Measuring Technology

Downtime is the biggest threat to production efficiency. Every minute a business-critical piece of equipment is down means lost revenue, but the costs don't stop there. The impact of downtime is felt throughout the entire company.

With SensoControl, end users can monitor their equipment in real time for system changes and optimize their equipment before a problem causes downtime. Effective diagnostics can also help users work more efficiently by helping them identify and eliminate process bottlenecks.

Measurement Technology

Measurement technology encompasses instruments and systems for the acquisition, transmission, and evaluation of physical quantities such as pressure, temperature, level, flow, force, and humidity. In industrial applications, the selection of the correct measurement principle is crucial for process stability, product quality, and maintenance effort. Our selection focuses on robust designs, precise sensor technology, and industrial interfaces, allowing devices to be directly integrated into manufacturing environments. Important criteria include measuring range, accuracy, long-term stability, material compatibility, protection class, and connection type.

Materials and Designs

Measuring transducers often consist of stainless steel (1.4301, 1.4404) for corrosive environments or brass and aluminum for less aggressive media. For liquid contact, suitable seals such as FKM, EPDM, or PTFE are crucial; FKM offers high resistance to oil and fuels, EPDM covers hot water and steam-resistant applications, and PTFE is chemically inert and ideal for aggressive chemicals. In pressure-loaded systems, welded or flange connections are used, while for hygienic processes, aseptic screw connections, VCR, or Tri-Clamp fittings are utilized. Electrical connections vary between M12 connectors, cable outlets with protective hoses, and field-configurable terminal boxes. For vibrating machinery, welded housings and reinforced diaphragms are required to minimize measurement deviations.

Measurement Principles and Suitable Applications

Pressure sensors operate with piezoresistive, capacitive, or thin-film measuring elements. Piezoresistive sensors offer high linearity and are suitable for static and dynamic pressure measurements in hydraulics and pneumatics. Capacitive sensors are characterized by high sensitivity and small measuring ranges, ideal for leak detection and level monitoring of non-conductive media. Thin-film resistance elements on ceramic substrates enable high overpressure resistance and are standard in oil-free process plants. Thermometers are based on PT100/RTD, thermistors, or thermocouples; PT100 offers the highest long-term stability for temperature monitoring in ovens and cooling circuits, while thermocouples are suitable for very high temperatures. Level sensor technology ranges from hydrostatic pressure probes to capacitive level sensors to radar and ultrasonic measuring devices; hydrostatic probes are the economical choice for liquids, and radar is suitable for dusty and turbulent tanks in the chemical industry.

Connections, Protection Classes, and Communication

Industrial measuring devices must offer appropriate protection classes (IP65, IP67, IP68, IP69K) and explosion protection classifications (ATEX, IECEx), depending on the place of use. Sensors with IP68/IP69K are essential for high-pressure cleaning and wet areas. Electrical interfaces include analog 4–20 mA, 0–10 V, as well as digital protocols such as HART, Modbus RTU/TCP, Profibus, and OPC UA. For predictive maintenance and Industry 4.0 applications, sensors with IO-Link and Ethernet/IP are recommended, as they transmit additional diagnostic data and calibration values. When selecting sensors for use near powerful drives or frequency converters, pay attention to galvanic isolation and EMC specifications.

Calibration, Accuracy, and Long-Term Behavior

Calibration determines the usability of measurement data. Industrial sensors should be supplied factory-calibrated and offer traceable calibration certification. Crucial factors are temperature coefficients, hysteresis, linearity, and drift. In plants with high process reliability, regular on-site calibration or an exchange concept with calibrated replacement devices is recommended. For measurements in the ppm range or with tight tolerances, devices with low drift and optional adjustment capabilities (via potentiometer, software, or HART commands) are necessary. For critical measuring points, redundant sensor technology and automatic plausibility checks are useful to minimize the risk of failure.

