SIST EN 12645:2014
(Main)Tyre pressure measuring instruments - Devices for inspection of pressure and/or inflation / deflation of tyres for motor vehicles - Metrology, requirements and testing
Tyre pressure measuring instruments - Devices for inspection of pressure and/or inflation / deflation of tyres for motor vehicles - Metrology, requirements and testing
EN 12645 defines metrological and technical requirements and tests of tyre pressure measuring instruments. Tyre pressure measuring instruments (often referred to as Tyre Pressure Gauges, [TPG]) are for the inspection of pressure and/or inspection of inflation/deflation of tyres of motor vehicles. It establishes in the context of motor vehicles tyres, the minimum characteristics of the chain of measurement of tyre pressure measuring instruments intended to inspect or adjust the pressure of tyres inflated by air or nitrogen. These devices, classified in different categories, are hereinafter referred to by generic term, “tyre pressure measuring instruments”. This chain of measurement consists of all the elements between the tyre valve and the display device (connector, hose, control device, measurement components, reservoir, preset device etc.). They indicate the pressure difference (pe) between the air or the nitrogen in the tyre and the atmosphere. The field of application established above can be extended to other applications where no specific standard exists. Because of the influence of tyre pressure on road safety and energy efficiency, periodical verification of tyre pressure measuring instruments is strongly recommended.
Reifendruckmessgeräte - Geräte zum Prüfen des Druckes und/oder zum Füllen / Entleeren von Reifen an Kraftfahrzeugen - Messtechnik, Anforderungen und Prüfungen
Diese Europäische Norm legt messtechnische und technische Anforderungen und Prüfungen von
Reifendruckmessgeräten fest.
Reifendruckmessgeräte (oftmals auch benannt als Reifendruckmesser, [en: TPG]) werden zur Kontrolle des
Drucks und/oder Kontrolle der Füllung/Ablassung von Kraftfahrzeugreifen verwendet.
Sie stellen im Zusammenhang mit Kraftfahrzeugreifen die Mindestmerkmale der Messkette von Anlagen zur
Erhöhung, Prüfung oder Einstellung des Druckes von mit Luft oder Stickstoff gefüllten Reifen dar.
Diese in vier Kategorien eingeteilten Anlagen werden nachstehend als „Reifendruckmessgeräte“ bezeichnet.
Die Messkette beinhaltet alle Elemente, die sich zwischen dem Reifenventil und der visuellen Anzeigeeinheit
(Anschluss, Schlauch, Regeleinrichtung, Bestandteile der Messeinrichtung, Behälter, Vorwahleinrichtung
usw.) befinden.
Die Reifendruckmessgeräte zeigen den Druckunterschied (pe) zwischen der Luft oder dem Stickstoff im Reifen
und der Atmosphäre an.
Der oben beschriebene Anwendungsbereich kann auf andere Anwendungen ausgedehnt werden, für die
keine besonderen Normen vorhanden sind.
Aufgrund der Bedeutung des Reifendruckes für die Verkehrssicherheit sowie für die Energieeffizienz werden
periodische Wiederholungsüberprüfungen dringend empfohlen.
Instruments de mesure de la pression des pneumatiques - Dispositifs de contrôle de la pression et/ou de gonflage / dégonflage des pneumatiques des véhicules motorisés - Métrologie, exigences et essais
Cette norme européenne définit des exigences métrologiques et techniques et les essais d’instruments de mesure de pression des pneumatiques.
Les instruments de mesure de pression des pneumatiques (souvent désigné comme des Manomètres de Pneumatiques, [TPG]) sont pour l'inspection de la pression et/ou l'inspection du gonflage/dégonflage des pneumatiques de véhicules motorisés.
Elle fixe dans le cadre d’une application aux pneumatiques des véhicules motorisés, les caractéristiques minimales de la chaîne de mesurage des instruments de mesure de pression des pneumatiques destinés à vérifier ou ajuster la pression des pneumatiques gonflés à l’air ou à l’azote.
Ces dispositifs classés dans différentes catégories sont désignés ci-après par le terme générique "instruments de mesure de pression des pneumatiques".
