oSIST prEN ISO 27971:2022

Cereals and cereal products - Common wheat (Triticum aestivum L.) - Determination of alveograph properties of dough at constant hydration from commercial or test flours and test milling methodology (ISO/DIS 27971:2022)

Getreide und Getreideerzeugnisse - Weizen (Triticum aestivum L.) - Bestimmung der Eigenschaften von Teig bei konstanter Flüssigkeitszufuhr zu handelsüblichen Mehlen oder Versuchsmehlen bei gleichen Versuchsmahlverfahren mittels Alveograph (ISO/DIS 27971:2022)

Dieses Dokument legt ein Verfahren zur Bestimmung der rheologischen Eigenschaften verschiedener Teigarten mittels eines Alveographen fest, die aus Mehl von Weichweizen (Triticum aestivum L.) erhalten wurden, das durch industrielles Vermahlen oder Laborvermahlung hergestellt wurde.
Es beschreibt das alveographische Prüfverfahren sowie die Art und Weise der Anwendung einer Labormühle zur Herstellung von Mehl in zwei Stufen:
   Stufe 1: Vorbereitung des Weizens (Korn) zum Vermahlen, damit die Kleie leichter vom Endosperm getrennt werden kann;
   Stufe 2: die Vermahlung, einschließlich der Schrotung zwischen drei Riffelwalzen, der Verringerung der Korngröße zwischen zwei Glattwalzen sowie der Verwendung einer Zentrifugalsiebmaschine zur Klassierung der Erzeugnisse.

Céréales et produits céréaliers — Blé tendre (Triticum aestivum L.) — Détermination des propriétés alvéographiques d'une pâte à hydratation constante de farine industrielle ou d'essai et méthodologie pour la mouture d'essai (ISO/DIS 27971:2022)

Žito in proizvodi iz žita - Navadna pšenica (Triticum aestivum L.) - Določevanje lastnosti testa iz običajnih komercialnih ali preskusnih mok z alveografom ob stalnem dodajanju vode in s preskusom postopka mletja (ISO/DIS 27971:2022)

General Information

• Status: Not Published
• Public Enquiry End Date: 29-Apr-2022
• ICS: 67.060 - Cereals, pulses and derived products
• Technical Committee: KŽP - Agricultural food products
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 16-Feb-2022
• Due Date: 06-Jul-2022
• Completion Date: 03-May-2022
• Ref Project: FprEN ISO 27971 - Cereals and cereal products - Common wheat (Triticum aestivum L.) - Determination of alveograph properties of dough at constant hydration from commercial or test flours and test milling methodology (ISO/FDIS 27971:2023)

Relations

• Revised: SIST EN ISO 27971:2015 - Cereals and cereal products - Common wheat (Triticum aestivum L.) - Determination of alveograph properties of dough at constant hydration from commercial or test flours and test milling methodology (ISO 27971:2015)
• Effective Date: 24-Feb-2021
• Revised: SIST EN ISO 27971:2015 - Cereals and cereal products - Common wheat (Triticum aestivum L.) - Determination of alveograph properties of dough at constant hydration from commercial or test flours and test milling methodology (ISO 27971:2015)
• Effective Date: 18-Jan-2023
• Revised: SIST EN ISO 27971:2015 - Cereals and cereal products - Common wheat (Triticum aestivum L.) - Determination of alveograph properties of dough at constant hydration from commercial or test flours and test milling methodology (ISO 27971:2015)
• Effective Date: 19-Jan-2023

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN ISO 27971:2022
01-april-2022
Žito in proizvodi iz žita - Navadna pšenica (Triticum aestivum L.) - Določevanje
lastnosti testa iz običajnih komercialnih ali preskusnih mok z alveografom ob
stalnem dodajanju vode in s preskusom postopka mletja (ISO/DIS 27971:2022)

Cereals and cereal products - Common wheat (Triticum aestivum L.) - Determination of

alveograph properties of dough at constant hydration from commercial or test flours and

test milling methodology (ISO/DIS 27971:2022)

Getreide und Getreideerzeugnisse - Weizen (Triticum aestivum L.) - Bestimmung der

Eigenschaften von Teig bei konstanter Flüssigkeitszufuhr zu handelsüblichen Mehlen

oder Versuchsmehlen bei gleichen Versuchsmahlverfahren mittels Alveograph (ISO/DIS

27971:2022)

