How Should Pressure Sensors Be Classified by Measurement Function

— A Systematic Analysis from Operating Conditions to Load Characteristics

I. The Role of Pressure Sensors in Industrial Measurement

Pressure sensors (Pressure Transducers) are among the most frequently used and widely applied sensors in industrial automation systems. Their core function is to convert the pressure signals of gases or liquids into electrical signals that can be used for acquisition, transmission, and control according to established physical laws.

In practical engineering applications, different process conditions impose very different requirements on pressure measurement, such as high temperature, high pressure, explosion-proof, waterproof, strong impact, or sanitary and clean environments. Therefore, selecting a sensor based solely on range or output type is far from sufficient. Classifying pressure sensors by measurement function has become a more instructive approach in engineering practice.

II. Types of Pressure Sensors Classified by Measurement Function

1. High-Temperature Pressure Sensors

High-temperature pressure sensors are mainly used in operating environments where the temperature of the measured medium is relatively high.

Typical medium temperature range: -40 to 150°C
Upper temperature limit of ordinary pressure sensors: typically -40 to 85°C

High-temperature products effectively reduce the impact of temperature drift on measurement accuracy through special thermal isolation structures, high-temperature-resistant sensing elements, and compensation algorithm design. They are suitable for:

• Steam pipelines

• High-temperature oil circuit systems

• Chemical reaction equipment

• Thermal energy and metallurgical industries

2. Explosion-Proof Pressure Sensors

Explosion-proof pressure sensors are used in hazardous locations where flammable or explosive gases or dust are present.

Their core feature is intrinsic safety or flameproof design, allowing safe application in:

• Zone 0 explosive gas environments

• Zone 1 and Zone 2 hazardous areas

Common applications include:

• Petrochemical installations

• Natural gas transmission and distribution systems

• Oil and gas storage, transportation, and refueling stations

• Coal chemical and energy industries

While meeting measurement accuracy requirements, explosion-proof pressure sensors place greater emphasis on electrical safety and system reliability.

3. Waterproof Pressure Sensors

Waterproof pressure sensors usually have an IP68 protection rating, which is one of the highest waterproof standards for industrial sensors.

Key features include:

• Fully sealed structure

• Capability for long-term immersion in liquids

• Flexible installation methods

Typical application scenarios:

• Level measurement

• Underground pipeline monitoring

• Water conservancy and water utility projects

• Wastewater treatment systems

In humid, submerged, or outdoor environments, waterproof performance directly determines the service life and stability of the sensor.

4. Shock-Resistant Pressure Sensors

Shock-resistant pressure sensors are specifically designed for operating conditions with severe pressure fluctuations and frequent mechanical impacts.

Key characteristics include:

• Resistance to strong vibration

• Resistance to frequent high-pressure impacts

• Resistance to sand and particulate erosion

• High wear resistance

Common application industries:

• Oil extraction

• Construction machinery

• Building engineering

• Cement grouting and injection equipment

In these scenarios, the mechanical strength of the sensor is often more important than ultimate measurement accuracy.

5. Sanitary Pressure Sensors

Sanitary pressure sensors are mainly used in the food, pharmaceutical, and medical industries.

Their core advantages include:

• Use of 316L or 316K stainless steel materials

• Dead-angle-free structural design

• Easy cleaning and sterilization

• Compliance with hygienic process requirements

Typical applications include:

• Food processing production lines

• Pharmaceutical process equipment

• Medical gas systems

• Bioengineering installations

In these industries, sensors are not only measurement components but also critical elements of process compliance.

6. Hammer Union Pressure Sensors

Hammer union pressure sensors are specialized products designed for extreme operating conditions.

Structural characteristics include:

• High-strength measuring diaphragms

• Special mechanical force transmission structures

• Compact and robust encapsulation processes

They offer the following performance advantages:

• Vibration resistance

• Resistance to high-frequency, high-pressure impacts

• Resistance to sand and gravel erosion

• Adaptability to various harsh environments

Typical application fields:

• Cement grouting

• Hydraulic fracturing

• Borehole reinforcement

• Geotechnical engineering

III. Analysis of Pressure Sensor Load Characteristics

What Are Load Characteristics

In an ideal state, a pressure sensor should only “sense” the measured pressure without affecting the system. However, in actual measurements, the integration of a sensor will:

• Absorb energy from the measured system

• Introduce electrical or mechanical interference

As a result, the measured pressure deviates from the true value. This phenomenon is known as load characteristics or the load effect.

Load characteristics are not installation errors but inherent properties of sensors, and their impact can only be minimized through proper design and selection.

Current Output Load Characteristics

Current output is the most common form in industrial applications, with 4–20mA being the typical representative.

Its advantages include:

• Strong anti-interference capability

• Suitability for long-distance transmission

• Relatively controllable load influence

The common load relationship is:

Current load of pressure sensor ≤ {(Us − 7.5) ÷ 0.02} Ω

Where:
Us is the supply voltage.

Voltage Output Load Characteristics

Common voltage output forms include 0–5V and 0–10V.

Characteristics:

• Simple wiring

• Lower cost

• Higher sensitivity to load impedance

General requirement:

Voltage load of pressure sensor ≥ 100 kΩ

If the load impedance is insufficient, measurement errors or even signal distortion may occur.

IV. Comprehensive Considerations in Engineering Selection

In practical applications, pressure sensor selection should not focus on a single parameter, but should comprehensively consider:

• Measurement function and operating environment

• Temperature, humidity, vibration, and corrosion factors

• Output signal type and load conditions

• System integration and maintenance convenience

Only through a combined analysis of functional classification and load characteristics can stable, reliable, and long-term pressure measurement be achieved.

Conclusion

Pressure sensors can be classified by measurement function into high-temperature, explosion-proof, waterproof, shock-resistant, sanitary, and hammer union types. Each type is structurally and performance-optimized for specific operating conditions. At the same time, load characteristics, as an important technical attribute of pressure sensors, directly affect measurement accuracy and system stability.

Against the backdrop of continuous industrial automation upgrades, a scientific understanding of pressure sensor functional classification and load characteristics is the foundation for achieving accurate measurement and reliable control. Nexisense always takes engineering applications as its orientation, providing more adaptable pressure measurement solutions for various industries.