LU77/78 Series EchoSwitch

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LU77/78 Series EchoSwitch

Ultrasonic Level Switch LU77/78 Series EchoSwitch

Ultrasonic Level Switch


The Model LU77/78 Ultrasonic Level Switch uses a non contact liquid level sensor to measure up to 24.6' (7.5m) with integral three-channel relay control. The level switches can be used as a water level sensor and switch or for other liquids for reliable liquid level control. The liquid level switch has relays that can be configured for a single setpoint alarm or two latched setpoints for automatic fill or empty in simplex, duplex, or triplex control modes. Calibration for accurate liquid level measurement is quick and easy using a sequence of push-button entries. The ultrasonic level switches include local LCD indication to signal level values and relay status. The LU77/78 is designed with a NEMA 4X enclosure, suitable for outdoor applications. All LU77/78 switches are compatible with Building Automation Systems, BAS, and HVAC applications.


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QtyModelDescriptionIn StockList PriceInternet Price
LU74-5004 ULTRASONIC LEVEL SWITCH, 18.0 FT INFO1,870.001,496.00
LU77-5004 ULTRASONIC LEVEL SWITCH, 9.8 FT INFO1,725.001,380.00
LU78-5004 ULTRASONIC LEVEL SWITCH, 26.2 FT INFO1,960.001,568.00


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  • Select sensing range of 9.8' (3.0m) or 26.2' (8.0m)
  • LCD display with digital push-button calibration
  • NEMA 4X enclosure
  • Non-volatile memory
  • 3″ maximum beam width
  • Integral timer for pump or valve delay
  • Pump simplex, duplex, or triplex control modes
  • 4-20 mA output can be used to provide local or remote level indication

Supply Voltage:95-250 VAC

Signal Output:

LU77: 4-20 mA @ 500Ω, 2-wire isolated sinking

LU77/8:Relay outputs, no continuous current

Measurement Range:

LU77 :4” to 9.8' (10 cm to 3m)

LU78: 8” to 26.2' (20 cm to 8m)

Memory: Non Volatile

Relay Type:(3) SPDT

Relay Rating:3 SPDT, 60 VA, 1A maximum


LU77:4″ (10.1 cm)

LU78:8″ (20.3 cm)

Repeatability: ±0.25″ (6.35 mm)

Operating Pressure:30 psig (206.9 kPA)

Process Temperature:-4° to 140℉ (-20° to 60℃)

Beam Width:

LU77: 2" (5.1 cm) diameter

LU78: 3" (7.6 cm) diameter

Fail Safe: Selectable: open, closed or last hold

Conduit Connection:Dual, 1/2″ NPT

Process Connection:

LU77:1″ NPT

LU78:2″ NPT

Operating Temperature -7° to 140℉ (-22° to 60℃):

Enclosure Rating:NEMA 4X (IP65)

Dimensions: 5.2″H x 5.2″W x 3.9″D (13.3 x 13.3 x 10.0 cm)


w/o bracket:1.5 lb (0.7 Kg)

w/ bracket:2.1 lb (0.75 Kg)

Approvals: CE, RoHS

Warranty: 1 year


Download Additional Data

document   LU77 78 Install Manual