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Explore Pressure Measurement Devices: Principles, Advantages & Drawbacks

In modern industrial and scientific fields, pressure measurement is crucial for monitoring fluid media, vital in petrochemicals, aerospace, energy, environmental monitoring, and medical devices. As technology advances, pressure sensors like strain gauge, Bourdon tube, electrical contact, capacitive sensors, and U-tube manometers have emerged, each with unique principles and applications. 
 
Strain Gauge Pressure Sensor
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Pressure Measurement Devices

Strain gauge pressure sensors are widely used for measuring larger pressures and play significant roles in various fields, such as measuring internal pipeline pressures, gas pressures in internal combustion engines, differential pressures, injection pressures, pulsating pressures in engine and missile tests, and fluid pressures in various scenarios.

Features:

The most commonly used type is the bonded strain gauge (i.e., strain gage). However, it has some drawbacks, such as small output signals, narrow linear range, and poor dynamic response. Nevertheless, strain gauges are compact, with multiple specifications commercially available, allowing flexible design of elastic sensitive elements to suit different applications.
 
Bourdon Tube Pressure Gauges
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The working principle of a bourdon tube pressure gauge involves an elliptical bourdon tube made of phosphor bronze installed inside the case. One end is fixed and connected to a siphon pipe, while the other end is sealed and connected to a linkage and lever, with the pointer fixed on the pinion shaft. When pressurized, the tube expands from an elliptical shape to a circular one, forcing the bourdon tube to extend outward, with greater pressure causing more extension.Pressure Measurement Devices

Features:
 
Bourdon tube pressure gauges feature simple structure, low cost, high accuracy, portability, ease of installation and use, and a wide pressure measurement range, making them widely applied. They primarily consist of components including the case, bourdon tube, fixed end, rod, sector gear, pinion, pointer, hairspring, and tube fitting.
 
Electrical Contact Pressure Gauge
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The operation of an electrical contact pressure gauge relies on the bourdon tube within the measurement system. Under the effect of the measured medium’s pressure, the bourdon tube’s free end undergoes corresponding elastic deformation—displacement. This displacement is transmitted and amplified through a gear mechanism by a rod, with the indicator (along with contacts) on the fixed gear showing the measured value on the dial. 

Features:
 
In the electrical contact pressure gauge, an adjustable permanent magnet is installed on the electrical contact signal needle, enhancing contact attraction, accelerating contact action, ensuring reliable contact, eliminating electric arcs, and effectively preventing frequent disconnections caused by vibration or pressure pulsations in the working environment or medium. Thus, the electrical contact pressure gauge offers reliable operation, long service life, and higher contact switch power.
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Capacitive pressure sensors typically use a circular metallic film or metal-coated film as one electrode of the capacitor. When the film deforms under pressure, the capacitance between the film and the fixed electrode changes, and this change can be converted into an electrical signal related to pressure through a measuring circuit. Capacitive pressure sensors belong to the variable gap type and can be divided into single-capacitance and differential-capacitance pressure sensors.
 
U-Tube Manometers
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The principle of a U-tube manometer is that before connecting to the pressure measurement point, the liquid levels on both sides of the U-tube are at the zero mark. Upon connection to the measurement point, the liquid levels within the U-tube change. If the liquid level on the side connected to the measurement point drops, it indicates positive pressure; conversely, it indicates negative pressure.

Features:
 
U-tube manometers are simple, robust, inexpensive, and long-lasting, virtually permanent if not externally damaged. They offer convenient reading, reliable data, and require no external power source, thus consuming no energy. Consequently, they find extensive application in industrial production and research processes.

Inclusion

Various pressure measurement devices, including strain gauge sensors, Bourdon tube gauges, electrical contact instruments, capacitive sensors, and U-tube manometers, each offer unique advantages such as adaptability, durability, precision control, sensitivity, and zero-energy operation. Together, they form a complementary technical ecosystem essential for modern industrial systems.

Driven by the need for intelligence, miniaturization, and high precision, pressure sensor advancements now focus on integration (e.g., MEMS), multifunctionality (e.g., temperature compensation, wireless transmission), and resilience in extreme environments (e.g., high temperatures, corrosive media). These innovations enhance industrial automation and provide critical data support for emerging fields like smart manufacturing and smart cities.

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