The WIKA model OLS-2 optoelectronic level switch is used for the detection of limit levels in liquids. The OLS-2 operates widely independent of physical characteristics such as refractive index, colour, density, dielectric constant and conductivity. Measurement of level change is also done in small volumes. Signal processing is made using a separate switching amplifier, model OSA-SC.

The model OLS-2 limit level switch consists of an infrared LED and a phototransistor. The light of the LED is directed into a prism. So long as the sensor tip of the prism is in the gaseous phase, the light is reflected within the prism to the receiver. When the liquid in the vessel rises and wets approximately 2/3 of the glass tip, the infrared light beam into the liquid is interrupted and only a small portion reaches the receptor.

This difference is evaluated by the electronics and triggers a switching operation.

The instruments are very robust and designed for rough operating conditions. The installation position can be as required. Thus, the OLS-2 can be installed from above, from below, vertically, horizontally or at an angle.

The cable to the model OSA-SC switching amplifier does not need any shield, enabling easy and economic cabling. The change in the alarm direction, the sensitivity of the switching threshold, as well as a time delay of up to 8 seconds can be easily transferred to the OSA-SC via Bluetooth® app and changed individually.


Greg Rusznyak

WIKA Instruments (Pty) Ltd
Tel. +27 11 621 0000

Share this article