Flow Meters & Metering Systems

I may be a third generation “meter man” but small water meter connection sizing has made me question my heritage.

Why does a 1” meter not have 1” pipe thread on the threaded end?  Why do 1.5”-2” meters have female threads when their smaller cousins have male thread?  For that matter, why do 1.5” & 2” meters have oval flanges and 3” and above have round flanges?  Now I know this will get me in real trouble, but why do meters being installed on ¾” pipe and 1” pipe say 5/8” and ¾” respectively on the dial faces?  What are all the color coding of odometer dials about and why are their so many different variants of body, housing and bottom plate materials?

Trying not to look dumb, I have researched some of these questions and thought I would share them with you, just in case you wanted to know the answers as well.

<strong>Water Meter Connections:</strong>

Instead of taking a sleeping pill you are welcome to read the American Waterworks Association standards C700 or C708 or their M-5 manual on water meter installation but here it is in nutshell.  Water Meter body sizing nomenclature historically lists the measuring chamber and internal diameter/bore size as the first number and the pipe size the meter is installed on, as the second number in the sizing.  For instance a 5/8”x3/4” meter has a 5/8” measuring chamber and 5/8” bore size and is installed on a ¾” pipe. <a href=”http://www.avanticompany.com/forms/C700sizing.pdf” target=”_blank”>Click here to view a chart with more details.</a>

While all this may seem confusing, through personal experience a ½” external straight thread will take a ¾” internal pipe thread connection.  ¾” external straight thread will take a 1” internal pipe thread connection and 1” external straight thread will take a 1.5” internal pipe thread connection.  If you don’t believe me you can make a Coupling tower of a ½”,3/4” and 1” coupling sets.  I find this useful when I have recently been trying to explain this issue to customers.

As you note from the chart 1.5” and 2” water meters are available in both internal pipe thread and two bolt oval flanged versions.  Due to the weight of these meters the internal pipe thread is thought to be more stable on the pipe and the 2 bolt oval flange is for ease of retrofit installation.

Another question frequently asked is why does the meter register have 5/8” printed on it for a 5/8”x3/4” meter going on a ¾” pipe.  The reason for this is that the 5/8”x1/2” meter and the 5/8”x3/4” meter have the same measuring chamber and use the same register.  Remember from our earlier discussion that the first number in the sizing sequence is also the measuring chamber size.  This also applies to the ¾”x1” meter that is installed on a 1” pipe but says ¾” on the register face.

<strong>Register Dial Faces:</strong>

I think that reading water meter dial faces is simple if you forget everything except the odometer.  You read the odometer left to right and what you see is what you get.  On a 5/8”x3/4” water meter for example  1234560 is 1,234,560 gallons on a US Gallons register.  Most Utilities bill in 1000 gallon increments and the odometers reflect this by having the far left wheels in white with black print representing thousands, ten thousand, hundred thousand and millions of gallons.  The two dials on the right and the fixed zero are black wheels with white print which represent non-billable units or hundreds, tens and ones.  The fixed zero is represented by a meter test sweep hand on the register.  In our previous example if the reading was 1234560 and the sweep hand was on the 3, the actual meter reading would be 1,234,563 US Gallons.  You will find two fixed zeros on 1” meters and a one hundred gallon sweep hand.  This is to accommodate larger volumes of water so the odometer can go to 100,000,000 gallons before turning over instead of 10,000,000 gallons on the smaller meter.

There are some other important features of the register that may help you:

Leak detector – This is a white or black triangle attached to the center of the sweep hand and goes around on a one to one ratio with the measuring chamber.  This is used to identify that the oscillating piston in the measuring chamber is moving.  Most utilities have customers turn off all the water in their homes and then check the leak detector to see if the customer has a leak on their side of the meter.

Manufacturing date code – The register should have an imprinted month and year date on the dial face, which is the date of Manufacture that the Company uses to determine age of the meter and warranties.

Meter information – The meter model number, register part number, chamber size (as previously explained), Calibration (i.e. US Gallon, Cubic Feet, M3) are also displayed on the meter.  Elster AMCO meters also have a 2P or 4P on the register.  This is the number of poles the register magnet has and is used to make sure the register magnet and chamber magnet match.

<strong>Water Meter Trim Variants:</strong>

The Elster AMCO 5/8”x3/4” C700 water meter can be ordered in over 2000 different variants. Many of the variants available today on residential water meters come from customer requests from decades ago.  Manufacturer’s quality processes and materials have improved so much that most customers can use the standard meter configuration with no problems.  The Standard meter consists of a bronze case, glass lens register and polymer register housing, lid and bottom plate.  I wanted to understand why all the variants existed so I asked some questions.  Here are the answers:

Main Case – The main cases are available in traditional bronze alloy, low lead bronze and polymer case ( in some sizes).  Traditional Alloy and Low Lead main cases are a customer requirement based legislation they must follow, but Polymer meters were popular in the early eighties and have lost favor with most customers.  They are still popular in industrial applications especially where bronze is not the best material.

Register material – While meters are available with polymer and glass lens we only sell glass lens meters in Florida for pit applications.  Polymer lens meters can be installed in basements in the North inside.

Register Housing material – Register Housings are available in polymer and bronze.  Some customers require bronze housing for reasons of length of service but most utilities today except polymer housing as the polymer materials have improved and are sufficient for the service requirements.

Bottom Plate materials –  Bottom plates are available in polymer, bronze and cast iron.  polymer and bronze bottom plates fall in the same category as housing materials but the cast iron bottoms are traditionally used in the north for frost protection.  The cast iron bottom is designed to fracture when the meter freezes to prevent damage to internal parts of the meters.  Florida meter pit set applications can use cast iron bottom plates but polymer is the standard.

I hope this information has cleared up some of the oddities of residential water meter connection sizing and helps you explain these things to your customers.

Note:  I would like to thank the Second Generation “meter man”  John Corey for his input and assistance with the editing of this article.

<em>Eric Corey is Avanti’s South Florida Sales Representative and son of John Corey, Avanti’s metering systems manager, who has been in the industry for 30 years. Eric’s grandfather James Corey, founded Corad meters.</em>

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