Céréales et produits céréaliers Blé tendre (Triticum aestivum L.) Détermination des

propriétés alvéographiques d'une pâte à hydratation constante de farine industrielle ou

d'essai et méthodologie pour la mouture d'essai (ISO/DIS 27971:2022)
Ta slovenski standard je istoveten z: prEN ISO 27971
ICS:
67.060 Žita, stročnice in proizvodi iz Cereals, pulses and derived
njih products
oSIST prEN ISO 27971:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN ISO 27971:2022
---------------------- Page: 2 ----------------------
oSIST prEN ISO 27971:2022
DRAFT INTERNATIONAL STANDARD
ISO/DIS 27971
ISO/TC 34/SC 4 Secretariat: SAC
Voting begins on: Voting terminates on:
2022-02-09 2022-05-04
Cereals and cereal products — Common wheat (Triticum
aestivum L.) — Determination of alveograph properties of
dough at constant hydration from commercial or test flours
and test milling methodology

Céréales et produits céréaliers — Blé tendre (Triticum aestivum L.) — Détermination des propriétés

alvéographiques d'une pâte à hydratation constante de farine industrielle ou d'essai et méthodologie pour

la mouture d'essai
ICS: 67.060
This document is circulated as received from the committee secretariat.
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
ISO/CEN PARALLEL PROCESSING
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 27971:2022(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. © ISO 2022
---------------------- Page: 3 ----------------------
oSIST prEN ISO 27971:2022
© ISO 2021 – All rights reserved
ISO/DIS 27971:2022(E)
ISO/TC 34/SC 4
Date : 2021-09-20
ISO/DIS 27971:2021(E)
ISO/TC 34/SC 4
Secretariat: SAC
Cereals and cereal products — Common wheat (Triticum
aestivum L.) — Determination of alveograph properties of dough
at constant hydration from commercial or test flours and test
milling methodology

Céréales et produits céréaliers — Blé tendre (Triticum aestivum L.) — Détermination des propriétés

alvéographiques d'une pâte à hydratation constante de farine industrielle ou d'essai et méthodologie pour

la mouture d'essai
DIS stage
Warning for WDs and CDs

This document is not an ISO International Standard. It is distributed for review and comment. It is subject to

COPYRIGHT PROTECTED DOCUMENT
change without notice and may not be referred to as an International Standard.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of

© ISO 2022
which they are aware and to provide supporting documentation.

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on

the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below

or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
© ISO 2022 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST prEN ISO 27971:2022
ISO/DIS 27971:2022(E) )
Contents

Foreword ................................................................................................................................................................ v

Introduction.......................................................................................................................................................... vi

1  Scope .......................................................................................................................................................... 1

2  Normative references .......................................................................................................................... 1

3  Principle ................................................................................................................................................... 1

4  Reagents ................................................................................................................................................... 1

5  Apparatus ................................................................................................................................................. 2

6  Sampling ................................................................................................................................................... 6

7  Preparation of the wheat for laboratory milling. ...................................................................... 7

7.1  Cleaning the laboratory sample ....................................................................................................... 7

7.2  Test portion ............................................................................................................................................. 7

7.3  Wheat moisture content determination ....................................................................................... 7

7.4  Wheat prep aration ................................................................................................................................ 7

7.4.1  General ...................................................................................................................................................... 7

7.4.2  Wheat with initial moisture content between 13 % and 15 % (one-stage

moistening) ............................................................................................................................................. 7

7.4.3  Wheat with a moisture content less than 13 % (two-stage moistening) .......................... 7

7.4.4  Wheat with a moisture content greater than 15 % (preliminary drying followed by

moistening, as described above) ..................................................................................................... 8

8  Laboratory milling ................................................................................................................................ 8

8.1  General ...................................................................................................................................................... 8

8.2  Milling procedure .................................................................................................................................. 8

8.2.1  Breaking ................................................................................................................................................... 8

8.2.2  Reduction ................................................................................................................................................. 9

8.2.3  Flour homogenization ......................................................................................................................... 9

8.2.4  Storage of the flour ............................................................................................................................... 9

8.3  Expression of milling results .......................................................................................................... 10

9  Preparation and alveograph test .................................................................................................. 10

9.1  Preliminary checks ............................................................................................................................ 10

9.2  Preliminary operations .................................................................................................................... 11

9.3  Kneading ................................................................................................................................................ 13

9.4  Preparation of dough test pieces .................................................................................................. 13

9.5  Alveograph test ................................................................................................................................... 15

9.5.1  Initial preparation ............................................................................................................................. 15

9.5.2  First operation: placing the patty on the lower plate ............................................................ 16

