Support Center: Guides & FAQs

A polymer-based humidity sensor works by measuring the change in electrical resistance of a polymer film as the humidity in the air changes.

The sensor typically consists of a thin film of polymer material that is sensitive to changes in humidity. The film is sandwiched between two electrodes, and when humidity changes, the electrical resistance of the film also changes. This change in resistance is then converted into a measurable electrical signal, which can be used to indicate the humidity level.

In compressed air systems, the humidity sensor is typically mounted in the compressed air pipe, where it is exposed to the air stream. As the air passes through the sensor, it causes the polymer film to absorb or release moisture, which in turn causes a change in the electrical resistance of the film. This change in resistance is then measured and used to determine the humidity level of the air.

Polymer-based humidity sensors have a number of advantages over other types of humidity sensors. They are typically more accurate and stable than other types of sensors, and they have a wide measurement range. They are also relatively low cost and easy to install.

It’s important to note that the accuracy of the humidity measurement may depend on several factors such as the specific polymer used, the temperature, the pressure and the contaminants present in the air. It’s also important to follow the manufacturer’s instructions for the installation and operation of the sensor to ensure accurate and reliable results.

In this particluar case a flow meter is used to determine the flow and the total consumption of compressed air. The flow Almost all modern flow sensors require a so-called fully developed flow profile for accurate measurement. This profile is disturbed by obstacles and the direction changes in the pipeline and must be “straightened” over longer straight runs. That`s why particular inlet and outlet sections are defined and specified in multiples of the pipe diameter.

To maintain a compressed air flow meter, you should follow these steps:

• Regularly check the calibration of the flow meter. It’s recommended to calibrate the meter at least once a year or as often as specified by the manufacturer or regulatory requirements.
• Keep the flow meter clean. Dirt, dust, and debris can accumulate on the flow meter over time, affecting its performance. Clean the meter regularly with a soft brush or compressed air.
• Check the installation of the flow meter. Make sure that the meter is installed correctly and that all connections are tight.
• Check the process conditions. Make sure that the process conditions, such as temperature and pressure, are within the range that the meter is designed to handle.
• Check the flow rate. Make sure that the flow rate through the meter is within the range that the meter is designed to handle.
• Check the control unit and software. Make sure that the control unit and software are working properly, and that the settings are correct.
• Keep the meter lubricated. Some flow meters require lubrication to function properly. Consult the manufacturer’s instructions to ensure that the meter is properly lubricated.
• Replace the sensor and other wearable parts as needed. The sensor and other wearable parts of the flow meter may need to be replaced over time. Consult the manufacturer’s instructions for recommended replacement intervals.
• Keep the flow meter protected. Flow meters are often exposed to harsh environments, so it is important to protect them from extreme temperatures, vibration, and other environmental factors.

It’s important to consult the manufacturer’s instruction manual for specific maintenance procedures and recommendations. It’s also recommended to contact the manufacturer or a qualified service technician if you are unsure about how to maintain your flow meter.

Every high precision device which is exposed to tough or fluctuating operational conditions therefore a sensor has to be checked and reset on a regular base. What many people do not know – this is even stipulated in the ISO 9001. We suggest to perform this calibration at least every 12 months.

• At the compressor outlet, to determine the amount of compressed air being produced.
• At the point of use, to determine the amount of compressed air being consumed by each piece of equipment or process.
• At the compressor inlet, to determine the amount of ambient air being drawn in by the compressor.
• At the point of storage, to determine the amount of compressed air being stored in receivers or tanks.
• At the point of distribution, to determine the amount of compressed air being distributed to different parts of the system.
• It is also good practice to have a monitoring system in place to continuously measure and record the pressure, temperature and humidity of the compressed air at various points in the system.

• At the compressor outlet, to ensure that the compressed air being produced is free of contaminants such as oil, water, and particles.
• At the point of use, to ensure that the compressed air being consumed by equipment or processes is of the appropriate quality for their intended use.
• At the compressor inlet, to ensure that the ambient air being drawn in by the compressor is not contaminated and does not contain harmful particles or gases that could damage the compressor or reduce the quality of the compressed air.
• At the point of storage, to ensure that the compressed air being stored in receivers or tanks is not contaminated by water, oil, or other impurities.
• At the point of distribution, to ensure that the compressed air being distributed to different parts of the system is not contaminated by leaks, corrosion, or other issues.
• It is also good practice to have a monitoring system in place to continuously measure and record the dew point, oil content, particle count, and other parameters that affect the purity and quality of the compressed air.

