OVERVIEW

Official designation: Siemens QBM81-5 (QBM81 series, Differential Pressure Switch)

Role/Application: The QBM81-5 monitors differential pressure, underpressure, and overpressure in air and non-corrosive gases within HVAC and ventilation systems.

KEY SPECS SUMMARY

Power: AC 24 to 250 V or DC 24 V

Interfaces / Ports: 3 screw terminals, PG11 cable gland

Indicators: N/A

Operating Temp: -20 to 85 degrees C

Platform / Compatibility: HVAC and air duct systems

Limit: Maximum pressure 7.5 kPa

Lifecycle: Greater than 1,000,000 switching cycles

FREQUENTLY ASKED QUESTIONS

Technical Specifications:

Q: What is the confirmed pressure measurement range for the QBM81-5 model?

A: The specific measuring range for the QBM81-5 is 50 to 500 Pa.

Wiring & Installation:

Q: What is the required mounting orientation to ensure calibration accuracy?

A: The device is factory-calibrated in the vertical position, and horizontal installation affects the switching point.

Troubleshooting & Compatibility:

Q: Does the differential pressure switch require external circuit protection?

A: Yes, the switch has no internal fuse, requiring external preliminary protection such as a max 10 A slow fuse.

Replacement & Upgrades:

Q: What is the enclosure material and ingress protection rating of the QBM81-5?

A: The housing is made of fiberglass reinforced polycarbonate with an IP54 protection degree.