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How to Select Pressure Transmitters in Different Industrial Environments
In industrial process control, pressure transmitters are core components that ensure system safety, stability, and efficient operation. Significant differences in medium characteristics, temperature range, degree of corrosion, installation conditions, and measurement requirements across various environments directly affect selection decisions.
As a system integrator or engineering company, you must comprehensively evaluate these factors and select products with strong compatibility and long-term stability to reduce project risks and improve overall performance. Nexisense focuses on providing reliable sensor solutions for industrial IoT and automation projects. Starting from typical industrial scenarios, this article systematically explains selection strategies to help you make accurate decisions in complex environments.
Core Selection Principles: Environment-Driven Decisions
Pressure transmitter selection is not a simple application of specification sheets, but a balance based on actual on-site conditions. Key considerations include:
Medium characteristics: corrosiveness, viscosity, crystallization tendency, cleanliness.
Temperature range: medium temperature and ambient operating temperature.
Pressure type: gauge pressure, absolute pressure, differential pressure.
Installation method: direct connection, impulse tubing, flange, remote diaphragm seal.
Accuracy and stability: process-required resolution and long-term drift.
Compatibility and safety: output protocols, explosion-proof rating, sanitary certifications.
Ignoring any of these factors may lead to measurement drift, equipment failure, or safety hazards. The following sections provide targeted selection guidance categorized by typical industrial environments.
Chemical Industry: Addressing Corrosion and Complex Media
Chemical production involves various corrosive media such as acids, alkalis, solvents, and organic compounds, requiring pressure transmitters with excellent corrosion resistance. 316L stainless steel is the basic wetted material, but for highly corrosive media (such as concentrated sulfuric acid or hydrofluoric acid), it is recommended to upgrade to Hastelloy C-276, tantalum, or titanium alloys.
Diffused silicon or ceramic sensor pressure transmitters perform exceptionally well in this field. The former offers fast response and good linearity, while the latter provides superior corrosion resistance and impact resistance, suitable for temperature ranges from −40°C to +135°C.
For media prone to crystallization or high viscosity (such as polymer slurries), diaphragm seal transmitters should be prioritized. External flush diaphragms or corrugated diaphragms prevent clogging. In terms of installation, flange connections are preferred over threaded connections to avoid dead zones where material can accumulate. Differential pressure transmitters are commonly used for flow measurement, combined with orifice plates or Venturi tubes, with flow calculated via DCS/PLC systems.
In high-temperature chemical processes (such as cracking furnaces), medium temperatures may exceed 150°C. Heat sinks or remote diaphragm seal designs are required to keep the sensor body away from high-temperature zones. Nexisense ceramic series products support direct contact with high-temperature media, reducing the need for auxiliary cooling.
Oil and Gas Industry: High Pressure, High Temperature, and Explosion Protection
Oil and gas extraction and refining environments feature high pressure (up to hundreds of bar), high temperatures (>200°C), and explosion risks. Selection should prioritize products with explosion-proof certifications (Ex d or Ex ia) and protection ratings of IP67 or higher.
Gauge or absolute pressure transmitters are used for pipeline monitoring, while differential pressure transmitters are applied in tank level or flow measurement. Media often consist of hydrocarbons or sulfur-containing gases, requiring wetted materials resistant to sulfide stress corrosion. 316L stainless steel or Inconel alloys are commonly used.
In high-temperature applications, remote diaphragm seal transmitters filled with silicone oil or fluorinated oil ensure that the sensor operates within a safe temperature range. In areas with strong vibration (such as pump stations), select vibration-resistant designs (>10 g) and fast response times (<5 ms) using piezoresistive technology.
Direct pipeline installation is suitable for clean gases, while impulse tubing installation is preferred for media containing solid particles. Nexisense high-pressure series supports a wide turndown ratio (>10:1), facilitating on-site adjustment, and integrates HART or Modbus protocols for remote diagnostics.
Pharmaceutical and Food Industries: Sanitary and Dead-Zone-Free Design
Pharmaceutical, food, and beverage production impose stringent hygiene requirements. Pressure transmitters must comply with certifications such as 3-A, EHEDG, or FDA. Sanitary products use polished 316L stainless steel surfaces (Ra < 0.8 μm), dead-zone-free structures, and support CIP/SIP cleaning.