9.5.3  Second operation: biaxial extension ........................................................................................... 17

9.6  Expression of alveograph test results ......................................................................................... 18

9.6.1  General ................................................................................................................................................... 18

9.6.2  Maximum pressure parameter, P ................................................................................................. 18

9.6.3  Mean abscissa at rupture, L ............................................................................................................ 18

9.6.4  Swelling index, G ................................................................................................................................. 19

9.6.5  Elasticity index, I ............................................................................................................................... 19

9.6.6  Curve configuration ratio, P/L ....................................................................................................... 19

9.6.7  Deformation work, W ........................................................................................................................ 19

10  Precision ................................................................................................................................................ 19

10.1  Interlaboratory tests ......................................................................................................................... 19

10.2  Repeatability limits ........................................................................................................................... 20

© ISO 2022 – All rights reserved iii
---------------------- Page: 5 ----------------------
oSIST prEN ISO 27971:2022
ISO/DIS 27971:2022(E) )

10.2.1  Commercial flour: limits established by the interlaboratory test .................................... 20

10.2.2  Flour obtained from laboratory milling ..................................................................................... 20

10.3  Reproducibility limits ....................................................................................................................... 20

10.3.1  Commercial flour: Limits established by the proficiency tests .......................................... 21

10.3.2  Flour obtained from laboratory milling ..................................................................................... 21

10.4  Uncertainty ........................................................................................................................................... 21

11  Test report ............................................................................................................................................ 21

Annex A (informative) Characteristics of the Chopin-Dubois CD1 mill ....................................... 22

A.1  Breaking ................................................................................................................................................ 22

A.2  Reduction .............................................................................................................................................. 22

A.3  Sieve material ...................................................................................................................................... 22

A.4  Milling ..................................................................................................................................................... 22

A.5  Break performance indicator ........................................................................................................ 23

A.6  Reduction performance indicator ................................................................................................ 23

A.7  Maintenance operations .................................................................................................................. 23

Annex B (normative) Quantity of water to be added to wheat for conditioning ...................... 24

Annex C (informative) Sample milling sheet ......................................................................................... 25

Annex D (informative) Conversion table from L to G .......................................................................... 26

Annex E (informative) Interlaboratory and proficiency test data for commercial flours .... 28

Annex F (informative) Interlaboratory data for laboratory milled flour ................................... 37

Annex G (informative) Routine maintenance instructions for the Alveograph ........................ 51

G.1  Before every test ................................................................................................................................. 51

G.2  Every day ............................................................................................................................................... 51

G.3  Every week ............................................................................................................................................ 51

G.4  Every month ......................................................................................................................................... 51

G.5  Every year ............................................................................................................................................. 51

Annex H (informative) Assessment of proteolytic activity in wheat (T. aestivum L.) or

flour ......................................................................................................................................................... 53

H.1  General ................................................................................................................................................... 53

H.2  Principle ................................................................................................................................................ 53

H.3  Reagents ................................................................................................................................................ 53

H.4  Apparatus .............................................................................................................................................. 53

H.5  Sampling and sample preparation ............................................................................................... 53

H.6  Preparation and alveograph test .................................................................................................. 53

Bibliography ....................................................................................................................................................... 55

iv © ISO 2022 – All rights reserved
---------------------- Page: 6 ----------------------
oSIST prEN ISO 27971:2022
ISO/DIS 27971:2022(E) )
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO

collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any

patent rights identified during the development of the document will be in the Introduction and/or on

the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the World

Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL:

www.iso.org/iso/foreword.html.

The committee responsible for this document is ISO/TC 34, Food products, Subcommittee SC 4, Cereals

and pulse.
© ISO 2022 – All rights reserved v
---------------------- Page: 7 ----------------------
oSIST prEN ISO 27971:2022
ISO/DIS 27971:2022(E) )
Introduction

The end-use value of wheat is determined by a number of properties that are useful in the manufacture

of baked products such as bread, rusks, and biscuits.

Such properties include the important viscoelastic (rheological) properties of dough formed as a result

of flour hydration and kneading. An Alveograph is used to study the main parameters by subjecting a

dough test piece to biaxial extension (producing a dough bubble) by inflating it with air, which is similar

to the deformation to which it is subjected during bread dough fermentation.

