Well Pump Flow Monitoring


Thread Starter

David Griffith

I need to interface to a flow meter at a remote location. The RTU needs to interface to a meter and digitally communicate to obtain totalized flow. Every RTU I've seen has digital I/O or analog I/O. However, I need ethernet or fieldbus communications to a smart device to read a totalized value. Any help would be appreciated.

Robert Dusza


Check out the RTUs from Bristol Babcock, Inc. The are able to talk ethernet and HART as well as a few other protocols. We are in the process of setting up a HART network for the level and flow indication at the Water plant.

Hope this helps.


Robert J. Dusza, Jr.
Treatment Manager
(V) 1-860-647-3219
(F) 1-860-647-3150
E-mail - [email protected]
Manchester Water & Sewer Dept.
125 Spring St. P.O. Box 191
Manchester, CT 06045-0191
doG, it sounds like you have to go 'round Katie's barn to get a simple variable.

What kind of RTU _is_ this?

If it is a PLC doubling in brass as an RTU, you don't need to do this, just set up a totalizer register and take a scaled pulse signal from the flow meter...in 90% of well pump installations, that is the _only_ signal the flow meter is capable of, anyway.

If that doesn't work, give us some more details.

What kind of flow meter is on the outlet of the well?

What are its outputs?

What kinds of input does this RTU have?

What math functions can it support internally?

Let us know so we can help you!

Walt Boyes

(wearing one of his other hats as Contributing Editor, Flow Control Magazine)

Walt Boyes -- MarketingPractice Consultants
[email protected]
21118 SE 278th Place - Maple Valley, WA 98038
253-709-5046 cell 425-432-8262 home office

Al Pawlowski

You didn't say whether you wanted the meter, the RTU or both.

A solution that can be used with any programmable RTU having time measurement capability and any meter with a rate output is to do (program) the totalization in the RTU. The calculation is straight forward.

If the RTU can accurately time intervals between, average the rate input (or pulse count from a pulse output meter) over an interval, multiply by
suitable scale factor, multiply by the interval time and add to the previous result.

Often the calculation intervals can not be measured accurately, but the time over which a lot of rate measurements are made can. In this case, multiply a running average (add new reading to old average, increment count of readings taken, divide by count, save both for next caculation) of the rate, the total elapsed time since starting the average and a scale factor.
Save (display) the result, but don't reset the elapsed time or average as you would for the first method. Uncertainties get averaged out as the number of rate readings, and elapsed time, increases.

For either method, don't forget to roll over your calculated totalization at an appropriate maximum count.

Al Pawlowski, PE
[email protected]
dba ALMONT Engineering
Baton Rouge, LA USA
Ha! Sensus has got you. The meter _may_ have an output, but if it does, it is to an AMR (automatic meter reading)system and isn't useable as a control system output. You have to buy a "pulse contact head" for the meter. It installs below the actual register head and the meterbody. It will put out a scaled pulse (in a 4" meter that is usually 1 pulse per 1000 gallons). Count it and you have your total...

If you haven't selected an RTU pick one that has a flow totalizer subroutine already established so you don't have to write one.

Actually, you are trying to be too "high tech" for the application.


Walt Boyes

Contributing Editor, Flow Control Magazine

> -----Original Message-----
> From: griffith, dave [mailto:[email protected]]
> To: '[email protected]'
> Subject: RE: PROC: Well Pump Flow Monitoring
> I haven't selected an RTU.
> I don't think the current meter has any outputs. It is a SENSUS
> 4" standard utility meter. That's why I was hoping that some
> meter manufacturer makes a smart meter with a fieldbus-type
> transmitter.
> Therefore, I need to select a meter and an RTU.
> Also, how do you scale the pulse signal from a standard meter? Which
> manufacturers have an electrical connection to the pulse? I have, in the
> past, run an output from an electric power meter to a high speed
> input on a PLC. However, I haven't seen water meters with similar
> outputs.
> Thanks for the help.
> David A. Griffith

Bob Dannenfelser

The OCS product from GE-Fanuc/Horner Electric has RTU capability plus it just came out with an Ethernet Comm module. Check it out with your nearby GE-Fanuc rep or go to www.heapg.com and get the latest on the OCS products. We use the OCS in our MAXX control products and will be using the Ethernet module for future communications access.

Bob Dannenfelser
Mottley Air Power
I know, I know...

The water utility business isn't high tech. It is about 25 years behind industrial automation.

If you want to do what you want, you need to add a higher tech flow meter upstream of the existing Sensus meter...because since it is a turbine meter, it disturbs the flow profile for many feet downstream. There are magmeters, and even a McCrometer V-cone with a Rosemount Multivariable transmitter will work. There are lots of flow meters with fieldbus outputs...

The way the water business does it is pure low tech. If they lose contact to the RTU, Joe the pump guy gets in his truck and drives to the station and looks to find out why. While he's there he writes down the total flow from the mechanical totalizer on the AWWA-style turbine meter.

I'm honestly not making fun of what you want to do...just letting you know that in the water utility market it is plumb overkill. In the electric utility market, it is way different.

The basic problem that keeps the water utility market low tech in flow is that billing meters don't have to have outputs...except for the AMR systems, and they are made in huge quantities. That Sensus 4" meter, which is probably made of brass, cost less than half what a 4" magmeter would sell for, probably.

Now, to answer the second part of your question: the signal can actually go to a counter input...it is a fractional hertz signal. Remember, a 4" meter has a maximum flow rate in this application of probably 300 gpm. At one
count per 1000 gallons, you will get one contact closure every three plus minutes, at maximum flow! If you can get a higher pulse rate, like one count per 100 gallons, you will still get only three counts per minute at maximum flow! This is really hard to visualize working if you are used to high speed automation. But it does work, because water flow is very predictable in this application, and unless it is a variable speed drive pump, it isn't going to change much either.

Hope this helps!

Walt Boyes
Contributing Editor, Flow Control Magazine

> -----Original Message-----
> From: griffith, dave [mailto:[email protected]]
> Sent: Friday, November 03, 2000 12:37 PM
> To: '[email protected]'
> Subject: RE: PROC: Well Pump Flow Monitoring
> I'm not trying to be high tech. I just want to be able to know how much
> water flowed if we ever lost communication to an RTU. It sounds
> very simple
> to me. I've communicated this way to numerous power meters via ethernet.
> That's why I wanted to know if a "smart" meter existed on the market that
> could communicate totalized flow. I've also communicated with
> panel meters
> via RS232 which totalized encoder counts.
> Can I connect the scaled pulse to a regular digital input or do most RTU
> manufacturers sell a separate high speed input like PLC's do?
****** There's a company called MeterMaster that can provide a retrofit kit(strap-on pickup) for a 4" Brass Sensus Turbine meter and provide a 4-20mA or scaled pulse output. I've used them SUCCESSFULLY in the past. Go get'em!