• At the compressor outlet, to ensure that the compressed air being produced is free of contaminants such as oil, water, and particles.
• At the point of use, to ensure that the compressed air being consumed by equipment or processes is of the appropriate quality for their intended use.
• At the compressor inlet, to ensure that the ambient air being drawn in by the compressor is not contaminated and does not contain harmful particles or gases that could damage the compressor or reduce the quality of the compressed air.
• At the point of storage, to ensure that the compressed air being stored in receivers or tanks is not contaminated by water, oil, or other impurities.
• At the point of distribution, to ensure that the compressed air being distributed to different parts of the system is not contaminated by leaks, corrosion, or other issues.
• It is also good practice to have a monitoring system in place to continuously measure and record the dew point, oil content, particle count, and other parameters that affect the purity and quality of the compressed air.

Measuring air purity at key points in a compressed air system ensures clean, reliable air for all applications. Quality should be checked after filtration to verify that contaminants such as oil, water, and particles are removed. It should also be monitored before distribution points and at critical equipment to ensure that air remains clean throughout the network. The most important location is the point of use, where compressed air directly affects processes and product quality. Regular system wide checks help detect issues early and maintain compliance with required standards.

Thermal mass flow meters for compressed air are flexible instruments that can also measure the flow of many other gases. Their working principle is based on heat transfer. A heated sensor loses heat to the passing gas and this cooling effect is proportional to the mass flow. By monitoring the temperature change, the meter determines the actual gas flow.

Because each gas has its own thermal conductivity and molecular properties, modern instruments use software algorithms to adjust these factors. A sensor calibrated in air can therefore be adapted to nitrogen, oxygen, carbon dioxide or other compressed gases by applying the correct gas settings.

This makes thermal mass flow meters a reliable choice for a wide range of gas applications where accurate mass flow measurement is needed.

A water flow meter can be used to measure the heat recovery of a compressed air system by measuring the flow rate of the water used to cool the compressed air. The heat generated by the compression process can be recovered by passing the compressed air through a heat exchanger, where it transfer heat to the water.

By measuring the flow rate of the water before and after it passes through the heat exchanger, the amount of heat transferred from the compressed air to the water can be calculated. This can provide information on the efficiency of the heat recovery system and identify any potential issues.

The purification system of a compressed air system consists out of staged filtration and drying systems. As the compressed air has to travel through filter elements, heat exchanges or desiccant layers with small diameters and many bends pressure is lost. Corrosion, retained particles or absorbed oil & water clog filters and dryers and cause significant pressure drops which is a loss of energy. Monitoring the pressure drop is easily performed by utilizing a pressure sensor up-streams and another one down-streams and calculating the differential pressure. The gained information helps for efficiently timing filter element exchange and dryer overhauls.

When discussing volumetric flow meters for gases, reference conditions are specific standardized parameters used to normalize the measurement of gas volume. The two typical reference conditions commonly encountered are Normal conditions and Standard conditions:

Normal Conditions:
Normal conditions are defined as a temperature of 0°C (32°F) and a pressure of 1013.25 hectopascals (hPa), equivalent to 1 atmosphere (atm) or 14.7 pounds per square inch absolute (psia).
Volumetric flow measurements taken under normal conditions provide a reference for comparing gas volumes, particularly when calculating gas consumption, energy usage, or emissions.

Standard Conditions:
Standard conditions are defined as a temperature of 20°C (68°F) and a pressure of 1000 hectopascals (hPa), equivalent to 1 bar or 14.504 psi.
Volumetric flow measurements taken under standard conditions are commonly used in various industries and applications, including HVAC (Heating, Ventilation, and Air Conditioning), process engineering, and environmental monitoring.
Standard conditions are often preferred for their practical relevance and ease of conversion, as they closely align with typical operating conditions in many industrial processes.

A typical compressed air system includes:

• Compressor to generate compressed air
• Air receiver tank to store air and stabilize pressure
• Air dryer to remove moisture
• Air filters to remove particles and oil
• Air regulator to set the correct pressure
• Air lubricator to add lubrication when required
• Air piping to distribute air throughout the system
• Control and monitoring system to track pressure, temperature, humidity and dew point
• Safety valves for overpressure protection
• Drain valves to remove condensate

Some systems may include additional or fewer components depending on the application.

