Friday, 7 October 2011 DIARIO OFICIAL (Section I) [Mexican Official Gazette]

SECRETARIA DE ECONOMIA MINISTRY OF THE ECONOMY

DRAFT Mexican Official Standard PROY-NOM-005-SCFI-2011, Measuring Instruments - System for Measuring and Dispensing Petrol and other Liquid Fuels - Specifications and Test and Verification Methods) In the margin, a stamp with the Mexican National Emblem, reading: Estados Unidos Mexicanos [United States of Mexico] – Secretaría de Economía [Ministry of the Economy] DRAFT MEXICAN OFFICIAL STANDARD PROY-NOM-005-SCFI-2011, MEASURING INSTRUMENTS - SYSTEM FOR MEASURING AND DISPENSING PETROL AND OTHER LIQUID FUELS - SPECIFICATIONS AND TEST AND VERIFICATION METHODS CHRISTIAN TUREGANO ROLDAN, Director General de Normas [Director-General of Standardization] and Chairman of the Comité Consultivo Nacional de Normalización de Seguridad al Usario, Información Comercial y Prácticas de Comercio [National Advisory Committee on Standardization for User Safety, Commercial Information and Trade Practices – CCNNSUICPC], on the basis of Article 34(XIII) and (XXXI) of the Basic Law on Federal Public Administration, Articles 39(V), 40(I) and (IV) and 47(I) of the Federal Law on Metrology and Standardization, Article 33 of its implementing Regulation and Article 19(I), (XIV) and (XV) of the Internal Regulations of the Ministry of the Economy, now issues for public consultation Draft Mexican Official Standard PROY-NOM-005-SCFI-2011, Measuring Instruments - System for Measuring and Dispensing Petrol and Other Liquid Fuels - Specifications and Test and Verification Methods, to enable interested parties to submit their comments within the next 60 calendar days to the CCNNSUIPC at Avenida Puente de Tecamachalco, No 6, Colonia Lomas de Tecamachalco, Sección Fuentes, Naucalpan de Juárez, CP 5390, State of Mexico, Tel: 57 29 93 00, ext. 43207, fax: 55 20 97 15 or to the following e-mail addresses: hector.espindola@economia.gob.mx, jose.fernandezdejauregui@economia.gob.mx and /or catarino.perez@economia.gob.mx, so that, in accordance with the law on such matters, they may be taken into consideration by the Committee proposing the Draft Standard. Mexico, D.F., 14 September 2011 – The Director-General of Standardization and the Chairman of the National Advisory Committee on Standardization for User Safety, Commercial Information and Trade Practices, Christian Turégano Roldán – Initials. DRAFT MEXICAN OFFICIAL STANDARD PROY-NOM-005-SCFI-2011, MEASURING INSTRUMENTS - SYSTEM FOR MEASURING AND DISPENSING PETROL AND OTHER LIQUID FUELS - SPECIFICATIONS AND TEST AND VERIFICATION METHODS 1. Purpose and scope This Draft Mexican Official Standard lays down the specifications and test and verification methods which are to be applied as a preventive measure to the various

systems for measuring and dispensing petrol and other liquid fuels, which are marketed and used in commercial transactions within the territory of the United States of Mexico. 2. References To ensure the correct application of this Draft Official Mexican Standard, the following Mexican Official Standards and Mexican Standards currently in effect or any which may replace them shall be applied: NOM-001-SCFI-1993, Electronic equipment – Electronic equipment for domestic use powered by different electrical power sources – Safety requirements and test methods for type approval published in the Mexican Official Gazette of 13 October 1993. NOM-001-SEDE-2005, Electrical installations – Use, published in the Mexican Official Gazette of 13 March 2006. NOM-008-SCFI-2002, General System of Measuring Units, published in the Mexican Official Gazette of 27 November 2002. NOM-016-ENER-2002, Energy efficiency of squirrel-cage type 3-phase AC induction motors of rated power 0.746 to 373 kW. Limits, test method and marking, published in the Mexican Official Gazette of 13 January 2003. NOM-092-SEMARNAT-1995, concerning atmospheric pollution and establishing the requirements, specifications and parameters for the installation of petrol vapour recovery systems at service stations and in-house filling stations located in Valle de México, published in the Mexican Official Gazette of 6 September 1995. NOM-093-SEMARNAT – 1995, establishing the test method for determining the efficiency under laboratory conditions of petrol vapour recovery systems at service stations and in-house filling stations, published in the Mexican Official Gazette of 6 September 1995. NMX-Z-12/1-1987, Sampling for attribute-based inspection – Part 2: Sampling methods, tables and graphs. Declaration of validity published in the Mexican Official Gazette of 28 October 1987. 3. Definitions For the purposes of this Draft Mexican Official Standard, the following definitions shall apply: 3.1. Adjustment The range of operations carried out during verification by a competent authority or accredited and approved bodies, designed to adjust a measuring instrument so as to obtain zero error performance and accuracy or, where this is not possible, to adjust it to the point closest to zero within the maximum permissible error range specified by this Draft Mexican Official Standard, using the mechanisms provided for that purpose.

