AS-MLLS Liquid Level Sensor

FCI provides multipoint liquid level and interface switches that include a “strip sensor” or a thermowell mounted sensing element with integral or remote electronics that provide indication of presence or absence of liquid or interface at the multiple sensor locations along the length of the element. The multipoint liquid level element is directly installed into tanks, reservoirs, sumps and gearboxes on commercial and military aircraft, spacecraft, vehicles and marine applications. Optional temperature output and controller function is available.

Please complete and submit the attached Application Data Sheet or contact FCI’s Field Representative in your area to receive a technical quotation for your Multipoint Liquid Level and Interface Switch application.


  • Hydraulic gearbox oil
  • Fuel tanks and reservoirs
  • Lubricating gearbox oil
  • Potable water
  • Coolant and heating fluids
  • Gray water


Service: Liquid multipoint level. Accuracy Liquid level: ± 0.25 inch of sensing point.

Temperature: ± 1% full scale.
Repeatability: ± 1% full scale.

Reliability (MTBF): 60,000+ Hours.

Qualifications: MIL STD 810 and RTCA/DO-160, customer project qualification support optionally available.

Quality System Approvals: ISO9001 and AS9000

Weight: Liquid Level Element: 1 to 2 lbs. [0.45 to 0.90 kgs] depending on configuration. Remote Control Unit Enclosures: 1 lb. [0.45 kgs].

Level Element

Materials of Construction:
  • Standard: 316 stainless steel mounting connection with PVC stilling well structure and Kapton polyimide RTD elements..
  • Optional: All 316 stainless steel level element with brazed or all-welded design.

Process Connection: Threaded fitting per MS33514-16 Style 3 (1.312-12 UNJ-3A) or mounting flange available per customer requirement.

Insertion Length: (Sensing Level Depth) Up to 40 inches [1016 mm] as required by customer.

Operating Temperature:
  • PVC/Kapton Polymide Design: -65° to +158° F [-54° to +70° C].
  • Stainless Steel Design: -65° to +650° F [-54° to +343° C].

Proof Pressure:
  • PVC/Kapton Polymide Design: Up to 300 psig [21 bar(g)].
  • Stainless Steel Design: Up to 2000 psig [138 bar(g)]

Electrical Connection: Connector on flying lead or element-mounted connector.


Operating Temperature: -40° to +131° F [-40° to +55° C] Higher temperature service optionally available.

Input Power: 28 Vdc nominal per MIL-STD-704. 7.5 Watts maximum.

Power Consumption: 50 to 85 mA.

Output Signal: Discrete ground/open switched array. Stepped 4-20 milliamp output optionally available.

Enclosure: Aluminum Alloy painted lusterless black per MIL-C-83286. Integral control unit enclosure optionally available.

Electrical Connection: Military or commercial connector.

Optional Equipment: All welded 316 Stainless Steel Construction. Integral Control Electronics. Process Mounting Flange. Calibration and/or material certificates.

Optional N.I.S.T. Test Lab Calibration Services
Factory N.I.S.T. calibration is available as an option for customer specified setpoint(s).