Electro optic systems and liquid level sensors

Traditional liquid level sensors based on pressure (diaphragm), mechanical or magnetic floating devices have moving parts in them. These moving parts make them less rugged, dependable and reduce their useful life.

Conductivity probes have no moving parts but are limited to conducting liquids and cannot be used for hydrocarbons. But more recently with the advent of electro optic systems, level sensing technology has undergone a sea change.

These systems are simple, solid state devices with no moving parts and are economical, compact in size and lightweight.

The electro optic systems based on infrared technology have an infrared emitter and an optical receiver.

When only air is present in the object to be sensed, all the light emitted is reflected internally by the dome of the probe and returned to the receiver. When there is liquid, a large amount of rays emitted is absorbed / refracted by the liquid.

As the amount of rays picked up by the receiver reduces when liquid is present, the IR sensor senses the presence of liquid.

The response time of these sensors is very fast, almost instantaneous and detection accuracy is +/- 2 mm.

IR sensors can be mounted in any angle and top, side or bottom fitted.

They can be used for a variety of liquids including water, oil, CO2 etc. They have long life and are reliable.

They can withstand extreme temperatures, pressures, vibrations and shocks.

They can have different output types.

They can be directly connected to a PLC system for further processing of the output signal.
They have a wide operating temperature range from - 40 deg C to +125 deg C.

The IR sensors are not affected by the liquid hardness or conductivity and hence can be used in any geographical area without any alteration.

They do not require recalibration.

They can sense the levels of clear, translucent, reflective, as well as opaque liquids.
These liquid level sensors have a programmable timer inside for delaying the output switching. It increases the reliability of the output and takes care of any transients in the input like waves, bubble, foams etc.

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Liquid Level Sensors

Monitoring the level of liquid can be accomplished through the use of a pressure transducer. The density of the liquid and its height create pressure on the diaphragm of the pressure transducer to generate an accurate and cost effective level measurement. Generally, pressure transducers can be used for level measurement from 10 inches of water column, up to 10,000 PSI (700 bar).

Pressure transducers can either be submerged in the liquid or mounted externally. Submersible pressure transducers can be installed freely or with a rigid conduit to monitor the hydrostatic liquid above it. As the liquid level decreases, the output decreases. Submersible sensors are commonly used in vented tanks such as diesel tanks or for water and waste water level.
 
Pressure transducers can also be mounted to the side or bottom of the tank through a separate line, feed line or drain line. This design can cost less, as it doesn't require a special cable, and installation is quick. Differential pressure transducers can be used on vented or sealed tanks, measuring the difference in pressure between the top and bottom of the tank.

Custom Liquid Level Sensors
AST manufactures a variety of custom liquid level sensors and solutions for OEM applications. If you find a product that is close to a solution, but not exactly what you hoped for, please contact us and an engineer will follow up with you regarding our custom capabilities for pressure ranges, outputs, sizes and materials.

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Liquid Level Sensors & Switches

Gems liquid level sensors and switches provide high-reliability monitoring and detection of a wide range of fluid media. Requirements can range anywhere from the sensing of cooking oil, to hydraulic fluids, to diesel fuel tanks (gas level indicator), to water and wastewater, to biohazards, to even deionized or potable water.

To effectively address such a wide variety of measurement challenges, Gems offers a broad range of contact, non-contact, and non-intrusive liquid level sensors and switches. These are available in multiple technology types, including magnetic reed switch-based floats, solid-state electro-optical, conductivity, capacitive, ultrasonic, and piezo-resonant. Multiple liquid level sensing technologies may also be incorporated within a single application. Sometimes, more than one “best fit” solution may also exist, with the ultimate decision simply a matter of customer preference.

Standard catalog products for liquid level sensing include single point level switches, continuous level transmitters, multi-point level switches, chemical vapor deposition (CVD) pressure transducers, coolant level sensors, and visual level indicators. Detailed specifications on these and other liquid level sensors and switches may be found in the links below.

Please consult our fully digital online standard product catalog for an up-to-date listing of available models for immediate customer shipment. Most Gems standard catalog products can be easily modified with alternate connectors and housings. Or, a custom solution can also be developed, many times delivered in OEM volumes with shorter lead times than most industry off-the-shelf solutions.

Still not sure what your application requires?  We are happy to help. Please give us a call on 1-855-877-9666. Or, feel free to simply use our convenient Contact Us form, and a member of our sales and engineering team will be in touch within one business day.

Find out why a growing number of liquid level sensing customers have placed their trust in Gems. Contact us today for a free application assessment.

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