3.2. Adjusting devices Mechanical or electronic devices incorporated into the primary measuring device, used to set the relevant errors within the maximum permissible error range. 3.3. Type- or prototype-approval A procedure to ensure that a system for measuring and dispensing petrol and other liquid fuels complies with requirements concerning metrological characteristics and technical and safety specifications. 3.4. Checksum A series of 32 characters in hexadecimal form, generated by a 128-bit MD5 cryptographic hash function, which is used to check the validity of the software application used to operate systems for measuring and dispensing petrol and other liquid fuels. 3.5. Volumetric flow rate A parameter representing flow, the units of which are expressed in terms of volume per unit of time. 3.6. Adjusting disc A device forming part of the primary measuring device, used for the mechanical adjustment of the volume delivered. 3.7. Pulse generator An electronic device connected to the rotor of the primary measuring device, which converts the mechanical movement into electrical pulses. 3.8. Calculating device A set of parts or components of the system for measuring and dispensing petrol and other liquid fuels which process and display, via an indicating device, the volume of liquid fuel dispensed, the price to pay for each transaction and also the price per litre. 3.9. Remote control systems A device built into or linked in any way to the system for measuring and dispensing petrol and other liquid fuels in order to perform various functions, excluding the volumetric adjustment referred to in the last paragraph of Section 5.3.3. of this Draft Mexican Official Standard. 3.10. Communication interface A port enabling the exchange of information between the system for measuring and dispensing petrol and other liquid fuels and another communication system.

3.11. Maximum permissible error Extreme error values permitted by the specifications, regulations and other requirements applicable to a specific measuring instrument. 3.12. Adjustment mode access switch An electrical device enabling access to the electronic adjustment mode of the system for measuring and dispensing petrol and other liquid fuels. 3.13. Electronic adjustment device An electronic device which enables the volume of fuel delivered to be adjusted electronically, whether the adjustment is effected by access to the device or by means of an electronic computer code. 3.14. Delivery selector by volume or price to pay A keypad used to pre-set the fuel delivery, in terms of volume or amount of money, selected by the consumer. 3.15. Mechanism synchronizing the switch with the calculating device An electromechanical device designed in such a way that, when a dispensing and measuring operation is completed, a further operation may not be carried out unless the meter or calculating device reading is set to zero. 3.16. Procuraduría Procuraduría Federal del Consumidor [Federal Consumer Protection Office] 3.17. Volumetric flow rate selector A device forming part of the nozzle outlet valve, which selects a maximum, medium or minimum delivery flow rate. 3.18. System for measuring and dispensing petrol and other liquid fuels A system for the automatic measuring and dispensing a volume of liquid fuel. This system shall consist, at least, of a primary measuring device, a mechanism to convert the measuring result to the price to pay in the national currency on the basis of an authorized price, and additional devices. Both the measuring instrument and the conversion mechanism may be made up of mechanical, electrical, electronic and computerised (software) components and components of any other kind. 3.19. Totalizers A device giving an indication of the volume of liquid fuel delivered. Totalizers are of two types: 3.19.1. Cumulative totalizer Provides a cumulative indication of each delivery of liquid fuel.

