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SureFlow Adaptive Offset Controller 8681

SKU: 8681

Discontinued Jan 1, 2020. Recommended replacement Lab Room Controller (LRC).

*A newer model of this product is now available.

Product Details

The TSI SureFlow™ Adaptive Offset Controller Model 8681 is an ideal digital controller for laboratories with fume hoods.

A stand-alone device, the 8681 ensures that the exhaust volume is always greater than the supply volume for negative spaces, and less than the supply volume for positive spaces. This negative air balance helps ensure that chemical vapors cannot diffuse outside the laboratory, complying with requirements in NFPA 45-2000 and ANSI Z9.5-2003.

The SureFlow 8681 also controls the temperature of the laboratory space by modulating reheat and the supply air volume. Optionally, a room pressure sensor can be connected to the 8681 controller to correct long-term changes in the building dynamics.

The 8681 uses TSI's unique through-the-wall pressure sensor to provide closed-loop control of the pressure differential. The pressure sensor slowly resets the offset between the supply and exhaust flows.

The 8681 easily integrates to the building management system using either alarm relays or digital communications. The 8681 supports the open Modbus® protocol.


  • Laboratories with fume hoods

Included items

  • Digital interface module
  • Through-the-wall pressure sensor
  • Controller output cable, 25 ft
  • Transformer, 120:24 VAC
  • Transformer cable, 25 ft

Features & Benefits

  • Stand-alone room pressure control provides system reliability
  • Integrates temperature control into laboratory ventilation control
  • Flow tracking control ensures stability in the HVAC system
  • Direct pressure measurement provides continuous, closed-loop control
  • Audible and visual alarms warn staff of unsafe conditions
  • Network communications allow for building-wide control efficiencies
  • Convenient keypad and display support local programming
  • Passwords prevent unauthorized access to controller functions

Related Resources

  • Application Notes
  • Brochures
  • Installation Instructions
  • Manuals