EN 12668-2:2001
(Main)Non-destructive testing - Characterization and verification of ultrasonic examination equipment - Part 2: Probes
Non-destructive testing - Characterization and verification of ultrasonic examination equipment - Part 2: Probes
This part of the standard covers probes used for ultrasonic non-destructive examination in the following categories with centre frequencies in the range 0,5 to 15 MHz, focusing and without focusing means: 1) single or dual transducer contact probes generating compressional or shear waves; 2) immersion probes. Periodic tests for probes are not included in this part of this standard. Routine tests for the verification of probes using onsite methods are given in part 3 of this standard.
Zerstörungsfreie Prüfung - Charakterisierung und Verifizierung der Ultraschall-Prüfausrüstung - Teil 2: Prüfköpfe
1 Anwendungsbereich
Diese Europäische Norm gilt für Prüfköpfe für die zerstörungsfreie Prüfung mit Ultraschall mit Mittenfrequenzen zwischen 0,5 MHz und 15 MHz, fokussierend oder ohne fokussierende Vorrichtungen in den folgenden Kategorien:
a) Prüfköpfe für den direkten Kontakt mit einem oder zwei Schwingern, die Longitudinalwellen oder Transver-salwellen erzeugen;
b) Tauchtechnik-Prüfköpfe.
Wenn materialabhängige Ultraschallwerte in dieser Norm angegeben werden, beruhen sie auf Stahl mit einer Schallgeschwindigkeit von (5920 ± 50) m/s bei Longitudinalwellen und von (3255 ± 30) m/s bei Transversalwellen.
Wiederkehrende Überprüfungen für Prüfköpfe sind nicht in diesem Teil der Norm enthalten. Routinemäßige Kontrollen zur Beurteilung von Prüfköpfen mit Methoden, die am Prüfort angewendet werden können, sind in EN 12668-3 aufgeführt.
Wenn mit Zustimmung der Vertragspartner außer den in EN 12668-3 aufgeführten Parametern auch noch zusätzliche Parameter während der Lebensdauer des Prüfkopfes gemessen werden müssen, so sollten die Verfahren zur Beurteilung für diese zusätzlichen Parameter aus den im vorliegenden Teil der Norm aufgeführten Verfahren ausgewählt werden.
Essais non destructifs - Caractérisation et vérification de l'appareillage de contrôle par ultrasons - Partie 2: Traducteurs
La présente Norme européenne concerne les traducteurs utilisés pour le contrôle non destructif par ultrasons des catégories suivantes avec fréquences centrales dans la bande 0,5 MHz à 15 MHz, avec et sans moyens de focalisation :
a) traducteurs par contact, simples ou émetteurs - récepteur séparés, générant des ondes de compression ou de cisaillement ;
b) traducteurs en immersion.
Lorsque des valeurs ultrasoniques dépendant des matériaux sont spécifiées dans cette norme, elles sont basées sur des aciers ayant une vitesse de propagation de l'onde ultrasonique de (5 920 ± 50) m/s pour les longueurs d'ondes longitudinales et de (3 255 ± 30) m/s pour les longueurs d'ondes transversales.
Les essais périodiques des traducteurs ne sont pas inclus dans cette partie de la norme. Les essais systématiques de vérification des traducteurs par application des méthodes sur site sont décrits dans l'EN 12668-3.
Si des paramètres, complémentaire à ceux spécifiés dans l'EN 12668-3 doivent être vérifiés au cours de la vie du traducteur conformément à un accord conclu entre les parties contractantes, il convient de choisir les méthodes de vérification correspondantes de ces paramètres complémentaires parmi celles données dans la présente norme.