The typical conditions of air directly at the compressor outlet are that it is wet and often dirty, primarily due to the presence of compressor oil. To ensure the quality of the compressed air, it must be filtered, and water and oil separators should be installed. The pressure at the compressor outlet can reach up to 90 bar, and the oil amount is expected to be around 10.00 mg/m³.

The actual flow rate is the volume of a gas somewhere in the system, independent of its density, that flows through a certain point. The term actual flow rate is not clear, when it comes to the mass of a gas flowing through a given point, because gas is compressible. If the pressure is doubled, then for an ideal gas, the mass which flows at a constant flow rate through a particular point is also doubled. To take this enlarged mass flow into account, for gases usually the standard volumetric flow is used, because this is based to certain standard conditions and is thus comparable to the mass flow. In compressed air the standard usually is at 1 bar absolute and 20 degrees C.

SUTO iTEC flow sensors are calibrated at almost real-world conditions in the lab. Several calibration points are used to achieve a good accuracy. Depending on the measuring range (Standard, Max, High-speed) the calibration and testing efforts in production are increasing. It is recommended that the range to be chosen can cover the maximum flow rate safely with enough “room” at the upper end.

I am assuming you want to measure parameters at the compressor outlet, but still before the filtration. This means you have wet air which might carry additional contaminations like oil or particles.

For flow measurements:
+Pitot Tube Flow Meter (S430): This is suitable for measuring wet air flow, as thermal mass flow sensors like S401, S421, and S415 cannot be used in dirty and wet conditions.

+Pressure Sensors (S010 / S011): These sensors are designed for measuring compressed air and gases, providing highly accurate pressure readings.

+Temperature Sensors (S020): These high-quality sensors are used for measuring the temperature of compressed air and gases.

These sensors play a crucial role in monitoring and optimizing the performance of compressed air systems. If you need more specific information or assistance, feel free to ask!

Insertion type flow meters, such as thermal mass flow meters and pitot tube flow meters, can be used in different pipe sizes without needing new calibration because they are designed to measure the flow of fluid within a pipe without being affected by the size or shape of the pipe. Both these types of flow meters measure the velocity of fluid, which is then paired with the cross-sectional area of the pipe to calculate the volume flow.

A thermal mass flow meter works by measuring the temperature difference across a heated sensor element inserted into the pipe. The flow of fluid through the pipe causes heat to be transferred from the sensor element to the fluid. By measuring the heat transfer, the flow rate of the fluid can be determined by using the fluid’s thermal properties and the known cross-sectional area of the pipe.

A pitot tube flow meter works by measuring the pressure difference across a tube that is inserted into the pipe. The tube is positioned so that the fluid flows around it and creates a pressure difference across the tube, which is proportional to the fluid velocity. By measuring the pressure difference, the flow rate of the fluid can be determined by using the fluid’s velocity and the known cross-sectional area of the pipe.

In both cases, the measuring principle is based on the determination of the fluid velocity in the pipe, which is then paired with the pipe cross-section, results in the volume flow, which is independent of the pipe size. This is the reason why these types of flow meters can be used in different pipe sizes without the need for new calibration.

Integrating flow, pressure, and temperature measurement into a single sensor offers significant benefits in terms of process insight, accuracy, safety, diagnostics, and cost efficiency—especially in compressed air and gas systems.

1. Complete Process Understanding

Flow, pressure, and temperature are interrelated. Measuring all three together allows for:

• Real-time insight into system performance
• Accurate calculation of mass flow, which is essential for energy management and system optimization

2. Improved Accuracy and Reliability

By capturing all key parameters at the same location, under the same conditions, measurement errors due to mismatched sensor locations or time lags are reduced. This improves:

• Measurement accuracy
• Data consistency for control and reporting systems

3. Advanced Diagnostics and Fault Finding

Combining flow and pressure helps in identifying system issues:

• Detecting pressure drops that may be caused by increased flow demand, restrictions, or leaks
• Evaluating if the compressor system can keep up with the actual consumption
• Supporting root cause analysis in case of inefficiencies or system failures

4. Enhanced Safety

Monitoring temperature and pressure helps detect abnormal operating conditions, such as:

• Overheating
• Overpressurization
This allows for early intervention and reduces the risk of damage or accidents.

