What is A Pressure Gauge?
A pressure gauge is an instrument used to measure the pressure of fluids, including liquids and gases. It consists of several key components:
- A pressure sensor or sensing element (e.g., Bourdon tube, diaphragm, or capacitive sensor) that deforms or changes its electrical properties in response to the applied pressure.
- A mechanism to convert the sensor’s deformation or electrical change into a readable display, such as a pointer or digital readout.
- A housing or casing that protects the internal components and provides a connection point to the pressure source.
How Does A Pressure Gauge Work?
A pressure gauge measures the pressure of gases or liquids by detecting the amount of force applied to an elastic sensing element. The most common sensing elements are:
- Bourdon tube: A flattened, curved tube that straightens out as pressure increases
- Diaphragm: A thin, flexible membrane that deforms under pressure
- Bellows: An accordion-like capsule that expands or contracts with pressure changes
The deflection of these sensing elements is converted into a rotary motion through mechanical linkages and gears, which drives a pointer to indicate the pressure on a calibrated dial.
Types of Pressure Gauges
Liquid Column Pressure Gauges
These gauges measure pressure by the difference in liquid levels between two vertical tubes. Examples include:
- U-tube manometers using mercury or other liquids
- Well-type manometers with a large reservoir and narrow tube
Elastic Element Pressure Gauges
These gauges use the deformation of an elastic element (bourdon tube, diaphragm, bellows) to measure pressure. Common types are:
- Bourdon tube gauges using a curved, flattened tube
- Diaphragm gauges with a flexible diaphragm and mechanical linkage
- Bellows gauges with an expandable bellows element
Electrical Pressure Gauges
These gauges convert pressure into an electrical signal for measurement:
- Capacitive gauges using a pressure-sensitive capacitor
- Piezoresistive gauges using strain gauges on a diaphragm
- Piezoelectric gauges using the piezoelectric effect
Specialty Vacuum Gauges
For measuring very low pressures, specialized gauges are used:
- Thermal conductivity gauges (Pirani)
- Ionization gauges measuring gas ionization
- Spinning rotor gauges (molecular drag)
Portable and Digital Gauges
Modern pressure gauges offer portability and digital features:
- Portable gauges with graphing/data logging capabilities
- Gauges with digital displays and setpoint alarms
- Wireless connectivity for remote monitoring
Applications of Pressure Gauge
Pressure Measurement and Monitoring
Pressure gauges are widely used for measuring and monitoring pressure in various industrial and commercial applications. They are essential for monitoring process media, weather instrumentation, aircraft systems, security systems, sleep monitors, automobiles, and machinery with pressure functionality. Pressure gauges provide real-time pressure readings, enabling users to monitor and control processes effectively.
Altitude and Navigation
Pressure gauges, particularly barometric pressure sensors, are crucial for altitude measurement in aircraft, rockets, satellites, and weather balloons. They leverage the relationship between pressure changes and altitude, offering altitude resolution better than GPS systems (about 20 meters). In navigation applications, altimeters using pressure sensors distinguish between stacked road levels for car navigation and floor levels in buildings for pedestrian navigation.
Flow Measurement
Pressure sensors are used in conjunction with the venturi effect to measure fluid flow rates. Differential pressure is measured between two segments of a venturi tube with different apertures, and the pressure difference is directly proportional to the flow rate. Low-pressure sensors are typically required due to the relatively small pressure differences involved.
Fluid Level Measurement
Pressure sensors can calculate the level of a fluid, such as the depth of a submerged body (e.g., divers or submarines) or the level of contents in a tank (e.g., water towers or liquid storage facilities). This technique relies on the direct proportionality between fluid level and pressure.
Leak Detection
Pressure sensors can detect system leaks by measuring pressure decay over time. This can be done by comparing the pressure readings to a known leak using differential pressure or by monitoring the pressure change rate.
Emerging Applications
There is a growing demand for high-quality, sensitive, and inexpensive pressure sensing elements and systems to enable a wide range of technical and commercial applications. Recent innovations include pressure gauges with adjustable indication intervals, external pressure range indicators, and electroluminescent pressure gauges for improved visibility and user experience.