Neporušitveno preskušanje - Ugotavljanje značilnosti in overjanje naprav za ultrazvočno preskušanje - 2. del: Preskuševalne glave
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 12668-2:2002
01-junij-2002
1HSRUXãLWYHQRSUHVNXãDQMH8JRWDYOMDQMH]QDþLOQRVWLLQRYHUMDQMHQDSUDY]D
XOWUD]YRþQRSUHVNXãDQMHGHO 3UHVNXãHYDOQHJODYH
Non-destructive testing - Characterization and verification of ultrasonic examination
equipment - Part 2: Probes
Zerstörungsfreie Prüfung - Charakterisierung und Verifizierung der Ultraschall-
Prüfausrüstung - Teil 2: Prüfköpfe
Essais non destructifs - Caractérisation et vérification de l'appareillage de contrôle par
ultrasons - Partie 2: Traducteurs
Ta slovenski standard je istoveten z: EN 12668-2:2001
ICS:
19.100 Neporušitveno preskušanje Non-destructive testing
SIST EN 12668-2:2002 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 12668-2:2002
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SIST EN 12668-2:2002
EUROPEAN STANDARD
EN 12668-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2001
ICS 19.100
English version
Non-destructive testing - Characterization and verification of
ultrasonic examination equipment - Part 2: Probes
Essais non destructifs - Caractérisation et vérification de Zerstörungsfreie Prüfung - Charakterisierung und
l'appareillage de contrôle par ultrasons - Partie 2: Verifizierung der Ultraschall-Prüfausrüstung - Teil 2:
Traducteurs Prüfköpfe
This European Standard was approved by CEN on 16 April 2001.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2001 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12668-2:2001 E
worldwide for CEN national Members.
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EN 12668-2:2001
Contents
page
Foreword.3
1 Scope .4
2 Normative references .4
3 Terms, definitions, symbols and abbreviations.4
4 General requirements for compliance .6
5 Manufacturer's technical specification for probes.6
6 Test equipment .10
6.1 Electronic equipment .10
6.2 Test blocks and other equipment.10
7 Performance requirements for probes .13
7.1 Physical aspects .13
7.2 Radio frequency pulse shape.13
7.3 Pulse spectrum and bandwidth.13
7.4 Relative pulse-echo sensitivity.14
7.5 Distance-amplitude curve .14
7.6 Electrical impedance or static capacitance .15
7.7 Beam parameters for immersion probes.16
7.8 Beam parameters for contact, straight-beam, single-transducer probes.20
7.9 Beam parameters for contact shear wave, angle-beam, single-transducer probes.23
7.10 Beam parameters for contact, straight beam, dual-transducer probes.26
7.11 Beam parameters for contact, shear wave angle beam, dual-transducer probes .28
Annex A (normative) Calculation of nearfield length of non-focusing probes.45
Annex B (informative) Calibration block for angle-beam probes .48
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EN 12668-2:2001
Foreword
This European Standard has been prepared by Technical Committee CEN/TC 138, "Non-destructive testing", the
secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an identical text or
by endorsement, at the latest by November 2001, and conflicting national standards shall be withdrawn at the latest
by November 2001.
This standard consists of the following parts :
EN 12668-1, Non-destructive testing - Characterization and verification of ultrasonic examination equipment -
Part 1: Instruments
EN 12668-2, Non-destructive testing - Characterization and verification of ultrasonic examination equipment -
Part 2: Probes
EN 12668-3, Non-destructive testing - Characterization and verification of ultrasonic examination equipment -
Part 3: Combined equipment
Annex A is normative. Annex B is informative.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,
France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden,
Switzerland and the United Kingdom.
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EN 12668-2:2001
1 Scope
This European standard covers probes used for ultrasonic non-destructive examination in the following categories with
centre frequencies in the range 0,5 MHz to 15 MHz, focusing and without focusing means:
a) single or dual transducer contact probes generating compressional or shear waves ;
b) immersion probes.
Where material dependent ultrasonic values are specified in this standard they are based on steels having an
ultrasonic sound velocity of (5 920 ± 50) m/s for longitudinal waves, and (3 255 ± 30) m/s for transverse waves.
Periodic tests for probes are not included in this standard. Routine tests for the verification of probes using on-site
methods are given in EN 12668-3.
If parameters in addition to those specified in EN 12668-3 are to be verified during the probe's life time, as agreed upon
by the contracting parties, the methods of verification for these additional parameters should be selected from those
given in this standard.
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed hereafter. For
dated references, subsequent amendments to or revisions of any of these publications apply to this European
Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the
publication referred to applies (including amendments).
EN 1330-4, Non destructive testing - Terminology - Part 4 : Terms used in ultrasonic testing.
EN 12223, Non-destructive testing - Ultrasonic examination - Specification for calibration block No. 1.
EN 12668-1, Non-destructive testing - Characterization and verification of ultrasonic examination equipment - Part
1 : Instruments.
EN 12668-3, Non-destructive testing - Characterization and verification of ultrasonic examination equipment - Part
3 : Combined equipment.
EN 27963, Welds in steel - Calibration block No. 2 for ultrasonic examination of welds (ISO 7963:1985).
