SIEMENS QBM3120-3D Differential Pressure Sensor 300 Pa with LCD Display
The SIEMENS QBM3120-3D is a high-accuracy differential pressure sensor designed for demanding HVAC and industrial applications. This sensor excels in measuring minute pressure differentials in air and non-aggressive gases, making it ideal for applications requiring precise control and monitoring of airflow. Its integrated LCD display provides immediate visual feedback on pressure readings, enhancing operational efficiency. With a measuring range of 0 to 300 Pascals and a robust 4-20 mA analog output signal, the QBM3120-3D offers reliable performance and seamless integration into various control systems. The device is also recognized for its maintenance-free operation and excellent long-term stability, ensuring consistent and dependable measurements over its lifespan.
Product Specifications
| Feature | Specification |
| :------------------ | :-------------------------------- |
| Manufacturer | Siemens |
| Model | QBM3120-3D |
| Measuring Range | 0–300 Pa |
| Analog Output | DC 4–20 mA |
| Operating Voltage | DC 8–33 V |
| Sensing Element | Pressure diaphragm |
| Response Time | < 20 ms |
| Pressure Connection | Connecting branch Ø 6.2 mm |
| Electrical Connection| Screw terminals |
| Medium Temperature | 0–70 °C |
| Max. Overpressure | 0.05 bar |
| Display | LCD |
| Degree of Protection| IP54 |
| Dimensions (W x H x D)| 101 x 86 x 49 mm |
| Characteristic Curve| Switchable: Pressure-linear or extracting-the-root |
Core Features & Market Positioning
The SIEMENS QBM3120-3D distinguishes itself through its high degree of measuring accuracy and the convenience of an integrated LCD display, offering immediate on-site visualization of differential pressure. This combination positions it as a premium choice for applications where precise airflow monitoring is critical. The sensor's ability to switch between a pressure-linear and an extracting-the-root characteristic curve adds significant flexibility, particularly for volume flow measurements where a non-linear relationship between pressure and flow exists. Its maintenance-free design, attributed to excellent long-term response, further solidifies its market standing by reducing operational overhead and ensuring reliable, long-term performance in demanding industrial environments. The unit is also CE and UL listed, underscoring its adherence to international safety and quality standards.
Key Application Scenarios
The SIEMENS QBM3120-3D is exceptionally well-suited for a range of critical applications within the HVAC and building automation sectors. Its primary use involves measuring the slightest differential pressures in ventilation and air conditioning ducts, ensuring optimal system performance and energy efficiency. This sensor is instrumental in monitoring air flows, checking filter status, and controlling fans to maintain desired environmental conditions. Furthermore, it finds application in pressure monitoring within laboratories, production facilities, and clean rooms where maintaining precise atmospheric conditions is paramount. For Variable Air Volume (VAV) systems, the QBM3120-3D accurately acquires variable air flow on both the supply and extract air sides, contributing to sophisticated climate control strategies.
Practical System Integration Guidance
Integrating the SIEMENS QBM3120-3D into existing systems is straightforward due to its standard DC 4-20 mA output signal and screw terminal connections. The sensor operates on a DC 8-33 V supply voltage, compatible with most standard control power supplies. For installation, it is crucial to mount the sensor correctly to prevent condensation buildup, which can damage the device. The pressure connection nipples should be oriented downwards and ideally positioned higher than the air duct probes to ensure proper drainage. The sensor supports both pressure-linear and extracting-the-root output characteristics, which can be selected via a DIP switch, allowing for direct integration with systems that require flow rate calculations. Zero-point adjustment is easily performed by pressing a button for over 2 seconds, with the LCD display confirming the zero-point calibration with "0 Pa". The included 2-meter PVC tubing simplifies the connection to air ducts.
Operation and Risk Mitigation
Operating the SIEMENS QBM3120-3D requires adherence to its specified operating parameters to ensure safety and longevity. The device is designed for air and non-aggressive gases only, with a maximum medium temperature of 70 °C and a maximum overpressure tolerance of 0.05 bar. To mitigate the risk of condensation-induced damage, mounting the sensor with pressure nipples facing downwards is essential, ensuring they are positioned higher than the duct probes. In case of horizontal mounting, value deviations can occur and may be compensated for using the zero-point adjustment feature. The sensor is maintenance-free, reducing the risk of operational failures due to wear and tear. Electrical connections should be made using copper wiring, and power supply should be SELV or Class 2 with a limited output of 15 W or less, as per UL requirements.
Scalability & Long-Term Value
The SIEMENS QBM3120-3D offers significant long-term value through its robust construction, maintenance-free operation, and inherent compatibility with modern industrial control platforms. Its standard 4-20 mA output makes it readily integrable with Programmable Logic Controllers (PLCs) and Building Management Systems (BMS), facilitating sophisticated automation and data logging. While direct IIoT integration specifics are not detailed in the provided data, the sensor's digital output and precise measurements provide a solid foundation for data acquisition systems that can feed into cloud-based analytics and Industrial Internet of Things (IIoT) platforms. The availability of comprehensive documentation, including datasheets and mounting instructions, ensures ongoing support and facilitates future system expansions or upgrades.