Cette chaîne de mesure se compose de tous les éléments situés entre la valve du pneumatique et le dispositif afficheur (raccord, tuyau, dispositif de commande, composants de mesure, réservoir, dispositif de prédétermination, etc.).
Ils indiquent la différence de pression (pe) entre l'air ou l'azote dans le pneumatique et l'atmosphère.
Le domaine d'application défini ci-dessus peut être étendu à d'autres applications dans le cas où il n’existerait pas de norme spécifique.
En raison de l'influence de la pression du pneumatique sur la sécurité routière et sur l’efficacité énergétique, la vérification périodique des instruments de mesure de pression des pneumatiques est fortement conseillée.
Merilniki tlaka v pnevmatikah - Naprave za nadzor tlaka in/ali napihovanje/izpuščanje pnevmatik motornih vozil - Meroslovje, zahteve in preskušanje
Standard EN 12645 določa meroslovne in tehnične zahteve ter preskuse merilnikov tlaka v pnevmatikah. Merilniki tlaka v pnevmatikah so namenjeni nadzoru tlaka in/ali nadzoru napihovanja/izpuščanja pnevmatik motornih vozil. V zvezi s pnevmatikami motornih vozil določa minimalne karakteristike merilne verige merilnikov tlaka v pnevmatikah za nadzor ali prilagajanje pnevmatik, ki se napihnejo z zrakom ali dušikom. Te naprave, razvrščene v različne kategorije, se v nadaljevanju opisujejo s splošnim izrazom »merilniki tlaka v pnevmatikah«. To merilno verigo sestavljajo vsi elementi med ventilom pnevmatike in prikazno napravo (povezovalni priključek, cev, nadzorna naprava, merilne komponente, rezervoar, prednastavljena naprava itd.). Kažejo razliko v tlaku (pe) med zrakom ali dušikom v pnevmatiki in atmosferi. Zgoraj določeno področje uporabe je mogoče razširiti na druge uporabe, kadar ni posebnega standarda. Zaradi vpliva tlaka v pnevmatikah na varnost na cesti in energetsko učinkovitost se močno priporoča redno preverjanje merilnikov tlaka v pnevmatikah.
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.SUHVNXãDQMHReifendruckmessgeräte - Geräte zum Prüfen des Druckes und/oder zum Füllen / Entleeren von Reifen an Kraftfahrzeugen - Messtechnik, Anforderungen und PrüfungenInstruments de mesure de la pression des pneumatiques - Dispositifs de contrôle de la pression et/ou de gonflage / dégonflage des pneumatiques des véhicules motorisés - Métrologie, exigences et essaisTyre pressure measuring instruments - Devices for inspection of pressure and/or inflation / deflation of tyres for motor vehicles - Metrology, requirements and testing83.160.10Pnevmatike za cestna vozilaRoad vehicle tyres43.180Diagnostic, maintenance and test equipment17.100Merjenje sile, teže in tlakaMeasurement of force, weight and pressureICS:Ta slovenski standard je istoveten z:EN 12645:2014SIST EN 12645:2014en,de01-november-2014SIST EN 12645:2014SLOVENSKI
STANDARDSIST EN 12645:20011DGRPHãþD
SIST EN 12645:2014
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 12645
August 2014 ICS 17.100; 43.180; 83.160.10 Supersedes EN 12645:1998English Version
Tyre pressure measuring instruments - Devices for inspection of pressure and/or inflation / deflation of tyres for motor vehicles - Metrology, requirements and testing
Instruments de mesure de la pression des pneumatiques - Dispositifs de contrôle de la pression et/ou de gonflage / dégonflage des pneumatiques des véhicules motorisés - Métrologie, exigences et essais
Reifendruckmessgeräte - Geräte zum Prüfen des Druckes und/oder zum Füllen / Entleeren von Reifen an Kraftfahrzeugen - Messtechnik, Anforderungen und Prüfungen This European Standard was approved by CEN on 31 August 2013.