EN ISO 9001, Quality systems - Model for quality assurance in design, development, production, installation and
servicing (ISO 9001:1994).
EN ISO 9002, Quality systems - Model for quality assurance in production, installation and servicing (ISO
9002:1994).
3 Terms, definitions, symbols and abbreviations
For the purposes of this European Standard the terms and definitions given in EN 1330-4 apply, together with the
following terms and definitions.
3.1
dead zone
depth of the zone immediately beneath the coupling surface of the work piece, in which it is not possible to detect a
given reflector
3.2
focal distance; (nearfield length)
point on the acoustical axis where the acoustic pressure is at its maximum
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3.3
horizontal plane of a sound beam
with angle-beam probes the plane perpendicular to the vertical plane of sound beam including the acoustical axis in
the material
3.4
operating frequency, f ; (centre frequency)
o
in the frequency spectrum of an echo the upper and lower cut-off-frequencies are determined at -6 dB compared to
the maximum amplitude. With these upper and lower frequencies f and f the centre frequency is calculated as :
u l
f f f
o u l
3.5
peak-to-peak amplitude, h
maximum deviation between the largest positive and the largest negative cycles of the pulse (see Figure 1)
3.6
probe data sheet
sheet giving information on probe performance which accompanies each probe. The data sheet need not
necessarily be a test certificate of individual probe performance
3.7
pulse duration
time interval over which the modulus of the unrectified pulse amplitude exceeds 10 % of its maximum amplitude, as
shown in Figure 1
3.8
reference side
reference side is the right side of an angle beam probe looking in the direction of the beam, unless otherwise
specified by the manufacturer
3.9
relative bandwidth, f
rel
ratio of the difference of the upper and lower cut-off frequencies f and f and the centre frequency f in percent
u l o
f = [(f - f )/f ] 100 %
rel u l o
3.10
squint angle for straight-beam probes,
deviation between the axis of the beam and a perpendicular to the coupling surface at the emission point
(see Figure 2)
For angle-beam probes
angle between the sides of the probe housing and the measured beam axis, projected onto the plane of the probe
face (see Figure 3)
3.11
transducer
element in the probe which transforms electrical oscillations to mechanical oscillations and vice versa, in most
cases piezoelectric elements
3.12
vertical plane of a sound beam
with angle-beam probes the plane in which the sound beam axis in the probe wedge and the sound beam axis in
the inspected component both lie
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4 General requirements for compliance
A probe complies with this standard if it satisfies the following conditions:
a) the probe shall meet the technical requirements of this standard ;
b) the probe carries a unique serial number, showing operating frequency, transducer size, angle, and wave
mode, or a permanent reference number from which this information can be traced ;
c) a data sheet is available for the appropriate type and series of probes which gives the performance in
accordance with clause 5 of this standard.
The quality of probes will be assured in one of the following ways :
a) where a large number of identical probes are manufactured under a quality management system, e.g.
EN ISO 9001 and EN ISO 9002, measurements are made on a statistically selected number of probes. The
manufacturer supplies a data sheet which includes the values of the specified parameters with tolerances ;
b) by issuing a declaration of conformity quoting the results of measurements made on an individual probe. This
is suitable where only a small number of probes of each type is manufactured or where probes are required for
special applications.
5 Manufacturer's technical specification for probes
Table 1 gives the list of information to be reported by a manufacturer in a data sheet for all probes within the scope of
this standard (I = Information, M = Measurement, C = Calculation). The data sheet shall also contain information
concerning the instrument used for the test, its settings and coupling conditions etc.
The manufacturer shall also state the operating temperature range of the probe, and any special conditions for storage
or protection during transport.
The supplier and the customer can agree where necessary to preclude some of the information and/or include some
other details not included in Table 1.
For probes intended for use at elevated temperatures the manufacturer shall provide information on the maximum
operating temperature in relation to the time of use, and the effect of temperature on the sensitivity and on the beam
angle.
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Table 1 — List of information to be given in a data sheet
Category of probe
Contact Immersion
Straight beam Angle beam Straight
Information Compressional Shear Compressional Shear Compressional
to be given Single Double Single Single Double Single Double Single
non-f. focus. non-f. focus. non-f. non-f. focus. non-f. focus. non-f. focus. non-f. focus. non-f. focus.
