In this ‘step-in-between’, it is essential to measure the critical fluids very accurately to draw the right conclusions in time. Dosing pumps are often used in pilot plants to control liquid flow rates, whilst accurate, fast and efficient data collection is key to success. In this article, we discuss the benefits of combining dosing pumps with mass flow meters.
When measuring critical fluids, the data for making the right decisions for the final plant must be collected accurately, fast, and efficiently. If fluids cannot be measured accurately enough, tests must run for a very long time to finally collect the required data on which to base decisions. Pilot plant tests are usually very expensive, especially when they involve a long testing time. However, when a system is equipped with accurate instrumentation, the test duration can be considerably reduced.
Dosing of fluids by means of a dosing pump
A volume-based dosing pump is a typical solution to dose a certain amount of fluid into a process. This approach is sufficient for non-critical processes. If the process is critical, however, the operator must be sure that the pump is precisely dosing the correct amount. Dosing pumps cannot check their own performance. Especially if there is a leak, if the backpressure changes or if the pump chamber becomes contaminated, the indicated flow is no longer reliable. These concerns can be overcome by applying an accurate flow meter.
Pump control, using a dosing pump with flow meter
By integrating a flow meter into a process, the flow created by a dosing pump (or metering pump) can be measured and corrected. The measured flow is used to directly adjust the (rotation speed of the) dosing pump. In other words, a flow meter with (external or internal) controller functionality converts the dosing pump into an advanced closed-loop dosing system.
Mass flow meters for pump control at a pilot plant
Which type of flow meter should you choose for your pilot plant? Because a dosing pump only measures the volume mechanically, and the volume of a fluid can be influenced by many parameters, a mass flow meter would be the preferred choice. It compensates for the weaknesses of the dosing pump. A Coriolis flowmeter measures the mass flow accurately and reliably, independent of fluid properties.
Accuracy, dimensions, and robustness of the flow meter
When you are considering the purchase of a Coriolis mass flow meter, the following aspects are particularly important:
- In laboratory applications, the flow meter should perform very accurately and be repeatable to enable scientists to determine the exact ‘recipe’ for success. Specifications from manufacturers are sometimes hard to achieve in practice. It may be recommended to perform a practical test to measure the performance of such a device.
- For industrial applications, reliability and robustness are usually the most important assets. This can come at the expense of other specifications, such as accuracy. In pilot plants, however, accuracy and precision often prevail, so Coriolis mass flow meters are considered the best choice.
- A third and final important factor concerns the dimensions of all the components in a (compact) pilot plant – size matters! The most typical industrial Coriolis flow meters bring a serious amount of space and weight into the equation. Therefore, the skid or the entire system must be scaled up significantly, introducing the necessary costs and system inertia.
Dosing solutions for pilot plants
We can conclude that two worlds come together in a pilot plant: lab and industry. Dedicated instrumentation offers you the best pilot plant performance. An accurate dosing pump is a good solution for non-critical processes. For critical processes in a pilot plant, however, we recommend combining the pump with the most suitable mass flow meter, weighing up the importance of practical accuracy, compactness and robustness of the various options.
