Video: How to Choose an Irrigation Meter for your Application

by Karin Grinzel on June 1, 2011

Liesbet Michiels, Seametrics Applications Engineer, describes different water flow meter options for consideration with your irrigation application. She highlights paddlewheel flow meters and a couple of Seametrics magmeters, how they work, and where they would be most suitable. We’ve provided some graphical elements to help you visual learners out there, and the verbal explanation helps those of us who need to see AND hear before we understand.

Seametrics manufactures a variety of flow meters for industrial, municipal, and irrigation applications. Product specifications and instructions are viewable under the downloads section of our website.

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Transcript of Video:
Hi. My name is Liesbet and I’m here to talk to you about how to choose an appropriate irrigation meter for your application.

There are two main types of irrigation meters, and there is one distinct difference between the two. One has moving parts and the other does not.

Here is an example of a propeller meter. You may already be familiar with this meter; it’s been around for over 50 years. It’s pretty easy to see how this meter works. As water flows through the pipe, it spins the propeller. The spinning motion is then carried into the head of the meter through either gears or a cable. In fact, some early versions of these meters actually used surplus drive cables from speedometers. The propeller meter has stuck around for so long because it’s easy to understand and relatively inexpensive. It also holds up great as long as the water is clean.

This is the most common problem. If you go around and look at a number of propeller meters, chances are you’ll find some that have stopped moving. As sand and grit get into the bearings that support the propeller, they’ll get worn out quickly. If the bearings become worn out they can jam or drag and make the propeller run slow.

Magmeters

This meter has also been around for 50 years, but not in irrigation. It has typically been used in the Municipal and Industrial water and wastewater applications. The technology on these meters has advanced so much that they can now be battery powered. This makes them great for irrigation use.

The increase in technology has also allowed for the cost of these meters to come down, making them more affordable than they once were.

The magmeter works the same as the alternator in your car. By Faraday’s law, as a conductive material such as irrigation water goes through a magnetic field it creates a small voltage. If you measure that voltage and you know the size of the inside of your meter, then you can calculate how much water is flowing through your pipe. The advantage of the magmeter is that there are no moving parts to wear out. This is very valuable in applications such as river or well water monitoring where there may be silt or grit in the water. Another advantage of the magmeter is that it doesn’t require nearly as much straight pipe as the propeller meter in order to function properly. In most cases it’s possible to connect the meter very close to an elbow and still get an accurate reading. Plus, telemetry and data logging are already built into this meter.

This is the Seametrics AG2000 Magmeter. There are a set of coils in here that create a magnetic field. Then on the inside are the electrodes that pick up the voltage and bring it up into the head of the meter. In the head of the meter there is a processor chip that then converts this signal into the rate and total indicated on the meter.

AG702

This meter is a segment of tubing, then a stationary pod mounted in the center. Inside the pod are electrodes and coils just like in the AG2000. There are no moving parts in this meter.

So, where would we recommend using a magmeter for irrigation? The worse the water quality, the more it makes sense to use a magmeter. If you have had previous experience with bearings wearing out, a magmeter may be a good option. If you don’t have much straight pipe in your configuration, we recommend the AG2000. If easy installation is more important to you, the AG702 might be the better meter for you.

Irrigation metering is here to stay as responsible water metering becomes more important. Meters can be a useful tool for water conservation and maximizing production through best irrigation practices.

For more information, please visit www.seametrics.com.

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