While both technologies can measure low flow rates; gear meters are able to accurately track and totalize intermittent flow such as in a chemical injection application.
Coriolis meters measure the mass flow directly, while a gear meter is a volumetric flow rate device. One form of measurement can be converted to the other by factoring in the fluid density (If the liquid’s temperature range is within a +/- 5°C band, one density can usually be used for all your conversions).
Low flow rates and zero-crossing applications benefit from the gear meter’s high resolution. With thousands to hundreds of thousands of pulses per liter, the gear meter can report flow rates to many decimal places. Plus, there is no “zero-drift” problem with a Max gear meter and anti-dither capabilities prevent over reporting of flow in applications that have hydraulic noise or are mounted in an area subject to vibration.
The gear meter’s resolution is based on its small displacement and high resolution encoder. The measurement principle is not velocity dependent and even at 1/200th of full scale the displacement per rotation is still within a tight accuracy band. This is in contrast to a Coriolis meter which is sized large enough to maintain a low pressure drop, but due to zero drift, usually slips outside of its accuracy band at 1/20th of full scale; basically cutting off its ability to approach or cross through zero flow.
Advantages of Max gear meters include:
- Measuring flows down to 15 cc/min
- Low pressure drop flow path reduces energy lost through metering
- Robust designs with pressure ratings to 6000 psi
- Fast response with user adjustable dither and damping settings
- Meter output linearized within 0.3% over a 100:1 range