5. Space and Cost Savings

A multi-parameter sensor reduces:

• The number of installed devices
• Wiring complexity
• Installation and maintenance costs

It also simplifies integration into monitoring or automation systems.

Conclusion

Combining flow, pressure, and temperature measurements into one sensor delivers a more complete picture of your system, supports efficient fault detection, enhances safety, and lowers total system cost. For compressed air and gas systems, this integrated approach is essential for performance optimization and reliable monitoring.

Due to the fact that the natural phenomena of equalization (balancing unstable conditions by flow) humidity from the ambient is able to penetrate compressed air piping even the air is pressurized. As a normal compressed air system has countless connection points through which humidity enters the piping. This results in influencing the dew point negatively. The effect has to be considered for applications where the dew point is critical and therefore point of use is the only reliable way to avoid any risks for the production.

Measuring all three phases of a power system is important because it provides a more complete understanding of the system’s behaviour. A three-phase system is a type of electrical power system that uses three separate conductors to supply power to loads. Each conductor carries a sinusoidal voltage waveform that is 120 degrees out of phase with the others. By measuring all three phases, it’s possible to determine the total power consumed or generated by the system, as well as the power consumed or generated by individual loads. In addition, by measuring all three phases, it is possible to detect any imbalances or problems within the system, such as a fault on one phase, which could indicate a problem that needs to be addressed.

Due to the fact that pollutants are in the ambient air which is sucked in by the compressor also the compressed air is loaded with dust, particles, humidity or oil vapors. Particles are harmful for many production processes, e. g. electronics industry, pharmaceutical industry or R & D labs and therefore have to be monitored reliably.

Thermal mass and differential pressure flow meters are two established technologies for measuring gas flow in industrial systems, including compressed air. Both offer reliable performance, yet differ in how they detect and calculate flow.

Thermal mass flow meters operate by heating a sensor and observing how the flowing gas cools it down. This cooling effect directly reflects the mass flow. Their key strengths are direct mass flow measurement, wide measuring ranges and a low pressure drop. With no moving parts, they provide stable long term operation. They can however react to changes in gas composition and their initial investment is often higher.

Differential pressure flow meters create a pressure drop across a restriction and determine flow based on the pressure difference. They are versatile and well established across many industries. Their initial cost is typically lower and they are less affected by gas composition. As they generate a pressure drop, this must be considered in system design. They also require calibration to match changing operating conditions and the measurement is indirect.

Compared to other technologies such as turbine, vortex or rotameters, these meter types offer good accuracy and suitability for gas flow. Thermal mass flow meters stand out for direct mass flow measurement, while differential pressure meters provide a robust and cost effective alternative. The best choice depends on the required accuracy, installation point and overall system conditions.

A desiccant dryer, also called an adsorption dryer, removes moisture from compressed air using a porous drying material. It is used when very low dew points and high air purity are required.

A desiccant dryer works by passing compressed air through a bed of desiccant such as silica gel or activated alumina. The desiccant attracts and holds moisture molecules, leaving the air dry as it flows through. Once the desiccant becomes saturated, it must be regenerated. This is done either by heating the desiccant to release the stored moisture or by using pressure swing adsorption, where the dryer is depressurized and purged with a small amount of dry air.

Desiccant dryers can achieve extremely low dew points, making them suitable for critical processes in manufacturing, laboratories, and other moisture sensitive environments. They are versatile, do not require refrigerants, and offer different regeneration methods to match operating conditions.

Their drawbacks include higher initial cost and higher energy consumption, especially for heat regenerated systems.

Overall, desiccant dryers provide reliable moisture removal where very dry compressed air is essential, offering strong performance despite their higher investment and operating costs.

A refrigerated air dryer removes moisture from compressed air by cooling it until water condenses and can be drained off.

It works on the principle of condensation. The compressed air is cooled inside a refrigeration circuit. Once the temperature drops below the dew point, moisture turns into liquid water, which is automatically removed. The dried air is then slightly reheated to prevent downstream condensation.

Refrigerated dryers offer effective moisture removal, reliable performance, low operating costs, and a simple design. They are easy to install and maintain and are suitable for many applications such as manufacturing, automotive, pharmaceuticals, and food and beverage.

Their limitations appear at very low dew points, as they typically reach around plus three degrees Celsius. The refrigeration system also requires energy to operate.

