The general purpose ultrasonic level sensor provides continuous level detection up to 26.2’ (8m) with 3 programmable relays for level switch or level control functions, and a 4-20mA signal output. The sensor is programmed via the integral push button display module. Each relay can be configured on a single set point alarm or latched on two set points for automatic fill or empty in simplex, duplex or triplex level control modes with selectable time delay and fail-safe logic. The embedded level controller can lower cost by replacing external control hardware. This non-contact liquid level sensor is ideally suited for corrosive, sticky or dirty liquids, and is broadly selected for pump lift station, sump and day tank level applications.


  • Offered in 3 level detection ranges from 9.8’ (3m) to 26.2’ (8m)
  • Configuration is simple via integral push button display module
  • Three programmable relays for switch, pump control and fail-safety
    • 1 pump or valve with 2 alarms
    • 2 pumps lead-lag with 1 alarm
    • 2 pumps duplexing with 1 alarm
    • 3 independent switch point alarms
  • 4-20 mA output provides local or remote process level monitoring
  • LCD display indicates level height in engineering units and relay status
  • Narrow 2” or 3” beam width for applications with limited space
  • Short 4” or 8” dead band maximizes the filling capacity of the tank
  • PVDF transducer and NEMA 4X PC enclosure for corrosive liquids
  • Automatic temperature compensation for accurate measurement


P/N Description From
LU74-5004 5.5m (18′) range, 95-250 VAC, 2″ NPT $1,100.00
LU74-5064 5.5m (18′) range, 95-250 VAC, 2″ G $1,110.00
LU77-5004 3m (9.8′) range, 95-250 VAC, 1″ NPT $1,035.00
LU77-5064 3m (9.8′) range, 95-250 VAC, 1″ G $1,045.00
LU78-5004 8m (26.2′) range, 95-250 VAC, 2″ NPT $1,165.00
LU78-5064 8m (26.2′) range, 95-250 VAC, 2″ G $1,175.00


Range: LU77: 4” to 9.8’ (10cm to 3m), LU74: 8” to 18.0’ (20cm to 5.5m), LU78: 8” to 26.2’ (20cm to 8m)

Repeatability: 0.25” (6.35mm)

Signal output: 4-20 mA, two-wire, isolated, sinking

Signal excitation: 12 to 28 VDC

Loop resist: 500 Ohms @ 24 VDC

Signal fail-safe: 4 mA, 20 mA, 21 mA or hold last

Dead band: LU77: 4” (10cm), LU74/78: 8” (20cm)

Beam width: LU77: 2” (5cm), LU74/78: 3” (7.6 cm)

Configuration: Push button

Memory: Non-volatile

Display type: LCD, 6 characters

Display units: Inch, cm, percent, feet or meter

Display indication: Level and relay status

Supply voltage: 95-250 VAC

Consumption: 20 watts @ 120 VAC

Contact type: Relay 1: SPDT, Relay 2 & 3: SPST N.O.

Contact rating: 2A, 30 VDC, 60W (DC), 125 VA 220 VDC, 250 VAC

Contact fail-safe: Programmable

Process temp.: F: -7° to 140°, C: -20° to 60°

Temp. comp.: Automatic

Ambient temp.: F: -40° to 160°, C: -40° to 71°

Pressure: MWP = 30 PSI (2 bar)

Enclosure rating: NEMA 4X (IP65)

Encl. material: Polycarbonate

Encl. hardware: Brass & stainless

Enclosure vent: Water tight membrane

Trans. material: PVDF

Conduit entrance: Dual, 1/2” NPT

Process mount: LU77: 1” NPT (1” G), LU74/78: 2” NPT (2” G)

Mount gasket: Viton®

Classification: General purpose

Compliance: RoHS

Approvals: CE


If you want help in selecting a sensor for your application, please submit a Level Questionnaire. An engineer will review your requirements and suggest a product solution via email.