Recording the pressure generated inside the bubble throughout the deformation of the dough test piece

until it ruptures provides information on the following:

a) the resistance of the dough to deformation, or its stiffness. It is expressed by the maximum pressure

parameter, P;

b) the extensibility or the possibility of inflating the dough to form a bubble; It is expressed by the

parameters of extensibility, L, or swelling, G;

c) the elasticity of the dough during biaxial extension. It is expressed by the elasticity index, I ;

d) the work required to deform the dough bubble until it ruptures, ot its strength, which is proportional

to the area of the Alveogram (sum of the pressures throughout the deformation process). It is

expressed by the parameter, W.

The P/L ratio is a measurement of the balance between stiffness and extensibility.

Alveographs are commonly used throughout the wheat and flour industry, for the following purposes:

— selecting and assessing different varieties of wheat and marketing batches of wheat;

— blending different batches of wheat or flour to produce a batch with given values for the alveographic

criteria (W, P, and L) complying with the proportional laws of blending.

Alveographs are used both on the upstream side of the industry for marketing, selecting and assessing

the different wheat varieties and on the downstream side throughout the baking industries

(see Bibliography).
vi © ISO 2022 – All rights reserved
---------------------- Page: 8 ----------------------
oSIST prEN ISO 27971:2022
ISO/DIS 27971:2022(E) )
Cereals and cereal products — Common wheat (Triticum
aestivum L.) — Determination of alveograph properties of dough
at constant hydration from commercial or test flours and test
milling methodology
1 Scope
Type text.

This International Standard specifies a method of determining, using an Alveograph, the rheological

properties of different types of dough obtained from common wheat flour (Triticum aestivum L.)

produced by industrial milling or laboratory milling.

It describes the Alveograph test and how to use a laboratory mill to produce flour in two stages:

— stage 1: preparation of the wheat grain for milling to make it easier to separate the bran from the

endosperm;

— stage 2: the milling process, including breaking between three fluted rollers, reduction of particle

size between two smooth rollers and the use of a centrifugal sieving machine to grade the products.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 660, Animal and vegetable fats and oils — Determination of acid value and acidity

ISO 712, Cereals and cereal products — Determination of moisture content — Reference method

NF EN 15948, Cereals — Determination of moisture and protein — Method using Near-Infrared-

Spectroscopy in whole kernels

ISO 7700-1:2008, Food products — Checking the performance of moisture meters in use — Part 1: Moisture

meters for cereals

NF EN ISO 12099, Animal feeding stuffs, cereals and milled cereal products — Guidelines for the application

of near infrared spectrometry
3 Principle

The behaviour of dough obtained from a mixture of flour and salt water is evaluated during deformation.

A dough disk (patty) is subjected to a constant air flow; at first it withstands the pressure. Subsequently,

it inflates into a bubble, according to its extensibility, and ruptures. The change in the dough is measured

and recorded in the form of a curve called an Alveogram.
4 Reagents

Unless otherwise specified, use only reagents of recognized analytical grade, and only distilled or

demineralized water or water of equivalent purity.
© ISO 2022 – All rights reserved 1
---------------------- Page: 9 ----------------------
oSIST prEN ISO 27971:2022
ISO/DIS 27971:2022(E) )

4.1 Sodium chloride solution, obtained by dissolving (25 ± 0,2) g of sodium chloride (NaCl) in water

and then making the volume up to 1 000 ml. This solution shall not be stored for more than 15 days and

its temperature shall be (20 ± 2) °C when used.

4.2 Refined vegetable oil, low in polyunsaturates, such as peanut oil. It is possible to use olive oil if its

acid value is less than 0,4 (determined according to ISO 660). Store in a dark place in a closed container

and replace regularly (at least every three months).

Alternatively, liquid paraffin (also known as “soft petroleum paraffin”), with an acid value of less than

or equal to 0,05 and the lowest possible viscosity [maximum 60 mPa·s (60 cP) at 20 °C].

4.3 Cold degreasing agent, optimum safety.
5 Apparatus
Usual laboratory apparatus and, in particular, the following.

5.1 Mechanical cleaner, fitted with sieves for wheat cleaning, in accordance with the manufacturer's

instructions.
5.2 Conical or riffle sample divider.
5.3 Analytical balance, accurate to 0,01 g.
5.4 Glass burette, of 50 ml in capacity, graduated in 1 ml divisions.

5.5 Rotary blender , for grain conditioning and flour homogenization, including the following

components:
5.5.1 Constant speed stirrer.

5.5.2 Two worm screws integral with the flask, possibly via the stopper (one for wheat preparation,

the other for flour homogenization).
5.5.3 Several wide-necked plastic flasks, 2 l capacity.