Application Cases
| Product/Project | Technical Outcomes | Application Scenarios |
|---|---|---|
| Pressure Transmitter for Industrial Processes | Utilising advanced sensor technology and digital signal processing, these transmitters offer high accuracy (±0.075% of span) and long-term stability for precise pressure monitoring in harsh environments. | Critical process monitoring and control in industries like oil & gas, chemical, power generation, and manufacturing. |
| Automotive Tyre Pressure Monitoring System (TPMS) | Employing robust and compact pressure sensors, TPMS accurately measures tyre pressures and alerts drivers to underinflation, improving fuel efficiency by up to 3.3% and extending tyre life. | Enhancing vehicle safety and optimising fuel economy in passenger cars, trucks, and other automotive applications. |
| Downhole Pressure Gauges for Oil & Gas Exploration | Leveraging high-temperature and high-pressure resistant materials, these gauges reliably measure and record formation pressures at depths exceeding 30,000 feet, enabling accurate reservoir characterisation. | Exploration and production activities in harsh downhole environments, facilitating well planning, drilling optimisation, and reservoir management. |
| Biomedical Pressure Monitoring Devices | Integrating miniaturised and biocompatible pressure sensors, these devices enable continuous and non-invasive monitoring of blood pressure, intracranial pressure, and other vital signs with high precision. | Critical care units, surgical suites, and home healthcare settings for monitoring patient health and guiding treatment decisions. |
| Aerospace Pressure Sensors | Utilising advanced materials and ruggedised designs, these sensors accurately measure pressure differentials in extreme conditions, enabling precise altitude determination and airspeed monitoring. | Aircraft, spacecraft, and satellite systems, ensuring safe and efficient operation through reliable pressure data acquisition. |
Latest Technical Innovations of Pressure Gauge
Improved Accuracy and Reliability
- Novel membrane designs and fabrication methods to enhance resonance modes and eliminate undesired structures, improving accuracy and repeatability.
- Friction/squeeze-film pressure transducers with better accuracy, repeatability, reliability, and measurement range compared to existing transducers.
- Capacitive pressure gauges using lead iron tungstate as a capacitive element, demonstrating accuracy better than 1 x 10^-3 over 418 MPa range, enabling use as a reliable transfer pressure standard.
Pressure Magnification and Sensitivity
- Pneumatic pressure magnifying gauges that amplify small pressure differences acting on corrugated diaphragms to larger differences on metallic bellows, allowing measurement of minute pressures with high sensitivity (< 0.01 mm Aq).
- Novel pressure sensor architectures with diaphragms integrally linked to supporting walls and strategically placed sensing elements at high-stress locations, achieving high sensitivity and bandwidth.
Dynamic and High Pressure Measurement
- High-pressure dynamic micro differential pressure gauges capable of real-time monitoring of minute differential pressures under extremely high pressures, enabling improved study of oil/gas well performance.
- Resonant gauge pressure sensors with double-ended tuning fork resonators and composite diaphragm structures involving vacuum packaging, reducing atmospheric pressure influence for high accuracy gauge pressure sensing up to 2.5 MPa with <0.01% FS non-linearity.
Intelligent Control and Monitoring
- Electronic pressure gauges with automatic operating mode adjustment based on predefined pressure thresholds and chronological operating statuses, enabling adaptive information display and optimized monitoring throughout the container’s lifecycle.
- Gauges with digital displays, audible indicators, and printed circuit boards interfaced with pressure sensors, allowing easy real-time monitoring and access to pressure levels for improved operational reliability.
Novel Sensing Principles
- Portable pressure gauges based on DC glow discharge plasma at low pressures, offering real-time, inexpensive, robust, and precise measurement from -50°C to 400°C and 5 to 500 Pa, independent of the mounting height.
- Non-contact diaphragm pressure gauges with small pressure bearing areas, enabling high pressure (up to 1000 kg/cm^2) measurement without direct medium contact, preventing corrosion and reducing cost.
Technical Challenges
| Improving Accuracy and Reliability | Developing novel membrane designs and fabrication methods to enhance resonance modes and eliminate undesired structures, improving accuracy and repeatability of pressure gauges. |
| Pressure Magnification and Sensitivity | Designing pneumatic pressure magnifying gauges that amplify small pressure differences acting on corrugated diaphragms to larger differences on metallic bellows, allowing measurement of minute pressures with high sensitivity. |
| Dynamic and High Pressure Measurement | Developing high pressure dynamic micro differential pressure gauges capable of bearing very high environmental pressures, satisfying the measurement accuracy requirement of micro differential pressures, and achieving real-time monitoring of dynamic micro differential pressures under high pressures. |
| Intelligent Pressure Monitoring | Developing intelligent pressure gauges with automatic modification of operating modes and information transmission based on predefined operating statuses, enabling closed-loop chronological monitoring of pressure inside containers throughout the entire cycle. |
| Novel Sensor Architectures | Designing novel pressure sensor architectures with diaphragms integrally linked to supporting walls and strategically placed sensing elements at high stress locations, achieving high sensitivity and bandwidth. |
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