Flow measurement challenges are process conditions that make it hard for a flow meter to read accurately. The most common are unpredictable flow fluctuations, high-viscosity fluids, low flow, turbulence, varying fluid densities, corrosive media, pulsating flow, vibration, and limited straight pipe runs. Each one can be managed with the right flow meter technology and installation practices.
Key Takeaways
- Vortex flow meters such as the DVH, DVE, and DVZ help hold accuracy when flow fluctuates, since shedding frequency is directly proportional to flow velocity.
- Positive displacement meters like the DON and OVZ are built for viscous media, and the DON with custom rotor elements is rated to 1,000,000 cP.
- The BGK/KDS and KDF variable area flow meters measure low flow rates accurately, for both liquid and gaseous media.
- The DUC measures flow in both directions, so it can monitor pulsating or reversing flow that would throw off a conventional one-way flow meter.
- Variable area flow meters such as the BGN and VKM have no straight run requirements, so they suit installations with limited straight pipe runs.
Here is each challenge in this guide, matched with the KOBOLD flow meters recommended for it.
| Challenge | Recommended KOBOLD models | Why they work |
|---|
| Unpredictable flow fluctuations | DVH, DVE, DVZ | Pulse output from vortex shedding, whose frequency is directly proportional to flow velocity |
| High-viscosity fluids | DON, OVZ | Positive displacement design for viscous media; the DON with custom rotor elements is rated to 1,000,000 cP |
| Low flow | BGK/KDS, KDF | Variable area meters that accurately measure low flow rates of liquids and gases |
| Turbulent flow | DVE, DVZ, DVH | Measure the lateral force of shed vortices, even in fluctuating or turbulent conditions |
| Varying fluid densities | DON | Oval gear positive displacement design stays accurate when density varies over time or between batches |
| Corrosive media | MIK, KSK | Wide variety of material combinations designed to withstand harsh, corrosive environments |
| Pulsating or bi-directional flow | DUC | Measures flow in both directions |
| High vibration | DF, DON, MIM | Engineered to operate reliably under significant vibration |
| Limited straight pipe runs | BGN, VKM, DF, DON | No straight run requirements (DF and DON for a variety of applications) |
Unpredictable flow fluctuations impacting measurement accuracy
Unpredictable flow fluctuations can distort flow profiles, introduce noise, and compromise sensor performance, leading to inaccuracies in flow measurements. These fluctuations may arise from changes in fluid velocity, turbulence, or environmental conditions, posing challenges for maintaining measurement accuracy in dynamic fluid environments.
Our Solution for Unpredictable Flow Fluctuations
The pulse outputs of KOBOLD's DVH, DVE, and DVZ flow meters, which operate based on the vortex principle, can help maintain measurement accuracy in scenarios where unpredictable flow fluctuations occur, as the frequency of the vortex shedding is directly proportional to the flow velocity, allowing for dynamic adjustments to compensate for irregular flow patterns.
Difficulty in obtaining accurate flow meter readings for high-viscosity fluids
Traditional flow meters may struggle to accurately measure the flow rates of high-viscosity fluids, leading to inaccuracies in measurement data. Additionally, these fluids may alter the flow profile within the meter, further complicating readings. To address these challenges and ensure precise measurements, specialized flow metering technologies and advanced calibration techniques are often required.
Our Solution for High-Viscosity Fluids
KOBOLD's positive displacement flowmeters, such as the DON and OVZ models, are designed to accurately measure high-viscosity media, making them suitable for a wide range of applications involving the flow measurement of viscous substances like petroleum, oils, and pastes. Our DON with custom rotor elements is even rated to 1,000,000 cP!
Inadequate flow meter performance in low-flow conditions
In low-flow conditions, flow meters may struggle to maintain measurement accuracy due to reduced flow velocities and flow rates approaching the lower limits of their operating range. This can result in measurement errors, fluctuations, or even signal loss. Selecting flow meters with a wide turndown ratio and employing appropriate calibration techniques can help mitigate these challenges and improve performance in low-flow conditions.
Our Solution for Low-Flow Conditions
KOBOLD offers a variety of products, including the BGK/KDS and KDF series variable area flowmeters, which are capable of accurately measuring low flow rates for both liquid and gaseous media, making them ideal solutions for applications requiring precise measurement of low flow conditions.
Challenges in accurately measuring flow rates for turbulent flow conditions
Turbulent flow conditions can cause flow disturbances, such as eddies and vortices, which can interfere with flow meter performance and accuracy. Traditional flow meters may struggle to maintain stability and precision in turbulent flow environments, leading to measurement uncertainties. Advanced flow metering technologies, such as ultrasonic and Coriolis flow meters, offer improved performance in turbulent flow conditions, providing accurate and reliable measurements despite the challenges posed by turbulence.
Our Solution for Turbulent Flow
KOBOLD's vortex flowmeters like the DVE, DVZ, and DVH rely on the vortex shedding phenomenon. As turbulent media flows past an obstruction, alternating low-pressure vortices are created and shed downstream. These vortices create a lateral force that can be accurately and repeatedly measured by the flowmeters to determine the flow rate, even in fluctuating or turbulent conditions.
Concerns about flow meter accuracy with varying fluid densities
Changes in fluid density can impact flow meter accuracy by altering the flow profile and affecting the performance of the flow meter sensor. Traditional flow meters may be calibrated for specific fluid densities, leading to inaccuracies when operating with fluids of different densities.
