Pitot Tubes
The In-Line Flow Sensors are two Series of averaging Pitot tubes for compatible gases and liquids that provide accurate and convenient flow rate sensing, for schedule 40 pipe, when purchased with suitable differential pressure gage with appropriate range. The Averaging Flow Sensors are designed to be inserted in the pipeline through a compression fitting and available for pipe sizes from 1 to 10 in. (2.5 to 25.4 cm). Accessories include adapters with 1/4 in. SAE 45° flared ends compatible with hoses supplied Averaging Flow Sensors are designed for insertion lengths up to 24 in. (61 cm) and include a pair of 1/8 in. NPT x 1/4 in. SAE 45° flared adapters which are compatible with hoses used in the Kit. The supplied solid brass mounting adapter has a 3/4 in. dia. compression fitting to lock in required insertion length and a 3/4 in. male NPT thread for mounting in a threaded branch connection (not included).
Specifications
PITOT TUBES – INLINE FLOW SENSORS
In-Line Flow Sensors are averaging Pitot tubes that provide accurate and convenient flow rate sensing for schedule 40 pipe.
Pitot tubes have been used in flow measurement for years. Conventional Pitot tubes sense velocity pressure at only one point in the flowing stream. Therefore, a series of measurements must be taken across the stream to obtain a meaningful average flow rate.
The flow sensor eliminates the need for ‘traversing’ the flowing stream because of its multiple sensing points and built-in averaging capability.
Flow sensors are designed to be inserted in the pipeline through a compression fitting. They are furnished with instrument shut-off valves on both pressure connections. The valves are fitted with 1/8′ female NPT connections.
Standard valves are rated at 200 psig (13.7 bar) and 200°F (93.3°C). Where valves are not required, they can be omitted at reduced cost. The flow sensors are available for pipe sizes from 1′ to 10′
- Multiple sensing point measurement and built-in averaging capability eliminates the need for ‘traversing’ the flowing stream with single point velocity pressure measurement saving time
- Extremely reliable, proven technology, Pitot tubes, have been used in flow measurement for years
- All models include convenient and quick-acting quarter-turn ball valves to isolate the sensor for zeroing with 1/8 in. female NPT valve assembly process connections
- Furnished with instrument shut-off valves on both pressure connections with 1/8 in. female NPT connections rated at 200 psig (13.7 bar) and 200 degrees F (93.3 C)
- Where valves are not required, they can be omitted at reduced cost
- The Series DS-400 Averaging Flow Sensors are quality constructed from extra strong 3/4 in. dia. stainless steel to resist increased forces encountered at higher flow rates with both air and water
- Economical flow indication when used with appropriate differential pressure gage
- Rugged construction yields, non-clogging, stable design
Installation
Proper installation of Pitot tubes is essential to ensure accurate measurements of fluid flow. Here’s a detailed guide to help you through the installation process:
Planning and Preparation
Review System Requirements:
- Understand the specific requirements of your application, including fluid type, flow conditions, and measurement accuracy.
Select the Appropriate Pitot Tube:
- Choose a Pitot tube with the right size, material, and design for your application. Ensure it’s suitable for the flow velocity and environmental conditions.
Safety Precautions:
- Follow safety guidelines to prevent accidents. Wear appropriate protective gear and ensure the system is shut down and depressurized if necessary.
Gather Tools and Materials:
- You will need tools like a drill, mounting brackets, wrenches, and sealing materials. Ensure you have the Pitot tube and any additional components such as pressure lines or adapters.
Determine Installation Location
Choose a Straight Section:
- Install the Pitot tube in a straight section of the pipe or duct, preferably at least 10 times the diameter of the pipe upstream of any bends or fittings to ensure a stable flow profile.
Avoid Disturbances:
- Position the Pitot tube away from areas with flow disturbances such as valves, elbows, or other obstructions that could affect accuracy.
Check for Adequate Space:
- Ensure there is sufficient space around the installation site for access, maintenance, and proper alignment of the Pitot tube.
Install the Pitot Tube
Mounting the Tube:
- Drill the Hole: If necessary, drill a hole in the pipe or duct at the chosen installation point. Ensure the hole is clean and smooth to avoid damage to the Pitot tube.
- Insert the Tube: Carefully insert the Pitot tube into the hole. For flange-mounted tubes, align the flange with the drilled hole and secure it with bolts or screws.
- Secure the Tube: Use mounting brackets or clamps to securely fasten the Pitot tube in place. Ensure it’s positioned perpendicular to the flow direction.
Seal the Connection:
- Apply appropriate sealing material (e.g., gasket or sealant) around the installation point to prevent leaks. Make sure the sealant is compatible with the fluid and operating conditions.
Connect the Pressure Lines
Attach Pressure Tubes:
- Connect the Pitot tube’s pressure lines to the measurement instrument or transmitter. Follow the manufacturer’s instructions for proper connection techniques and materials.