5.6 Test mill (laboratory mill), manually or automatically operated (see Annex A).

5.7 Complete alveograph system (see Table 1 for specifications and characteristics of the

accessories) including the following devices:

5.7.1 Kneading machine [see Figure 1 for Alveo NG and Alveo PC models; for model Alveolab,

see Figure 2], with accurate temperature control, for dough sample preparation.

5.7.2 Dedicated software on to record the pressure curve as a function of time, perform the

calculations and store the tests or other registration systems such as the Alveolink

The Chopin MR 2 l rotary blender is an example of a suitable product available commercially. This information

is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO

of this product.

For the details concerning the use of the different registration systems please refer to the manufacturer’s instructions.

2 © ISO 2022 – All rights reserved
---------------------- Page: 10 ----------------------
oSIST prEN ISO 27971:2022
ISO/DIS 27971:2022(E) )

5.7.3 Alveograph for measuring the biaxial deformation of the dough test pieces.]. [for models Alveo

NG and Alveo PC, see Figure 1; for model Alveolab, see Figure 2; Including accurate temperature control

and hygrometry control for the AlveoLab mode., It has two rest chambers (Three for the Alveolab), each

containing five plates on which the dough test pieces can be arranged for resting prior to deformation.

5.8 Burette with stopcock, supplied with the apparatus (only for models NG and PC), 160 ml capacity,

graduated in divisions of 0,1 % of moisture content.

NOTE Throughout this International Standard, “content” is expressed as a “mass fraction” (see ISO 80000-9,

[6]

12 ), i.e. the ratio of the mass of substance in a mixture to the total mass of the mixture.

5.9 Thermohydrograph for recording the test environment conditions (temperature and relative

air humidity) as specified in 8.1 and 9.1. In the case of the Alveolab, the test conditions (temperature and

humidity) around the swelling bubble are automatically checked and controlled by the device.

5.10 Volumetric flask, 1 000 ml capacity, complying with the requirements of ISO 1042, class A.

5.11 Pipette, 25 ml capacity, graduated in divisions of 0,1 ml, complying with the requirements

of ISO 835, class A.

The methods specified in this International Standard are based on the use of the NG, PC and Alveolab models of Chopin

alveograph which are examples of suitable products commercially available. This information is given for the convenience of

users of this International Standard and does not constitute an endorsement by ISO of this product.

© ISO 2022 – All rights reserved 3
---------------------- Page: 11 ----------------------
oSIST prEN ISO 27971:2022
ISO/DIS 27971:2022(E) )
Key
A Mixer
B Alveograph
1 Burette for adding water
2 Mixer screen
3 Mixing bowl
4 Mixer control panel
5 Alveograph control panel
6 Test plate of the Alveograph unit
7 Resting chamber
Figure 1 — Mixer and Alveograph part of models Alveo NG and Alveo PC
4 © ISO 2022 – All rights reserved
---------------------- Page: 12 ----------------------
oSIST prEN ISO 27971:2022
ISO/DIS 27971:2022(E) )
Key
1 Mixing bowl
2 Water injection nozzle
3 Aveolab control panel
4 Alveograph test chamber
5 Storage compartment for accessories
6 Dough collector and humidifier
7 Resting chamber
8 Salt water tank
Figure 2 — Mixer and alveograph part of the Alveolab Model
© ISO 2022 – All rights reserved 5
---------------------- Page: 13 ----------------------
oSIST prEN ISO 27971:2022
ISO/DIS 27971:2022(E) )

Table 1 — Specifications and characteristics of the accessories required for the test

Quantity Value and tolerance
Rotational frequency of the kneading blade (60 ± 2) Hz
Height of sheeting guides (12,0 ± 0,1) mm
Large diameter of the sheeting roller (40,0 ± 0,1) mm
Small diameter of the sheeting roller (33,3 ± 0,1) mm
Inside diameter of the dough cutter (46,0 ± 0,5) mm
Diameter of the aperture created when the moving plate opens (which determines
(55,0 ± 0,1) mm
the effective diameter of the test piece)

Theoretical distance between the fixed and moving plates after clamping (equal to

(2,67 ± 0,01) mm
the thickness of the test piece before inflation)

Volume of air automatically injected to detach the test piece prior to inflating the

(18 ± 2) ml
bubble
Air flow ensuring inflation (96 ± 2) l/h

On models Alveo Ng and Alveo PC, to adjust the flow rate of the air generator used to inflate the bubble, fit the nozzle

(Figure 4) to
...