3.19.2. Instantaneous totalizer Provides a non-cumulative indication of each delivery of liquid fuel. 3.20. Remote pump A mechanism external to the system for measuring and dispensing petrol and other liquid fuels, designed to supply the fuel which passes through the primary measuring device. 3.21. Primary measuring device A mechanism which measures the passage of fuel and, on measuring it, produces a movement which it transmits to the pulse generator. 3.22. Verification body The legal or natural person conducting verifications. 3.23. Pressure relief valve A set of components installed for the purpose of maintaining constant pressure throughout the measuring system, designed to damp any pressure surges which may occur or stop the measuring operation if there is a lack of liquid fuel supply to the system. 3.24. Control valve (solenoid) A device which opens and closes the system for measuring and dispensing petrol and other liquid fuels. 3.25. Non-return valve (check valve) A set of components installed for the purpose of preventing reverse flow of the fuel through the delivery hose. 3.26. Nozzle outlet valve A device enabling the fuel to be dispensed, consisting of a volumetric flow rate selector and a non-return valve. 3.27. Safety valve A set of components installed for the purpose of preventing fuel spillages if the delivery hose becomes detached. 3.28. Additional devices Components facilitating the measuring operations and preventing the distortion of measurements, such as:

• Gas elimination devices

• Filters

• Auxiliary or satellite supply modules

• Valves

• Hoses. 3.29. Ancillary devices Any component with specific functions unconnected with measurements, such as remote control systems. 3.30. Verification Visual inspection or checks by means of sampling, measuring, laboratory tests or examination of documents carried out to assess conformity at a given time. It shall include evaluation of the metrological and functional characteristics of the measuring instrument within the tolerances and other requirements laid down in Mexican Official Standards and Mexican Standards and, where appropriate, the adjustment of those characteristics where the necessary adjusting devices are present. 3.31. Initial verification Verification which must be carried out in the first instance and before the instruments are used for commercial transactions or for determining the price of goods or services, covering the functional and performance characteristics of the measuring instruments, in order to determine whether they operate in accordance with the metrological characteristics laid down in the relevant Mexican Official Standards and Mexican Standards. 3.32. Periodic verification Verification which must be carried out once the validity of the initial verification has expired, to be carried out at intervals determined by the Ministry of the Economy, covering the functional and performance characteristics of measuring instruments, in order to determine whether they operate in accordance with the metrological characteristics laid down in the relevant Mexican Official Standards and Mexican Standards. 3.33. Extraordinary verification Verification which is neither initial nor periodic verification, covering the functional and performance characteristics of measuring instruments, which is carried out in order to determine whether they operate in accordance with the metrological characteristics laid down in the relevant Mexican Official Standards and Mexican Standards, when so requested by the users of those instruments, when they lose their ‘verified instrument’ status or when so determined by the competent authorities. 3.34. Tamper-proof characteristics These are characteristics which facilitate verification of the legality and performance of systems for measuring and dispensing petrol and other liquid fuels. They shall include:

3.34.1. Tamper-proof integrated circuits Characteristic achieved by means of an encapsulated integrated circuit or main electronic card with embedded system. 3.34.1.1. Encapsulated integrated circuit An integrated electronic circuit containing the software application controlling the operation of the system for measuring and dispensing petrol and other liquid fuels. 3.34.1.2. Main electronic card with embedded system An integrated system consisting of a printed circuit board on the surface and a high degree of integration, the software application which controls the operation of the system for measuring and dispensing petrol and other liquid fuels, and possibly components thereof. 3.34.2. Validation of software applications used in the system for measuring and

dispensing petrol and other liquid fuels. A check that the software application or applications used to operate the system for measuring and dispensing petrol and other liquid fuels have been authorised by the manufacturer of the system for measuring and dispensing petrol and other liquid fuels. 3.34.3. Audit trails or event logger Records of all interventions involving the measuring, configuration and adjustment devices forming part of the system for measuring and dispensing petrol and other liquid fuels. 4. Classification For the purposes of this Draft Mexican Official Standard, systems for measuring and dispensing petrol and other liquid fuels shall be classified as 2 types: Type I: Calculating type: display the volume of liquid fuel, the price to pay and the price per litre. Type II: Metering type: only display the volume of liquid fuel. For both types, pumping is effected by means of remote pumps, supplying the fuel at constant pressure. 5. Specifications 5.1. Errors 5.1.1. Maximum permissible error These errors concern the difference between the reading given by the measuring instrument and the volumetric test measure carried out in accordance with Section 7.2. It shall be obtained as follows:

a) The maximum permissible error (Emax) for type- or prototype-approval and

initial verification of systems for measuring and dispensing petrol and other liquid fuels must not exceed 10 mL plus 2 mL per litre, using the following formula:

Where: Vn is the nominal capacity of the volumetric test measure in L Emax is the maximum permissible error in mL.

b) The maximum permissible error (Emax) for periodic and extraordinary verification must not exceed 20 mL plus 4 mL per litre

Where:

Vn is the nominal capacity of the volumetric test measure in L

Emax is the maximum permissible error in mL.

c) The maximum permissible error for zero error adjustment shall be forty percent of the maximum permissible error specified in Section 5.1.1. b) of this Draft Mexican Official Standard.