Check for Leaks:
- After connecting the lines, check for leaks by pressurizing the system gently. Tighten connections or adjust seals as necessary to prevent any leakage.
Calibrate the System:
- If applicable, calibrate the measurement system according to the manufacturer’s guidelines to ensure accurate readings.
Verify Installation and Operation
Inspect the Installation:
- Check that the Pitot tube is correctly aligned and securely mounted. Ensure all connections are tight and there are no leaks.
Conduct a Flow Test:
- Run the system and observe the Pitot tube’s performance. Verify that it’s providing accurate readings and that there are no issues with flow measurement.
Adjust as Needed:
- Make any necessary adjustments to ensure optimal performance. This may involve repositioning the tube, realigning it, or fine-tuning the connections.
Documentation and Maintenance
Document the Installation:
- Record the installation details, including the location, orientation, and calibration settings of the Pitot tube. This documentation will be useful for future maintenance and troubleshooting.
Establish a Maintenance Schedule:
- Plan for regular inspections and maintenance to ensure the Pitot tube remains in good working condition. This includes cleaning, recalibration, and checking for any signs of wear or damage.
By following these installation instructions, you can ensure that your Pitot tube is set up correctly and will provide accurate and reliable flow measurements for your process line. Regular maintenance and proper care will help extend the life of the Pitot tube and maintain its performance over time.
Maintenance
Routine Inspection
Visual Checks:
- Inspect the Tube: Regularly examine the Pitot tube for any visible damage, wear, or corrosion. Look for signs of physical damage, such as dents, cracks, or bent sections.
- Check Mounting: Ensure the Pitot tube is securely mounted and aligned correctly. Verify that it hasn’t shifted or become loose.
- Examine Pressure Lines: Inspect the pressure lines for any signs of leaks, kinks, or damage.
Verify Alignment:
- Ensure the Pitot tube is still perpendicular to the flow direction and in the correct position, away from any obstructions or disturbances.
Cleaning
Frequency:
- Clean the Pitot tube as needed, depending on the type of fluid and the amount of particulate matter or deposits. In applications with high levels of contaminants, more frequent cleaning may be required.
Cleaning Procedure:
- Turn Off the System: Ensure the system is shut down and depressurized before starting the cleaning process.
- Remove Debris: Use a soft brush or compressed air to remove any loose debris from the Pitot tube.
- Use Appropriate Solvents: For more stubborn deposits, use cleaning solvents compatible with the tube material and fluid. Follow the manufacturer’s recommendations for suitable cleaning agents.
- Rinse and Dry: After cleaning, rinse the Pitot tube with clean water (if applicable) and dry it thoroughly to prevent any residual solvent or moisture from affecting performance.
Reinstallation:
- Reinstall the Pitot tube carefully, ensuring it’s positioned and secured properly after cleaning.
Calibration
Frequency:
- Regularly calibrate the Pitot tube, especially if it’s used in critical applications where accuracy is paramount. Calibration frequency depends on the application and manufacturer recommendations.
Calibration Procedure:
- Refer to Manufacturer’s Instructions: Follow the specific calibration procedures provided by the manufacturer.
- Use Calibration Equipment: Utilize calibration equipment such as a calibration rig or flow simulator to compare the Pitot tube’s readings against known standards.
- Adjust if Necessary: Make necessary adjustments to ensure that the Pitot tube provides accurate measurements. This might involve recalibrating the connected instrument or adjusting the tube’s settings.
Leak Testing
Frequency:
- Perform leak tests periodically to ensure that the connections and seals are intact. Leak tests are particularly important after any maintenance or repair work.
Leak Testing Procedure:
- Pressurize the System: Gently pressurize the system and monitor for any signs of leaks around the Pitot tube and pressure lines.
- Inspect for Leaks: Use a leak detection solution or soap and water to identify any bubbles that indicate leaks. Alternatively, use specialized leak detection equipment if available.
- Repair Leaks: Tighten connections or replace seals and gaskets as needed to address any leaks.
Documentation
Record Maintenance Activities:
- Keep detailed records of all maintenance activities, including inspections, cleaning, calibration, and repairs. Document any issues found and the actions taken to address them.
Update Maintenance Logs:
- Maintain an up-to-date maintenance log that includes dates, procedures performed, and observations. This documentation is useful for tracking the performance of the Pitot tube and planning future maintenance activities.
Troubleshooting
Identify Common Issues:
- Be aware of common issues such as inaccurate readings, blockage, or response time delays.
Perform Troubleshooting Steps:
- Check for Blockages: Ensure that the Pitot tube is free of obstructions that could affect flow measurement.
- Inspect Connections: Verify that all connections are secure and that there are no leaks or loose fittings.
