Siemens Building Technology QFM81.21 Hygrostat
The Siemens Building Technology QFM81.21 is a commercial-grade duct hygrostat designed for precision relative humidity control in HVAC systems. Engineered for both monitoring and regulation, this device features a stabilized sensing strip that ensures superior linearity and long-term stability, even in high-humidity environments or air contaminated with dust. Unlike baseline models, the QFM81.21 utilizes an internal setpoint adjuster to prevent unauthorized tampering after installation. It operates as an on/off controller with a single-pole, double-throw (SPDT contact) microswitch, making it highly versatile for managing both humidification and dehumidification equipment. With a switching differential of 4% RH and a setpoint range of 15% to 95% RH, this hygrostat provides the reliable switching accuracy required for clean rooms, data centers, and industrial air handling units. The robust housing is rated IP55, providing essential protection against dust and water splashes.
- Precise Control: Features a fixed switching differential of 4% RH for stable HVAC humidity monitoring and equipment cycling.
- Internal Setpoint Adjustment: Safeguards system parameters by locating the adjustment dial beneath the cover to prevent field tampering.
- Versatile Application: Functions as a maximum or minimum limiter in supply air ducts to protect sensitive downstream components.
- Durable Sensing Element: Utilizes a temperature-compensated plastic sensing strip resistant to environmental contaminants.
- Easy Installation: Supplied with a mounting flange for adjustable immersion lengths between 130mm and 156mm.
Common Questions
How do I calibrate the Siemens QFM81.21 in the field?If field calibration is required, use a 7mm wrench to adjust the internal mechanism until an audible click is heard at the known relative humidity level. This ensures the SPDT contact trips accurately according to local duct conditions.
Can this unit be mounted on a wall instead of a duct?Yes, while primarily designed for ductwork, the QFM81.21 can be wall-mounted using the supplied mounting flange. Ensure it is placed in an area with natural air circulation, away from drafts or direct heat sources.
What is the maximum electrical load for the switching contacts?The potential-free microswitch is rated for a switching voltage of AC 250V with a switching current capacity of 5 (3) A, suitable for direct control of most humidifiers and dehumidifier contactors.
This item is not eligible for free shipping.
Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.
Original: $203.90
-65%$203.90
$71.36Siemens Building Technology QFM81.21 Hygrostat
The Siemens Building Technology QFM81.21 is a commercial-grade duct hygrostat designed for precision relative humidity control in HVAC systems. Engineered for both monitoring and regulation, this device features a stabilized sensing strip that ensures superior linearity and long-term stability, even in high-humidity environments or air contaminated with dust. Unlike baseline models, the QFM81.21 utilizes an internal setpoint adjuster to prevent unauthorized tampering after installation. It operates as an on/off controller with a single-pole, double-throw (SPDT contact) microswitch, making it highly versatile for managing both humidification and dehumidification equipment. With a switching differential of 4% RH and a setpoint range of 15% to 95% RH, this hygrostat provides the reliable switching accuracy required for clean rooms, data centers, and industrial air handling units. The robust housing is rated IP55, providing essential protection against dust and water splashes.
- Precise Control: Features a fixed switching differential of 4% RH for stable HVAC humidity monitoring and equipment cycling.
- Internal Setpoint Adjustment: Safeguards system parameters by locating the adjustment dial beneath the cover to prevent field tampering.
- Versatile Application: Functions as a maximum or minimum limiter in supply air ducts to protect sensitive downstream components.
- Durable Sensing Element: Utilizes a temperature-compensated plastic sensing strip resistant to environmental contaminants.
- Easy Installation: Supplied with a mounting flange for adjustable immersion lengths between 130mm and 156mm.
Common Questions
How do I calibrate the Siemens QFM81.21 in the field?If field calibration is required, use a 7mm wrench to adjust the internal mechanism until an audible click is heard at the known relative humidity level. This ensures the SPDT contact trips accurately according to local duct conditions.
Can this unit be mounted on a wall instead of a duct?Yes, while primarily designed for ductwork, the QFM81.21 can be wall-mounted using the supplied mounting flange. Ensure it is placed in an area with natural air circulation, away from drafts or direct heat sources.
What is the maximum electrical load for the switching contacts?The potential-free microswitch is rated for a switching voltage of AC 250V with a switching current capacity of 5 (3) A, suitable for direct control of most humidifiers and dehumidifier contactors.
This item is not eligible for free shipping.
Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.
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Description
The Siemens Building Technology QFM81.21 is a commercial-grade duct hygrostat designed for precision relative humidity control in HVAC systems. Engineered for both monitoring and regulation, this device features a stabilized sensing strip that ensures superior linearity and long-term stability, even in high-humidity environments or air contaminated with dust. Unlike baseline models, the QFM81.21 utilizes an internal setpoint adjuster to prevent unauthorized tampering after installation. It operates as an on/off controller with a single-pole, double-throw (SPDT contact) microswitch, making it highly versatile for managing both humidification and dehumidification equipment. With a switching differential of 4% RH and a setpoint range of 15% to 95% RH, this hygrostat provides the reliable switching accuracy required for clean rooms, data centers, and industrial air handling units. The robust housing is rated IP55, providing essential protection against dust and water splashes.
- Precise Control: Features a fixed switching differential of 4% RH for stable HVAC humidity monitoring and equipment cycling.
- Internal Setpoint Adjustment: Safeguards system parameters by locating the adjustment dial beneath the cover to prevent field tampering.
- Versatile Application: Functions as a maximum or minimum limiter in supply air ducts to protect sensitive downstream components.
- Durable Sensing Element: Utilizes a temperature-compensated plastic sensing strip resistant to environmental contaminants.
- Easy Installation: Supplied with a mounting flange for adjustable immersion lengths between 130mm and 156mm.
Common Questions
How do I calibrate the Siemens QFM81.21 in the field?If field calibration is required, use a 7mm wrench to adjust the internal mechanism until an audible click is heard at the known relative humidity level. This ensures the SPDT contact trips accurately according to local duct conditions.
Can this unit be mounted on a wall instead of a duct?Yes, while primarily designed for ductwork, the QFM81.21 can be wall-mounted using the supplied mounting flange. Ensure it is placed in an area with natural air circulation, away from drafts or direct heat sources.
What is the maximum electrical load for the switching contacts?The potential-free microswitch is rated for a switching voltage of AC 250V with a switching current capacity of 5 (3) A, suitable for direct control of most humidifiers and dehumidifier contactors.
This item is not eligible for free shipping.
Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.