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 CEN-CENELEC 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 CEN-CENELEC Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2014 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12645:2014 ESIST EN 12645:2014
EN 12645:2014 (E) 2 Contents Page Foreword .4 1 Scope .5 2 Normative references .5 3 Terms and definitions .6 4 Categories .8 5 Metrological requirements . 10 5.1 Maximum permissible errors . 10 5.2 Hysteresis error . 10 5.3 Zero . 10 5.3.1 Return of the instrument's indication to zero . 10 5.3.2 Zero setting . 10 5.4 Units . 11 6 Technical requirements . 11 6.1 Construction . 11 6.2 Analog indicating tyre pressure measuring instrument . 11 6.2.1 Scale angle . 11 6.2.2 Scale interval . 11 6.2.3 Scale spacing . 11 6.2.4 Index . 12 6.3 Digital indicating tyre pressure measuring instrument . 12 6.3.1 Scale interval . 12 6.3.2 Readability . 12 6.4 Additional constructional requirements . 12 6.4.1 Mechanical tyre pressure measuring instruments . 12 6.4.2 Electronic tyre pressure measuring instrument . 12 6.4.3 Electronic and mechanical tyre pressure measuring instruments . 13 6.4.4 Preset device . 13 6.5 Operating conditions . 13 6.5.1 Climatic requirements . 13 6.5.2 Mechanical requirements . 14 6.5.3 Electromagnetic immunity requirements for electronic tyre pressure measuring instruments (with digital display and/or electronic sensor) . 15 6.5.4 Software requirements for electronic tyre pressure measuring instruments . 16 6.5.5 Mounting position requirements . 17 6.5.6 Kind of pressure indication requirement . 17 7 Type approval testing to check for compliance with metrological and technical requirements . 17 7.1 General . 17 7.2 Determination of accuracy error . 18 7.3 Determination of hysteresis error . 18 7.4 Determination of return of instrument’s indication to zero . 18 7.5 Determination of error after/during a disturbance or influence . 18 7.6 Climatic tests . 18 7.6.1 Determination of the MPE in the rated temperature in service . 18 7.6.2 Rated storage temperature . 19 7.6.3 Humidity . 19 SIST EN 12645:2014
EN 12645:2014 (E) 3 7.6.4 Corrosion test . 19 7.7 Mechanical tests . 19 7.7.1 Protection against ingress of water and foreign particles (degree of protection) . 19 7.7.2 Examination of the durability of the measuring instrument . 20 7.7.3 Vibration (random) . 20 7.7.4 Free fall . 21 7.8 Electromagnetic immunity. 21 7.8.1 AC mains voltage variations . 21 7.8.2 DC mains voltage variations . 21 7.8.3 AC mains power . 21 7.8.4 Bursts on AC and DC mains. 21 7.8.5 Electrostatic discharges . 21 7.8.6 Fast transients on signal and I/O lines . 22 7.8.7 Surges on signal and I/O lines . 22 7.8.8 DC mains power . 22 7.8.9 Ripple on DC input power ports . 22 7.8.10 Surges on AC and DC mains lines . 22 7.8.11 Radiated radio-frequency electromagnetic fields . 22 7.8.12 Conducted radio-frequency fields . 22 7.8.13 Voltage variations (if powered by vehicle battery) . 22 7.8.14 Electrical transient conduction along supply lines (if powered by vehicle battery) . 23 7.8.15 Load dump (if powered by vehicle battery) . 23 7.9 Software examination . 25 7.10 Mounting position . 26 7.11 Determination of pressure sensor — kind of pressure test . 26 8 Inscriptions and marking . 26 8.1 Inscriptions . 26 8.1.1 Obligatory inscriptions . 26 8.1.2 Optional inscriptions . 27 8.2 Verification marks and sealing . 27 9 Metrological control . 27 9.1 Type approval . 27 9.2 Initial Verification . 27 9.3 Subsequent verification . 27 9.4 In-service control . 28 Annex A (normative)
Correspondence between requirements and tests . 29 Annex B (normative)
MPE graphics . 30 Annex C (informative)
Examples of type approval test sequence for multiple samples . 32 Annex D (informative)
Recommended solutions for special test conditions . 35 Bibliography . 36
SIST EN 12645:2014