Practical Examples

Hydraulic Test Bench, Pressure Measurement: In a test bench for the final inspection of hydraulic cylinders, a piezoresistive pressure sensor with a stainless steel diaphragm and FKM seal is installed. The sensor is connected via an M12 connector, provides 4–20 mA, and communicates diagnostic parameters via HART. A welded connection cap protects against oil mist; regular factory calibrations ensure measurement accuracy with changing temperatures and high pulsations. Data is centrally logged and documented in test reports.

Food Production Line, Level and Temperature: In a filling line, capacitive level sensors monitor the liquid level in stainless steel containers with Tri-Clamp connections. PT100 temperature sensors with hygienic screw connections monitor sterilization temperatures. Devices comply with IP69K and are equipped with PTFE seals, allowing high-pressure cleaning. The sensor technology is connected to an Ethernet-enabled gateway and provides real-time data to the MES, immediately alarming for limit value exceedances.

Wastewater Treatment Plant, Flow and Chemical Resistance: A wastewater treatment plant uses magnetic-inductive flow meters for conductive media, mounted with flange connections and NBR seals. For pH and conductivity measurements, electrode-based sensors with PTFE coating are used, as aggressive media and cleaning agents are expected. Measured values are processed in a PLC system and forwarded via Modbus to the process visualization; regular electrode flushing prevents deposits.

Product Categories — Brief Overview

• Pressure sensors, temperature sensors, level sensors, flow meters, force and humidity sensors

Installation Instructions and Maintenance

Sensors should be mounted in a way that minimizes thermal loads, vibrations, and direct mechanical stress. For wall or flange mounting, sealing surfaces must be cleaned, and tightening torques applied according to manufacturer specifications to avoid diaphragm damage. Cable glands and connectors must comply with the device's protection class; for wet conditions and high-pressure cleaning, IP69K connections must be used. Maintenance intervals depend on process load: abrasive media and strong temperature fluctuations require shorter intervals. Calibrations should be documented, and calibration certificates retained to meet traceability and audit requirements.

Selection Criteria for Purchasing

Select sensors based on specific process requirements: medium, temperature range, pressure, chemical compatibility, necessary protection class, and communication interface. Check the scope of delivery (factory settings, calibration certificate, connection cable), availability of replacement seals, exchange diaphragms, and optional measuring ranges. Pay attention to manufacturer specifications regarding life cycles and MTBF, especially for sensors in continuously loaded systems. For series orders, it is worthwhile to coordinate connection standards and configurations to reduce installation and storage efforts. Further technical information and application examples can be found at https://maku-industrie.de/technik and https://maku-industrie.de/anwendungsbeispiele.

Compliance and Certifications

For use in certified plants, relevant standards must be observed: EN 61010/IEC 61010 for measuring and laboratory equipment, IEC 61508/ISO 13849 for functional safety, as well as industry-specific standards such as FDA hygiene guidelines and 3-A for food. Potentially explosive areas require ATEX/IECEx certificates. Electrical devices must be CE-compliant and pass EMC tests. Also, check whether calibration certificates are traceable to national standards if measurement values are contractually or legally relevant.

Frequently Asked Questions (FAQs)

1. How do I choose the right seal for my measuring transducer?

The choice depends on the medium, temperature, and operating pressure: FKM for oils and fuels, EPDM for hot water and steam applications, PTFE for chemically aggressive media. Also, consider compatibility with cleaning media and the required elasticity for flange seals. Manufacturer specifications and chemical resistance lists should be consulted.

2. Which communication interface is future-proof for industrial sensor technology?

Ethernet-based protocols (OPC UA, Modbus TCP, Ethernet/IP) offer scalability and integration into Industry 4.0 architectures. IO-Link is suitable for parametric diagnostics at the field level. For simple control tasks, 4–20 mA remains robust and reliable; the combination of analog signal transmission and a digital interface for diagnostic data is often the most pragmatic solution.

3. How often should pressure and temperature sensors be calibrated?

Calibration intervals depend on process requirements, permissible tolerances, and influences such as temperature changes, vibration, and chemical stress. Typical intervals are between 6 and 24 months. For safety-relevant measuring points or testing tasks, shorter intervals or redundant systems are recommended. Documentation and traceability of calibrations are mandatory in auditable environments.