How Does an FLP Digital Temperature Indicator Work?

Key Components
1. Flameproof Enclosure: Made from robust materials like aluminum LM-6 or stainless
steel, certified for hazardous areas with ingress protection ratings like IP65 or IP66.
2. Temperature Sensor Input: Accepts signals from RTD Pt-100, thermocouples (e.g., J,
K, T), or analog inputs (e.g., 4-20 mA) for temperature measurement.
3. Digital Display: High-visibility LED or LCD (e.g., 4-digit, 7-segment) shows real-time
temperature readings with high accuracy.
4. Microcontroller: Processes sensor signals, supports software calibration, and may
include programmable features like alarm setpoints or display ranges.
5. Power Supply: Typically operates on 230 V AC, 110 V AC, or 24 V DC, designed for
low power consumption.
6. Communication (Optional): RS485 Modbus, RS232, or 4-20 mA retransmission for
integration with control systems like SCADA or PLC.
Working Principle
 Sensor Connection: A temperature sensor (e.g., RTD or thermocouple) is connected to
the indicator, placed in the process environment (e.g., pipeline, reactor).
 Signal Processing: The microcontroller converts the sensor’s electrical signal (e.g.,
resistance for RTDs, voltage for thermocouples) into a temperature value, compensating
for factors like lead wire resistance.
 Display: The temperature is displayed on a bright LED/LCD screen, often with a
resolution of 0.1°C or 1°C, depending on the sensor and range.
 Safety: The flameproof enclosure contains any potential sparks or heat, ensuring safe
operation in hazardous areas classified as Zone 1 or Zone 2.
 Data Output: Optional retransmission or communication interfaces allow data logging or
integration with process control systems.