EN 12645:2014 (E) 4 Foreword This document (EN 12645:2014) has been prepared by Technical Committee CEN/TC 301 “Road vehicles”, 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 February 2015, and conflicting national standards shall be withdrawn at the latest by February 2015. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 12645:1998, and additionally to the tyre pressure mechanical measuring instruments, introduces new clauses for the electronic devices (requirements, test methods) and for the metrological control (during type approval, initial and subsequent verification, and in-service control). This document has been prepared under a mandate (M/457) given to CEN by the European Commission and the European Free Trade Association. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 12645:2014
EN 12645:2014 (E) 5 1 Scope This European Standard defines metrological and technical requirements and tests of tyre pressure measuring instruments. Tyre pressure measuring instruments (often referred to as Tyre Pressure Gauges, [TPG]) are for the inspection of pressure and/or inspection of inflation/deflation of tyres of motor vehicles. It establishes in the context of motor vehicles tyres, the minimum characteristics of the chain of measurement of tyre pressure measuring instruments intended to inspect or adjust the pressure of tyres inflated by air or nitrogen. These devices, classified in different categories, are hereinafter referred to by generic term, “tyre pressure measuring instruments”. This chain of measurement consists of all the elements between the tyre valve and the display device (connector, hose, control device, measurement components, reservoir, preset device etc.). They indicate the pressure difference (pe) between the air or the nitrogen in the tyre and the atmosphere. The field of application established above can be extended to other applications where no specific standard exists. Because of the influence of tyre pressure on road safety and energy efficiency, periodical verification of tyre pressure measuring instruments is strongly recommended. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 837-1, Pressure gauges - Part 1: Bourdon tube pressure gauges - Dimensions, metrology, requirements and testing EN 837-3, Pressure gauges - Part 3: Diaphragm and capsule pressure gauges - Dimensions, metrology, requirements and testing EN 60068-2-1, Environmental testing - Part 2-1: Tests - Test A: Cold EN 60068-2-2, Environmental testing - Part 2-2: Tests - Test B: Dry heat EN 60068-2-11, Environmental testing - Part 2: Tests - Test Ka: Salt mist EN 60068-2-30, Environmental testing - Part 2-30: Tests - Test Db: Damp heat, cyclic (12 h + 12 h cycle) EN 60068-2-32, Basic environmental testing procedures — Part 2: Tests — Test Ed: Free fall (IEC 60068-2-32) EN 60068-2-47, Environmental testing - Part 2-47: Tests - Mounting of specimens for vibration, impact and similar dynamic tests EN 60068-2-64, Environmental testing - Part 2-64: Tests - Test Fh: Vibration, broadband random and guidance SIST EN 12645:2014
EN 12645:2014 (E) 6 EN 60068-3-8, Environmental testing - Part 3-8: Supporting documentation and guidance - Selecting amongst vibration tests EN 60529, Degrees of protection provided by enclosures (IP Code) EN 60654-2, Operating conditions for industrial-process measurement and control equipment - Part 2: Power EN 61000-4-1, Electromagnetic compatibility (EMC) - Part 4-1: Testing and measurement techniques - Overview of IEC 61000-4 series EN 61000-4-2, Electromagnetic compatibility (EMC) - Part 4-2: Testing and measurement techniques - Electrostatic discharge immunity test EN 61000-4-3, Electromagnetic compatibility (EMC) - Part 4-3: Testing and measurement techniques - Radiated, radio-frequency, electromagnetic field immunity test EN 61000-4-4, Electromagnetic compatibility (EMC) — Part 4-4: Testing and measurement techniques — Electrical fast transient/burst immunity test (IEC 61000-4-4) EN 61000-4-5, Electromagnetic compatibility (EMC) - Part 4-5: Testing and measurement techniques - Surge immunity test EN 61000-4-6, Electromagnetic compatibility (EMC) — Part 4-6: Testing and measurement techniques — Immunity to conducted disturbances, induced by