Positive displacement flow technology allows for precise flow measurement of most clean liquids. When liquid flows through a positive displacement flowmeter, two oval geared rotors measure a constant volume per rotation, within a precisely machined measuring chamber. With each rotation, a constant volume of liquid is measured. The rotation of the oval gears is sensed by means of magnets embedded within the rotors.

Process control instrumentation and industrial electronics company Instrotech supplies Kobold DOE, an oval gear flowmeter that uses positive displacement flow technology. The meter can be used with a wide range of media and chemicals and the aluminium version is particularly suited for applications with motor and heating fuels or lubricating liquids.

The embedded magnets transmit a high-resolution pulse output. The output signal can be processed externally by means of a remote display controller or programmable logic controller, or by means of a variety of output/display options available as accessories attached to the flowmeters.

The positive displacement flow technology allows for precise flow measurement of most clean liquids regardless of the media conductivity, and other liquid properties also have a minimal effect on the performance of this type of meter. Flow profile conditioning is not required, as it is with other flow technology options, making oval gear installations simple to install in tight spaces and at an economical price.

Technical specifications of Kobold DOE:

• Pressure up to a maximum of 64 bar
• Temperature up to a maximum of 80 °C
• Viscosity range of up to 1000 cP
• Accuracy of about 1% of reading
• Material: stainless steel
• Pulse output

Product features include:

• Compact measuring device
• Exact measurement, even with significant temperature differences between supply and return
• Can be used in harsh conditions such as rain, snow, salty atmosphere
• Durable
• Economical

The meter is most often used for the measurement of diesel engine fuel consumption in transport or conventional power plants. One DOE is installed on each fuel pipe, both the supply and return pipes, and the differential flow computer ZFC determines the actual fuel consumption. Temperature sensors are used to increase the accuracy of the measurement and the flow computer can compensate for the effect of fuel expansion due to increasing temperatures.