Manufacturer's name I I I I I I I I I I I I I I I
Type of probe I I I I I I I I I I I I I I I
Weight & size of probe I I I I I I I I I I I I I I I
Type of connectors I I I I I I I I I I I I I I I
TR connect. interchangeable I I I I I I
Material of transducers I I I I I I I I I I I I I I I
Shape & size of transducers I I I I I I I I I I I I I I I
Material of wedge, delay I I I I I I I I I I I I
Material of wear plate I
Wear allowance I I I I I I I I I I I I
I = Information ;
M = Measurement ;
C = Calculation
continued
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Table 1 (continued)
Category of probe
Contact Immersion
Straight beam Angle beam Straight
Parameters to be Compressional Shear Compressional Shear Compressional
measured or calculated Single Double Single Single Double Single Double Single
non-f. focus. non-f. focus. non-f. non-f. focus. non-f. focus. non-f. focus. non-f. focus. non-f. focus.
Cross talk damping M M M M M M
Pulse shape (time & frequency) M M M M M M M M M M M M M M M
Centre frequency, band width M M M M M M M M M M M M M M M
Pulse-echo sensitivity M M M M M M M M M M M M M M M
Distance-amplitude curve M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C
Impedance, static capacitance M M M M M M M M M M M M M M M
I = Information ;
M = Measurement ;
C = Calculation ;
M,C = Measurement or calculation
continued
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Table 1 (concluded)
Category of probe
Contact Immersion
Straight beam Angle beam Straight
Parameters to be Compressional Shear Compressional Shear Compressional
measured or calculated Single Double Single Single Double Single Double Single
non-f. focus. non-f. focus. non-f. non-f. focus. non-f. focus. non-f. focus. non-f. focus. non-f. focus.
Probe index MMM M M M M M
Beam angle MMM M M M M M
Angles of divergence M M M M M
Beam axis offset M M M M M M M M M M M M M
Squint angle M M M M M M M M M M M M M
Focal distance, nearfield M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C
Focal width M M M M M MMM M M M M M M M
Focal length M M M M M M M M M M M M M M M
Physical aspects M M M M M M M M M M M M M M M
I = Information ;
M = Measurement ;
C = Calculation ;
M,C = Measurement or calculation
Non-f. = non-focusing
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6 Test equipment
6.1 Electronic equipment
The ultrasonic instrument (or laboratory pulser/receiver) used for the tests specified in clause 7 shall be of the type
designated on the probe data sheet, and shall comply with EN 12268-1 as applicable. Where more than one type of
ultrasonic instrument is designated the tests shall be repeated with each of the additional designated types.
Testing shall be carried out with the probe cables and electrical matching devices, specified on the probe data sheet
for use with the particular type of ultrasonic instrument.
NOTE Probe leads more than about 2 m long could have significant effect on probe performance.
In addition to the ultrasonic instrument or laboratory pulser/receiver the items of equipment essential to assess
probes in accordance with this standard are as follows :
a) an oscilloscope with a minimum bandwith of 100 MHz ;
b) a frequency spectrum analyzer with a minimum bandwith of 100 MHz, or an oscilloscope/digitizer capable of
performing Discrete Fourier Transforms (DFT) ;
c) an impedance analyzer.
The following additional equipment is optional :
For contact probes only :
d) an electromagnetic-acoustic probe (EMA) and receiver ;
e) a plotter to plot directivity diagrams.
For immersion probes only :
f) hydrophone receiver with an active diameter less than two times the central ultrasonic wavelength
of the probe under test but not less than 0,5 mm. The bandwidth of the amplifier should be higher
than the bandwidth of the probe under test.
6.2 Test blocks and other equipment
The following test blocks shall be used to carry out the specified range of tests, for contact probes only :
a) semi-cylinders with different radii (R) in the range from 12 mm to 200 mm steps of R 2 are recommended.
Steel quality is as defined in EN 27963. The thickness of each block shall be equal to or larger than it's
radius, up to a maximum thickness of 100 mm ;
b) steel blocks with parallel faces and side-drilled holes of 3 mm diameter as shown in Figure 4 a). The
dimensions of the blocks shall meet the following requirements :
length, l, height, h, and width, w, shall be such that the sides of the blocks shall not interfere with the
ultrasonic beam ;
depths of the holes, d , d , . shall be such that at least 3 holes shall fall outside the near field ;
1 2
the distance between the holes, s, shall be such that the amplitude profile across the holes shows an
amplitude drop of at least 26 dB between two adjacent holes ;
steel quality is as defined in EN 27963.
