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Changes to Meter Rating Tables
Announced by USGS

Important: The new USGS Standard 2 current meter ratings for the Price AA and Pygmy current meters are built in to all new AquaCalc 5000 Advanced and AquaCalc Pro’s sold since 2001. No action is needed. If you have questions on upgrading very old AquaCalc 5000’s with new firmware chips, please contact us at JBSI.


The New Standard Rating Tables

In technical Memorandum No. 99.05, The Office of Surface Water of the USGS has announced new Standard Rating tables for the Price AA and pygmy current meters.

The full text of the memorandum is available on the USGS web site at http://water.usgs.gov/osw/pubs/sw9905.html

Selected portions of the memo follow:

“Office of Surface Water Technical Memorandum No. 99.05

June 2, 1999

Subject: Development of New Standard Rating Tables for the Price Type AA and Pygmy Current Meters

This memorandum is to inform you of the development of new standard rating tables for the Price type AA and pygmy current meters. Copies of the new rating tables are attached. The Hydrologic Instrumentation Facility (HIF) plans to make laminated copies available. ... These tables should be placed in use immediately for AA and pygmy meters with cat-whisker contact chambers and for AA meters with magnetic heads.”...

...At a velocity of 1.5 feet per second (fps) the new AA-meter standard rating equation gives a result that is 0.74 percent more than given by the old standard rating and at 8 fps, 1.4 percent more, compensating for the AA meter turning more slowly than predicted by the old standard rating.

The Meter-Exchange Program and procurement-testing data for pygmy meters show that these meters tend to run faster than predicted by the standard rating table. For the average pygmy meter, a correction is needed of 1.2 percent less at 0.75 fps, ranging to 1.6 percent less at 3.0 fps. ...

...About 95 percent of the AA meters fall within 1.5 percent of the new standard rating. For pygmy meters this variability is about 2 percent. ....

Obtaining New Tables

A copy of the new meter tables in an Adobe Acrobat (pdf) format can be obtained from the USGS website. Your must have an Adobe Acrobat Reader to view and print the files.

Standard Rating Table No. 2 for AA Current Meters

Standard Rating Table No. 2 for Pygmy Current Meters

The meter rating curves have changed from a two segment rating to a one segment rating.

Updating Your Firmware / EPROM

We call the Price type AA and pygmy current meters “standard meters”. They have their rating curves preprogrammed into the “firmware” of AquaCalc 5000 and the AquaCount. These programming instructions in your unit are called “firmware” instead of software, because they are contained in a “firm” electronic chip (EPROM) on the circuit board.

These EPROM chips can be replaced with new updated versions containing changes to the program instructions and standard meter tables. See below for the particulars relating to your model.


All AquaCount units must have new EPROM chips to update the built-in meter rating curves. See our Ordering Your Update page for more information on updating your EPROM firmware chip. For information on contacting Customer Support, click here.

The AquaCalc 5000

The AquaCalc 5000 models can continue to be used without updating the firmware by taking advantage of the “non-standard” meter capabilities. See the following instructions for your specific firmware version. If you need help in identifying your firmware version click here.

AquaCalc 5000 with the Advanced
(H Series) firmware

The AquaCalc 5000 with the Advanced firmware (H Series)  can store ten user-defined custom current meters with their associated rating curves by directly entering the meter rating curves into the user-defined / “non-standard” meter setup routine.

You may contact JBS Customer Support for information on upgrading your AquaCalc firmware EPROM chip to include the new Standard 2 in the default settings and the changes to the number of decimals.

The AquaCalc 5000 with the Basic (G) firmware

Unlike the Advanced (H) firmware, the Basic (G) firmware cannot store a table of user-defined meters. Each transect can store a meter rating equation for use in that transect.

Contact JBSI for more information on updating your EPROM firmware chip to include the new standards in the default settings. For information on contacting Customer Support, click here

New Current Meter Standards

AquaCalc LLC. telephone +1.916.372.0534 e-mail: sales@aquacalc.com

Need Accessories or Cables?

We have replacement parts and cables for the AquaCalc line of stream flow computers including the Digital Pygmy Magnetic Head retro fit your old Pygmy Current Meter with a new digital magnetic sensor.

Find Accessories and Cables here.

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