Connections Between Flow Switches, Flow Sensors, and Flow Meters
1. Jointly Serving Flow Measurement and Control
Whether in simple fluid conveying systems or complex industrial automated production lines, these three types of equipment are designed to achieve accurate measurement, monitoring, and control of fluid flow, ensuring the safe and efficient operation of production processes. They are widely used in industries such as petrochemicals, water treatment, energy, food and beverage, etc.
2. Cooperating and Working in Synergy
In many complex fluid control systems, flow switches, flow sensors, and flow meters are often used in conjunction. Flow sensors provide basic flow measurement signals for flow meters; flow meters perform precise metering and data processing of flow; and flow switches monitor and control based on the set flow threshold. When abnormal flow occurs, they promptly send signals to activate corresponding protection or control measures.
3. Concept Scope
Flow sensor is a relatively broad concept, referring to a device used to detect fluid flow and convert it into a usable signal for output. Both flow switches and flow meters fall under the category of flow sensors and are specific product forms of flow sensors adapted to different application scenarios.
4. Monitoring Based on Fluid Properties
The working principles of all three are related to the properties of fluids. Flow sensors determine flow by detecting changes in the velocity, pressure difference, vibration, etc., of the medium flowing through the pipeline. Flow switches usually judge whether the flow reaches the set value based on pressure changes, flow velocity changes, or other related physical properties caused by fluid flow. The measurement principle of flow meters is also based on various physical properties of fluids—for example, vortex flow meters detect flow by using eddy currents and oscillations generated when fluid passes through a vortex street.
5. Signal Conversion and Output
All of them need to convert fluid flow information into electrical signals or other forms of signals for output. Flow sensors convert flow signals and transmit them to subsequent processing equipment or control systems; flow switches output switch signals (usually on-off signals) when they detect that the flow reaches the set value, to realize the control or alarm of equipment; the flow data measured by flow meters is also output in specific signal forms, such as analog signals (4-20mA) or digital signals, for display, recording, and control.
Distinctions Between Flow Switches, Flow Sensors, and Flow Meters
Category
Function
Accuracy
Output Form
Flow Switch
Mainly used to detect whether the fluid flow reaches the set threshold and output a switch signal. When the flow exceeds or falls below the set value, it triggers the switch action to control the start/stop of related equipment or issue an alarm.
Relatively low accuracy; usually only able to judge whether the flow is within a specific range, not to accurately measure the specific value of flow.
Generally switch output, such as normally open or normally closed contact signals, digital signals (high level/low level), etc.
Flow Sensor
Can detect changes in fluid flow and convert flow information into electrical signals for output. It enables continuous flow measurement.
Higher accuracy than flow switches; can provide relatively accurate information on flow changes.
Outputs electrical signals, such as voltage signals, current signals, or digital signals, which can be transmitted to the control system for further processing.
Flow Meter
A specialized instrument for measuring fluid flow. It can accurately measure the flow rate and perform functions such as flow accumulation, display, and recording. It usually has high accuracy and stability, and can meet various strict flow measurement requirements.
Varies by type; some high-precision flow meters can achieve very high measurement accuracy. The measurement range of flow meters is usually wide, which can adapt to flow measurement needs of different magnitudes.
