Sight Flow Indicators

A sight flow indicator, as the term implies, indicates the level, flow, and characteristics of fluid in the process pipeline. You can see through this indicator which is mostly made of metal with a glass portion making the inside fluid visible. It can be mounted either horizontally or vertically. At Cannon Water Technology, we offer various types of sight flow indicators which helps you accurately measure the liquid or gas levels and attributes. They are made of sturdy metals such as brass or steel with a glass portion in between.

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    Neptune FI-20 Flow Indicators

    5% accuracy, Polysulfone and CPVC with 316SS float. Male pipe connections. Rated to 150 psi at 120°F(10.3 bar at 48.9°C)

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    Neptune FI-10 Flow Indicators

    5% accuracy, Polysulfone and CPVC with 316SS float. Male pipe connections. Rated to 150 psi at 120°F(10.3 bar at 48.9°C) 

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    Neptune FI-5 Flow Indicators

    5% accuracy, Polysulfone and CPVC with 316SS float. Male pipe connections. Rated to 150 psi at 120°F(10.3 bar at 48.9°C) 

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    Neptune FI-2 Flow Indicators

    5% accuracy, Polysulfone and CPVC with 316SS float. Male pipe connections. Rated to 150 psi at 120°F(10.3 bar at 48.9°C) 

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    Neptune FI-1 Flow Indicators

    5% accuracy, Polysulfone and CPVC with 316SS float. Male pipe connections. Rated to 150 psi at 120°F(10.3 bar at 48.9°C)

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How Does a Sight Flow Indicator Work?

These indicators employ a mechanical or electronic mechanism to detect and display the fluid flow rate within a system. They consist of an impeller positioned within the fluid path and respond to the force exerted by the flowing fluid. When the fluid flows, it applies pressure onto the impeller, causing it to rotate proportional to the flow rate. This movement of fluid can be moved through the glass. In some designs, magnetic coupling facilitates movement detection, involving coupling the impeller to a magnetic element, which interacts with a sensor outside the fluid path. The magnetic field changes with the impeller's movement, allowing the sensor to detect fluid movement.

What Parts do Sight Flow Indicators Comprise?

The construction of these indicators depends on the intended application and their usage. Here is a general overview of how they are constructed.

  • Body: The body or enclosure of these indicators play a vital role as all crucial components are housed inside it. These indicators' bodies are made of durable and chemically resistant material such as brass, stainless steel, or plastic. The physical and chemical properties of these materials make them suitable to work even in challenging environments.
  • Flow Tube: This is one of the essential components of these indicators through which the fluid flows. This flow tube is usually transparent, allowing visual observation of the flow. Flow tubes are made of materials such as acrylic or glass.
  • Indicator Mechanism: This shows the flow rate of the fluid that passes through the flow tube. This mechanism varies depending on the type of flow indicator used. For instance, a rotating paddlewheel can be used in paddlewheel flow indicators, while in a variable area flow meter, a float or piston may be used to indicate the flow rate.
  • Scale: Most sight flow indicators have a scale alongside the flow tube. This scale shows numerical or calibrated markings indicating the flow rate. This helps users interpret the flow rate depending on the position of the indicator mechanism.
  • Inlet and Outlet Connections: These connections act like enter and exit points. They allow the fluid to enter from an inlet connection and exit from another connection. Depending on the installation requirements these connections may be threaded, flanged, or designed for specific types of fittings.
  • Seals and Gaskets: They are used at critical points, such as connecting components, to ensure leak-free operation. These seals prevent the fluid from escaping or entering areas where it shouldn't flow.
  • Mounting Hardware: Depending on the application requirement, these indicators may include mounting hardware, such as clamps or brackets, to attach the device to a mounting surface securely.

Installation and Maintenance Guidelines for Sight Flow Indicators

The installation process of industrial sight flow indicators involves several steps to ensure efficiency and safety. Here is a general guideline for installing these indicators.