- Review Calibration: Confirm that the Pitot tube is properly calibrated and that the measurement instrument is functioning correctly.
Consult Manufacturer:
- If problems persist, consult the Pitot tube manufacturer for guidance or technical support. They may provide additional troubleshooting steps or recommend service options.
Replacement
Monitor for Wear:
- Keep an eye on the Pitot tube’s performance and appearance. If significant wear or damage is observed, or if the tube consistently provides inaccurate readings despite calibration and maintenance, consider replacing it.
Follow Replacement Procedures:
- Remove the Old Tube: Carefully remove the old Pitot tube following standard safety procedures.
- Install New Tube: Install a new Pitot tube, following the proper installation instructions to ensure accurate and reliable performance.
By adhering to these maintenance procedures, you can ensure the reliable operation of your Pitot tube and maintain accurate flow measurements in your process lines. Regular upkeep will help in avoiding unexpected issues and extend the life of your equipment.
Q&A
Q1: What is a Pitot Tube and how does it work?
A1: A Pitot tube is a device used to measure fluid flow velocity. It operates on the principle of comparing the total pressure (stagnation pressure) with the static pressure of a fluid. The Pitot tube has two main parts: an impact tube that measures the total pressure when fluid flows into it, and a static tube that measures the static pressure of the fluid. The difference between these pressures, known as dynamic pressure, is used to calculate the flow velocity using the formula:
V=2ΔPρV = sqrt{frac{2 Delta P}{rho}}V=ρ2ΔP
where ΔPDelta PΔP is the difference between total and static pressure, and ρrhoρ is the fluid density.
Q2: What are the different types of Pitot tubes?
A2: There are several types of Pitot tubes, including:
- Standard Pitot Tube: Basic design used for straightforward applications in clean, steady flows.
- Pitot-Static Tube: Features additional static ports to provide more accurate measurements by reducing errors from flow disturbances.
- Multi-Point Pitot Tube: Contains multiple impact and static ports to measure flow at different points, useful for complex flow profiles.
- Customized Pitot Tubes: Tailored for specific industrial needs, considering factors like fluid characteristics and environmental conditions.
Q3: What are some common applications of Pitot tubes in process lines?
A3: Pitot tubes are used in various industries for:
- Chemical Processing: Monitoring and controlling flow rates of chemicals and reactants.
- Oil and Gas: Measuring flow rates of crude oil, natural gas, and refined products for production optimization.
- Water Treatment: Measuring flow rates in water and wastewater treatment processes.
- HVAC Systems: Ensuring proper airflow in heating, ventilation, and air conditioning systems.
- Aerospace: Measuring airspeed in aircraft to ensure safe and efficient flight operations.
Q4: How should a Pitot tube be installed for accurate measurements?
A4: For accurate measurements, a Pitot tube should be:
- Positioned Perpendicular: Ensure the tube is installed perpendicular to the flow direction to get accurate readings.
- Located in a Straight Section: Place the tube in a straight section of the pipe or duct, away from bends, fittings, or obstructions that could disturb the flow.
- Properly Sized: Choose a tube length and diameter that are appropriate for the flow conditions to minimize errors.
Q5: What maintenance is required for Pitot tubes?
A5: To maintain accuracy and performance, regular maintenance of Pitot tubes includes:
- Calibration: Periodically calibrate the tube against known standards to ensure measurement accuracy.
- Cleaning: Regularly clean the tube, especially in applications with particulate-laden fluids, to prevent clogging and ensure accurate readings.
- Inspection: Periodically inspect the tube for wear, damage, or other issues that might affect its performance.
Q6: What are the limitations of using Pitot tubes?
A6: Pitot tubes have several limitations:
- Flow Profile Sensitivity: They are most accurate in steady, fully developed flow conditions. Turbulent or non-uniform flows can lead to less accurate measurements.
- Pressure Loss: The presence of the Pitot tube can cause minor pressure drops in the flow, though this is usually minimal.
- Environmental Factors: In extreme temperatures or corrosive environments, the tube’s material must be chosen carefully to avoid damage.
- Accuracy: Factors such as tube alignment, length, and flow disturbances can impact measurement accuracy.
Q7: How does the Pitot tube measurement compare to other flow measurement devices?
A7: Compared to other flow measurement devices:
- Accuracy: Pitot tubes are generally accurate in steady flows but can be less reliable in turbulent or complex flow conditions compared to devices like electromagnetic or ultrasonic flow meters.
- Cost: Pitot tubes are typically less expensive than many other flow measurement technologies.
- Installation: Pitot tubes require careful installation and alignment, whereas other devices might offer more flexibility in placement.
Q8: What factors should be considered when selecting a Pitot tube for a specific application?
A8: When selecting a Pitot tube, consider:
- Fluid Characteristics: The type, temperature, and pressure of the fluid being measured.