Overall, refrigerated air dryers are a cost effective and versatile solution for drying compressed air in a wide range of industrial environments.

A laser particle counter with light scattering method works by using a laser beam to illuminate particles in a sample, and then measuring the scattered light to determine the size and number of particles present. The scattered light is collected by a detector, which then sends the signal to a computer for analysis.

The amount of light scattered by a particle is directly proportional to its size, so the larger the particle, the more light it will scatter. By analyzing the scattered light, the particle counter can determine the size distribution of the particles in the sample.

Additionally, the scattered light can be directed into different detectors for counting the number of particles in the sample. This method is widely used for measuring particle size and concentration in liquids, gases, and aerosols.

A quartz crystal microbalance (QCM) sensor is a type of sensor that uses the principle of a quartz crystal oscillator to measure the humidity in compressed air. The QCM sensor consists of a quartz crystal oscillator, which is a thin slice of quartz crystal that vibrates at a precise frequency when an electrical current is applied to it. When the humidity in the compressed air changes, the weight of the crystal changes due to the adsorption or desorption of water molecules on the surface of the crystal. This causes a change in the frequency of the crystal’s oscillation, which can be measured and used to calculate the humidity.

The QCM sensor is typically coated with a hygroscopic material, such as aluminum oxide, which attracts and adsorbs water molecules. As the humidity in the compressed air increases, more water molecules are adsorbed on the surface of the crystal, increasing its weight and causing a decrease in the frequency of the crystal’s oscillation. Conversely, as the humidity in the compressed air decreases, fewer water molecules are adsorbed on the surface of the crystal, decreasing its weight and causing an increase in the frequency of the crystal’s oscillation.

By using the changes in frequency in the quartz crystal the sensor can measure the humidity in the compressed air. QCM sensors are known for their high accuracy, fast response time, and excellent long-term stability. They are also relatively low-cost and have a small footprint, making them suitable for use in compressed air systems.

A Pitot tube flow meter is a differential pressure device that measures the velocity of a gas based on Bernoulli’s principle. It uses two pressure points. The stagnation port captures the impact pressure of the flowing gas, while the static port records the static pressure inside the pipe. The difference between these two pressures gives the differential pressure, which increases with higher gas velocity.

To determine the mass flow rate, the measured differential pressure is combined with temperature and system pressure. These parameters define the density of the gas, which is essential for converting velocity into mass flow. With this approach, a Pitot tube flow meter provides a reliable method to measure mass flow in compressed air and gas systems, supporting stable operation and consistent consumption monitoring.

A dew point sensor for compressed air measures the temperature at which moisture begins to condense. Keeping this value low is essential to avoid corrosion, contamination, and equipment damage.

Capacitive dew point sensors are widely used because they are accurate, fast, robust, and cost effective. They work by detecting changes in electrical capacitance as water vapor interacts with the sensor surface. These changes allow the sensor to calculate the dew point of the compressed air.

Capacitive sensors offer several advantages. They provide reliable accuracy, fast response times, and long term stability even in harsh industrial environments. They are also far more affordable than chilled mirror systems and suitable for many industries such as manufacturing, pharmaceuticals, food and beverage, and automotive.

Monitoring dew point is essential to protect equipment, maintain product quality, and ensure efficient operation of compressed air systems.

Overall, capacitive dew point sensors are key tools for maintaining dry and clean compressed air across a wide range of industrial applications.

Principle of operation: A pitot tube flowmeter for wet compressed air operates on the differential pressure principle. It consists of two ports: a stagnation (or impact) port facing upstream and a static port facing sideways. As the wet compressed air flows through the pipe, the stagnation port faces directly into the flow, causing the air to decelerate momentarily and creating a high pressure point. The static port measures the static pressure of the flowing air.

Differential pressure measurement: The pressure difference between the stagnation pressure and the static pressure is measured by a pressure sensor. This pressure difference, known as the dynamic pressure, is directly proportional to the velocity of the air flow according to Bernoulli’s principle.

Calculating the flow rate: By measuring the differential pressure, the pitot tube flow meter calculates the velocity of the wet compressed air. In addition, the meter typically includes temperature measurement capabilities. Using the temperature data, the meter can calculate the volume flow of the air and compare it to reference conditions, ensuring accurate measurement regardless of changes in temperature and pressure.

