Siemens BPZ:QBM81-3 Small Size Pressure Sensor

The Siemens BPZ:QBM81-3 is a compact and highly reliable differential pressure sensor designed for precise monitoring in various industrial and HVAC applications. This small-size pressure sensor offers a robust solution for critical processes requiring accurate airflow and pressure differential measurements. Its key advantages include a wide operating temperature range, durable construction, and straightforward installation, making it a valuable component in systems where consistent performance and long-term stability are paramount.

Product Specifications

| Specification             | Value                                     |

| :------------------------ | :---------------------------------------- |

| Product Number            | BPZ:QBM81-3                               |

| Manufacturer              | Siemens                                   |

| Type                      | Differential Pressure Switch/Monitor      |

| Measuring Range (Pressure)| 20 to 300 Pa (0.08 to 1.20 Inches WC)     |

| Maximum Operating Pressure| 7.5 kPa                                   |

| Output                    | 1 x Potential-free relay contact (SPDT)   |

| Switching Voltage         | AC 24–250 V; DC/AC 24 V                   |

| Switching Current         | 0.01–5 A (≈3 A inductive)                 |

| Ambient Temperature (Op.) | -20 to +85 °C                             |

| Degree of Protection      | IP54                                      |

| Pressure Connection       | Hose nipple Ø 6.2 mm                      |

| Dimensions (Ø x L)        | 81 x 90 mm                                |

| Warranty                  | 60 Months                                 |

| Mounting Position         | Diaphragm vertical, pressure port down    |

Core Features & Market Positioning

The Siemens BPZ:QBM81-3 distinguishes itself through its highly accurate measurement capabilities within a narrow pressure range, making it ideal for sensitive HVAC and cleanroom applications. Its market positioning is defined by its reliability, ease of use, and Siemens' reputation for industrial-grade quality. Unlike many competitors, the QBM81-3 offers a factory-calibrated setup for vertical installation, simplifying initial commissioning and ensuring consistent performance right out of the box. The device is built for over one million switching cycles, underscoring its long-term stability and suitability for demanding operational environments.

Key Application Scenarios

This Siemens differential pressure sensor is extensively used for monitoring air filters in ventilation and air conditioning systems, ensuring optimal performance and preventing equipment damage. It also serves as a crucial airflow switch, detecting changes that could indicate issues with fan belts or blockages. Furthermore, the BPZ:QBM81-3 is vital for maintaining precise pressure differentials in cleanrooms and other controlled environments, where even slight deviations can impact operational integrity. Its versatility extends to monitoring positive and negative relative pressures within HVAC installations, contributing to overall system efficiency and safety.

Practical System Integration Guidance

Installation of the Siemens BPZ:QBM81-3 is designed for efficiency. It typically comes supplied with a set of air duct connectors and PVC tubing, facilitating direct connection to the system being monitored. The recommended mounting position is vertical, with the pressure connection port facing downwards, to ensure accurate readings and prevent condensation buildup. While factory-calibrated for vertical installation, any orientation is acceptable, though non-vertical positions may slightly affect the switching point calibration. Electrical connections involve a single potential-free relay contact, compatible with AC 24–250 V or DC/AC 24 V circuits, and a switching current of up to 5 A. It is advisable to ensure tubing is routed with a gradual incline to the sensor to prevent condensate accumulation.

Operation and Risk Mitigation

The QBM81-3 operates by using a spring-loaded diaphragm that deflects based on the differential pressure between its two connection points. This mechanism ensures long-term stability of the switching points. Risks are mitigated through its robust IP54 protection class, safeguarding against dust and water ingress. The operational temperature range of -20 to +85 °C allows for deployment in a variety of ambient conditions. While the device is designed for reliability, users should be aware of potential issues such as inaccurate readings due to incorrect mounting or tubing issues. Regular checks of the air connections and ensuring the system is clean can prevent common faults. The unit features a potential-free relay output, which simplifies integration and reduces the risk of electrical interference.

