Calibration and Certification in Flow Measurement in Open Channels

Calibration and Certification in Flow Measurement in Open Channels An open channel is any measurement system with gravity flow such as Parshall, Leopold Lagco, Saniiri, Palmer Bowlus, H, HS, Vertedores and others.

When measuring flow in open channels there are three types of certificates, for example, in the Parshall flume:

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1) Ultrasonic flowmeter calibration certificate - measures the level of the fluid passing through the gutter, transforming the level into the flow indication, in the engineering unit, on the meter display. This calibration consists of comparing the information obtained on the display and at the equipment outputs with the actual measurement taken directly at Parshall using a calibrated measurement standard “RBC”. After comparing the measurement obtained in the standard and that indicated and transmitted, if necessary, an adjustment is made to the equipment to minimize the error. After adjustment, a comparison is made between the measurement obtained in the standard and that indicated and transmitted if the meter is within the standards, a calibration certificate for the ultrasonic meter is provided.

NOTE: This certificate refers to the ultrasonic flow meter and does not guarantee the effectiveness of the measurement system.

2) Parshall gutter Manufacturing Certificate - The Manufacturing certificate guarantees that the gutter was manufactured with dimensions within the tolerances required by the standard. It is part of the new certification model for Incontrol's Parsahll gutter, a dimensional drawing specifying the standard with revision that the Parshall was manufactured and a table where in one column there are the “expected” measurements which are the dimensions informed by the standard in another column “found” in a third column the difference between what was expected and what was found. Remembering that a Parshall gutter within the standard tolerances means 30% of the entire system.

NOTE: This certificate refers to the Parshall gutter and does not guarantee the effectiveness of the measurement system.

3) Parshall gutter installation certificate

3.a - Parshall gutter installation certificate: This is the most important one, even required by CETESB in the Liquid Effluent Monitoring Plan – PAEL, it is the certification of the Parshall installation because in the process the installation can change the factory dimensions. The upstream and downstream channels are integral parts of the “Parshall Measurement System”, a set that must meet the same standard as Parshall. The channels are measured by identifying all the important points of the installation through the spreadsheet in the “expected” and “found” columns. This certificate includes items 1 and 2 described above. When requested, our consultant monitors the installation of the gutter and issues a Technical Report with ART. If irregular, non-conformity will be issued, which must be remedied and, once corrected, a new assessment will be requested.

3.b - Certificate of old installation with Parshall gutter: In order to be sure of the correct measurement when disposing of the effluent and/or to comply with the Liquid Effluent Monitoring Plan – PAEL of CETESB. This service is similar to 3.a but carried out, “if necessary”, without stopping disposal. If the channel and installation comply with the standards, a certificate and technical report of compliance with ART will be issued. If irregular, non-compliance will be issued, which must be remedied and, after adjustment, a new assessment will be requested.

NOTE:This certificate guarantees the effectiveness of the measurement system