  • Select the Location: It is important to choose an appropriate location where these indicators can be easily observed. Consider factors such as accessibility for maintenance and visibility for monitoring flow.
  • Preparing the Pipeline: Make sure the pipeline to be used is depressurized and the flow of the substance through the pipeline is shut off. Clean the surrounding area from dirt, debris, or contaminants that may affect installation.
  • Mounting the Sight Flow Indicator: Ensure the indicator being used is compatible with the size and material of the pipeline. Install the required adapters or fittings to connect them to the pipeline. Mount these indicators using appropriate hardware such as clamps or bolts. Follow the manufacturer's instructions for the installation process.
  • Connect the Pipeline: Next, connect the indicator to the pipeline. Ensure all connections are tight with zero scope for leakage; this ensures seamless operation. Use appropriate gaskets or thread sealants to ensure a proper seal between the indicator and the pipeline.
  • Testing: Once done with the installation, open the indicator to check the fluid flow through the pipeline. Check for leakage or spills around the indicator, and ensure all the connections are tightened securely. Observe the flow through the flow indicator to ensure it matches the expected direction and rate.
  • Calibration: Some flow indicators may require calibration to ensure appropriate flow readings. If you don't know how to calibrate flow indicators, follow the manufacturer's instructions.
  • Securing and Finalizing: Check if everything is functioning correctly. If yes, then secure the remaining connections and fittings. Label the flow indicator to ensure easy identification and monitoring in the future.
  • Safety Precautions: When working with pipelines and industrial equipment, use appropriate personal protective equipment (PPE) such as gloves and safety glasses. Ensure proper ventilation and containment measures are in place while working with hazardous substances.
  • Documentation: Document the flow indicator installation, including calibration procedures and test results. Document the indicator's location for future reference.
  • Regular Maintenance: Inspect the flow indicator periodically for any signs of damage or wear. Clean and maintain them for clear visibility of flow.

You can install a sight flow indicator in your pipeline system with the pointers above. Always refer to the installation instructions provided by the manufacturer for your particular sight flow indicator model.

How Do You Choose the Right Sight Flow Indicators for Your Applications?

There are several factors to consider when selecting appropriate sight flow indicators for your applications. These factors help ensure functionality, reliability, compatibility, and more. Here are some key factors that will help you make a firm decision.

  • Fluid Compatibility: The compatibility of the flow indicator with the fluid type flowing through the enclosed system is a critical parameter to consider. Factors such as chemical composition, temperature, pressure, and fluid viscosity can all impact compatibility. These indicators must be compatible with the specific fluid type to ensure reliable and accurate performance while avoiding damage or deterioration. For instance, corrosive fluids may require flow indicators constructed from corrosion-resistant materials like stainless steel or certain plastics.
  • Pressure and Temperature Ratings: Flow indicators must withstand the system's operating conditions without compromising safety or accuracy. Manufacturers typically provide these ratings, and they must match the application requirements. It's essential to adhere to these ratings to maintain the integrity and functionality of these indicators, thereby enhancing the safety and efficiency of industrial processes.
  • Flow Rate Range: This is another important parameter when evaluating visual flow indicators. Select the appropriate flow indicators with a wide range to accommodate fluctuation in flow.
  • Visibility and Size: Optimal visibility and the size of the flow indicator must be considered for easy flow monitoring, thereby ensuring safe and efficient operation. Check the indicator's size and ensure it fits within your system without any interference.
  • Material of Construction: The construction material is one of the crucial considerations as it impacts the indicator's performance, compatibility, and durability. Different materials are used for constructing these materials, such as stainless steel, brass, or aluminum, as well as plastics such as PVC. This is decided based on factors such as the fluid's chemical composition, temperature, pressure, and operating conditions.
  • Mounting Options: Choose the appropriate flow indicator that offers suitable mounting options. Before making any firm decision, consider factors such as horizontal or vertical mounting, and threaded or flange connections.
  • Sealing and Gasketing: The industrial sight flow indicator you select must provide a secure seal to prevent leaks and maintain the integrity of the pipeline system. Ensure the indicator has O-rings, gaskets, or seals that provide a tight seal between the indicator and the pipeline.
  • Maintenance and Serviceability: Consider the lifespan and maintenance of the flow indicator. Select a model that allows easy cleaning, testing, inspection, and the replacement of components if required.
  • Certifications and Compliance: Ensure the sight flow indicator meets relevant industry standards and regulations for your application. Check for certifications such as ISO, ASME, ANSI, or FDA compliance, where applicable.
  • Cost: It is important to consider your budget, which can vary widely depending on factors such as features, construction materials, brand reputation, and supplier pricing.

