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SiemensDuct Temperature & Humidity Sensors

Siemens Humidity Sensor: Duct Mount, Flange Mount, 100 mA to 5 A/24 V AC/DC

The Siemens QFM81.2 is a duct-mount humidity sensor with a flange-mount housing and included mounting flange. It measures relative humidity from 15 to 95% and provides a temperature signal output of 100 mA to 5 A at…

SKU 3G-OTH-68802

Also listed as: QFM812 · QFM81 2 · QFM81-2

Brand
Siemens
Item
Humidity Sensor: Duct Mount, Flange Mount, 100 mA to 5 A/24 V AC/DC
Category
Duct Temperature & Humidity Sensors
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Worldwide DHL shipping from Singapore; 7–14 business days door-to-door for most destinations.
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Technical Specifications

Siemens
Manufacturer Part Number
QFM81.2
Type
Flange Mount, 100 mA to 5 A/24 V AC/DC, Fiberglass Reinforced PPS
Display
No Display
Includes
Mounting Flange
Housing Type
Flange Mount
Product Type
Duct Humidity Sensor
Mounting Location
Duct Mount
Temperature Signal
All-Polymer 24 V AC/DC
Relative Humidity Range
15 to 95%
Temperature Signal Output
100 mA to 5 A
Electrical Connection Type
Screw Terminals

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Siemens Products
3G Electric (S) Pte. Ltd. — Singapore

Product Description

The Siemens QFM81.2 is a duct-mount humidity sensor with a flange-mount housing and included mounting flange. It measures relative humidity from 15 to 95% and provides a temperature signal output of 100 mA to 5 A at 24 V AC/DC, using all-polymer sensing technology. The unit features screw terminals for electrical connection and a fiberglass-reinforced PPS housing.

Frequently Asked Questions

What is the Siemens QFM81.2 duct humidity sensor used for?

The Siemens QFM81.2 measures relative humidity from 15 to 95% in HVAC ducts, outputting a 100 mA to 5 A temperature signal at 24 V AC/DC. It is used in building automation and environmental control systems to monitor and regulate air conditions in commercial and industrial facilities.

What are the specifications of the Siemens QFM81.2 humidity sensor?

The Siemens QFM81.2 is a duct-mount humidity sensor with a flange-mount housing and included mounting flange. It measures 15 to 95% relative humidity, outputs 100 mA to 5 A at 24 V AC/DC, uses all-polymer sensing technology, and has screw terminals for electrical connection in a fiberglass-reinforced PPS housing.

Where to buy the Siemens QFM81.2 humidity sensor worldwide?

3G Electric supplies the Siemens QFM81.2 humidity sensor worldwide. As a global industrial solutions provider, we handle full logistics, customs clearance, and delivery to your facility. Contact us to source this duct-mount sensor with flange housing and 100 mA to 5 A output.

How to install the Siemens QFM81.2 duct humidity sensor?

Mount the Siemens QFM81.2 in the duct using the included flange, ensuring the sensing element is exposed to airflow. Connect screw terminals to 24 V AC/DC power and the 100 mA to 5 A signal loop. Follow standard HVAC sensor placement practices for representative humidity readings.

Used in

Common applications for Siemens
District cooling plants — LME73 + RWF55 for condenser-water modulation
Inflight catering and food-processing steam boilers — LMG22 with SQN90 air-fuel cross-damper
Hospital steam-plant redundancy — LME41 with QRA2 UV flame detection for dual-fuel boilers
Semiconductor fab process heat — LME23 and SKP55 gas valves on hot-oil heater skids
Container-terminal reefer-deck heating — LMG22 retrofit onto legacy burner racks

Siemens Products

3G Electric supplies Siemens duct temperature & humidity sensors. We supply genuine products with in-stock availability on common SKUs, technical documentation, commissioning support, and warranty service — worldwide.

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