Detailed Explanation of Common Pressure Transmitter Types and Selection Guidelines

In the field of industrial automation and process control, pressure transmitters serve as core sensors that convert medium pressure into standard electrical signals for real-time monitoring and regulation. This article provides an in-depth analysis of the technical principles, performance advantages, and application scenarios of common types such as diffused silicon, monocrystalline silicon, and ceramic pressure transmitters, and offers a practical selection guide to help engineers choose products suitable for specific operating conditions.

Introduction: The Core Role of Pressure Transmitters in Industry

Pressure measurement is a fundamental aspect of modern industry, from pipeline monitoring in petrochemical plants, to pump station regulation in water treatment systems, to hygiene control in food production. Pressure transmitters capture the mechanical force exerted by media such as liquids, gases, or steam on sensitive elements and convert it into standard signals like 4–20 mA or 0–10 V for processing by PLC or DCS systems. This conversion relies on precision sensing diaphragms and circuit design to ensure accuracy and stability.

As operating conditions become increasingly complex, pressure transmitter types have diversified. Nexisense, a brand focused on sensing technology, offers a comprehensive product line covering multiple types and, combined with local manufacturing advantages, provides cost-effective solutions. Understanding different types helps avoid selection errors and ensures efficient system operation.

Detailed Explanation of Common Pressure Transmitter Types

Pressure transmitters are mainly classified based on sensing element materials and technical principles. Each type has distinct characteristics in terms of accuracy, stability, and corrosion resistance.

Diffused Silicon Pressure Transmitters: The Mainstream General-Purpose Choice

Diffused silicon pressure transmitters use silicon-based semiconductors, where a resistor bridge is formed on a silicon wafer through diffusion processes. When pressure acts on the diaphragm, resistance changes generate a voltage signal that is output after amplification. This structure features high sensitivity, good linearity, and fast response times, typically at the millisecond level.

The advantages include moderate cost and a wide measurement range (from several kPa to hundreds of MPa), making it suitable for general industrial environments such as machinery manufacturing and hydraulic systems. Nexisense diffused silicon series products feature optimized temperature compensation, low drift rates of up to ±0.1%FS/year, and strong overload resistance (up to 2–5 times the rated range).

However, isolation diaphragms are required for strongly corrosive media. In practice, they are commonly used for air compressor or water pump pressure monitoring.

Monocrystalline Silicon Pressure Transmitters: The Preferred Choice for High-End Precision Applications

Monocrystalline silicon pressure transmitters use pure silicon crystals as sensing elements, forming resonant beams or strain bridges through micromachining. Pressure changes cause variations in vibration frequency or resistance, producing highly accurate signals. Accuracy can reach ±0.05%FS, with excellent long-term stability and minimal temperature influence (after compensation, ±0.02%FS/10°C).

They are suitable for applications requiring high accuracy, such as aerospace testing, energy metering, and laboratory calibration. Their strong anti-interference capability makes them ideal for complex electromagnetic environments. Nexisense monocrystalline silicon products integrate digital compensation chips and support the HART protocol for remote diagnostics.

The main drawback is higher cost, but their fatigue resistance makes them outstanding in dynamic pressure measurement applications such as gas turbine monitoring.

Ceramic Pressure Transmitters: A Reliable Solution for Corrosive and High-Temperature Environments

Ceramic pressure transmitters are based on piezoresistive or capacitive principles and use alumina or zirconia ceramic diaphragms. Pressure-induced deformation changes resistance or capacitance to generate output signals. They offer excellent corrosion resistance, compatibility with acidic and alkaline media, high-temperature limits above 150°C, and accuracy around ±0.5%FS.

They are widely used in chemical, pharmaceutical, and food industries, especially in hygienic applications. Oil-free designs eliminate contamination risks. Nexisense ceramic series products feature IP67 protection and support flush diaphragm connections for easy cleaning.

Compared to silicon-based types, ceramic transmitters offer better impact resistance but slightly lower linearity. Typical applications include wastewater treatment and beer fermentation tank pressure control.

Other Types: Supplementary Roles of Strain Gauge and Sputtered Thin-Film Transmitters

Strain gauge (resistive) pressure transmitters are among the earliest types, using metal foil strain gauges to detect diaphragm deformation. They are low cost but offer limited accuracy (±1%FS), making them suitable for low-requirement applications such as construction machinery.

Sputtered thin-film transmitters deposit insulating and resistive layers onto metal substrates, offering ultra-high pressure resistance (up to thousands of MPa) and strong vibration resistance. They are commonly used in oil drilling or military applications. Nexisense provides customized sputtered thin-film products to meet extreme operating conditions.

Although not mainstream, these types fill specific application gaps.

Pressure Transmitter Selection Guidelines: From Requirements to Matching

Selection should be systematic to avoid blindly pursuing high-end specifications.

First, clarify the measurement range and type: absolute pressure, gauge pressure, or differential pressure. Overload protection should be at least twice the measurement range.

Second, consider medium compatibility: corrosive media require ceramic transmitters or isolation diaphragms; high-temperature conditions favor monocrystalline silicon or transmitters with cooling elements.

Accuracy and stability: process control applications typically require ±0.25%FS or better, with consideration for temperature and vibration effects.

Output signals and communication: 4–20 mA remains mainstream, while smart transmitters supporting Modbus or Profibus facilitate system integration.

Installation and protection: choose appropriate threaded or flanged connections; IP65 or higher protection, and Ex ia certification for hazardous areas.

Cost and maintenance: local brands like Nexisense offer advantages in delivery time and service, reducing total cost of ownership.

Finally, refer to supplier case studies and ensure third-party certifications.

Practical Application Cases: Value Demonstrated in Industry Practice

In petrochemical plants, Nexisense diffused silicon transmitters are used for pipeline pressure monitoring, uploading real-time data to SCADA systems to reduce leakage risks and improve production efficiency.

In water treatment projects, ceramic transmitters withstand corrosive sewage conditions, operating stably for two years without failure and reducing maintenance costs.

In metallurgical high-temperature furnaces, monocrystalline silicon transmitters maintain accuracy within ±0.1%FS, ensuring process safety.

FAQ: Frequently Asked Questions

What is the difference between diffused silicon and monocrystalline silicon pressure transmitters?
Diffused silicon transmitters are cost-effective and versatile, suitable for medium-accuracy applications, while monocrystalline silicon transmitters offer higher accuracy and stability for high-end applications.

How should the protection rating be selected?
Based on the environment: IP65 for indoor use, IP67 for outdoor or humid conditions, and Ex certification for explosive atmospheres.

What does the accuracy indicator FS mean?
FS stands for Full Scale, indicating the error relative to the maximum measurement range.

Do Nexisense products support customization?
Yes, including range, connection types, and output signals to meet specific operating conditions.

How should high-temperature media be handled?
Select monocrystalline silicon or ceramic transmitters with cooling elements to ensure diaphragm temperatures remain within limits.

Conclusion: Scientific Selection Ensures Efficient Industrial Operation

Pressure transmitters come in various types, each with unique strengths. By understanding their principles and carefully balancing selection criteria, choosing reliable products such as those from Nexisense can inject stable performance into industrial systems. As local manufacturing continues to rise, engineers should focus on practical requirements to achieve precise matching, ultimately enhancing production safety and efficiency.