Temperature measurement in industrial silos
Semi-distributed fiber optic measurement system
Semi-distributed fiber optic measurement system designed to measure the temperature of gaseous, liquid, and solid substances in chemical or industrial silos, based on FBG (Fiber Bragg Grating) technology. Passive sensor designed for specialized measurements in electromagnetically disturbed, explosive, chemically aggressive, mechanically stressful, or radioactive environments.
The sensor system is integrated into a durable multi-sheath metal cable that can withstand high vertical and horizontal mechanical stress. Thanks to the small diameter of the cable, friction with stored material is minimal, and the surface sheath made of Alloy 825 is also suitable for the food industry. However, it is also highly resistant to chemically aggressive environments with reducing and oxidizing substances, which can be advantageously used for chemical storage tanks and silos. The length of the sensor and the number of measuring points are determined by the specific application at the range from 2 to 30 m with a maximum of 12 measuring points. For special applications, it is possible to custom-made a cable with a larger number of measuring points. In addition to temperature measurement, it is also possible to monitor the level of stored material with a resolution given by the number of measuring points.
Application
- Chemical industry
- Agriculture (storage of bulk materials, grains, fermented feed, food materials)
- Storage of bulk materials in harsh environments (coal, cement, sand, soot, fly ash, wood chips, metal scrap, etc.)
Key features
- Early detection of spontaneous ignition of stored materials
- Large dynamic range, sensors can be located up to several kilometers away from the evaluation electronics
- Galvanic isolation of the measured location and evaluation electronics
- Measurement without the need for a power supply at the measurement location.
- Immune to electromagnetic interference
- Suitable for harsh and explosive environments
- Resistance to chemically aggressive substances, resistance to radioactive radiation
- Long-term stability, accuracy, and repeatability of measurements
- Thin, self-supporting, mechanically resistant cable
Accessories
- Fiber optic distribution cable between sensors and evaluation electronics
- Optical switch that allows measurement of up to 8 silos simultaneously using a single evaluation unit
- Converter to RS485 and other commonly used standards
The standard communication interface is Ethernet; however, the evaluation unit can also be equipped with an RS-485 converter or other communication standards, enabling the monitoring system to communicate with higher-level systems. In autonomous operation mode, the acquired data are processed by the evaluation electronics and transmitted via a 4G interface to a server, which collects and stores the data in an SQL database using the MQTT protocol. The data are presented to users through a web interface with a wide range of customization options tailored to the specific installation and application. Remote data access enables integration of the system into commonly used supervisory systems and is always secured against unauthorized access.
System parameters
| Measuring range | -50 °C up to 200 °C |
| Sensor type | Quasi-distributed FBG |
| Measurement period | 3.5 s |
| Accuracy class | A |
| Resolution | 0.5 °C |
| Absolute accuracy | ± 1 °C |
| Optical interface | LC/APC |
| Power supply | 230 VAC/50 Hz |
| Power consumption | 10 W |
| Communication interface | Ethernet (RJ-45), RS-485 (Modbus) |
| Operating temperature range of the unit | 0–40 °C |
| Unit weight | 1.5 kg |
| Unit dimensions | 230 × 115 × 80 mm |
| Warranty | 1 year |
Parameters
Sensor parameters
| Length | 2–30 m |
| Average | 6.35 mm |
| Shell material | Alloy 825 |
| Tensile strength | up to 20 kN |
| Number of measuring points | up to 12 |
| Coverage | IP 67 according to EN 60529 |
| Sensor surface | Smooth stem |
| Optical connector | LC/APC |
