Dwyer Instruments AVFS-1 | Thermo air flow switch | 80-250 AC/DC.
The Dwyer AVFS-1 is a mains-powered thermal air flow switch accepting 80-250 V AC/DC. It proves duct airflow from 197 to 1969 FPM (1-10 m/s) without a moving paddle, using a flush titanium sensor, IP65 PBT housing and red/green status LEDs. Genuine Dwyer Instruments stock at General Tech Services LLC, Saudi Arabia, with free Saudi Arabia shipping. Request a quote in under a minute - call +966 569 289 544.
Product Overview
Many fan-proving applications are located in plant rooms and mechanical spaces where a mains supply is already available. The Dwyer AVFS-1 can operate directly from 80-250 V AC or DC, eliminating the need for a separate low-voltage transformer for the airflow switch.
The AVFS-1 uses thermal dispersion sensing rather than a mechanical paddle. A heated titanium sensor sits flush in the airstream and detects the cooling effect produced by moving air. When air velocity falls below the selected set point, the 3 A N.O. SPST contact changes state.
Because the AVFS-1 has no paddle, lever or spring, there are no mechanical components in the airflow-sensing mechanism that can wear or jam. This makes the thermal design suitable for applications where dust, grease or other contaminants may affect mechanical airflow switches.
The switch covers an air velocity range of 197-1969 FPM (1-10 m/s) with ±5% full-scale repeatability. Its response time is 3-60 seconds depending on airflow velocity and the selected set point, helping accommodate normal fan start-up conditions.
Red and green LEDs provide a visual indication of airflow status, making setup and troubleshooting easier. The PBT housing provides IP65 protection against dust and moisture, while the unit is rated for a maximum operating pressure of 1 bar and 0-90% RH.
The AVFS-1 operates from 80-250 V AC/DC, with AC operation from 47-63 Hz, making it suitable for 60 Hz mains supplies within its rated voltage range. Operating temperature is -10 to 50°C. The unit consumes approximately 3 VA, weighs 203 g and is supplied with a mounting bracket and 2 m cable.
Key Benefits
- Direct operation from 80-250 V AC/DC without an additional transformer
- Thermal airflow sensing with no moving parts to wear or jam
- Air velocity range of 197-1969 FPM (1-10 m/s)
- ±5% full-scale repeatability for consistent airflow trip points
- Flush titanium sensor for airflow detection
- Red and green LEDs provide clear airflow status indication
- IP65 PBT housing for protection against dust and moisture
- 3 A N.O. SPST output contact
- 3-60 second response time depending on airflow and set point
- 47-63 Hz AC operation suitable for 60 Hz supplies within the rated voltage range
- Mounting bracket and 2 m cable included
- Genuine Dwyer Instruments stock with free Saudi Arabia shipping
Call +966 569 289 544 for pricing and availability.
Who This Product Is Best For
- Maintenance teams installing airflow proving where mains power is readily available
- Kitchen extract, car-park and toilet exhaust systems exposed to dust or grease
- HVAC contractors replacing mechanical paddle switches
- Facility managers who need visible LED airflow status at the duct
- Clean-air HVAC applications where a non-mechanical airflow sensor is preferred
- Panel builders integrating airflow proving into mains-powered control systems
How to Use / How It Works
- Install the mounting bracket and position the sensor in the duct with the sensing element correctly oriented to the airflow.
- Connect the 80-250 V AC/DC supply and wire the N.O. SPST contact to the required alarm or interlock circuit.
- Run the fan at normal operating airflow and adjust the trip point while monitoring the status LEDs.
- Stop or reduce the fan airflow and confirm that the output contact and LED status change as expected.
- Verify the complete fan-proving or alarm sequence before returning the system to normal operation.
Frequently Asked Questions
What supply voltage does the AVFS-1 accept?
The AVFS-1 accepts 80-250 V AC or DC. AC operation is rated for 47-63 Hz.
Will the AVFS-1 work on Saudi Arabia's 60 Hz mains?
Yes. The 47-63 Hz AC rating includes 60 Hz operation when the supply voltage is within the specified 80-250 V range.
What airflow range can the AVFS-1 monitor?
The AVFS-1 covers 197-1969 FPM, equivalent to 1-10 m/s.
Why choose a thermal airflow switch instead of a paddle switch?
The AVFS-1 uses thermal sensing with no moving airflow-sensing parts. This avoids mechanical paddle, lever and spring components that can wear or become affected by dust and grease.
What type of output does the AVFS-1 provide?
The AVFS-1 provides a 3 A N.O. SPST contact for connection to an alarm, interlock or control circuit.
What is the difference between the AVFS-1 and AVFS-2?
The two models share the same thermal sensing principle and 197-1969 FPM (1-10 m/s) airflow range. The AVFS-1 is designed for an 80-250 V AC/DC supply, while the AVFS-2 is designed for 24 VDC control circuits.
What comes with the AVFS-1?
The AVFS-1 is supplied with a mounting bracket and a 2 m cable.
Is the Dwyer AVFS-1 suitable for dusty or greasy duct applications?
Its thermal sensing design has no moving paddle mechanism, while the IP65 PBT housing provides protection against dust and moisture. Application suitability should still be checked against the specific operating environment and temperature limits.
Is the Dwyer AVFS-1 genuine stock?
Yes. General Tech Services LLC supplies genuine Dwyer Instruments products in Saudi Arabia with free Saudi Arabia shipping. Call +966 569 289 544 for pricing and stock availability.
Request a Quote Today
Get the Dwyer AVFS-1 thermal air flow switch delivered free anywhere in Saudi Arabia.
Call +966 569 289 544 | www.generaltechshop.sa
