What is ISO 3455- Calibration of current-meters about?
ISO 3455 specifies a calibration method for mechanical type, electromagnetic type, and acoustic type hydrometric current-meters used for point velocity measurement of flowing water. The method requires towing the instrument through still water in a straight open tank.
ISO 3455 includes measuring apparatus, the calibration procedure, the method of presenting the results, and the uncertainties associated with the method.
Who is ISO 3455 - Calibration of current-meters for?
ISO 3455 on the calibration of current-meters in straight open tanks is beneficial for:
- Hydrologists
- Civil or environmental engineers
Why should you use ISO 3455 - Calibration of current-meters?
Calibration of a current meter means an experimental determination of the relationship between water velocity and either the rate of revolution of the rotating element or the velocity directly indicated by the current meter.
The current meter is mounted on a towing cart and drawn through still water contained in a straight tank with a uniform cross-section at a number of steady speeds of the towing cart. The towing method gives an absolute measurement of water speed, which in principle only requires position and time measurements. This method can be considered very accurate.
Overall, ISO 3455 is helpful as it provides details on the calibration of current meters in straight open tanks which can be beneficial for your business. ISO 3455 describes the length of a rating tank which comprises accelerating, stabilizing, measuring, and braking sections. The depth and width of the tank are therefore chosen to suit the size and the maximum velocity limits of the current meters which is to be calibrated.
What’s changed since the last update?
BS ISO 3455:2021 cancels and replaces the second edition (ISO 3455:2007), which has been technically revised.
The main changes compared to the previous editions are as follows:
- A subclause for calibration of acoustic current-meters for point velocity measurement has been added
- Clauses referring to outdated tracking systems like track systems using tooth belts have been removed
- Clauses referring to outdated technique for data acquisition like strip chart recorder or magnetic tapes have been removed
- The clause for computerized data acquisition and processing system has been removed
- The clause discussing the Epper effect has been removed
