AS-FS Flow Sensor

FCI provides flow switches that utilize a no moving parts thermowell mounted sensing element with either integral or remote electronics, that indicate flow rate above or below a predetermined set point at the sensing location. The flow element is directly installed into piping or ducting on commercial and military aircraft, spacecraft, vehicles and marine applications.

Please complete and submit an FCI Aerospace Application Data Sheet or contact FCI’s Field Representative in your area to receive a technical quotation for your Flow Switch application.


  • Liquid Cooling Systems
  • Fuel Transfer
  • Fuel Tank Inerting Systems
  • Lubricating Oils
  • PACK Air Systems
  • Hydraulic Fluids
  • Bleed Air Systems
  • Ground and in-flight refueling


Service: Flow monitoring of liquid or gas.

Material: Wetted parts 316 stainless steel, all welded construction

Electronics Enclosure: Hermetically sealed units; 316 stainless steel

Electrical Connection: D38999 or compatible

Process Connection: Flanged with O-ring seal

Insertion Length: Per customer requirement

Output Options
  • Flow Signal: Source 240 mA at 28 Vdc
  • No Flow Signal: Source 0 Vdc
  • Flow Signal: Source 0 Vdc
  • No Flow Signal: Source 240 mA at 28 Vdc

Open Collector
  • Flow Signal: Closed, sinking up to 100 mA at < 0.5 Vdc
  • No Flow Signal: Open, leakage < 10µa at 30 Vdc
  • Flow Signal: Open, leakage < 10µa at 30 Vdc
  • No Flow Signal: Closed, sinking up to 100 mA at < 0.5 Vdc

Electrical Power Input: 28 VDC nominal per MIL-STD-704

Power Consumption: 3 watt maximum

Weight: 8 oz. [227 g] maximum

Operating Pressure: Standard up to 2000 psig [138 bar (g)]; higher pressures available by request, contact FCI

Switch Point Adjustment
Factory set at customer specified switch point within flow range listed:
Flow Range
Process Fluid Switch Point Range
Air 0.25 SFPS to 1,000 SFPS [0.07 MPS to 305 MPS]
Fuel, Hydraulic Fluid, Coolant 0.01 SFPS to 10 SFPS [0.003 MPS to 3 MPS]
Water 0.01 SFPS to 5 SFPS [0.003 MPS to 1.5 MPS]
Operating Temperature Range
Flow Element: - 65 °F to 500 °F [- 54 °C to 260 °C] Specify actual requirement
Electronics: - 40 °F to 257 °F [- 40°C to 125 °C]

Repeatability: ± 2% of full signal range

Time Response: 1 to 10 seconds typical, depending on fluid type and switch point

EMI and Lightning Protection: MIL-STD-461 and RTCA/DO-160

Qualifications: MIL-STD-810 and RTCA/DO-160

Quality Systems Approval: ISO 9001, AS9100