For fermentation tank level measurement, atmospheric vessels typically use single-flange diaphragm seal transmitters. Sealed vessels (such as nitrogen-blanketed tanks) require dual-flange differential pressure transmitters, with both positive and negative pressure chambers connected remotely to prevent vapors from entering the sensor. For open tanks or sludge-containing bottoms, single-flange flush diaphragm designs prevent clogging.
Medium temperatures generally range from −10°C to +120°C, making ceramic or diffused silicon sensors suitable. A 4–20 mA output combined with HART simplifies integration with SCADA systems. Nexisense sanitary series emphasizes easy-to-clean interfaces (such as Tri-Clamp), reducing contamination risks.
Water Treatment and Environmental Applications: Fouling Resistance, Low Temperature, and Cost Efficiency
Wastewater treatment involves sewage, sludge, and chemical reagents with high corrosiveness and particulate content. Diaphragm seal or submersible transmitters are recommended, using ceramic or coated materials to prevent clogging and corrosion. Differential pressure transmitters are used for filter differential pressure monitoring, while gauge pressure transmitters measure pump outlet pressure.
Low-temperature environments (<−20°C) require low-temperature fill fluids to prevent freezing. Vibration and moisture are common, so products with IP68 protection and polyurethane cables should be selected. From an economic perspective, diffused silicon pressure transmitters offer high cost-performance, with 0.25% FS accuracy sufficient for most applications.
Other Special Environment Selection Considerations
Very low pressure (<500 Pa): Direct measurement is unstable; differential pressure transmitters are recommended.
Steam or high-temperature gas: Use cooling tubes and inject condensate to prevent thermal shock.
Hazardous areas: Ex ia IIC T6 certification, two-wire 4–20 mA output.
Strong vibration: Solid-state designs with no moving parts; ceramic or diffused silicon sensors outperform traditional strain gauges.
General Installation and Maintenance Considerations
Regardless of environment, during installation keep impulse tubing short (<5 m) with appropriate slope (liquids upward 1/12, gases downward), eliminating air bubbles or liquid accumulation. Avoid contact between hard objects and the diaphragm, and add heat dissipation devices for high-temperature media.
Maintenance includes periodic calibration (every 6–12 months), seal inspection, and diaphragm cleaning. Supply voltage should not exceed 36 V, and the medium must not freeze.
FAQ: Common Questions on Pressure Transmitter Selection in Different Industrial Environments
How should strong acid media be handled in chemical applications? Upgrade to Hastelloy or tantalum materials and prioritize ceramic sensor transmitters.
What is recommended for high-temperature and high-pressure oil industry applications? Remote diaphragm seal transmitters with explosion-proof certification and high-pressure ranges.
What certifications are critical for pharmaceutical sanitary transmitters? 3-A, EHEDG, FDA, with surface roughness Ra < 0.8 μm.
What is suitable for level measurement in open food industry vessels? Single-flange diaphragm seal transmitters resistant to sludge clogging.
How can clogging be avoided in sludge media? Use external flush diaphragms or ceramic diaphragm designs.
Why choose differential pressure transmitters for very low pressure? Direct measurement is unstable; differential measurement is more stable.
What should be noted when measuring high-temperature steam? Add cooling tubes and inject condensate to protect the sensor.
Which output signal is suitable for explosive environments? Two-wire 4–20 mA output compatible with Ex ia certification.
What are key points for strong vibration environments? Vibration resistance >10 g and solid-state sensors such as diffused silicon or ceramic.
How to balance accuracy and cost? Process requirements determine accuracy; 0.25% FS is usually sufficient, avoiding over-specification.
Conclusion
Pressure transmitter selection across different industrial environments must focus on medium characteristics, temperature, corrosion, installation, and safety requirements. Chemical industries emphasize corrosion resistance, oil and gas prioritize high pressure and explosion protection, pharmaceutical and food industries highlight hygiene, and water treatment focuses on fouling resistance.
By systematically evaluating these factors and selecting appropriate types (such as diaphragm seals, remote designs, or ceramic sensors), measurement reliability and project success rates can be significantly improved.
Nexisense provides solutions ranging from standard to customized offerings, including OEM support and bulk supply, helping integrators address diverse challenges. If your project involves specific industrial environments, please contact our technical team to jointly develop the optimal selection strategy and ensure long-term stable system operation.