radio-frequency fields (IEC 61000-4-6) EN 61000-4-11, Electromagnetic compatibility (EMC) - Part 4-11: Testing and measurement techniques - Voltage dips, short interruptions and voltage variations immunity tests EN 61000-4-17, Electromagnetic compatibility (EMC) - Part 4-17: Testing and measurement techniques - Ripple on d.c. input power port immunity test EN 61000-4-29, Electromagnetic compatibility (EMC) - Part 4-29: Testing and measurement techniques - Voltage dips, short interruptions and voltage variations on d.c. input power port immunity tests ISO 7637-2, Road vehicles — Electrical disturbances from conduction and coupling — Part 2: Electrical transient conduction along supply lines only ISO 16750-1, Road vehicles — Environmental conditions and testing for electrical and electronic equipment — Part 1: General ISO 16750-2, Road vehicles — Environmental conditions and testing for electrical and electronic equipment — Part 2: Electrical loads 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 air gases used to inflate tyres of vehicles EXAMPLE Air or nitrogen. SIST EN 12645:2014
EN 12645:2014 (E) 7 3.2 tyre pressure measuring instrument instrument measuring the tyre pressure comprising all the elements from the tyre valve connector up to and including the display device Note 1 to entry: Often referred to as TPG (Tyre Pressure Gauge). Note 2 to entry: The elements may include tyre valve connector, hose, control device, measurement components, display device, software, reservoir, etc. 3.3 gauge pressure (pe) pressure difference between an absolute pressure and the absolute pressure of the atmosphere Note 1 to entry: The tyre pressure is the pressure difference between the air in the tyre and the atmosphere and therefore a gauge pressure 3.4 category subdivision of possible configurations of the measuring instrument Note 1 to entry: For the purpose of selecting the correct test method, the parts in the measuring chain are defined to be fixed, portable or hand-held. The control device is not relevant in defining the category. 3.5 preset device device which permits the selection of the (target) pressure and which automatically stops inflation/deflation process when the target pressure is reached 3.6 electronic tyre pressure measuring instrument tyre pressure measuring instrument with one or more electronic parts in the chain of measurement 3.7 mechanical tyre pressure measuring instrument tyre pressure measuring instrument without electronic parts in the chain of measurement 3.8 index means to indicate the tyre pressure value (for example: a pointer with scale or a cursor with scale) 3.9 indication display of the tyre pressure value Note 1 to entry: For example a digital display or an index with scale. Note 2 to entry: Normally a scale is arc shaped. Note 3 to entry: The display may be an index with scale on a screen. 3.10 MPE acronym often used for “Maximum Permissible Error” SIST EN 12645:2014
EN 12645:2014 (E) 8 4 Categories For the purposes of this document, the following categories apply. 4.1 category 1 - Fixed device tyre pressure measuring instrument where the measuring components and the displaying device are fixed Note 1 to entry: They are generally connected to a source of air and are equipped with a control device. See Figure 1.
Key A fixed components B portable components Figure 1 — Fixed device EXAMPLE Wall fixing inflation devices. 4.2 category 2 - Portable device tyre pressure measuring instrument where the measuring components and the displaying device are portable Note 1 to entry: They are generally connected to the control device and a reservoir under limited pressure or an integrated compressor or a source of air. See Figure 2. SIST EN 12645:2014
EN 12645:2014 (E) 9
Figure 2 — Portable device EXAMPLE Inflation terminal. 4.3 category 3 - Handheld device tyre pressure measuring instrument where the measuring components and the displaying device are handheld Note 1 to entry: They can be connected to the control device or grouped together with the control device. See Figure 3.
