USGS Type AA Current Meter

The USGS Type AA current meter is commonly known as the Price-type current meter. This current meter is suspended in the water using a cable with sounding weight or wading rod (taking the tail section off) and will accurately measure streamflow velocities from 0.1 to 25 feet per second (0.025 to 7.6 meters per second). The main features of this meter are the uniquely designed bucket wheel shaft bearings and the two post contact chamber. The bucket wheel has six conical shaped cups, is five inches (12.7 cm) in diameter and rotates on a vertical axis inside the yoke. The tungsten carbide bearings for the bucket wheel shaft are located in deeply recessed inverted cups. When the meter is in use, these cups become air chambers and the entrapped air effectively excludes water and silt from the bearing surfaces giving extremely low starting velocities and minimal friction in the bearings.

The contact chamber houses a penta gear and two binding posts, each having a fine platinum alloy contact wire. One wire makes contact with the bucket wheel shaft once during every revolution; the other is used when fast velocities are encountered, and makes contact with the penta gear once during every five revolutions of the bucket wheel.

Each current meter is provided with a U.S. Geological Survey approved standard rating table to convert bucket revolutions to stream velocity in either English units (feet per second) or metric units (meters per second), spare parts, instrument oil, cleaning cloth, screwdriver and an instrument case with a water tight o-ring seal that floats if dropped in the water and provides proper protection of the meter during transportation and storage.

The meter is made from brass and stainless steel and all exposed surfaces are plated for corrosion-free service. The standard Type AA was designed for use with all of the counters as well as the AquaCalc 5000 Digital Flow Computer. No conversion kits or replacement contact chambers are necessary to use the latest digital technology with this meter.