ISO 2975-6:1977 PDF

Name: ISO 2975-6:1977 — Measurement of water flow in closed conduits — Tracer methods — Part 6: Transit time method using non-radioactive tracers
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Measurement of water flow in closed conduits — Tracer methods — Part 6: Transit time method using non-radioactive tracers

Название (английский):

ISO 2975-6:1977

Measurement of water flow in closed conduits — Tracer methods — Part 6: Transit time method using non-radioactive tracers

Статус документа:: Действующий
Формат:: Электронный (PDF)
Количество страниц:: 13
Дата публикации:: 1 февраля 1977 г.
Издание:: ISO IS 2975 edition 1 version 1
ICS:: 17.120.10

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Описание (английский):

Tracer methods apply to flow measurement in conduits into which a solution can be injected and those cases where effective mixing of this solution with the water flowing in the conduit can be achieved, this last condition being fundamental. Describes the transit time method using non-radioactive tracers for the measurement of water flow rate in closed conduits.

Abstract

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Overview

ISO 2975-6:1977 - Measurement of water flow in closed conduits - Tracer methods - Part 6: Transit time method using non-radioactive tracers specifies the transit time (Allen velocity) method for measuring water flow in closed pipes by tracking the time delay of a non-radioactive tracer between two detector cross-sections. The standard addresses practical requirements for tracer selection (commonly sodium chloride), injection, detector arrangement (electrodes/flow-cells), data recording and calculation of transit time and flow rate.

Key topics and technical requirements

Principle: Determine flow rate from the transit time of labelled fluid particles between two detectors a known distance apart. The tracer concentration vs. time curves at each detector are used to compute mean arrival times.

Tracer: Non-radioactive tracers are specified; sodium chloride is recommended because conductivity is linear with concentration over a wide range and simple electrodes can be used.

Mixing and injection:

The tracer must be effectively mixed at the first detector position; the injection-to-first-detector distance should be at least the calculated mixing distance (defined by <0.5% cross-section concentration variation in examples).
Injection must be rapid to minimize pulse duration and avoid tailing (spring-loaded valves, ampoules, pressure injection or symmetric central injection are suggested).

Measuring length and detector spacing:

The section between detectors should preferably be a straight pipe of uniform cross-section and free of fittings that create dead zones.
Recommendations for detector spacing account for longitudinal dispersion and recorder type: for single-channel recording, detectors must be spaced so recorded pulses do not overlap (practical guidance: p > 1; multi-channel recorders allow shorter spacing, with guidance p > 0.5).
Example guidance: keep injection-to-first-detector spacing such that 99.7% of the tracer pulse passes.

Detection and data processing:

Electrode detectors or flow-cells produce concentration/time distributions. Transit time may be derived from centres of gravity, mid-area (half-area) points, half-height or other characteristic points.
Corrections may be required for detector response differences and flow-cell transit differences.

Volume measurement: Accurate internal volume of the measuring section is critical; direct capacity measurement is preferred over relying on drawings.

Test practice: At least five successive injections are recommended to assess random uncertainty.

Applications

On-site flow measurement in water distribution, hydraulic machine testing, irrigation systems, and industrial process piping where invasive flowmeters are impractical.

Situations requiring non-invasive, short-length measurements in closed conduits.

Useful for calibration, commissioning, troubleshooting and acceptance testing of pipe systems.

ISO 2975-6:1977 PDF

Abstract

Похожие стандарты

Overview

Key topics and technical requirements

Applications

Who uses this standard

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