In the field of industrial process control and automation, flange pressure transmitter has become the core equipment for pressure measurement due to its high precision, strong stability and wide media adaptability. Its selection needs to comprehensively consider core parameters such as measurement range, medium characteristics, and environmental conditions. Starting from the technical principles, this article systematically sorts out the key parameters required for selection, and combines actual engineering cases to provide users with practical references.
1. Technical principles and core advantages
Flange pressure transmitter converts pressure signals into electrical signals through sensors. Common technical types include capacitive, diffused silicon and ceramic. Its core advantages are reflected in:
High precision and stability
The accuracy can reach ±0.075%FS, and the long-term stability is <0.1%FS/year, which is suitable for scenarios requiring high-frequency measurement (such as chemical reactor pressure control).
Wide medium adaptability
It can measure corrosive media (such as acid and alkali solutions), high-viscosity media (such as crude oil) and high-temperature media (maximum temperature up to 350℃).
Easy installation and low maintenance cost
The flange structure is suitable for direct installation of pipelines, with an annual failure rate of <0.3%, and is suitable for scenarios with limited space (such as equipment cabins).
2. Analysis of core parameters: key basis for selection
1. Measurement range and overpressure protection
Range: It is necessary to cover the actual working pressure and leave a margin of 20%-80% to ensure the best accuracy. For example, a chemical plant reactor pressure monitoring uses a model with a range of 0-10MPa, and the data stability is improved by 30% in actual use.
Overpressure protection: It is necessary to select a model with overpressure protection function to avoid damage to the sensor due to instantaneous pressure shock. A petrochemical company did not consider the overpressure scenario, which caused the sensor diaphragm to rupture. After replacing it with a double diaphragm structure, the problem was solved.
2. Medium compatibility
Corrosive media (such as hydrochloric acid, sodium hydroxide): Hastelloy or tantalum diaphragms need to be selected to avoid electrochemical corrosion.
High viscosity media (such as heavy oil): It is necessary to select a model with self-cleaning function to avoid measurement errors caused by medium adhesion.
Medium containing particles (such as sewage): It is necessary to install a filter device or choose a ceramic diaphragm to avoid clogging or wear.
3. Temperature and pressure type
High temperature scenario (>200℃): The sensor needs to be equipped with a heat sink or ceramic filling coupling agent, and some models can withstand temperatures up to 350℃.
Low temperature scenario (<-50℃): It is necessary to select a low-temperature special model to avoid leakage caused by material embrittlement.
Pressure type: It is necessary to specify whether it is gauge pressure, absolute pressure or differential pressure measurement. For example, an absolute pressure transmitter is required for boiler drum pressure monitoring.
4. Accuracy level and response time
Accuracy requirements: For trade settlement scenarios (such as natural gas pipeline pressure measurement), a high-precision model of ±0.075%FS is required; for process control scenarios (such as factory circulating water pressure monitoring), an accuracy of ±0.1%FS is acceptable, and the cost is reduced by 40%.
Response time: For fast switching scenarios (such as laser cutting air pressure control), a model with a response time of <50ms is required, and for steady-state monitoring scenarios (such as tank pressure), a response time of <200ms can meet the requirements.
5. Output signal and interface
Signal type: 4-20mA output is suitable for traditional PLC/DCS systems, and HART protocol supports remote adjustment; digital signals (such as Modbus-RTU) are easy to integrate into the Internet of Things platform.
Wireless transmission: Models with built-in LoRa/NB-IoT modules can realize remote data transmission, reduce wiring costs, and adapt to remote scenarios (such as field oil and gas wells).
3. Environmental Condition Adaptation: Ensure Long-term Stable Operation
1. Protection and Explosion-proof Requirements
Protection Level: IP68 protection is required for outdoor scenes, equipped with rain cover and lightning protection device; moisture-proof circuit design is required for humid environments (such as paper mills), and some models use glue sealing process.
Explosion-proof certification: The petrochemical industry requires Ex d IIC T6 Ga explosion-proof level, independent grounding resistance <4Ω, to avoid static electricity or lightning damage to equipment.
2. Installation location and space restrictions
Straight pipe section requirements: 10D upstream and 5D downstream straight pipe sections (D is the pipe diameter) must be guaranteed to avoid turbulent sources such as valves and elbows interfering with measurement.
Space adaptation: Space-constrained scenes (such as equipment cabins) need to choose compact designs with an outer diameter of <DN50. Some models can be side-mounted or top-mounted to adapt to small spaces.
IV. Industry application cases: practical verification of parameter optimization
1. Petrochemical industry
Scenario: Pressure control of reactor in catalytic cracking unit.
Parameter requirements: high temperature resistance (>300℃), corrosion resistance (containing hydrogen sulfide gas), high precision (±0.075%FS).
Case: A refinery increased the reaction efficiency by 10% and saved more than 30 million yuan in raw material costs annually by selecting flange-type pressure transmitters with Hastelloy diaphragms and temperature compensation.
2. Power and energy field
Scenario: Boiler drum pressure monitoring.
Parameter requirements: fast response (<50ms), high pressure resistance (>10MPa), explosion-proof certification.
Case: A power plant reduced the drum pressure fluctuation from ±0.5MPa to ±0.1MPa by deploying flange-type pressure transmitters to link safety valves, and the boiler efficiency was increased by 2%.
3. Municipal and environmental protection engineering
Scenario: Air pressure control of aeration tanks in sewage treatment plants.
Parameter requirements: corrosion resistance (containing chlorine disinfectants), low power consumption (wireless transmission), IP68 protection.
Case: An environmental protection project increased aeration efficiency by 25% and reduced energy consumption by more than 1.5 million kWh per year by selecting a flange pressure transmitter with self-cleaning function.