The Question

From: Dale Banks <dale@inletkeeper.org>
Subject: [volmonitor] Flow meters
To: VOLMONITOR <volmonitor@lists.epa.gov>

Hi,
Anyone have any experience (positive or negative) with the 'Flowatch' flowmeter? Any other inexpensive flowmeters anyone can recommend? These would be used for stream flow monitoring.

Thanks!

Dale

Dale Banks
Volunteer Monitoring Coordinator
Cook Inlet Keeper
(907) 235-4068
dale@inletkeeper.org
www.inletkeeper.org

Responses

From: Dennis <hvama@bcn.net>
Subject: [volmonitor] Re: Flow meters
To: VOLMONITOR <volmonitor@lists.epa.gov>

Hi Dale,

I have seen the Flowatch flow meter, and considered using it on a monitoring project, however, the company doesn't have a way to calibrate it. For our DEP to accept the results of our monitoring, I need to show how we are going to calibrate our equipment, and apparently the Flowatch does not have a
method for the customer to do that. If you don't need to calibrate it, however, it seems like an easy to use and straightforward meter.

Hope this helps,
Carolyn

Carolyn W. Sibner
Water Quality Coordinator
Housatonic Valley Association

From: Phil Emmling <pemmling@facstaff.wisc.edu>
Subject: [volmonitor] Re: Flow meters
To: VOLMONITOR <volmonitor@lists.epa.gov>

Flow meters:

Perhaps a nearby university civil engineering department has a small hydrology flume to calibrate meters. If they have a course, they usually have a flume.

You should make certain that any meter can read down to your expected base flow velocity. For example, the Price Pygmy meters AA used by some professionals are rated at 0.1 ft/s. I have found, however, that it takes about 0.3 ft/s to start the cups moving and then the resolution is fine at 0.1 ft/s increments. I don't think there are too many units that do well between 0.1 and 0.5 ft/s.

If anyone knows of any units that are accurate to 0.05 ft/s (0.05-1 ft/s), I would be interested in them.

Phil Emmling
Environmental Chemistry & Technology Program
660 N. Park St.
Madison, WI 53706
Phone: 608 262-2899
FAX: 608 262-0454

From: Revital Katznelson <Rk@rb2.swrcb.ca.gov>
Subject: [volmonitor] Re: Flow meters
To: VOLMONITOR <volmonitor@lists.epa.gov>
Cc: Raquel Gutierrez...snip... xhernand.RB4Post.Region4@rb4.swrcb.ca.gov>

Phil and Carolyn -

I am not really clear what you mean when you use the word "calibrate" - are you referring to adjusting the output of the instrument, or only to checking whether it shows the "true" value?
Our Clean Water Team (the Citizen Monitoring Program of the California State Water Resources Control Board) is now using two separate terms, defined below for water quality (rather than flow):

Calibration: The action of adjusting the readings of an instrument to have it match a "true" value as represented by known natural conditions (e.g., freezing point) or by a Standard Solution (e.g., Standard pH buffer).
Accuracy Check: Comparison of the reading, or output, of a measurement device with a value believed the "true" value (see above). An "Accuracy Check" is different from a Calibration, since it is only a
comparison and does not result in an adjustment of an instrument or procedure.

I have encountered many instruments that have been calibrated by the manufacturer prior to sale, and are not amenable to any adjustments by the user. If your flow meter is one of those, you can use the flume (or the apron&bucket method for very low flow discharge) to conduct an "accuracy check" and provide that information with your flow data. "Accuracy check" results - i.e., the difference between the "true" value and what your instrument actually reads - can then be used to either "correct" your measurement Results or to compute the inaccuracy of your measurement.

I hope this is useful -
Revital

=======================================================
Revital Katznelson, Ph.D.
Regional Citizen Monitoring Coordinator
State Water Resources Control Board


From: Dale Banks <dale@inletkeeper.org>
Subject: [volmonitor] Re: Flow meters
To: VOLMONITOR <volmonitor@lists.epa.gov>

Thanks for the useful comments. One possible way to check accuracy of the Flowatch would be to measure flow on a stream alongside USGS or someone else who is using an approved method. This might satisfy QC requirements in Carolyn's case, but not sure what you would do if the results were bad and the meter can't be calibrated...

Dale

Well, if nothing else works for measuring flow then the old orange or lemon in the water does
an adequate job of determining stream flow. I stop by the supermarket and pick up the old
oranges, lemons and limes (for free) and lay out a 10 meter strip along shore. A student at
the top and bottom and a stop watch is all that is needed. This method could also be used to
calibrate a device. All this is outlined in chapter 3 of Rivers Chemistry, the curriculum
developed by the Rivers Project.
Dr. Bob

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