Figure 3 — Hand-held device EXAMPLE Inflation gun, pressure inspector. SIST EN 12645:2014
EN 12645:2014 (E) 10 5 Metrological requirements 5.1 Maximum permissible errors The maximum permissible errors positive or negative given in the tables below are defined as absolute values according to the measured pressure, expressed in kPa or bar. Table 1 — Maximum permissible errors ± in kPa Measured pressure
in kPa Maximum permissible errors (MPE) ± in kPa Ambient temperature (tamb) in °C for tyre pressure measuring instruments below 15 °C from 15 °C to 25 °C above 25 °C ≤ 400 0,5 * (15 - tamb) + 8 8 0,5 * (tamb - 25) + 8 > 400 to ≤ 1 000 0,5 * (15 - tamb) + 16 16 0,5 * (tamb - 25) + 16 > 1 000 0,5 * (15 - tamb) + 25 25 0,5 * (tamb - 25) + 25 Table 2 — Maximum permissible errors ± in bar Measured pressure
in bar Maximum permissible errors (MPE) ± in bar Ambient temperature (tamb) in °C for tyre pressure measuring instruments below 15 °C from 15°C to 25 °C above 25 °C ≤ 4 0,005 * (15 - tamb) + 0,08 0,08 0,005 * (tamb - 25) + 0,08 > 4 to ≤ 10 0,005 * (15 - tamb) + 0,16 0,16 0,005 * (tamb - 25) + 0,16 > 10 0,005 * (15 - tamb) + 0,25 0,25 0,005 *(tamb - 25) + 0,25 A graphical representation of these two tables is provided in Annex B. 5.2 Hysteresis error Hysteresis error of tyre pressure measuring instruments shall not exceed the absolute value of the maximum permissible error, given in 5.1 in the column “from 15 °C to 25 °C”. 5.3 Zero 5.3.1 Return of the instrument's indication to zero If the instrument indicates zero, the ‘real’ indication shall be within MPE or the instrument shall not indicate values below the minimum value of measured pressure. At atmospheric pressure, the index shall stop at the zero mark or at a predetermined mark clearly differentiated from the scale intervals, within the limits of the maximum permissible error. 5.3.2 Zero setting An instrument may be equipped with an automatic or semi-automatic zero-setting device. The semi-automatic zero-setting device has to check being at the atmospheric pressure before setting to zero. Manual zero-setting is not allowed except by switching OFF and ON. NOTE Manual means the operator can influence the result. SIST EN 12645:2014
EN 12645:2014 (E) 11 5.4 Units The SI unit of pressure is the pascal (Pa). Often scales indicate kilopascal (kPa) or bar. 1 bar = 100 kPa. 6 Technical requirements 6.1 Construction Tyre pressure measuring instruments shall be robustly and carefully constructed to ensure that they retain their metrological characteristics taking into account the rapid pressure increase due to tyre valve matching and inflation/deflation. They permit the inspection and adjustment of tyre pressure and the filling of unpressurised tyres. Measuring instruments with a sensing element susceptible for mechanical wear and tear shall be fitted with a protection system in order to prevent the supply pressure arriving up to the sensing element during inflation. During the inflating and deflating process, it shall be made clear to the user that the value indicated is not the actual value of the tyre pressure, for instance by flashing. The final tyre pressure on the display shall be read under normal conditions of use. 6.2 Analog indicating tyre pressure measuring instrument 6.2.1 Scale angle The scale normally covers 270° of arc. 6.2.2 Scale interval The scale interval graduation is in kPa (bar) and the value of each scale interval is fixed at 10 kPa (0,1 bar). The scale intervals shall be equal over the entire scale. 6.2.3 Scale spacing The scale spacings, which are not less than 1,25 mm, shall be either virtually equal or only show slight variations. Variation of scale spacing is permitted if the difference between two consecutive scale spacings does not exceed 20 % of the largest value and if the difference between the smallest and largest scale spacings does not exceed 50 % of the largest value. For linear scales, the scale spacing applies to the visible spacing (for example the scale spacing is magnified with a magnifying glass to give an apparent scale interval of > 1,25 mm). Every fifth mark shall be distinguished from the others by its greater length; every fifth or tenth mark shall be numbered. The thickness of the marks shall be virtually constant and shall not exceed one fifth (1/5) of the scale spacing. SIST EN 12645:2014
EN 12645:2014 (E) 12 6.2.4 Index In the measurement range, the indicating device (index) shall make it possible to read off, directly and accurately, the value of the measured pressure. To this end, the thickness of the part of the index which covers the scale marks shall not be greater than the thickness of the scale marks themselves. The index shall be capable of covering approximately half the length of the shortest scale marks. The maximum distance between the index and the plane of the scale marks shall not be greater than th
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