Advantages of Pitot tube flow meters:

• Simple design: Pitot tube flow meters have a simple design, consisting of only a tube and a pressure sensor. This simplicity makes them easy to install and maintain.
• Suitable for wet air: Pitot tube flowmeters are suitable for measuring wet compressed air because they do not rely on heat transfer and are less sensitive to moisture content than thermal mass flowmeters.
• Wide range of applications: They can be used in a wide range of industrial applications, including HVAC systems, pneumatic conveying and compressed air systems.
• Low pressure drop: Pitot tube flowmeters typically have a low pressure drop, minimising energy loss in the system.
• Reliable performance: With no moving parts, pitot tube flowmeters offer reliable performance and long-term stability.

Disadvantages:

• Limited measurement range: Pitot tube flow meters may not be able to accurately measure very low flow rates due to the lack of a high enough pressure differential.
• Cost-effectiveness compared to thermal mass flowmeters: While pitot tube flowmeters offer reliable performance, they may not be as cost effective as thermal mass flowmeters in certain applications.

A pulse output is a type of digital signal that switches between two states, typically high (1) and low (0), in a repeating pattern. The duration of the high state is called the “pulse width” and the duration of the low state is called the “pulse period”. The frequency of the pulses, or the number of pulses per second, is called the “pulse frequency”. Pulse outputs are commonly used in digital electronics, including control systems and digital communications.

A thermal mass flow meter measures compressed air and gas using convective heat transfer. It contains a heated sensor and a temperature sensor. As gas flows past, it cools the heated sensor, and the meter calculates mass flow based on how much heat is removed.

Thermal mass flow meters offer direct mass flow measurement, fast response time, wide rangeability, low pressure drop, and no moving parts, making them reliable and low maintenance.

They are sensitive to changes in gas composition, not suitable for wet or contaminated air, and work best with clean, dry gases.

Overall, they provide accurate and stable flow measurement for many industrial compressed air and gas applications.

An ultrasonic flowmeter for liquids measures flow using transit time technology. It sends ultrasonic signals upstream and downstream through the liquid. By comparing the travel times of these signals, the meter accurately calculates the flow rate.

Transit time flowmeters offer high accuracy, non intrusive installation, and suitability for many liquids with varying viscosities and temperatures. They can also measure flow in both directions.

Their accuracy can decrease in very turbulent flows or liquids with air bubbles or solids. They also have a higher initial cost, though low maintenance often balances this over time.

Overall, transit time ultrasonic flowmeters provide precise, reliable, and versatile liquid flow measurement in closed pipe systems.

A 4 to 20 mA analogue output is a common industrial signal used to transmit measurement values from a sensor to a controller or monitoring device. The current represents the measurement range, with 4 mA as the zero point and 20 mA as the full scale value.

This signal is popular because it is accurate, resistant to electrical noise, and can be transmitted over long distances without losing quality. It also interfaces easily with controllers, indicators, and recorders.

The 4 to 20 mA output is widely used in process control and automation to transmit values such as temperature, pressure, flow, and level.

Modbus TCP is a version of the Modbus protocol that runs over TCP/IP networks. Instead of serial communication, it uses Ethernet, enabling devices to exchange data across local networks or the Internet. It follows a client server model, where the server stores data and clients read or write to it. Modbus TCP is widely used in industrial automation because it is flexible, scalable, and compatible with equipment from many manufacturers.

Atmospheric dew point is the dew point at no pressure under normal ambient conditions, such as in expanded compressed air. If the air is compressed the moisture contained therein is forced into a smaller volume. Thus, the moisture per unit of volume increases so does the dew point. The pressure dew point is always measured under pressure.

In compressed air and gas systems, volumetric flow measures how much gas volume passes a point over time, standardized to fixed temperature and pressure conditions.

Mass flow measures the actual mass of the gas moving through the system and is not affected by changes in temperature, pressure, or gas composition. Because it reflects true gas quantity, mass flow is more accurate for process control and energy monitoring.

Oil droplets refer to small particles of oil suspended in a liquid or gas. Liquid oils refer to oils that are in a liquid state at room temperature. Oil vapor refers to oils that are in a gaseous state, typically as a result of being heated or evaporated.

The main difference between these three forms of oil is their physical state – droplets are suspended in another substance, liquid oils are in a liquid state, and oil vapor is in a gaseous state.

Nm³/h and m³/h both describe gas flow rates, but they use different reference conditions.

