Different types of sensors are available, each with a specific working mechanism. One popular type among those is the vacuum pressure sensor. These sensors detect the pressure in a vacuum environment. The vacuum pressure sensor working principle is something that makes it unique compared to other types of sensors.
The usage of vacuum pressure sensors is common in laboratories and high-end machinery. So, laypeople are less familiar with them. In this article, we will discuss everything about vacuum pressure sensors. You’ll learn about what they are and how they work. So, let’s begin!
What are Vacuum Pressure Sensors?
Before discussing the working principle, let’s first look at the basics of vacuum pressure sensors.
These sensors are small electronic devices used to measure the pressure inside the vacuum. They do this by comparing the pressure of the vacuum system with atmospheric pressure. They are used in systems where operators need to create a vacuum (low pressure) for specific purposes.
A prime example of vacuum sensor usage is in the brake booster system. In this system, a vacuum must be maintained. If pressure is present, the brakes won’t work effectively. So these systems come with dedicated vacuum pressure sensors.
These sensors detect the pressure inside the system. If they detect some pressure, they send an electrical signal to the car. In this way, drivers understand that the brake efficiency has reduced. The driver takes the vehicle to the mechanic, fixes the issue, and removes the pressure from the system. There are different types of vacuum pressure sensors.
The working mechanism of each sensor is unique. Here is the list:
- Pirani Vacuum Sensor
- Tuning Fork Vacuum Sensor
- Piezoelectric Vacuum Sensor
- Strain Gauge Vacuum Sensor
- Electromagnetic Vacuum Sensor
- Capacitive Vacuum Pressure Sensor
- Hot Cathode Ionization Vacuum Sensor
- Piezoresistive Vacuum Pressure Sensor
- Cold Cathode Ionization Vacuum Sensor
Interestingly, the working principles of each type of vacuum pressure sensor differ. For example, the Pirani vacuum sensor operates based on thermal conductivity. On the other hand, capacitive vacuum pressure sensors detect changes in capacitance. Remember that capacitive and piezoresistive vacuum pressure sensors are most common in different industries.
Parts & Components of Vacuum Pressure Sensors
The vacuum pressure sensors appear to be simple devices. However, they are not as they consist of various parts and components. Those parts work together to ensure the proper functionality of these pressure sensors. Here is a table showing the components of vacuum pressure sensors and their role.
| Component | Function |
| Diaphragm. | Bends with pressure |
| Sensing Element | Detects diaphragm movement |
| Electrodes (Capacitive) | Measure capacitance change |
| Strain Gauges (Piezoresistive) | Measure resistance change |
| Signal Conditioning Circuit | Amplifies and processes signal |
| Output Interface. | Sends readable signal (e.g. voltage) |
| Housing/Enclosure. | Protects internal parts |
Working Principle of Vacuum Pressure Sensors
As I mentioned earlier, each type of vacuum pressure sensor operates differently from the others. However, most pressure vacuum sensors use a diaphragm to detect the pressure of the evacuated system. Their working principle is as follows:
These sensors work by comparing the pressure inside the system with atmospheric pressure. The sensor detects pressure differences when the system pressure falls below atmospheric pressure. This pressure difference causes the sensing element, such as a diaphragm, to respond.
This enables the sensor to determine the exact vacuum pressure level present in the system. Remember, when pressure drops below atmospheric pressure, the sensing element (membrane) bends. This bending of the membrane is crucial as it helps us know the pressure inside the vacuum.
The special material, i.e., piezoresistive element, remains attached to this membrane. When a membrane bends, the electrical resistance in the piezoresistive element changes. This change is converted into electrical data. After processing this data, the exact pressure reading is displayed on the control system’s screen.
Step-by-Step Working Process of Vacuum Pressure Sensors
Here are the exact steps involved in measuring vacuum pressure using vacuum pressure sensors:
- The vacuum pressure sensor is first connected to the evacuated system.
- The membrane of the sensor (sensing element) remains inside the vacuum. The other side remains outside under atmospheric pressure.
- As the pressure inside the vacuum is low, this makes the membrane bend. If the pressure is very low, the membrane will bend more; conversely, if the pressure is high, the membrane will bend less.
- The extent to which a membrane bends is determined by the portion outside the system. As I said earlier, some membrane portions remain outside under atmospheric pressure. This outer part shows no deflection or changes. If the membrane inside and outside remain the same, it means both systems have the same atmospheric pressure.
- The piezoresistive element is present on the body of this membrane. When this membrane deflects, the electrical resistance of the piezoresistive element changes. This change is detected in the electrical signals.
- Different sensor types utilize the deflection of membranes in various ways. In capacitive sensors, the deflection of membranes causes a change in capacitance. This change is then recorded into the electrical signals.
- After that, the electrical signal undergoes further processing and amplification. Once done, the exact reading shows up on the screen of the control system.
Advantages & Applications of Vacuum Pressure Sensors
The use of vacuum pressure sensors is increasing in different industries. In the early days, this sensor type was only available in labs to maintain a controlled environment. However, things have changed as their usage has become more diverse and widespread. All the credit for their usability goes to the advantages that these sensors offer. Here are some of those:
- Top-notch accuracy and reliable pressure reading of the evacuated system
- The size of these sensors is small, making them easy to use in small spaces.
- These vacuum pressure sensors monitor real-time pressure inside the vacuum system.
- The price of these sensors is relatively low, making them an affordable option for everyone. Its ideal accuracy in pressure measuring is worth the value.
Here is a table showing the applications of vacuum pressure sensors in various industries.
| Industry | Devices Using Vacuum Pressure Sensors |
| HVAC & Refrigeration. | Refrigeration units and HVAC vacuum gauges |
| Automotive | Brake boosters, turbochargers, and EVAP leak detection systems |
| Medical & Healthcare | Autoclaves (sterilizers) and suction equipment |
| Semiconductor | Etching machines, vacuum deposition tools, lithography systems |
| Food Packaging. | Vacuum sealing machines, atmosphere packaging systems |
| Laboratory | Vacuum chambers, distillation units, freeze dryers |
| Pharmaceutical | Lyophilizers (freeze dryers), vacuum filtration units |
| Industrial Automation. | Robotic vacuum grippers, CNC vacuum tables, CNC milling machines. |
Conclusion
The vacuum pressure sensor offers many advantages. From automobiles to aerospace and pharmaceutical industries, they show their value. The most common and widely used vacuum pressure sensors come with sensing elements. This element deflects when subjected to pressure changes from the atmospheric level.
This deflection of the membrane changes the electrical resistance of the piezoresistive element. This change in resistance is measured in electrical signals. These signals, after processing, appear on the screen as digital numbers. Remember, there are different types of vacuum pressure sensors. The operation of each sensor can vary.