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c) steel blocks with inclined faces with a notch as shown in Figure 4 b), and steel blocks with hemispherical
holes as in Figures 4 c) and 4 d). Steel quality is as defined in EN 27963. These blocks are used to measure
the beam divergence in the vertical and horizontal plane respectively ;
d) an alternative steel block to measure index point, beam angle and beam divergence for angle beam probes
is given in annex A ;
e) ruler ;
f) feeler gauges starting at 0,05 mm.
NOTE Not all blocks are required if only special kinds of probes are to be checked, e.g. blocks to measure the index
point and beam angle are not necessary if only straight-beam probes have to be measured.
For testing immersion probes the following reflectors and additional equipment shall be used :
g) a steel ball or semi-spherical ended rod with smooth reflective surface. For each frequency range the
diameter of ball or rod to be used is given in Table 2.
Table 2 — Steel ball (rod) diameters for different frequencies
d
Probe centre frequency Diameter of ball or rod
(MHz) (mm)
3 < f 15 d 3
0,5 f 33 < d 5
h) a large plane and flat reflector target. The target's lateral size shall be at least ten times wider than the
diameter of the beam of the probe under test at the end of focal zone, as defined in 7.7.2.2.
Thickness is at least five times the wave length of the probe under test, calculated using the velocity of
ultrasound in the material of the target.
i) immersion tank equipped with a manual or automatic scanning bridge with five free axes :
three linear axes X, Y, Z ;
two angular axes and .
j) Automatic recording means: If the amplitudes of ultrasonic signals are recorded automatically, then it is the
responsibility of the manufacturer to ensure that the system has sufficient accuracy. In particular
consideration shall be given to the effects of the system bandwidth, spatial resolution, data processing and
data storage on the accuracy of the results.
Throughout this standard the coordinate system shown in Figures 12 and 13 is used.
The scanning mechanism used with the immersion tank should be able to maintain alignment between the target
and the probe in the X and Y directions, i.e. within ± 0,1 mm for 100 mm distance in the Z direction.
The temperature of the water in the immersion tank shall be maintained at (20 ± 2) °C during the beam
characterization of immersion transducers described in 7.7.
Care shall be taken about the influence of sound attenuation in water, which, at high frequencies, causes a downshift
of the echo frequency when using broadband probes.
Table 3 shows the relation between frequency downshift and water path.
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Table 3 — Frequency downshift in percent of centre frequency fo depending on total water path length, for relative bandwidths (b.w.) 50 % and 100 %
b.w. Total water path in mm
f
o
MHz % 10 20 30 40 50 60 70 80 90 100 150 200 250 300 350 400
5 50 000000111 1122233
100 011122233 35679 10 11
10 50 011122233 35679 10 11
100 13456789 10 11 16 21 24 28 31 34
15 50 112344566 7 10 13 15 18 20 23
100 3 6 8 10 13 15 17 19 21 23 30 37 42 47 50 54
20 50 13456789 10 11 16 21 24 28 31 34
100 51013172124272932 34445156616467
25 50 24679 11 12 14 15 17 23 29 34 38 41 45
100 71420242933363942 45556267707476
30 50 3 6 8 10 13 15 17 19 21 23 30 37 42 47 50 54
100 10 19 26 32 37 41 45 48 51 54 64 70 74 78 80 82
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7 Performance requirements for probes
7.1 Physical aspects
7.1.1 Method
Visually inspect the outside of the probe for correct identification and assembly and for physical damage which can
influence its' current or future reliability. In particular for contact probes measure the flatness of the contact surface of
the probe using a ruler and feeler gauges.
7.1.2 Acceptance criterion
For flat faced probes, over the whole probe face the gap shall not be larger than 0,05 mm.
7.2 Radio frequency pulse shape
7.2.1 Method
The amplitude and pulse duration of the echo is determined with a measurement setup as in Figure 5 (contact probe)
or Figure 13 (immersion) :
a) for contact probes with a single transducer the echo out of a semi-cylinder is used whose radius is larger than
1,5 of the nearfield length of the probe or within the focal range of focused probes ;
b) for dual-transducer probes a semi-cylinder is used whose radius is nearest to the focal point of the probe ;
c) for immersion probes a large flat reflector is used at the focal distance for focused probes or at more than 1 of
the nearfield length for flat transducers.
The pulser setting shall be recorded, and the peak-to-peak amplitude of the transmitter pulse shall be measured. It is
recommended to plot the transmitter pulse shape and it is preferable that the plot of the transmitter pulse be included in
the results of this test.
