Introdunoitcuction

Pressure sensors are highly useful devices that measure the physical pressure of gases or liquids through a sensor and output a signal. Pressure is defined as the force needed to stop a fluid from expanding, typically presented as force per unit area. These sensors are employed to control and monitor a wide array of everyday applications, including indirect measurements of gas/fluid flow, speed, altitude, and water levels. Due to their diverse applications, they vary significantly in technology, design, performance, stability, and cost. This article will explore the different types of pressure sensors, explain their working principles, and review common applications that utilize them.

What Is A Pressure Sensor?

Th.edutiere are several terms often used interchangeably to describe pressure sensors, such as pressure transducers, pressure transmitters, and pressure indicators. Regardless of the term, they all measure pressure and produce an output signal. Pressure is the force (exerted by a gas or liquid) applied to a unit of “area”. Pressure sensors enable more specialized maintenance strategies as they operate on real - time data, allowing for the prediction and preparation for risk failures. When a pressure sensor is installed in an application, maintenance teams are alerted when necessary, enabling them to address issues immediately. The most commonly used pressure sensors are transducers (piezoelectric and strain gauge), which are applied in applications to monitor flow, airspeed, level, pump systems, or altitude.

Pressure Sensor Terminology

Before delving into the different types of pressure sensors, it's essential to understand some key terminology:

  • Gauge Pressure: The measurement of pressure relative to ambient pressure.
  • Absolute Pressure: The measurement relative to a pure vacuum of space, crucial for measuring altitude pressure changes.
  • Differential Pressure: The pressure difference between two applied pressure values.
  • Vacuum Pressure: The pressure measurement less than the surrounding atmospheric pressure.

How Do Pressure Sensors Work?

All pressure sensors operate on the same basic principle of measuring a physical change in pressure differences. Once the sensor detects a physical change, the information is converted into an electrical signal and displayed as usable data for the user. The working process can be broken down into four steps:

  1. The apparatus that allows expansions and contractions converts pressure into voltages or electrical signals.
  2. The electrical signals produced by the pressure sensor are measured and recorded.
  3. The CMMS (Computerized Maintenance Management System) receives the electrical signal from the pressure sensor in real - time.
  4. The CMMS alerts maintenance teams when the pressure is too high or too low. High pressure ratings often indicate rupturing risks, while a loss of pressure may indicate leakage.

The Difference Between Transducers, Transmitters, And Sensors

It's important to distinguish between pressure sensors, transducers, and transmitters, despite their often being used interchangeably.

  • Pressure Sensors: A “true” pressure sensor operates based on a physical reaction. The sensor module inside produces an output voltage. Calibration, amplification, and temperature compensation are necessary to ensure reliable and stable results.
  • Pressure Transducers: Similar to pressure sensors, they produce an output voltage due to a physical reaction in the sensing element. However, they can handle signal conditioning, enabling transmission over longer distances.
  • Pressure Transmitters: These work similarly to pressure transducers but output a current signal across a low - impedance load instead of a voltage reading.

Seven Types Of Pressure Sensors

Pressure sensors are designed and classified according to the configuration used to sense pressure changes:

  1. Aneroid Barometer Pressure Sensors: These are purely mechanical devices for measuring pressure. They consist of a hollow, airtight metal casing with a flexible surface like a capsule. Atmospheric changes cause the capsule to compress and expand, and the deformation is measured and translated into a pressure reading on a dial. They are compact and durable, commonly used in aircraft and environmental applications to measure atmospheric pressure. However, the mass of the pressure - sensing elements limits the response rate, making them less effective for dynamic pressure sensing.
  2. Manometer Pressure Sensors: These are glass tube, fluid - type pressure sensors with a simple design. They measure the pressure difference between two surfaces by the movement of liquid in a tube. The most common type is U - shaped. When pressure is applied to one side, the liquid level changes at both ends, and the height difference indicates the pressure. They are used for calibrating equipment in laboratory applications but have a slow response rate and limited pressure range.
  3. Bourdon Tube Pressure Sensors: Functioning on a similar principle as aneroid barometers, they have a helical or C - shaped sensing element. One end of the tube is closed, and the other is exposed to the measured environment. As pressure increases, the tube straightens until the fluid pressure matches its elastic resistance. The physical motion of the coil moves a pointer on a dial to display the pressure. They are commonly used as gauge and differential sensors due to their simplicity, toughness, and low cost. However, they are susceptible to shock and vibration and are not suitable for low - pressure applications requiring high precision.
  4. Vacuum Pressure Sensors: When mechanical methods become complex at low pressures, vacuum pressure sensors are used. The Pirani sensor is the most common for measuring low - vacuum pressure ranges. It measures the resistance of a heated sensor filament (usually made of thin tungsten, nickel, or platinum wire) in the gauge chamber. As the chamber is exposed to vacuum pressure, gas molecules collide with the filament, transferring heat. The resistance change is calibrated to obtain the pressure reading. At low pressures, thermal conductivity is low; at high pressures, it is high.
  5. Sealed Pressure Sensors: These are used to measure atmospheric pressure at sea level on submersible vehicles to determine depth. The sealed chamber maintains a constant air pressure, which serves as the internal reference pressure.
  6. Piezoelectric Pressure Sensors: They generate an electric charge in response to physical changes in the material. The charge is directly proportional to the applied force. The sensor measures and calibrates the changes in the electrical charge to display the pressure. They have high frequency and rapid response times and are small, making them suitable for applications with space constraints, such as engine combustion applications.
  7. Strain Gauge Pressure Sensors: These sensors use the proportional expansion or contraction of a spring element to measure pressure. When a force is applied, the spring deforms, causing the resistance to change. The voltage readings are recorded as electrical signals and converted into pressure readings. They are used for long - term monitoring tasks, such as measuring residual stress in vehicles, ship hulls, dams, and oil drilling platforms.

Pressure Sensor Considerations

When choosing a pressure sensor, consider the following:

  • Sensor type
  • Operating pressure range and maximum pressure
  • Onboarding times
  • Process conditions of the application
  • Output type
  • Output level
  • Accuracy
  • Resolution
  • Drift
  • Supply voltage
  • Operating temperature range

Pressure Sensor Applications

Pressure sensors have a wide range of applications:

  • Pipeline Hoses: They ensure that hoses in gas pipelines and wire - braided hydraulic hoses do not exceed their pressure limits.
  • Vacuum Technology: Used in composite molding production, flight instrument manufacturing, medical applications, and semiconductor processing to measure low - vacuum pressure.
  • Environmental Applications: Employed in emission testing, wind management, and pollution devices.
  • Manufacturing Processes: Detect anomalies in hydraulic and pneumatic systems, such as leaks or compression issues.
  • Automotive Industry: Used in brake systems to detect faults and in engines to prevent oil pressure from exceeding recommended levels.
  • Medical Equipment: Critical in ventilators, hyperbaric chambers, and spirometry equipment for measuring pressure.
  • HVAC Systems: Measure the condition of air filters and monitor airflow speed in radiators and air - conditioning units.
  • Industrial Applications: Detect clogged filters by assessing the pressure difference between influent and effluent.

Summary

Pressure is the force exerted by a gas or liquid on a unit area. Pressure sensors help maintenance teams identify risks before failures occur. There are seven types of pressure sensors, with piezoelectric and strain gauge sensors being the most commonly used. If you have questions about pressure sensors or need help choosing the right one for your testing needs, contact our team at Sensorlist.

FAQs

  • Q: What is the most accurate type of pressure sensor?A: The accuracy depends on the application. For high - pressure applications, bourdon tube pressure sensors can provide high accuracy. For dynamic pressure measurements, piezoelectric pressure sensors are often a good choice.
  • Q: Can pressure sensors be used in harsh environments?A: Some pressure sensors, like sealed pressure sensors and certain types of strain gauge sensors, can be designed to withstand harsh environments. However, it's important to consider factors such as temperature, humidity, and vibration.
  • Q: How often should pressure sensors be calibrated?A: The calibration frequency depends on the application and the sensor's specifications. In general, it's recommended to calibrate pressure sensors regularly, typically annually or as specified by the manufacturer.