AFS-900 Series
Air Pressure Sensing Switches

Series AFS-900
  • NEMA-1, -5, -7 and -9 housings
  • Operation indicator
  • Positive, negative, or differential pressure (flow) of air and noncombustible gases
  • 03″ wc to 12.0″ wc field-adjustable set point range
  • Available time delay relay sequence: 8‑second (± 3 seconds) and/or 20-second
  • Series 900 Air Pressure Sensing Switches provide precise operation for industrial and commercial air handling applications. Three NEMA-rated enclosures are available: plant-standard NEMA-1 rated, NEMA-4-weather proof, and NEMA-7/ NEMA-9 explosion-proof.

Series 900 switches monitor positive, negative, or differential pressure (flow) of air and noncombustible gases, in applications such as combustion air, furnace pressure, ventilating blower operation, inflatable structure pressure, fume hood operation, bag house air flow, dirt accumulation in air filters, and heat-transfer air flow. The most common application is as a high pressure or low draft cutoff switch in combustion draft control systems.

Series 900 models have field-adjustable set point ranges of 0.03″ wc to 2.0″ wc or 12.0″ wc. AFS-951 and AFS-961 switches have no time delay sequence. Models (AFS-9×2,  and AFS-9×2-55) have an 8-second  delay relay most often used to prevent nuisance shutdowns due to normal draft fluctuations in applications where this is necessary. AFS-953’s have an additional 20-second delay that usually interlocks with a sequencing burner management system, providing features such as a pre-purge or post-purge sequence.

Precision. Every Day.