Frequently Asked Questions
What is the primary function of the SIEMENS QBM3120-3D?
The SIEMENS QBM3120-3D is a differential pressure sensor. It measures the pressure difference between two points, commonly used for air flow monitoring in HVAC systems.
Its main purpose is to provide accurate readings of air pressure variations. This data is critical for controlling ventilation systems and ensuring optimal indoor air quality. The sensor is designed for use with air and non-aggressive gases, offering high precision for demanding applications.
The device features an integrated LCD display for direct pressure readouts. It outputs a standard 4-20 mA signal, compatible with most control systems and data loggers for further analysis and automation.
What are the key technical specifications of the SIEMENS QBM3120-3D?
This sensor operates within a pressure range of 0 to 300 Pascals (Pa). It utilizes a DC operating voltage between 8 and 33 Volts.
The output signal is a 4-20 mA analog current loop. The response time is very quick, less than 20 milliseconds, ensuring real-time data.
It features an IP54 degree of protection, making it suitable for dusty environments. The operating temperature range is from 0 to 70 °C.
How is the SIEMENS QBM3120-3D installed and configured?
Installation involves mounting the sensor in the air duct and connecting pressure nipples using the provided PVC tubing. It's crucial to orient the nipples downwards and ensure they are higher than the air probes to prevent condensation.
Configuration options include selecting between a pressure-linear or extracting-the-root characteristic curve via a DIP switch. This allows for direct measurement of flow rates. The sensor also features a simple one-button zero-point adjustment for calibration.
Electrical connections are made via screw terminals, requiring a DC power supply within the specified voltage range. The 4-20 mA output can be directly wired to control panels or PLCs.
What applications is the SIEMENS QBM3120-3D best suited for?
This sensor is ideal for precise differential pressure measurements in HVAC systems. It is used for monitoring airflow in ducts and ensuring optimal air exchange rates.
It's also employed to monitor filter status, control fans, and manage air pressure in critical environments like clean rooms and laboratories. The sensor's accuracy makes it valuable for VAV systems to regulate supply and extract air volumes.
The ability to switch to an extracting-the-root characteristic makes it suitable for volume flow calculations. Its robust design ensures reliable performance in industrial settings as well.
What is the typical accuracy of the SIEMENS QBM3120-3D?
The SIEMENS QBM3120-3D offers a high degree of measuring accuracy. Specific accuracy figures are often detailed in the technical datasheets provided by Siemens.
Generally, differential pressure sensors of this caliber provide precise readings within a small tolerance range. This is critical for applications where even minor pressure fluctuations need to be detected and acted upon.
The sensor is calibrated and temperature-compensated, ensuring consistent and reliable measurements across its operating temperature range.
Can the SIEMENS QBM3120-3D measure volume flow?
Yes, the SIEMENS QBM3120-3D can be used to measure volume flow. This is achieved by utilizing its switchable extracting-the-root characteristic curve.
When this mode is activated, the sensor's output signal is adjusted to reflect the square root of the differential pressure. This aligns with the physical relationship between differential pressure and airflow velocity.
By selecting the appropriate characteristic curve, the sensor provides a signal that can be directly interpreted as volume flow in compatible control systems or data acquisition units.
What are the electrical connection requirements for the QBM3120-3D?
The sensor requires a DC operating voltage ranging from 8 to 33 Volts. It utilizes screw terminals for its electrical connections, facilitating secure and straightforward wiring.
The standard output signal is a 4-20 mA current loop. This current-based output is robust against electrical noise over longer cable runs compared to voltage signals.
For power supply, it is recommended to use SELV (Safety Extra Low Voltage) or Class 2 power supplies with a limited output of 15 W or less, in accordance with UL requirements.
What is the significance of the LCD display on the QBM3120-3D?
The integrated LCD display provides immediate, on-site visualization of the measured differential pressure in Pascals. This offers operators and technicians real-time feedback without needing external monitoring equipment.
The display also aids in configuration and diagnostics. For instance, during zero-point adjustment, the display will show "0 Pa" to confirm the calibration is complete.
This feature enhances user convenience and operational efficiency by allowing quick checks and troubleshooting directly at the sensor's location.
What are the environmental considerations for operating the SIEMENS QBM3120-3D?
The sensor is designed for use with air and non-aggressive gases. It has a degree of protection of IP54, meaning it is protected against dust ingress and splashing water.
The admissible medium and ambient operating temperature range is from 0 to 70 °C. It can withstand a maximum overpressure of 0.05 bar.
Proper mounting is crucial to prevent condensation from entering the sensor, which can occur if the pressure nipples are not oriented downwards or are lower than the air probes.
Is the SIEMENS QBM3120-3D maintenance-free?
Yes, the SIEMENS QBM3120-3D is described as maintenance-free. This is due to its excellent long-term response and robust design.
This characteristic significantly reduces the total cost of ownership, as it minimizes the need for routine servicing and potential downtime associated with maintenance activities.
The reliable performance over extended periods makes it a dependable choice for critical applications where consistent operation is paramount.