By carefully evaluating these factors and selecting an appropriate flow indicator that meets your specific requirements, you can ensure precise flow monitoring and efficient operation of your pipeline system.

Beneficial Features of Sight Flow Indicators

These indicators are useful in many process industry applications which need regular continuous monitoring of fluid level and properties. Here are some beneficial features of these indicators we offer.

  • They are ideal for low to medium pressure applications around 100-150 psig.
  • Their maximum operating temperature is around 100 degrees Celsius.
  • We can offer clamps, threaded NPT connections, ANSI-certified flanges, and so on along with the indicators, if required.
  • We offer good quality indicators and help you in the selection process once we understand your requirements.
  • They can be easily attached to pipeline fittings and fixtures through threaded connectors, flanges, welding or clamp connections.
  • They are simple to use and involve no electronics or complicated circuits.
  • They are cost effective and offer accurate output.


Visual sight flow indicators are used across industries where manual systems still exist. Here are some application areas:

  • Food & Beverages
  • Oil & gas
  • Chemicals
  • Pharmaceutical
  • Medical
  • Agriculture
  • Environmental
  • Water & wastewater

Frequently Asked Questions and Answers on Fluid Flow Indicators

Here are some commonly asked questions about fluid flow indicators by our clients.

  • Are Sight Flow Indicators Capable of Handling Corrosive or Abrasive Fluids?

Yes, some fluid flow indicators are designed to handle corrosive fluids. We offer indicators made from materials that can resist corrosion to ensure durability and reliability.

  • How Do I Maintain a Sight Flow Indicator?

Our fluid flow indicator requires minimal requirements when handling carefully. The maintenance of sight flow indicators involves:
• Periodic inspection to prevent damage or wear.
• Regular cleaning to maintain visibility.
• Proper sealing to prevent leaks.

  • Are There Any Additional Accessories Required for the Installation of Sight Flow Indicators?

Depending on the installation requirements and specific application, sight flow indicators may require additional accessories such as mounting brackets, flanges, gaskets, and seals. These accessories help ensure proper installation and functionality.

  • How Accurate Are Sight Flow Indicators in Measuring Flow Rates?

The accuracy of flow indicators varies depending on factors such as design, construction, and installation.

  • Can Flow Indicators be Retrofitted onto Existing Pipelines?

Yes, most of our flow indicators can often be retrofitted onto existing pipelines, provided there is sufficient space and compatibility with the pipeline material and operating conditions. However, it's essential to ensure proper installation to prevent leaks or other issues.

  • Do Sight Flow Indicators Require Regular Calibration?

Sight flow indicators typically do not require regular calibration. However, it's essential to periodically inspect and maintain sight flow indicators to ensure proper functionality and accuracy.

If you are looking for these indicators for your existing pipelines, we can help you in terms of getting the right type and fitment. Cannon Water Technology offers various types of visual sight flow indicators in terms of temperature and pressure ranges, depending on your application requirements. If you have any questions regarding the indicators we offer, our highly experienced and resourceful team is there to help you with all your enquiries as well as technical questions. In case of you want to enquire about these flow indicators or share your requirements, you can reach us via phone or email.