Flow Tube

Instrumentation flow tube is a specially designed section of piping used to house and support flow-measurement instruments so that fluid flow can be measured accurately and repeatably.  It provides a controlled internal geometry, as a precise diameter, smooth bore, and defined length, ensuring that the flow profile passing through the instrument (for example, an orifice plate, venturi, flow nozzle, magnetic sensor, or ultrasonic path) is well defined and stable.  Flow tubes are typically manufactured to tight tolerances and installed with sufficient straight pipe lengths upstream and downstream to minimize turbulence, swirl, and flow disturbances.  In industrial applications, instrumentation flow tubes are essential for reliable measurement of flow rate, mass flow, or velocity in process control, energy monitoring, and custody transfer systems.

Common Instrumentation Flow Tube Types  -  Instrumentation flow tubes come in various types, each designed for specific applications and measurement principles.

• Orifice Plate  -
  
  • Description  -  An orifice plate is a thin plate with a hole (orifice) in the center.  When fluid flows through the orifice, the pressure drop across the plate is measured to determine the flow rate.
  • Application  -  Commonly used in industrial processes for measuring the flow of liquids and gases.
• Venturi Tube  - 
  • Description  -  A Venturi tube is a constricted tube that causes a pressure drop in the fluid as it passes through the narrow section.  The pressure difference is used to calculate the flow rate.
    
  • Application  -  Used for measuring the flow of fluids in pipelines.
• Rotameter  -
  
  • Description  -  A rotameter consists of a tapered tube and a float.  As the fluid flows through the tube, the float rises, and the position of the float indicates the flow rate.
  • Application  -  Commonly used for measuring the flow of gases in laboratories and industrial processes.
• Magnetic Flow Meter  -
  
  • Description  -  Utilizes a non-conductive tube with electrodes on opposite sides.  A magnetic field is applied, and as the conductive fluid flows through, a voltage is generated, which is proportional to the flow rate.
  • Application  -  Suitable for measuring the flow of conductive liquids.
• Coriolis Flow Meter  -
  
  • Description  -  Involves a vibrating tube through which the fluid passes.  The Coriolis effect causes a distortion in the tube's motion, and sensors measure this distortion to determine the mass flow rate.
  • Application  -  Provides accurate measurements for various fluids, including liquids and gases.
• Ultrasonic Flow Meter  -
  
  • Description  -  Uses ultrasonic waves to measure the velocity of the fluid.  Transit time or Doppler shift principles are commonly employed.
  • Application  -  Suitable for a wide range of fluids and pipe sizes, including liquids and gases.
• Vortex Shedding Flow Meter  -
  
  • Description  -  Utilizes a bluff body placed in the fluid stream.  Vortex shedding occurs, and the frequency of vortices is proportional to the flow rate.
  • Application  -  Commonly used for measuring the flow of liquids and gases.
• Differential Pressure Flow Meter  -
  
  • Description  -  Measures the pressure drop across a restriction in the flow path, such as an orifice or a venturi tube.
  • Application  -  Widely used in various industries for measuring the flow of liquids and gases.

The choice of flow tube depends on factors such as the type of fluid, flow range, accuracy requirements, and the specific conditions of the application.