Water meter manufacturers (ABB, Hydrometer, Sensus Metering System—formerly Meinecke, Schlumberger, etc.) use several types of mutually incompatible “slots” to mount the OPTO sensor heads, which corresponds to the range of available OPTO sensor heads. Depending on the head type, OPTO sensors are designated by the numerical series OPTO6 through OPTO11.
In addition to the sensor head type, optical sensors are also classified according to their power consumption. The standard version of sensors designated with the code “VC” in their name requires, in the long term, connection to a data logger powered by a mains voltage source, because the continuous current consumption of a standard OPTO sensor in the range of 5 –10 mA does not allow for long-term operation from a battery or rechargeable battery. Low Power OPTO sensors, identified by the code “VLP” in their name, are designed for battery operation. The current consumption of these sensors is less than 0.1 mA, so they do not place an excessive load on the connected data logger—the telemetry unit from which they are powered. Low-power VLP sensors are typically more expensive than standard VC sensors.