7.2.2 Acceptance criterion
The pulse duration shall not deviate by more than ± 10 % from the manufacturer's specification.
7.3 Pulse spectrum and bandwidth
7.3.1 Method
Use the same blocks and the same setup is used as in 7.2. Gate the reflector echo and determine the frequency
spectrum using a spectrum analyzer or a Discrete Fourier Transform.
Spurious echoes from the probe's wedge, housing, damping block, etc. are not to be analyzed together with the echo
from the reference block. The gate has to be twice the pulse duration as a minimum and centered on the maximum of
the pulse.
The lower and upper frequencies for a - 6 dB drop of echo amplitude have to be measured. For immersion technique
the values shall be corrected according to Table 3.
From these upper and lower frequencies f and f the centre frequency f is calculated :
u l o
f f f (1)
o u l
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The bandwidth is :
f = f – f (2)
u l
and the relative bandwidth is calculated, in percentage, as :
f = (f / f ) 100 (3)
rel o
7.3.2 Acceptance criteria
The centre frequency has to be within ± 10 % of the frequency quoted in the data sheet.
The - 6 dB bandwidth has to be within ± 15 % of the nominal bandwidth. If the spectrum between f and f has more
l u
than one maximum, the amplitude difference between adjacent minima and maxima shall not exceed 3 dB.
For broadband probes with a relative bandwidth exceeding 100 %, the lower frequency shall not be higher than
f + 10 %, and the upper frequency shall not be lower than f - 10 %.
l u
7.4 Relative pulse-echo sensitivity
7.4.1 Method
Set the ultrasonic instrument to separate pulser/receiver mode. Relative pulse-echo sensitivity is defined as :
S = 20 log (V /V ) (4)
rel 10 e a
where V is the peak-to-peak voltage of the echo from a specified reflector, preferable flat, before amplification and V is
e a
the peak-to-peak voltage applied to the probe as measured in 7.2.
Probe sensitivity comparisons made with different types of ultrasonic instruments can vary, because the probe
sensitivity is influenced by the coupling conditions and by the impedances of pulser, probe, cable and receiver.
Therefore, these parameters have to be specified in the data sheet.
7.4.2 Acceptance criterion
The relative pulse-echo sensitivity shall be within ± 3 dB of the manufacturer's specification.
7.5 Distance-amplitude curve
7.5.1 Method
The amplitude of ultrasonic pulses varies with distance from the probe. Therefore, to evaluate echos of reflectors, for all
kinds of probes, distance-amplitude curves are needed using the reflectors in Table 4.
Table 4 — Reflectors for distance-amplitude curves
Contact Immersion
Disk shaped reflectors Flat bottom holes Flat ended rod
Cylindrical reflectors Side drilled holes Cylindrical rod
Spherical Hemispherical bottom hole Hemispherical ended rod or ball
Disk-shaped reflectors, side-drilled holes and hemispherical bottom holes are used as equivalent reflectors when using
contact probes. With immersion probes usually a small-sized steel ball is used to measure a distance-amplitude curve
(see 7.7.2). For dual-transducer probes the separation layer shall be perpendicular to the side-drilled holes.
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Using a series of reflectors of constant size but at different distances to the probe the received echo amplitudes are
plotted against distance. At least 8 measurement points on each curve shall be available. The distances used shall
cover the focal range of focusing probes or the range including the nearfield length of non-focusing probes.
Distances and amplitudes are determined on the calibrated screen of an ultrasonic instrument mentioned in the data
sheet.
To generate a noise curve, at each position of a maximized reflector echo the difference between noise and the
reflector echo is determined by increasing the gain until the noise reaches the former height of the reflector echo.
If it is not possible to increase the gain by such an amount, the difference can be estimated.
If, e.g. the reflector echo was at 40 % of full screen height, then the noise at :
20 % means an additional difference of 6 dB ;
10 % means an additional difference of 12 dB ;
5 % means an additional difference of 18 dB
to the difference given by the attenuator readings.
The noise curve is measured with the reflector removed and the surface of the probe cleaned from couplant.
A diagram showing at least one distance-amplitude curve shall be available for each probe type, attached to the
manufacturer's data sheet. This diagram shall also include a distance-noise curve.
Figure 6 a) shows an example of different distance-amplitude curves for disk-shaped reflectors, calculated for disk-
shaped reflectors in steel (distance-gain-size diagram -
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