Improved Dosing Performance by Using Flow Meters
Published on : Friday 01-12-2023
It is important to measure critical fluids very accurately to draw the right conclusions in time.
A pilot plant is an important step between a lab scale and a large production scale. In the chemical industry, it is common to build pilot plants to minimise risks in the final plant, especially in advanced chemicals.
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 flow meters for low flow rates.
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 back pressure 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 a 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.
Ultrasonic or Coriolis?
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 mini-CORI-FLOW Coriolis flow meter measures the mass flow accurately and reliably, independent of fluid properties.
Alternatively, if the highest precision is not required, cost-effective ultrasonic flow meters of the ES-FLOW series instruments can be applied in combination with a control valve or pump.
These volumetric liquid flow meters are available for flow ranges between 2 and 1500 ml/min, using ultrasound in a very small, straight tube. The innovative operating principle of ES-FLOW is independent of fluid density, temperature, and viscosity. By default, the electronics of the flow meter include a PID controller for optional flow control. Combining an ES-FLOW ES-103I flow meter with a GEMÜ 650 pneumatic diaphragm valve makes an excellent, compact, hygienic flow controller (3-A authorised) for a wide range of applications within the food & beverage market.
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