This specification shall apply to measured volumes of 10 L or more.

5.1.2. Repeatability error (R)

Error range defined as the maximum difference between the indication errors obtained for measurements carried out on the same delivery, using the following formula:

Where:

R is the repeatability error in mL

The specification states that the repeatability error must not exceed 20 mL plus 2 mL per litre for any flow rate (maximum, medium or minimum) used during the test, using the following formula:

Where: Vn is the nominal capacity of the volumetric test measure in L. This specification shall apply to measured volumes of 10 L or more. 5.2. Exterior finish All parts of systems for measuring and dispensing petrol and other liquid fuels must be coated with paint which is resistant to the action of the product being pumped, sunlight and moisture, except for parts made of stainless steel, chromium-plated parts or other parts which, owing to the nature of the materials, provide the necessary resistance to the actions of the aforementioned agents. This shall be checked by visual inspection. 5.3. Specifications for parts Within systems for measuring and dispensing petrol and other liquid fuels, the following parts must be identified:

- The metering or calculating device

- The primary measuring device(s)

- The safety device(s)

- The delivery device(s). 5.3.1. The filtering device The system for measuring and dispensing petrol and other liquid fuels must be fitted with a No 100 mesh or equivalent filter to prevent the passage of particles larger than 150µm. This shall be checked by visual inspection against the filter specifications. 5.3.2. Metering or calculating device 5.3.2.1. The metering or calculating device, which indicates the volume delivered in litres, must revert to zero at the start of each delivery. This shall be checked by visual inspection of the indicating device. 5.3.2.2. The indicating device of the metering or calculating device must, as a minimum, indicate:

a) For Type I: the volume of liquid fuel dispensed, the price per litre and the price to pay. This shall be checked by visual inspection.

b) For Type II: the volume of liquid fuel dispensed. This shall be checked by

visual inspection.

5.3.2.3. Indicating device The indications shown on the calculating and metering device displays must be explicit, so that there can be no confusion in interpreting the figures displayed; the figures indicating the volume of liquid fuel dispensed and the price per litre must consist of at least 4 digits and 5 digits in the case of the price to pay. It must also be clear which display relates to which delivery hose. 5.3.2.4. Indicating device resolution It must indicate the volume of liquid fuel with a minimum interval of 0.1 L and the price to pay with the exact amount of centavos. This shall be checked by visual inspection. 5.3.2.5. The electronic calculating or metering devices must comply with the specifications and tests laid down in Mexican Official Standard NOM-001-SCFI-1993 (see Section 2 ‘References’ of this Draft Mexican Official Standard). 5.3.2.5. Totalizers The systems for measuring and dispensing petrol and other liquid fuels must have a cumulative totalizing device, which may be mechanical, electromechanical or electronic, fitted within the calculating or metering device, in order to indicate the cumulative amount of liquid fuel dispensed. They must also be fitted with an instantaneous totalizer, in order to indicate the volume of liquid fuel dispensed up to a given point during each delivery. The arrangement of both totalizers shall be checked by visual inspection. 5.3.3. Adjusting mechanism The primary measuring device and the calculating or metering device must have an adjusting disc or an electronic adjusting device respectively, which can be used to adjust the volume in accordance with the procedure indicated by the manufacturer. This shall be checked by visual inspection. The adjusting disc must include the perforations specified by the manufacturer and a locking pin, whilst the access switch to the adjustment mode must include a protective lock which does not allow an electrical bridge to be established across its terminals, to enable the official security devices to be affixed. This shall be checked by visual inspection. Volumetric adjustment of the system for measuring and dispensing petrol and other liquid fuels, either directly at the primary measuring device (adjusting disc) or electronically via the metering or calculating device must be carried out exclusively by means of the devices provided for that purpose. Such adjustment must be carried out directly within the system for measuring and dispensing petrol and other liquid fuels and never remotely by means of another device. The adjustment procedures must be checked against the manufacturer’s specifications and the relevant operating manual. 5.3.4. Safety devices Systems for measuring and dispensing petrol and other liquid fuels must be fitted with protective and safety devices to ensure that they can be used without risk of accidents due to explosion or fire, such as:

- A control valve

- Explosion-proof electrical installations

Compliance with this Section must be checked in accordance with Mexican Official Standards NOM-001-SEDE-2005 and NOM-092-SEMARNAT-1995 (see Section 2 ‘References’ of this Draft Mexican Official Standard). 5.3.4.1. Pressure relief valve The measuring systems must be fitted with a device to ensure that the pressure remains constant throughout the system and to ensure that air and gases can easily be expelled, thereby damping any pressure surges which will inevitably occur when the measuring systems are in operation. The control valve must perform this function. This shall be checked by visual inspection. 5.3.4.2. Explosion-proof electrical installations The electrical installations supplying electricity to the systems for measuring and dispensing petrol and other liquid fuels must comply with technical specifications and requirements so that they do not present a hazard to persons and property as regards protection against electric shocks, thermal effects, overcurrents, fault currents, overvoltages, atmospheric phenomena and fires inter alia and must comply with the requirements of Mexican Official Standard NOM-001-SEDE-2005 (see Section 2 ‘References’ of this Draft Mexican Official Standard). 5.3.5. Delivery devices 5.3.5.1. Delivery hose Only hoses which are in good condition may be used for dispensing fuel from systems for measuring and dispensing petrol and other liquid fuels, that is to say without damage to the external wall or cracks allowing constant dripping, or adaptations which could prevent them operating in accordance with the specifications of the manufacturer of the system for measuring and dispensing petrol and other liquid fuels. This shall be checked by visual inspection (see Section 5.4. of this Draft Mexican Official Standard). 5.3.5.2. Non-return valve In order to ensure that the delivery hose is permanently filled, it must be fitted with a non-return valve, either at its lower end or within the body of the nozzle outlet valve. This shall be checked by visual inspection. 5.3.5.3. Nozzle outlet valve The material from which the nozzle outlet valve is manufactured must ensure that no sparks or electrical discharges are generated as a result of friction, impact or normal use and must be of the appropriate shape (nozzle or pistol type) in order to perform the intended function. It must be leaktight when closed (see Section 5.4. of this Draft Mexican Official Standard). Where it is fitted with a protector or guard, this must be of the colour designated to identify the liquid fuel in question.

5.3.5.4. Characteristics of the delivery system safety device Systems for measuring and dispensing petrol and other liquid fuels must be fitted with a safety valve on each delivery hose in order to prevent fuel spillages should the hoses become detached. This shall be checked by visual inspection. 5.3.5.5. Mechanism synchronizing the switch with the computing device This device must stop the delivery of fuel within a period not exceeding 80 seconds once the fuel in question is no longer being dispensed. Once delivery has been stopped, it must not be restarted until the system for measuring and dispensing petrol and other liquid fuels has been reset to zero. This shall be checked using a stopwatch. 5.3.6. Communication interface Within systems for measuring and dispensing petrol and other liquid fuels, the wiring loom providing the communication function must be identified, together with the port and the communication protocol used and the list of communication commands and instructions. This must be checked visually against the manufacturer’s specifications and the relevant operating manual, which must also specify the specific function to be performed by the interface and the components listed. 5. 4. Vapour recovery system Systems for measuring and dispensing petrol and other liquid fuels must comply with Mexican Official Standards NON-092-SEMARNAT-1995 and NOM-093-SEMARNAT-1995 (see Section 2 ‘References’ of this Draft Mexican Official Standard) under the terms and conditions stated therein, and also with the provisions of Section 7.3.1.1. if they require electronic cards for their operation. 5.5. Design restrictions 5.5.1. It shall not be permitted to install devices, mechanisms or systems, including remote control systems, which alter the measurements made or indications given by the metering or calculating devices and their indicating devices displaying the current price per litre and the total sale during delivery. 5.5.2. Systems for measuring and dispensing petrol and other liquid fuels must possess the tamper-proof characteristics defined in Section 3.34 in order to ensure that the indications of the volume dispensed, price per unit and total sale may not be illegally altered, in accordance with Section 7.1.1. of this Draft Mexican Official Standard. 6. Sampling Where it is necessary to take samples in order to check compliance with the requirements of this Draft Mexican Official Standard, an attribute-based statistical sampling method must be used for the purposes of standard simple inspection, with an acceptable quality level of 0.01%, in accordance with Mexican Standard NMX-Z-012/2 (see Section 2 ‘References’ of this Draft Mexican Official Standard).

