Maximizing Accuracy and Efficiency: The Advantages of a Transit Time Ultrasonic Flow Meter

Discover the power of ultrasonic flow meters for precise and reliable measurement of fluid flow. Our cutting-edge ultrasonic flow meter technology provides accurate readings without the need for intrusive installation or disrupting the flow. Monitor and optimize your water processes with ease, ensuring efficiency and cost savings. Explore the benefits of bluebot ultrasonic flow meters and revolutionize your flow measurement capabilities today.
homeowner installing bluebot, a transit time flow meter for water pipes

Are you tired of inaccurate readings and unreliable measurements from your traditional flow meters? It’s time to upgrade to a transit time ultrasonic flow meter.

More specifically, a transit time flow meter that offers non-invasive installation, improved accuracy, and real-time monitoring capabilities, like bluebot.

In this blog, we’ll dive into the history and evolution of transit time ultrasonic flow meters, explore their various applications, and discuss why they’re a smart choice for your flow measurement needs.

See how Hawaii University used bluebot to save $3,500,000 in water credits and enable campus expansion >

The Evolution of Ultrasound Technology

When people think of ultrasound they unusually think of the technology used to see an unborn baby in the womb. It’s interesting to think that over the last 60 years, ultrasonic technology has evolved to accurately and reliably measure fluid flow as well. 

Today, transit-time flow meters like the bluebot smart water flow meter and app have been innovated so that any homeowner or property manager can utilize the unique and powerful advantages of ultrasound.

Invented in 1959 by Shiego Satomura, the first use of ultrasound to measure flow still had medical uses. Satomura designed an ultrasonic flowmeter using the Doppler Effect for use in blood flow analysis. 

Over the next 30 years, ultrasonic flow measurement technology evolved. 

However, it wasn’t until the mid-1990s that transit-time ultrasonic technology emerged as the leading ultrasonic flow technology as it does not depend on dirty or sonically conductive fluids to operate.

Now that we have a better understanding of the history and evolution of ultrasonic flow measurement technology, let’s explore the differences between the two most commonly used types of ultrasonic flow meters: Doppler ultrasonic flow meter and transit-time ultrasonic flow meter.

Doppler Ultrasonic Flow Meter vs Transit-Time Ultrasonic Flow Meter

When it comes to ultrasonic flow meters, there are two main types: Doppler and transit-time. While both use ultrasonic technology to measure fluid flow, they operate in different ways and have their own unique advantages and disadvantages.

Doppler Ultrasonic Flow Meter

Doppler ultrasonic flowmeters measure the velocity of a fluid with ultrasound to calculate volumetric flow. Doppler ultrasonic flow meters are extremely effective in applications involving dirty process fluids that are water-based or sonically conductive. This limited their broader use in industrial applications.

Pros & Cons

The main advantage of a Doppler meter is that it can measure the flow of opaque fluids, such as slurry, without the need for a clear view of the fluid. However, Doppler meters can be less accurate at low flow rates and may not be suitable for clean fluids.

Transit-Time Ultrasonic Flow Meter

Transit-time ultrasonic flow meters measure the difference in time from an ultrasonic signal transmitted from one upstream transducer until it crosses or “transits” the inner pipe and is received by a secondary downstream transducer. 

A comparison between upstream and downstream measurements is then made. If there is zero flow, the transit-time will be the same in both directions. When flow is present, sound moves faster traveling with the flow and slower if moving against it. The difference in the upstream and downstream transit-time measurements is used to calculate the flow through the pipe.

Pros & Cons

Transit-time ultrasonic flow meters are more commonly used in applications where the fluid is clean and has no particles or bubbles. They’re generally more accurate at low flow rates and have a wider range of applications. The main disadvantage of a transit-time meter is that it requires a clear view of the fluid, which can be a challenge in some applications

3 Types of Transit-Time Flow Meters

Three versions of transit-time flow meters are used in industry today. These are in-line, insertion, and clamp-on. In addition, industrial versions can measure both gas and liquid.


The most accurate transit-time flow meters are in-line, multi-path flow meters that use sometimes dozens of ultrasonic transducers for extremely accurate measurement on natural gas pipelines where the meter is used as a billing or custody-transfer meter on the supply of large quantities of natural gas. Custody transfer versions cost from $50,000 to $300,000 each, so they are not ideal for general purpose.


The majority of ultrasonic flow meters used in general industry are clamp-on ultrasonic flow meters. These clamp-on versions measure liquids in industries ranging from industrial manufacturing and petrochemical to facilities management and water/wastewater applications.


Insertion transit-time ultrasonic flow meters are an alternative to clamp-on and in-line models. As the name suggests, insertion meters are inserted into a pipe to measure flow. These meters are ideal for situations where an in-line meter cannot be used due to pipe size or material. They work by inserting two ultrasonic transducers into the pipe and measuring the time it takes for an ultrasonic pulse to travel from one transducer to the other.

Industries and Applications for Transit-Time Ultrasonic Flow Meters

Transit-time ultrasonic flow meters have a wide range of applications across various industries due to their accuracy, reliability, and versatility. Let’s explore some examples of how these flow meters have been used in different industries and applications.

Industrial Manufacturing

In the industrial manufacturing sector, transit time ultrasonic flow meters have been used to measure and monitor the flow rate of liquids, such as coolants and lubricants, in machining and manufacturing processes. 

By accurately measuring the flow rate, manufacturers can ensure that their machines are operating at optimal levels and avoid costly downtime due to machine failure or poor performance.


In the petrochemical industry, transit time ultrasonic flow meters have been used to measure the flow rate of various fluids, including crude oil, gasoline, and other refined petroleum products. 

Accurate flow rate measurement is essential for the efficient and cost-effective operation of petrochemical plants, as well as for environmental compliance and safety.

Facilities Management

In facilities management, transit time ultrasonic flow meters have been used to measure and monitor the flow rate of water and other liquids in heating and cooling systems, such as HVAC systems. 

This enables facilities managers to optimize energy usage and reduce costs while maintaining a comfortable indoor environment for building occupants.


In the water and wastewater industry, transit time ultrasonic flow meters have been used to measure and monitor the flow rate of water and other fluids in municipal water systems and wastewater treatment plants. 

By accurately measuring flow rates, these systems can ensure that the proper amount of treatment chemicals and other additives are added to the water, and that the treated water meets regulatory standards before it is discharged back into the environment.

Each of these applications has unique requirements and challenges, but transit time ultrasonic flow meters have proven to be a versatile and reliable tool for measuring and monitoring fluid flow in a wide range of industries and applications.

The bluebot Transit-Time Ultrasonic Water Flow Meter

The bluebot water flow meter has its roots in general industrial transit-time technology. The current breed of clamp-on ultrasonic meter is highly advanced, with critical improvements such as increased data acquisition speed, speed-of-sound measurement and digital communications. The bluebot capitalizes on the latest advancements in increased signal resolution capability making it capable of measurement down to a true zero flow condition.

Because transit-time clamp-on flow meters attach to the exterior of the pipe, have no moving parts, and are able to measure a wide range of pipe sizes and types with a single unit, the overall cost of ownership is much lower than common inline devices that need to be resized at increased cost as the pipe gets larger.

Try a bluebot transit-time flow meter to start tracking your home water usage today!