check the price-performance ratio carefully and plan for long-term use.
• Maintenance, calibration and, if necessary, the replacement of sensors should be taken into account when making a purchase decision. A device with low maintenance costs and stable measurements is often the more economical choice.

When purchasing a humidity transmitter, it is crucial to thoroughly analyze the application and specific requirements. Aspects such as measurement accuracy, interfaces, environmental conditions and calibration capability should be taken into account in order to find an optimal and durable solution. In this way, a device can be selected that meets the requirements and maintains measurement accuracy in the long term.

Humidity transmitters can be purchased from various suppliers. Comprehensive information about manufacturers and suppliers of Humidity transmitters from all over the world can be found on Exportpages.