There are several different types of water meters that are commonly used for measuring water usage in residential, commercial, and industrial settings. The most common types of water meters are briefly described below.
Single-jet
Single-jet water meters are among the oldest meters available. They use a rotating impeller that is driven by the flowing water coming through one jet. They must be installed horizontally with the register facing upwards to ensure accuracy and prevent premature wear on the bearing shaft.
Most are not ideal for low flow rates or water with a high level of impurities. For these reasons, we do not offer single-jet meters.
Multi-jet
Multi-jet water meters are similar to single-jet. Most also must be installed horizontally with the register up. The difference is that they split the water flow into multiple jets which provides better accuracy at lower flow rates. They will also tolerate impurities better.
Multi-jet meters are a time-proven technology and are amongst the most common found in residential water metering applications.
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Positive Displacement
The single and multi-jet meters above both rely on the velocity of the water, The impeller spins based on that velocity. If there is drag on the impeller from debris, worn components, or improper installation, the meter will under measure. Positive displacement type water meters, however, will not allow any water to pass without being metered
There are 3 common types of positive displacement meters:
• Nutating Disc
• Oscillating Piston
• Oval Gear
Shop for Positive Displacement Water Meters
Ultrasonic
Unlike traditional water meters that rely on mechanical components to measure flow, ultrasonic water meters use sound waves to determine the velocity of the water passing through the meter. They are capable of measuring both high and low flow rates accurately and are not affected by changes in water temperature, pressure, or density. Additionally, they are less prone to wear and tear since they do not have moving parts that come into contact with the water.
Ultrasonic water meters are commonly used in residential, commercial, and industrial settings where accurate measurement of water flow rates is essential. They are particularly useful in situations where traditional meters may struggle, such as in environments with high levels of sediment or air bubbles in the water.
The USM Series Ultrasonic Flow Meters install inline, but there are also "clamp-on" types that don't even require the pipe to be cut... no plumbing involved! at Flows.com we offer 2:
Bluebot for sizes 1/2" to 2" (larger coming soon)
Streamlabs only for 3/4"
Turbine
Turbine flow meters work like a windmill or pinwheel. The turbine is placed directly in the center of the flow path and has angled blades or vanes that cause it to rotate when moving fluid passes through. There is a small magnet embedded in one of the blades or somewhere on the turbine. Each time this magnet passes a sensor, it creates a pulse. Measuring the number of pulses allows for the calculation of flow rate and volumetric total.
There are also mechanical turbine meters that use a geared drive train to advance a register. The turbine spins the numbered dials revolve, and the numbered roller wheels roll, just like the multi-jet meters above
It is crucial for the water to be clean and free from debris of any kind, especially fibers, which can get stuck in the turbine and render the meter inaccurate. Strainers are typically recommended upstream.
3, 4, and 6 inch Mechanical Turbine Water Meters
Paddle Wheel
Paddle wheel water meters are extremely similar to turbine meters. The difference is that the paddle wheel has flat blades and the axis that it spins on is perpendicular to the flow rather than parallel. The paddle wheel is also placed where only one half of the wheel is in the side of the flow path. The other half is hidden in a pocket outside of the flow path.
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Magnetic Inductive
Magnetic inductive flow meters, often called Mag Meters, are similar to ultrasonic meters, but they measure the velocity of the liquid using magnetic fields rather than sound waves. They have no moving parts. The one important item to note is that the liquid must have a certain level of conductivity. You may be surprised to learn that not all water is conductive. De-Ionized and Reverse Osmosis water is TOO PURE to be conductive.
Pulse (Output) Meters
Mechanical water meters with pulse output use a small reed switch that closes each time a magnet passes by it. These pulses represent an even unit of measure. 1 pulse per gallon, 1 pulse per cubic foot, 10 pulses per gallon, 1 pulse per 10 gallons, etc. The pulses are received by whatever device the meter is connected to. Digital displays, wireless transceivers, PLCs, and control panels are a few common applications.
The connected device sends a small voltage signal on one of the two wires that lead to the reed switch. When the reed switch closes, that signal is returned to the device on the other wire.
One downfall of this type of output is that if by chance the meter runs in reverse due to a backwards flow (which you do not want to happen! - add a check valve) it will pulse just the same... so your device will record another pulse as though it was forward flow even though the register is subtracting.
Some digital meters use a different called "active voltage" where it simply transmits a short duration electric pulse on it's own.
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Encoded (Output) Meters
In contrast with pulse output, there are now meters with encoded output. In these meters, the physical register is actually read by a sensor each time it is called upon to do so. In this case... reverse flow will actually subtract from the total because it rolls the register backwards.
Pit Rated
If meters are to be installed in a pit, they require certain characteristics that are not necessary on meters that are installed indoors.