Pirani vacuum sensors

Vacuum Sensors – Function and applications

Vacuum sensors are intriguing devices that measure the pressure below atmospheric levels, essentially quantifying the absence of air. In simpler terms, while a pressure sensor measures the pressure above atmospheric levels, a vacuum sensor does the opposite. One of the renowned names in this field is Posifa, whose vacuum sensors are designed specifically for high vacuum applications. They operate based on the thermal “Pirani” principle.

Applications of Vacuum Sensors

Vacuum sensors have a wide range of applications, including:

• Freeze dryers (Lyophilizers): These devices are used to preserve perishable materials by freezing them and then reducing the surrounding pressure to allow the frozen water to sublimate directly from the solid phase to the gas phase.
• Measurement and calibration equipment: Ensuring the accuracy of measurements in various scientific and industrial applications often requires the creation of a vacuum.
• Spacecraft in orbit: The vacuum of space is not perfect. Sensors help monitor and maintain the internal pressures of spacecraft.
• High vacuum chemical/physical processes: Many scientific experiments and industrial processes require high vacuum conditions to proceed without interference from air molecules.

Detection process of a Vacuum Sensor

At their core, vacuum sensors function similarly to other thermal sensors. They consist of a silicon chip embedded with a heating element and a thermopile. The heat from the heating element is transferred to the surrounding air. As the vacuum level increases, air is removed. With less air, there are fewer molecules to transfer heat, similar to how sound requires a medium to travel. When there’s no air left, no heat can be transferred, causing the thermopile to cool down. This change in temperature results in a change in resistance, which the sensor measures and interprets as a vacuum level.

Vacuum Sensors from Posifa Technologies

Posifa Technologies has brought about a significant revolution in vacuum measurement based on the Pirani principle. Traditionally, this principle involved the cooling of a thermistor. However, Posifa has transitioned from this conventional method to MEMS semiconductor technology. This change means that the heat transport from the heating element used in the silicon chip to the thermopile is now considerably smaller and more cost-effective.

With this innovation, Posifa achieves vacuum measurements up to 10E-4 Torr. Users can choose from various housing designs, such as PVC3001 in TO5 or SMD housing with access to the heating element and thermopile. The compact design of PVC4001 allows it to be seamlessly integrated into any vacuum application. The output signal from these sensors is compensated, with the PVC4101 model also being calibrated. The PVC4101 sensor is housed within the PVC5116, which comes in a stainless-steel casing with a KF16 connection. This design ensures an end-user-friendly version is available. As a vacuum gauge, the PVC6116 offers direct alternatives to models like the PGS500, TTR91, APG100-XM, APG100-XLV, and 925.

Vacuum Sensors – BS-rep is your partner!

• Technical edge: Our patented product design gives us a technical advantage over competitors.
• Experienced technical support: With over 30 years of experience in pressure and airflow measurement, we provide unparalleled technical support.
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• Inventory and delivery: Our stockholding practices and delivery times are notably shorter than competitors.
• Competitive offerings: We offer better prices, delivery times, and extended contract durations (18 months instead of the typical 12).

FAQ

Vacuum sensors, like other sensors, require periodic calibration to ensure accuracy. However, due to their specific function of measuring the absence of air, they might be less susceptible to contaminants than some other sensors. Still, it’s essential to keep them clean and free from dust or debris. The lifespan of a vacuum sensor varies based on its usage and the conditions of its environment, but with proper care, they can last for several years.

Vacuum sensors, like many electronic devices, can be susceptible to EMI. Electromagnetic interference can distort the readings of a vacuum sensor, leading to inaccurate results. It’s crucial to install vacuum sensors away from strong electromagnetic sources and, if possible, use shielding techniques or EMI filters to minimize interference. Always refer to the manufacturer’s guidelines regarding EMI precautions.

The frequency of calibration for a vacuum sensor largely depends on its usage and the critical nature of its application. For high-precision tasks or industries where even a slight deviation can have significant consequences, calibration might be required more frequently, perhaps every few months. For less critical applications, annual calibration might suffice. However, it’s always a good practice to monitor the sensor’s performance and calibrate it whenever discrepancies are noticed.

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