ASTM D2458-69(1975)

Method for Flow Measurement of Industrial Water and Industrial Waste Water by the Venturi Meter Tube (Withdrawn 1981)

General Information

• Status: Withdrawn
• Technical Committee: D19 - Water
• Drafting Committee: D19.03 - Sampling Water and Water-Formed Deposits, Analysis of Water for Power Generation and Process Use, On-Line Water Analysis, and Surveillance of Water

Standards Content (Sample)

~~r~ Designation: o 2458- 69 (Reapproved 19751
Standard Method of
FLOW MEASUREMENT OF WATER BY THE
VENTURI METER TUBE'
~his .~tandtrd_ is ~studd uryder the. fixt:d designatio~ p 2458; the number immediately following the designation indicates
'l'r"'r o ongma a opt1on or, m the case of revJsJon, the year of last revision. A number in parentheses indicates the
year o ast n:approval.
I. Scope ter, d, to the inlet diameter, D. The quantity
dl Dis expressed as a decimal and represented
1.1 This method covers the measurement
by the Greek letter Beta.
of the rate of flow of water in pipelines using
the Herschel Standard Venturi meter tube.
3. General Principles
1.2 VenturF meter tubes are applicable for
3.1 The standard (long-type) Herschel'
the measurement of industrial water llow and
Venturi meter. tube is a specially constrUcted
particularly for slurries or similar nonhomo­
primary differential producer and flow-meas­
geneous liquids containing large concentra­
uring device which is installed between two
tions of suspended solids. Individually cali­
flanges in a pipeline to form a constricted sec­
brated, the Venturi tube is used as a standard
tion (Fig. 1). The device operates on the prin­
of measurement for acceptance tests on
ciple that when a fluid passes through a re­
pumping and similar equipment. Pressure
duced cross sectional area, an increase in ve­
losses through Venturi tubes are less than for
locity and a c.orresponding decrease in pres­
other primary flow measuring devices in­
sure (head) will occur (Fig. 2). This reduction
stalled in pipelines. Thus, substantial savings
in pressure is a simple function of the rate of
in pumping power consumption can be real­
flow. Two pressure measurements are made
ized by its use.
one each at the high-pressure inlet point and
at the low-pressure throat section. The differ­
2. Definitions
ence in head, H (hu ), expressed either as
0 2
2.1 head, H-the energy (capacity to do
inches of water column or feet of water, is a
work) possessed by a liquid because of its ele­
measure of velocity, which is a measure of
vation, velocity, pressure, or any combination
rate of flow, with the flow varying as the
of these. Each source of energy may be ex­
square root of the differential.
pressed in terms of equivalent head in feet,
3.1.1 The increase in velocity is given as
inches of water, or pounds per square inch,
follows:
and each can be converted into the other two.
2.2 differential head, H -the difference in
0
pressure head H n in Fig. 2 between the inlet
and the throat of the Venturi tube.
'This method is under the jurisdiction of ASTM Com­
2.3 loss of head-the difference in line
mittee D-19 on Water.
pressure at the inlet end and just downstream
Current edition effective Oct. 3, 1969. Originally issued
from the Venturi tube. It is also termed "non­ 1966. Replaces D 2458- 66 T.
'The principle of th~: Venturi meter was lirst stated in
recoverable head."
1797 by J. B. Venturi. an Italian, and wa~ fir~t upplied by
2.4 hydraulic gradient-a line in any se­
Clemens Herschel to the measurement of flow in pipes in
1887.
lected plane, connecting all points repre­
a I:~er~che!: Clemens, "Flui~ Meters: Their Theory and
senting pressure head in any system.
Appl1catwn, Report of Spec1al Research Committt:e on
Fluid Mctm, ASME, 1924.
2.5 beta ratio-the ratio of throat diame-
98

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D 2458
where: 3.3 The formula for Venturi tube measure­
ment evolved from consideration of the con­
V velocity, theoretical, ft/s,
C discharge coefficient (average value cept of flow, pressure, velocity, and the neces­
0.98), sary correction factors becomes:
g acceleration constant of gravity
Q~Ac( .l \x(2gHn)"'
32.16 ft/s', and
_(I - B•)u·~j
hu velocity head, theoretical, ft of water.
2
3
3.1.2 The fluid flow formulas for the Ven­
where Q = ft /unit of time. By the use of
turi tube are derived from this basic relation­
proper additional numerical factors, this
ship. The flow formula then becomes the fol­
equation can be converted into ga.flons per
lowing:
unit of time.
4. Apparatus
where:
4.1 Venturi Meter Tube (Primary Device)
3
Q = ft /unit time, and
-The apparatus shall consist of the Venturi
2
A = area of pipe, ft • meter tube referred to as the primary meas­
3.2 In addition to the simple determination uring device suitably constructed in accord­
of the differential head, H , there are two
ance with standard dimensions selected to
0
factors to be considered in measurement with
give accurately measurable differential pres­
a Venturi tube. These are the velocity of ap­
sures over the entire required variation of
proach and friction. Flowing fluid in a pipe­ quantity flow. At no time should the throat
line as it reaches the inlet section of the Ven­ pressure drop below atmospheric. The Venturi
turi tube has a certain velocity of approach.
tube should consist of inlet, thr
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