ISO 9827:1994 PDF

Measurement of liquid flow in open channels by weirs and flumes — Streamlined triangular profile weirs

Название (английский):

ISO 9827:1994

Measurement of liquid flow in open channels by weirs and flumes — Streamlined triangular profile weirs

Статус документа:: Действующий
Формат:: Электронный (PDF)
Количество страниц:: 14
Дата публикации:: 16 июня 1994 г.
Издание:: ISO IS 9827 edition 1 version 1
ICS:: 17.120.20

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Язык документа:

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Цена:210 €

Описание (английский):

Specifies methods for the measurement of the flow of water in open channels under steady flow conditions. The flow conditions considered are free flow, which is dependent on the upstream head only, and drowned flow, which depends on both upstream and downstream water levels.

Технические детали

Технический комитет: ISO/TC 113/SC 2 - Flow measurement structures
SKU: ISO 9827:1994

Abstract

Overview

ISO 9827:1994 specifies methods for measuring liquid flow in open channels using streamlined triangular profile weirs. It covers steady-flow conditions and treats both free (modular) flow - dependent only on upstream head - and drowned (submerged) flow - dependent on upstream and downstream water levels. The standard uses SI units and is intended for hydrometric determinations where reliable volumetric discharge measurements are required.

Key topics and technical requirements

Weir geometry and construction
- Streamlined triangular profile: upstream slope 1:2, downstream slope 1:q, with a circular arc crest joining slopes tangentially and a horizontal crest at right angles to flow.
- Construction tolerances: width and height ±0.5%, crest radius ±1%, slope ±1%.
- Weir width should equal channel width.
Site selection & installation
- Preliminary survey of approach channel shape, velocity distribution and absence of steep channel.
- Approach channel must be kept clean and free of silt/vegetation.
- For measurements under drowned conditions, downstream channel should be straight for at least 8 × maximum head and subcritical flow.
Head and tailwater measurement
- Head (upstream) gauge station: recommended 3–4 × maximum head upstream from crest.
- Tailwater (downstream) gauge station: recommended 5–6 × maximum head downstream from weir toe to avoid fluctuations.
- Stilling/float wells: watertight, vertical, with 0.6 m margin above estimated maximum water level; connecting pipe/slot must allow quick response.
Discharge calculation & coefficients
- Discharge depends on measured head, weir width and coefficients C (discharge coefficient) and Cdr (drowned-flow coefficient). The discharge varies approximately with h^(3/2) (head power 1.5).
- Modular limits and coefficient curves are provided for specified weir shapes (weirs 1–5). Weir No. 5 is restricted to modular flow; others have defined h/P limits (e.g., weirs 1–3: h/P

Overview

Key topics and technical requirements

Weir geometry and construction
- Streamlined triangular profile: upstream slope 1:2, downstream slope 1:q, with a circular arc crest joining slopes tangentially and a horizontal crest at right angles to flow.
- Construction tolerances: width and height ±0.5%, crest radius ±1%, slope ±1%.
- Weir width should equal channel width.
Site selection & installation
- Preliminary survey of approach channel shape, velocity distribution and absence of steep channel.
- Approach channel must be kept clean and free of silt/vegetation.
- For measurements under drowned conditions, downstream channel should be straight for at least 8 × maximum head and subcritical flow.
Head and tailwater measurement
- Head (upstream) gauge station: recommended 3–4 × maximum head upstream from crest.
- Tailwater (downstream) gauge station: recommended 5–6 × maximum head downstream from weir toe to avoid fluctuations.
- Stilling/float wells: watertight, vertical, with 0.6 m margin above estimated maximum water level; connecting pipe/slot must allow quick response.
Discharge calculation & coefficients
- Discharge depends on measured head, weir width and coefficients C (discharge coefficient) and Cdr (drowned-flow coefficient). The discharge varies approximately with h^(3/2) (head power 1.5).
- Modular limits and coefficient curves are provided for specified weir shapes (weirs 1–5). Weir No. 5 is restricted to modular flow; others have defined h/P limits (e.g., weirs 1–3: h/P

ISO 9827:1994 PDF

Технические детали

Abstract

Overview

Key topics and technical requirements

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Abstract

Overview

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