What Is a Micro Flow Meter?
- A micro flow meter is a flowmeter that can measure very low flow rates. In the case of liquids, a micro flow meter is a flowmeter that can measure fluids with flow rates lower than a liter per minute. However, there is a wide range of microflow meters that can measure flow rates as low as microliters (0.001 milliliter/minute).
The measurement methods of micro flow meters vary from manufacturer to manufacturer, and the performance of micro flow meters is improving day by day as the stability of measurement, the range of viscosity of the fluid that can be measured, and the minimum flow rate that can be measured are all contested.
Uses of Micro Flow Meters
Microflow meters are used in chemical, food, and pharmaceutical plants where small amounts of chemicals must be handled accurately. In these plants, the continuous supply of small quantities of chemicals in constant quantities affects the quality of the products, making micro flow meters highly necessary.
Microflow meters are also indispensable for lens polishing and silicon wafer polishing operations, where very small amounts of abrasives must be supplied regularly.
Principles of Micro Flow Meters
There are various methods of measuring micro flow rate and new measurement methods are still being developed, but the following three methods are representative.
- Anemometer Method
In this method, a heater is heated to a certain temperature in the liquid flow. The higher the flow rate, the more heat is lost from the heater, requiring more power to maintain the heater at a certain temperature, while the lower the flow rate, the less power is required. The anemometer method uses this amount of power to measure the flow rate. - Calorimetric Method
This method places two temperature sensors upstream and downstream in the fluid, with a heater between the sensors. The presence of the heater between the sensors creates a temperature difference between the upstream and downstream of the fluid, which is measured. In other words, a faster flow velocity will create a smaller temperature difference between upstream and downstream. Conversely, a slower flow velocity equates to a larger temperature difference, making it possible to measure the flow velocity. - Time of Flight (TOF) Method
In this method, a heater is installed upstream of the fluid and a temperature sensor is installed downstream. The temperature of the fluid heated by the upstream heater when it reaches the downstream temperature sensor is measured to determine the flow rate.