Nm³/h refers to gas volume at 0°C and 1013 hPa, while m³/h (standard m³/h) uses 20°C and 1000 hPa. Because the temperature and pressure differ, the values are not interchangeable. Industries choose one unit depending on their standards, so it is important to always specify the reference conditions to ensure correct comparison and accurate measurement.

ISO 8573 is a series of international standards for compressed air purity. The standard specifies the maximum allowable levels of impurities, such as water, oil, and particulate matter, in compressed air systems. The standard is divided into several parts, each covering a different aspect of compressed air purity.

Part 1 of the standard, for example, covers the general requirements for compressed air purity, while part 2 covers the measurement methods to be used for determining the levels of impurities in compressed air. The standard also defines classes of compressed air purity, with class 1 being the highest and class 8 the lowest.

Each class corresponds to a different set of maximum allowable impurity levels, and the class that a particular compressed air system is required to meet will depend on the application for which the compressed air will be used.

I am assuming you want to measure parameters at the compressor outlet, but still before the filtration. This means you have wet air which might carry additional contaminations like oil or particles.

For flow measurements:
+Pitot Tube Flow Meter (S430): This is suitable for measuring wet air flow, as thermal mass flow sensors like S401, S421, and S415 cannot be used in dirty and wet conditions.

+Pressure Sensors (S010 / S011): These sensors are designed for measuring compressed air and gases, providing highly accurate pressure readings.

+Temperature Sensors (S020): These high-quality sensors are used for measuring the temperature of compressed air and gases.

These sensors play a crucial role in monitoring and optimizing the performance of compressed air systems. If you need more specific information or assistance, feel free to ask!

The thermal mass flow principle measures the heat loss of a heated sensor a moving gas. Depending on the mass and the velocity of the gas passing through, the signal is proportional to the standard flow rate. This principle is very reliable over a wide range. Specifically for the detection of small air flows, as caused for example by leakage. Due to the small size an easy installation under pressure without interrupting the production is possible – another advantage over other principles.

To clean a thermal mass flow meter, always handle the sensor with care to avoid damage.

First power off and disconnect the meter. Inspect the sensor area for contamination. Remove loose debris with clean, dry compressed air, using only gentle pressure. Never touch the sensor element or use abrasive tools.

If needed, use mild cleaning solutions approved by the manufacturer and keep them away from the sensor element. Allow all parts to dry completely before powering the device again.

After cleaning, perform a calibration check to ensure accurate operation. Regular inspections, cleaning, and calibration help maintain long term performance and prevent buildup.

If unsure about any step, follow the manufacturer’s instructions or consult a qualified technician.

Pressure drops in a compressed air system can occur for a variety of reasons. Some common causes of pressure loss include:

Leaks: Leaks in the compressed air system can cause pressure drops by allowing air to escape from the system. Leaks can occur in pipes, fittings, valves and other components of the system.

Restrictions: Restrictions in the compressed air system can cause pressure drops by restricting the flow of air. Examples of restrictions include clogged filters, partially closed valves and restricted piping.

Improperly sized piping: If the piping is not properly sized for the flow rate, it can cause pressure drops in the system.

Air dryer: If the air dryer is not working properly, it can cause pressure drops in the system.

Corrosion: Corrosion in the pipes, fittings and other components of the air system can cause pressure drops by reducing the internal diameter of the pipes and fittings.

Excessive use of compressed air: If the compressed air system is used more than it was designed for, this can cause pressure drops.

Insufficient compressor capacity: if the compressor does not have sufficient capacity to meet demand, it can cause pressure drops in the system.

Incorrectly set pressure regulators and control valves: If the pressure regulators and control valves are not set correctly, this can cause pressure drops in the system.

Piping and clearances: Improperly selected pipe diameters and long pipes will cause pressure drops, especially at high air flow rates.

It’s important to regularly check and maintain the compressed air system to identify and correct any potential problems that could cause pressure drops. This includes checking for leaks.

• The pipe diameter or measuring range may be incorrectly set in the software.
• Moisture or liquid water may be entering the sensor, especially in thermal mass models.
• The sensor could be heavily contaminated with oil or particles.

• Review the sensor settings in S4C-FS and correct any errors in diameter or flow range.
• Check the compressed air system’s dew point to ensure no water condensation is reaching the sensor.
• Inspect and clean the sensor, and make sure filters and dryers are functioning properly upstream.

