8 reasons to use low-flow Coriolis mass flow instruments
Coriolis mass flow instruments have several key features that set them apart from other mass flow measurement solutions and make them ideal for use in many applications. Here, we highlight compact Coriolis instruments (for flow rates ≤ 100,000 g/h) which excel in precision low-flow and high-pressure processes.
1. Direct mass flow measurement
Coriolis instruments measure the mass flow rates of liquids and gases directly. To do this, the process fluid is directed through a vibrating tube. As it flows, the fluid causes a change in the tube’s vibration which is measured by sensors in the Coriolis instrument. This change is directly proportional to mass flow rate (read more about the Coriolis flow meter operating principle). Since this measurement is independent of conditions such as pressure and temperature, the measurement accuracy is consistent even if conditions change throughout the process.
2. Measurement independent of fluid composition
Since Coriolis instruments measure mass flow directly rather than by calculating from known fluid properties, the composition of the process fluid can be unknown or changing. As long as the fluid is compatible with the instrument’s wetted materials, a change in the percent composition will not affect the measurement accuracy. It is important to note that most low-flow Coriolis instruments require the fluid to be in single-phase.
3. Changing between different fluids
A single Coriolis instrument can switch between measuring different fluids. There are only two recommendations:
- Completely flush out the instrument before switching between fluids.
- Tare the instrument each time a new fluid is used.
This versatility enables you to use a single instrument for a variety of different processes.
4. Wide dynamic range
Most compact Coriolis instruments operate across a high dynamic range (the ratio between the largest and smallest measurable flow rates). Alicat’s CODA-Series Coriolis instruments have a dynamic range of 500:1, meaning the full-scale flow rate is 500x higher than the minimum measureable flow rate. Make sure to check the instrument’s technical spec sheet and ensure the dynamic range is sufficient for your application.
5. Fast response
These features don’t slow the Coriolis instrument down. Coriolis mass flow instruments have response times that are comparable with DP and MEMs technology, and are much faster than thermal bypass mass flow meters. Alicat’s standard CODA-Series Coriolis instruments have a T98 response time of less than 100 ms for meters and 500 ms for controllers (T98 is the time it takes for the signal to reach 98% of a new flow rate).
6. Compact package
Many low-flow Coriolis instruments boast a small form factor, making them viable for applications with tight or limited space. For example, the standard CODA KM meter weighs no more than 1.5 lb (0.7 kg), and is just over 4.2 inches (107 mm) in the largest dimension. These instruments leave a small footprint without compromising capability.
7. No annual re-calibration required
Most mass flow instrument types require annual re-calibrations, but Coriolis meters and controllers do not. While the initial price for these instruments may be higher than other instruments, the savings from not having to recalibrate annually mean lower long term ownership costs.
8. Convenient installation
Most Coriolis instruments are position insensitive and can be mounted in any orientation, making them flexible to the needs of a wide variety of applications. It is often recommended to simply tare the instrument after making these changes. Additionally, straight runs of pipe are typically not required upstream or downstream of the instrument. This makes it easier to integrate Coriolis instruments into highly complex systems with minimal disruption of design.