Flow measurement is an action to measure the flow of liquids, gases and vapors using a flow measurement instrument or device, which measures the rate of flow or the quantity of flow. We measure flow in industrial processes, utility pipelines, HVAC systems, municipal water and wastewater, automotive, food and pharmaceutical plants, hospitals, commercial and retail stores, weather stations, our homes, and many more. Flow measurements indicate flow rate, flow total, flow velocity, the absence of flow, presence of flow, too much flow, too little flow, and flow direction.
Electromagnetic flowmeters or mag flowmeter for short. Uses the simple principle of Faraday's Law of electromagnetic induction to calculate the speed/velocity of liquids in a pipe. This concept is ideal in conductive liquids such as waste water, mud, pulps etc.
- Clamp-on (contained).
- Open-channel (exposed).
Open channel concept uses the free flow of water through Manning's equation to calculate the total volume of water the flows in a preset condition i.e. Parshall flumes, v-notch weirs, rectangular weirs etc. They use ultrasonic pulses to measure the depth and velocity of the water.
Process manufacturing usually requires temperature measurements. These range from finding the temperature of fluid (liquid or gas) within a pipe or vessel to determining how hot an equipment surface is. Either contacting or non-contacting methods can provide readings.
A direct measurement requires immersing a temperature sensor in the medium, allowing heat to flow through a thermowell or other component to the sensing element. The most common temperature sensors used for direct measurements at plants are thermocouples (TCs) and resistance temperature detectors (RTDs).
Pressure measurement is the analysis of an applied force by a fluid, liquid, or gas on a surface. Pressure is normally measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressure and vacuum. Instruments used to measure and display pressure in an integral unit are called pressure meters or pressure gauges or vacuum gauges. The most widely known used gauges is the Bourdon gauges which is a mechanical device, which both measures and indicates.
Accurate pressure measurement is critical in any process. It can be life or death in extreme cases. Pressure is the second most common measurement in process control, after temperature. Measurement equipment should be regularly calibrated and provide accurate data to ensure the process runs safely and smoothly.