• The output signal wiring might be connected incorrectly.
• A fuse or component in the measurement system may be blown.
• The analog output scaling (e.g., 4–20 mA) might not be correctly configured.
• The installed output board might not match your system’s signal requirements.

• Double-check the output wiring using the instructions in the user manual.
• Use a multimeter to check whether any signal is present on the output lines.
• Open the S4C-FS software and ensure the correct signal scaling is selected.
• Confirm that the sensor’s output (e.g., 4–20 mA, Modbus) matches the input expectations of your data logger or PLC.

• There might be leaks or bypasses between the sensors.
• One or more sensors might have incorrect scaling or pipe diameter settings.
• Some sensors might not be measuring the full flow path due to poor installation locations.

• Check the system for any leakage or open bypass valves.
• Make sure every sensor has the correct settings for pipe diameter, gas type, and measurement range.
• Verify that the sensors are installed in locations where they can measure the complete flow in the pipeline.

• The sensor may be incorrectly installed — for example, not centered or installed at the wrong depth.
• The wrong gas type, flow units, or reference conditions may be selected in the settings.
• The inner pipe diameter might be entered incorrectly in the software.
• The sensor technology may not be suitable for the current application (e.g., thermal mass sensors in very humid environments).
• There may not be enough straight pipe before or after the sensor, causing turbulent flow.

• Verify the sensor is properly centered in the pipe and installed at the recommended depth and orientation.
• Check the gas type, measurement units, and reference pressure/temperature conditions in the S4C-FS software.
• Enter the correct inner pipe diameter to ensure proper flow calculation.
• Make sure the sensor technology is appropriate for the gas conditions (e.g., avoid thermal mass sensors where liquid water may be present).
• Install the sensor with adequate straight pipe lengths before and after, as specified in the manual.

• The air or gas might be contaminated with moisture, oil, or particles.
• Turbulent flow caused by nearby elbows, valves, or other obstructions may be affecting readings.
• The sensor could be loose or not inserted to the correct depth.

• Inspect filters and dryers upstream of the sensor to ensure clean, dry air.
• Check for rust, oil, or debris that could be interfering with the sensor element.
• If possible, move the sensor to a more stable section of the pipe, away from bends or valves.
• Make sure the sensor is firmly secured at the correct insertion depth and orientation.

• The sensor may be physically installed in the wrong direction.
• The flow direction configuration in the software may be reversed.

• Look for directional arrows on the sensor housing and confirm that they match the actual flow direction.
• If necessary, update the flow direction settings in the S4C-FS software to correct the reading.

• A zero-flow calibration has not been performed or was done incorrectly.
• High humidity or oil residue may cause thermal sensors to register false readings.
• Nearby machinery or vibrations might create noise signals that are interpreted as flow.

• Use the S4C-FS software to perform a proper zero-flow calibration with the pipe completely depressurized.
• Check for moisture or oil using a dew point sensor or monitor.
• Avoid installing the sensor near sources of vibration, such as compressors or motors, which could affect accuracy.

The compressed air has to pass many obstacles between the generation of the compressor to the point of use. This leads to a pressure drop.

Regular calibration ensures that instruments remain accurate, reliable, and safe to use. Over time, sensors can drift due to environmental changes or wear, and calibration corrects this drift.

Many industries require calibrated instruments to meet regulations such as GMP. Accurate measurements support quality control, improve product consistency, and reduce safety risks in critical processes.

Routine calibration is also cost effective. It helps prevent production errors, unnecessary retesting, and equipment issues that could become expensive if left undetected.

In short, regular calibration ensures accuracy, compliance, safety, and long term efficiency.

• The wiring might be incorrect or the cable could be damaged.
• The Modbus communication lines (D+ and D−) may be reversed.
• If you’re using Modbus TCP, the sensor might be connected directly to a PC instead of through a network switch or hub.
• The configured Modbus address might not match the sensor’s actual address.
• The sensor may not be powered or the supply voltage could be too low.

• Compare the wiring with the sensor’s user manual to ensure all connections are correct.
• Use a multimeter to check for a stable 24 VDC power supply.
• Test the cable for continuity or try a known working replacement cable.
• Verify the Modbus address and communication settings using the S4C-FS configuration software.
• Ensure the cable from the splitter to the sensor is shorter than 30 cm for proper detection.
• Use the S4C-FS software’s address scan function to detect the sensor on the network.