Choosing a Water Flow Meter Type That’s Right for You

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In an age where almost everything is measured and tracked, queue in water flow meters to do just that. Imagine the piping in your home as water rushes to and fro the essential zones, how is the amount of water, the pressure of water, and so on measured and tracked? With a water flow meter!

In this article, we will focus on understanding water flow meters, their applicability, and the pros and cons of different water flow meter types. Choosing which meter will perform optimally will depend on your specific application, accuracy levels, budget, and experience with meter technology. All in all, water meters can be essential to many different industries, both commercial and noncommercial, and are therefore important to understand for any water application.

What is a water flow meter and how does it work?

A water flow meter kit measures the volume of water moving per unit of time. These meters will normally attach directly to piping and measure the amount of water flowing through the pipe per time. Most commonly this unit will be measured in liters or meters cubed per minute (L/min = m3/min), or gallons per minute (gal/min) for those lagging behind the metric system. 

A variety of designs and types of water flow meters exist, but they all achieve the same result—measuring the amount of moving water directly or indirectly. Flow meters utilize a variety of technologies from mechanical gears to electromagnetic technology to ultrasonic technology to measure this water flow. 

Think of a classic water wheel being pushed by a river, and imagine that wheel is now inside of a water pipe. Based on how fast the wheel spins it will correlate to a specific flow rate of the water inside the pipe. This is an example of direct water measurement via a mechanical flow meter.

Basically, by measuring how long it takes a volume of water to pass through the flow meter dimensions, one can relate that number to liters per minute (and the meter will perform this calculation). The advantage of each approach technology depends on the level of accuracy, maintenance, and environment in which these meters will operate.

Why would you use a water flow meter?

Water flow meters are essential to many areas where liquid is flowing, and the amount of liquid is a necessary measurement. For example, home water usage so the water company can charge for the amount of consumed water. Many chemical manufacturing processes require extremely accurate flow rates and amounts of liquid to create proper reactions and finished products. Wastewater treatment plants will need to know how much water is flowing into and out of limited volume tanks so as not to overflow or underutilize their equipment.

As you can see, water flow meters can practically apply to any industry or hobby setting like medical device manufacturing or hydroponics, respectively. Even a backyard pool setting could benefit from a flow meter to protect the pool pump from experiencing unsafe operating conditions, and so on.

What are different types of water flow meters?

Several different types of flow meters exist, all created to measure the amount of liquid flow, and work in slightly different ways. Here we will highlight the most common flow meters and areas where they are applicable:

Mechanical, or Positive Displacement, Flow Meters

Referring back to the water wheel example, a mechanical flow meter utilizes a physical wheel or gear that spins due to water flow. Therefore the gear spins and this rate is proportional to the water flow rate and can be converted to a volumetric flow rate, as is the goal of a flow meter.

Mechanical flow meters are most commonly used due to their simplicity and easy conceptual understanding. When one thinks of a flow meter they normally think of a paddle wheel, which is the main concept of a mechanical, or positive displacement, flow meter. However, due to the physical part of the meter being rotated by the water, if the water is very dirty or contains large contaminants this can degrade and break a mechanical flow meter rather easily. Therefore mechanical flow meters are best suited for clean water processes or applications. 

Vortex Flow Meters

Vortex flow meters take the flow measuring process a step further. These meters measure the flow of water with some sort of obstruction inside the meter like a fallen tree obstructs a river flow. This obstruction or tab, usually a flexible material, will vibrate back and forth creating a frequency that’s proportional to the volumetric flow rate. 

Since it’s just one tab oscillating, instead of a whole gear, vortex flow meters can be used in a wider variety of water environments since they are less prone to damage via “dirty” water. These meters can also become more advanced measuring temperature, pressure, and other variables simultaneously. 

Choosing a Water Flow Meter Type That’s Right for You
Vortex flow meter diagram

Magnetic Flow Meters

Magnetic flow meters utilize generated magnetic fields on the flowing water to measure how fast it’s flowing. These meters eliminate physical parts suspended in water, but are significantly more expensive. The largest disadvantage, however, is that this magnetic concept only works on conductive water and liquids otherwise the metallic piping will interfere with the signal and the volumetric flow rate will be incorrect. Either way, this is most commonly used in industrial settings since the cost is much higher; and magnetic flow meters provide a great option for wastewater plants since physical meters will break easily in the dirty water, yet the water is conductive due to all the contaminants.

Choosing a Water Flow Meter Type That’s Right for You
Magnetic flow meter diagram

Ultrasonic Flow Meters

Ultrasonic flow meters also take the hands-off approach by eliminating flow meter parts directly in the water. The ultrasonic principle acts like radar, bouncing sound waves in two opposite directions (downstream and upstream) to measure the time offset and therefore the volumetric flow rate. A lot of math and angles involved, but the result is an extremely low maintenance meter that measures flow rate and can be clamped on the outside of the piping—avoiding any in-line piping installation for some models.  

Choosing a Water Flow Meter Type That’s Right for You
Ultrasonic flow meter diagram

Single and Multi-jet Flow Meters

Jet flow meters are most applicable for small-scale applications as they do not operate under high or large flow rates. The meter redirects water into an internal propeller and measures the speed at which this propeller blades spin, much like a mechanical flow meter. Again, since the parts are directly in contact with water, residential and clean water applications are best for this meter.

Choosing a Water Flow Meter Type That’s Right for You
Multi-jet flow meter

Turbine Flow Meters

Turbine flow meters find a happy medium between simple concept, low price, and complex technique, high price. They are best suited for in-line pipe installations (as they require straight pipes in and out for best performance) and come in a variety of piping sizes from ⅜” flow meters to even a foot in diameter. 

These meters are also best suited for clean water applications due to the spinning parts in the water. However, at Atlas Scientific, these flow meter kits come equipped with water filters to better maintain the lifetime of these devices. Shown below is a ¼ inch flow meter with a filter.

Choosing a Water Flow Meter Type That’s Right for You

Overall, choosing which water flow meter is best suited for your specific application will depend on the cleanliness of your water, budget, and accuracy of flow measurements. For dirty water with large particulates, lean more towards magnetic, ultrasonic, and vortex meters to prevent many maintenance headaches. For smaller scale, cleaner water applications, lean on the turbine, mechanical, and jet flow meters to accurately measure flow rate.

If you would like to learn more about other water quality measurements, characteristics, or applications for water flow meters, do not hesitate to reach out to the world-class team at Atlas Scientific.

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