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An Ultimate Selection Guide for Flow Transmitters

Brian Craig

July 23, 2021

Factors to Consider To Select an Appropriate Flow Transmitter

Selection Guide for Flow Transmitters

The consideration of the following factors can lead to a selection of appropriate 
flow transmitters for industrial processes.

  • Fluid Properties:

    Different types of fluids, liquids, or gases are used during industrial processes. Measuring, monitoring, and controlling the flow of certain fluids differs based on their properties. The following properties of fluid should be considered while selecting a flow sensor or transmitter.
    • State of fluid- The fluid can be liquid or gaseous which should be considered while selecting flow sensors.
    • Density- The density of the fluid can impact fluid pressure, therefore should be considered.
    • Viscosity- The fluid flow is affected by viscosity, therefore, it should be checked.
    • Chemical composition and reactivity- Several industrial fluids may react with different materials. This may lead to toxic chemical reactions, therefore chemical composition and reactivity of fluid must be tested before choosing flow sensors and transmitters.
  • Metering Setup:

    The flow sensors feature different types of flow metering setups. There are different methodologies by which the flow measurement can be performed. Commonly, the following metering methodologies are implemented in the flow sensors.
    • Orifice Plates:

      The flow sensors are sometimes equipped with orifice plates to measure the liquid flow. In this type of flow metering methodology, the pressure difference at entering and departing ends of the narrow orifice opening of the varying cross-section are calculated.
    • Venturi Tubes:

      If the Venturi tube system is incorporated in the flow sensor, the flow measurement takes place according to the Bernoulli Effect of pressure and flow variation. This type of flow sensing methodology is considered effective as 90% of pressure drop can be recovered during flow measurement.
    • Flow Nozzles:

      The flow nozzle methodology works similarly to Venturi tubes. However, pressure recovery is not done in flow nozzles. The differential pressure is calculated in order to meter the variations in the fluid flow.
    • Pilot Tubes:

      This metering setup consists of two pilot tubes of small diameter. One measures the pressure impact and the other measures the potential difference that causes the difference in flow transmission rate.

    Based on the type of metering setup utilized in the flow sensor, the sensitivity, accuracy, and other measuring, monitoring, and control capabilities of the flow transmitter differ. Therefore, consideration of metering setup must be considered.

  • Electronic Considerations:

    Since the flow transmitters are electro-mechanical devices, the electronic circuitry must be considered before buying a flow transmitter. The flow transmitters consist of electronic feedback circuitry. The efficiency of feedback circuitry defines the efficiency of the monitoring and control mechanism of the transmitter. That is why it is essential to check the electronic circuitry of flow transmitters. 

    The factors like electric input, analog current, voltage, frequency and pulse signals, etc come under the consideration of electronic considerations.

  • Accuracy:

    The accuracy of flow measurement and monitoring is essential. The transmitters with at least 0.15% accuracy should be chosen for optimum results.
  • Material:

    The material consideration is essential because the flow sensors are exposed to harsh environmental conditions, temperature and pressure fluctuations, etc. The material of the transmitter should be chosen after considering chemical tolerance, corrosion resistance, temperature tolerance, etc.
  • Quality Standards:

    The quality standards should be checked before the purchase of the flow transmitter. In order to select high-quality flow transmitters, compliance with industry standards such as ISO, RoHS, etc must be checked.

    Now that all the considerations for the selection of flow transmitters are discussed, it is essential to choose a reliable manufacturer or supplier to source these devices from. You should source from a trusted supplier like The Transmitter Shop in order to ensure the quality and performance of the flow transmitters. The company offers high-quality flow transmitters from trusted brands like Foxboro flow transmitters, Rosemount flow transmitters, etc.


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