To address this challenge, some flow meters employ density compensation techniques or offer configurable settings to accommodate varying fluid densities and maintain measurement accuracy across different operating conditions.
Our Solution for Varying Fluid Densities
While we offer many options not directly impacted by density changes, in circumstances where density fluctuations are a concern, we would recommend our DON flow meter line. The DON Oval Gear Positive Displacement Flow Meters are designed to provide accurate and reliable flow measurement even when the density of the fluid being measured varies over time or between batches.
Inadequate flow meter performance in corrosive media environments
Corrosive fluids can damage flow meter components, degrade sensor accuracy, and affect measurement reliability over time. Flow meters made of incompatible materials may be susceptible to corrosion in aggressive chemical environments, leading to decreased performance and shortened lifespan.
Selecting flow meters with corrosion-resistant materials and protective coatings, and implementing proper maintenance practices, can help mitigate corrosion effects and ensure long-term performance in corrosive fluid environments.
Our Solution for Corrosive Media
When dealing with corrosive media, KOBOLD's MIK and KSK models provide a rugged solution for maintaining accurate flow measurement. These flowmeters are available in a wide variety of material combinations all designed to withstand harsh, corrosive environments.
Challenges in obtaining accurate flow meter readings for pulsating flows
Pulsating flows can cause fluctuations in flow rates, leading to measurement errors and inaccuracies in flow meter readings. Certain flow meter technologies may struggle to accurately capture rapid changes in flow velocity and flow direction associated with pulsating flows, resulting in distorted measurement data.
Our Solution for Pulsating Flows
For applications involving pulsating or bi-directional flow, KOBOLD's DUC flow meter provides a solution to overcome the challenges of obtaining accurate readings. This flow meter can measure flow in both directions, enabling it to reliably monitor fluctuating or reversing flow conditions that would compromise the accuracy of conventional one-way flow meters.
Inadequate flow meter performance in environments with high levels of vibration
High levels of vibration can disrupt flow meter operation, causing sensor drift, signal noise, and mechanical failures. Certain flow meter types may be sensitive to vibration-induced disturbances, leading to measurement inaccuracies and reduced reliability. Mounting flow meters securely, using vibration-resistant materials, and implementing vibration isolation techniques can help mitigate the effects of vibration and maintain flow meter performance in vibrating environments.
Our Solution for High Vibration
We offer a wide range of vibration-resistant flowmeters designed to ensure adequate performance, including our DF, DON, MIM, and a number of other flow meter models. These KOBOLD solutions are specifically engineered to operate reliably and provide accurate measurements even when subjected to significant vibrations.
Concerns about flow meter accuracy in installations with limited straight pipe runs
Insufficient straight pipe runs can cause flow disturbances, flow profile distortions, and measurement inaccuracies in flow meter readings. Some flow meter technologies require a certain length of straight pipe upstream and downstream of the meter to achieve optimal flow conditions and maintain measurement accuracy.
Selecting flow meters with built-in flow conditioning elements or using flow straighteners and flow regulators can help mitigate the effects of limited straight pipe runs and improve measurement accuracy in constrained installations.
Our Solution for Limited Straight Pipe Runs
Our solution for limited straight run installations is our line of variable area flow meters, such as the BGN and VKM, which provide accurate measurements without any straight run requirements. We also offer other options like our DF and DON flow meter lines that can measure without straight run requirements for a variety of applications.
If one of these challenges is affecting your process, our engineers can help you choose the right flow meter in a free engineering consultation.
Common Questions
Shifts in fluid velocity, turbulence, and the surrounding environment can all make flow swing without warning. Those swings bend the flow profile and add noise to the signal, which pulls readings off. The DVH, DVE, and DVZ vortex meters help here, because their pulse output tracks how often vortices shed, and that rate follows flow velocity.
Yes. The KOBOLD DUC reads flow going either way, so it can reliably follow flow that pulses, fluctuates, or reverses. A conventional meter built to read in only one direction would lose accuracy under those same conditions, which is why the DUC is the recommended choice when flow can change direction.
Variable area meters such as the KOBOLD BGN and VKM read accurately with no straight run, which makes them a natural pick for cramped piping. The DF and DON lines can also do without straight pipe in a variety of applications. For other meters, built-in flow conditioning or a flow straightener can ease the effects of a short run.
Three installation practices help: mount the meter firmly, use materials that stand up to vibration, and isolate the meter from the shaking. A vibration-resistant meter adds another layer of protection. KOBOLD's DF, DON, and MIM are among the models engineered to keep reading accurately when the line is exposed to significant vibration.
Match the meter's materials to the fluid. A meter built from incompatible materials can corrode in aggressive chemicals, losing performance and wearing out early. Corrosion-resistant materials, protective coatings, and good maintenance habits all extend service life. KOBOLD's MIK and KSK come in many material combinations made for harsh, corrosive service.
Positive displacement meters are built for them. KOBOLD's DON and OVZ are designed for viscous media such as petroleum, oils, and pastes, and a DON fitted with custom rotors handles fluids up to 1,000,000 cP. Thick fluids can also reshape the flow profile inside a meter, which is why many other designs struggle to read them accurately.
A vortex meter places an obstruction in the stream. As fluid moves past it, low-pressure vortices form on alternating sides and break away downstream, creating a side-to-side force the meter can measure again and again. The faster the flow, the more often vortices shed, so the shedding rate becomes the flow reading.
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