Product Overview
Hi-G Electro-Optic Point Level Switch with Conical Prism Probe
Condition
Unused new old stock (NOS). Markings legible: LIQUA SENSE, HI-G ELECTRONICS, WINDSOR LOCKS, CT., LQD-5. Brass threads and hex flats are clean with no evidence of prior mounting. Sold each.
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Product Overview
Manufactured by Hi-G Electronics under the Liqua-Sense line, model LQD-5 is a solid-state electro-optic liquid level sensor designed for point fluid detection. The unit uses a conical prism optical probe tip to detect the presence or absence of liquids through internal reflection and refraction. When dry, light internally reflects back to the internal photodetector; when immersed in fluid, light refracts into the surrounding liquid, altering the output signal. Housed in a solid brass hex body with male pipe threads, the sensor provides four male spade terminals for power, ground, output, and testing.
Key Features
- Solid machined brass hex body with integral male pipe threads
- Electro-optic sensing via conical prism tip with no moving parts
- Four spade quick-connect terminals clearly stamped GND, OUT, IN, and TEST
- Point-level fluid detection via internal reflection and refractive index differential
- Documented operating temperature range of -32°C to +121°C (-25°F to +250°F)
Applications
- Monitoring coolant, hydraulic fluid, or lubricant reservoirs in industrial machinery.
- Detecting high- or low-level fluid conditions in marine, automotive, or stationary equipment tanks.
- Integrating into custom maker fluidics test benches or automated liquid transfer rigs.
Frequently Asked Questions
How does the optical sensing probe detect liquid?
The conical tip functions as a prism. In air or gas, the internal light source reflects off the conical faces back to the photodetector. When immersed, the liquid changes the refractive index, letting the light escape into the fluid and triggering the output switch.
What do the four electrical terminals connect to?
The terminal board at the rear features four male quick-connect tabs stamped IN (supply voltage), GND (ground), OUT (switched signal output), and TEST (diagnostic check line).
What thread type is on the brass body?
The housing has tapered male pipe threads for direct threaded installation into tank walls, fluid manifolds, or pipe fittings.
A solid brass optical sensor from the era of indestructible industrial monitoring, using pure refraction instead of floats that stick. Thread it in, hook up the spades, and let physics handle your tank levels.