Scalability & Long-Term Value

The Siemens BPZ:QBM81-3 offers significant long-term value through its durable construction and the reliability associated with the Siemens brand. While not a digitally integrated sensor in the IIoT sense, its dependable relay output can be seamlessly integrated into larger control systems, SCADA, or building management systems (BMS) for data acquisition and further analysis. Its compatibility with a wide range of existing HVAC and industrial control platforms makes it a sound investment for maintaining operational efficiency. The availability of different pressure ranges within the QBM81 series also allows for system expansion or upgrades to other Siemens differential pressure monitors as application needs evolve.

Frequently Asked Questions

What is the primary function of the Siemens BPZ:QBM81-3?

The Siemens BPZ:QBM81-3 functions as a differential pressure switch, primarily used for monitoring pressure differences in air ducts.

Its key applications include ensuring proper airflow, monitoring air filter status, and detecting over or underpressure conditions in HVAC systems. It provides a reliable output signal for control or alarm functions based on these pressure differentials.

This device is engineered for accuracy within its specified range of 20 to 300 Pascals, making it suitable for sensitive environments like cleanrooms.

What is the measuring range of the Siemens BPZ:QBM81-3?

The Siemens BPZ:QBM81-3 has a specific measuring range for differential pressure.

This range is from 20 to 300 Pascals (Pa), which is equivalent to 0.08 to 1.20 inches of water column (WC).

This precise range allows it to detect subtle changes critical for HVAC filter monitoring and airflow control.

Can the Siemens BPZ:QBM81-3 be used in harsh industrial environments?

The Siemens BPZ:QBM81-3 is designed for industrial use, with an IP54 protection class.

This rating means it offers protection against dust ingress and splashing water, making it suitable for many industrial settings.

However, it is primarily intended for air and non-aggressive gases, so aggressive chemical atmospheres would require a different solution.

What type of output signal does the Siemens BPZ:QBM81-3 provide?

The Siemens BPZ:QBM81-3 features a potential-free relay contact output.

This is a single-pole, double-throw (SPDT) switch that can be used to control external devices or signal an alarm.

The relay is rated for AC 24–250 V or DC/AC 24 V, with a switching current of up to 5 A (3 A inductive).

How is the Siemens BPZ:QBM81-3 typically installed?

Installation is straightforward, often involving mounting on air ducts or walls using provided connectors and tubing.

It's recommended to mount the unit vertically with the pressure port facing downwards for optimal performance.

The pressure connections utilize a standard hose nipple with a 6.2 mm diameter.

What are the key applications for the Siemens BPZ:QBM81-3?

Its primary applications are in HVAC systems for monitoring air filters and airflow.

It is also used to maintain pressure in cleanrooms and kitchens, and to detect issues like torn fan belts.

The sensor is suitable for monitoring both positive and negative relative pressures in air handling units (AHUs) and variable air volume (VAV) systems.

Does the Siemens BPZ:QBM81-3 require calibration after installation?

The BPZ:QBM81-3 comes factory-calibrated for vertical installation, simplifying initial setup.

While calibration is typically not needed for standard vertical mounting, non-vertical installations might slightly affect the switching point.

Users can adjust the setpoint via a knob located under the cover if needed.

What is the operating temperature range of this sensor?

The Siemens BPZ:QBM81-3 can operate reliably within a wide ambient temperature range.

This range spans from -20°C to +85°C, allowing its use in diverse environmental conditions.

This broad operational capacity ensures consistent performance across different climate zones and industrial settings.

Is the Siemens BPZ:QBM81-3 suitable for monitoring liquid pressure?

No, the Siemens BPZ:QBM81-3 is specifically designed for monitoring air and non-aggressive gases.

Its pressure range and construction are not intended for liquid media.

Using it with liquids could lead to inaccurate readings or damage to the device.

What is the warranty period for the Siemens BPZ:QBM81-3?

The Siemens BPZ:QBM81-3 comes with a comprehensive warranty to ensure customer confidence.

This device is backed by a 60-month (5-year) warranty.

This extended warranty reflects Siemens' commitment to the product's durability and reliability.