Eastern Instruments - Solids Mass Flow and Air Flow Measurement Equipment

Know Your Flow Experts answering your Process Questions   The Question: Should I use a Multivariable Pressure Transmitter or DP-only Transmitter for Air Flow Measurement? The Expert: James Seagraves Senior Sales Engineer, Eastern Instruments - Over 30 years of experience in Air Flow and Solids Flow Measurement This is a question I receive all the time, as both types of transmitters measure the differential pressure (DP) of the air flow in a duct. To provide the best answer, let's first review the fundamentals of air flow measurement. Basics of Air Flow Measurement A Typical Pitot Tube in an Air Stream Typical Pitot Tube in an air stream One of the most reliable and time-tested methods of measuring the air flow in a duct is to use a differential pressure device like a pitot tube.  The pitot tube is inserted into the air stream to measure the pressure differential created between the High port and Low port on the pitot, also known as the Dynamic or Velocity Pressure. High Port (...

When it comes to measuring the flow rate of air or gas in a duct, there are many different devices used.  For example, there are thermal sensors, hot wire anemometers, rotating vane anemometers, static pressure drop devices (venturi, orifice plate), and differential pressure devices (pitot, annubar, primary element).  The most widely used and considered a true measurement of the flow is the differential pressure device.  The most widely used differential pressure device is a velocity averaging pitot tube. Velocity Averaging Pitot Tube The velocity averaging pitot tube is a device that when inserted into the air or gas flow stream, provides a high pressure measurement port and a low pressure measurement port.  The high pressure port measures the total pressure created when the air or gas stream impacts the port, where the low pressure port typically measure the static pressure in the duct. VAP³ Velocity Averaging Pitot Tube from Eastern Instruments The dif...