- Flow Conditions: Whether the flow is steady or turbulent, and if there are any potential disturbances.
- Material Compatibility: The material of the Pitot tube should be compatible with the fluid to avoid corrosion or damage.
- Accuracy Requirements: The precision needed for your application to ensure the chosen Pitot tube meets those needs.
This Q&A guide provides a comprehensive overview of Pitot tubes, addressing common questions about their operation, types, applications, and considerations. Understanding these aspects can help in selecting and using Pitot tubes effectively in various industrial settings.
Advantages / Disadvantages
Advantages
Simplicity: Pitot sensors are relatively simple in design and operation, making them easy to install and maintain.
Cost-Effective: Compared to some other flow measurement technologies, pitot tubes can be more affordable, both in terms of initial cost and maintenance.
No Moving Parts: The lack of moving parts in a pitot sensor means there’s less wear and tear, which can lead to greater reliability and longevity.
Suitable for High-Speed Flows: Pitot sensors are particularly effective for measuring high-speed flows, such as those found in aerodynamics and certain industrial processes.
Versatility: They can be used in a variety of environments and for different types of fluids, including gases and liquids.
Low Pressure Drop: Pitot tubes cause minimal obstruction to the flow, which helps in maintaining the process efficiency.
Disadvantages
Limited Accuracy in Low-Flow Conditions: Pitot sensors can be less accurate at very low flow rates, where the pressure differential may be too small to measure effectively.
Flow Profile Sensitivity: They require a well-developed flow profile to provide accurate measurements. Distortions in the flow profile due to pipe bends, valves, or other disturbances can affect accuracy.
Susceptibility to Contamination: Particles or contaminants in the fluid can clog the pitot tube, leading to measurement inaccuracies and requiring regular maintenance and cleaning.
Not Ideal for Turbulent Flows: In highly turbulent or pulsating flows, pitot sensors may not provide reliable measurements due to variations in the flow profile.
Installation Challenges: Proper installation is critical for accurate readings. Incorrect positioning or alignment can lead to errors, and in some cases, it may require a specific installation setup to achieve accurate measurements.
Temperature and Pressure Sensitivity: The performance of a pitot sensor can be affected by changes in temperature and pressure, which might necessitate additional compensation or calibration.
Overall, while pitot sensors are a practical and cost-effective choice for certain flow measurement applications, their effectiveness can be influenced by the specific conditions and requirements of the process.
Applications
Pitot sensors are well-suited for various process applications, especially where their particular advantages align with the needs of the process. Here are some examples of process applications where pitot sensors are commonly used:
Aerospace and Aerodynamics Testing
- Application: Measuring airspeed and flow dynamics around aircraft and aerospace components.
- Reason: High-speed flow measurement and low pressure drop characteristics make pitot tubes ideal for these applications.
HVAC Systems
- Application: Measuring airflow in ducts and ventilation systems.
- Reason: Pitot sensors help in balancing and monitoring airflow, ensuring efficient heating, ventilation, and air conditioning.
Industrial Ventilation Systems
- Application: Monitoring airflow in industrial exhaust systems and cleanrooms.
- Reason: Provides accurate measurement in various flow conditions, helping to ensure proper ventilation and compliance with safety standards.
Fluid Flow Measurement in Pipes
- Application: Measuring the flow of liquids or gases in pipelines, especially in high-speed or high-pressure applications.
- Reason: Suitable for various fluids, including high-speed and high-pressure gases.
Environmental Monitoring
- Application: Measuring wind speed and direction in meteorological stations.
- Reason: Effective for capturing high-speed wind measurements with minimal interference.
Automotive Testing
- Application: Evaluating airflow over vehicle surfaces and through engine components.
- Reason: Useful in wind tunnel testing and engine performance evaluations due to its ability to measure high-speed flows.
Combustion Systems
- Application: Monitoring airflow in burners and combustion chambers.
- Reason: Helps in optimizing combustion efficiency by measuring and controlling the air/fuel ratio.
Pulp and Paper Industry
- Application: Measuring airflow in drying processes and pulp handling systems.
- Reason: Reliable for monitoring high-speed flows and ensuring efficient processing.
Chemical and Pharmaceutical Manufacturing
- Application: Monitoring airflow in reactors and processing equipment.
- Reason: Useful for maintaining controlled environments and ensuring proper reaction conditions.
Water Treatment Plants
- Application: Measuring airflow in aeration tanks and other treatment processes.
- Reason: Assists in optimizing aeration and maintaining process efficiency.
While pitot sensors are versatile and can be applied in many different scenarios, the effectiveness of the measurement will depend on factors like flow profile, flow speed, and the specific characteristics of the fluid being measured. Proper installation and calibration are key to ensuring accurate and reliable results in these applications.
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