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Glass switches for harsh industrial environments

Complementing its standard Optomax liquid level switch offering, SST Sensing’s Optomax industrial glass devices are targeted at installation within harsh industrial environments. Due to their stainless-steel construction and glass sensor tip, these single point liquid level switches exhibit elevated operational robustness. As a result, these devices are suited to applications where they are exposed to extreme temperatures (up to 125°C) and high pressures (up to 600bar).

The switch can detect the presence or absence of almost any liquid type, whether it is oil or water based. As an infra-red (IR) signal is used, the device is not impaired by the effects of ambient light, nor is its accuracy affected by foam when in air or by small bubbles when in liquid. An array of different N and P type output configurations can be specified – allowing the sinking or sourcing of up to 1A of current at supply voltage ranges from 4.5V to 15.4VDC or 8V to 30VDC (thus optimising it for integration within modern industrial automation systems). These also allow the output to be configured so that either a high or low signal corresponds to a wet or dry state respectively. Options for connecting to inductive loads or digital interfaces are also available.

Relying on the same optoelectronic technology as the other devices in the Optomax family, the Optomax industrial glass switches each comprise an IR emitter and a phototransistor. When the sensor tip is in air, the IR emitter and phototransistor are optically coupled to one another (with the light emanating from the emitter being internally reflected off the inside of the tip). If, however, the tip becomes immersed in a liquid, some of the IR signal will be dispersed rather than being reflected. The change in this signal will trigger a reaction from the built-in microcontroller connected to the phototransistor. Via this mechanism, the switch offers a highly accurate and responsive way of detecting the presence of liquid.

Since they are free of moving parts, the sensors do not require ongoing maintenance. Their low-profile construction allows them to be integrated into small spaces, as well as tanks with stirrers and agitators. They can be mounted in horizontal or vertical orientations.

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