7. Test methods This Chapter specifies the test methods to be used for type- or prototype-approval. 7.1. Type- or prototype-approval 7.1.1. Design Type- or prototype approval must be carried out using the information supplied by the manufacturer, in Spanish, which must include: 7.1.1.1. The make, model and serial number of the system for measuring and dispensing petrol and other liquid fuels and a means of identifying the models within the category and the series. 7.1.1.2. The make, model, serial number, range and type of the primary measuring device and a mean of identifying the model and the series. 7.1.1.3. User, installation, servicing, operating, configuration and programming instructions and manuals. 7.1.1.3.1. Connection diagrams for the electronic system and also a means of identifying each of the cards comprising it and a description of the functions they perform. 7.1.1.3.2. Where the software application controlling the function of any component of the card may be updated, a means of identifying that component must be given and information as to how to validate the application it contains must be provided. 7.1.1.3.3. The pulse generator conversion factor, so that the ratio of pulses to the volume delivered in litres is known. 7.1.1.3.4. A hydraulic diagram of the type of system for measuring and dispensing petrol and other liquid fuels, with a description of each of its components. 7.1.1.3.5. The procedure for adjusting the volume on the measuring instrument. 7.1.1.4. The code in which the software application used is written, the name of the version used and the number of the integrated circuit where that application is loaded. Calculation of the checksum to be used as a reference for the purposes of Section 7.3.1.7.2. of this Draft Mexican Official Standard. 7.1.1.5. Procedure for full validation of the system for measuring and dispensing petrol and other liquid fuels, including the electronic system and the calculation programs comprising it and their reliability characteristics. Direct checks must be made by testing and using the information referred to above to ascertain whether the systems for measuring and dispensing petrol and other liquid fuels specified by the manufacturer possess the devices which are essential for performing exact, correct and safe measurements in accordance with the specifications laid down in this Draft Mexican Official Standard.

7.2. Accuracy of measurements 7.2.1. Materials Liquid fuels (petrol, diesel, jet fuel, aviation spirit, kerosene or others, apart from liquefied petroleum gas). 7.2.2. Apparatus and equipment

- A volumetric test measure of 20 L and other capacities (except less than 10 L) graduated in minimum scale intervals of 10 mL, with a minimum measurable volume of 2 L. It may have a built-in thermometer with a resolution of 1°C.

- An immersion thermometer with a resolution of 1°C if the volumetric test

measure does not have a built-in thermometer.

- A stopwatch with a minimum scale interval of 0.01 s.

- These measuring instruments must possess a current calibration report issued by an accredited and, where appropriate, approved calibration laboratory.

7.2.3. Characteristics of the system for measuring and dispensing petrol and other liquid fuels to be used for the tests. The system for measuring and dispensing petrol and other liquid fuels used for the tests must be fitted with all the appropriate devices, operating at rated voltages. 7.2.4. Preparation of the system for measuring and dispensing petrol and other liquid fuels With the nozzle outlet valve activated but still closed, a check must be made to ensure that pressure surges originating from:

- the remote pump do not cause any movement of the instantaneous totalizer indications, when the pump is operating with the nozzle outlet valve closed.

- the opening of a nozzle outlet valve on the side opposite to the system for

measuring and dispensing petrol and other liquid fuels selected for testing does not cause any movement of the instantaneous totalizer indications relating to the nozzle outlet valve which is closed.

- The continuous opening and closing of a nozzle outlet valve on the side

opposite to the system for measuring and dispensing petrol and other liquid fuels selected for testing does not cause any movement of the instantaneous totalizer indications relating to the nozzle outlet valve which is closed.

7.2.4.1. Levelling the volumetric test measure and checking that it is clean. This procedure may be carried out without any additional devices using the level surface provided by the island on which the system for measuring and dispensing petrol and other liquid fuels is installed (zero degrees), a provision which is included

by PEMEX-Refinación in the technical specifications for the design and construction of service stations. Where the test measure cannot be levelled by this means, a levelling plate must be used. This must be checked using a spirit level. 7.2.4.2. Conditioning run Once the measuring device of the system for measuring and dispensing petrol and other liquid fuels has been selected, its delivery devices shall be filled in order to open the nozzle outlet valve gate. The volumetric test measure shall then be filled up to a point close to the nominal volume. This fulfils the following purposes:

- wetting the walls of the container, since the volumetric test measures used are normally calibrated for dispensing

- setting the volumetric flow rate at which the test will be carried out, using the

nozzle outlet valve

- eliminating air bubbles present in the delivery devices

- ensuring that there are no leaks in the hydraulic system. 7.2.5. Volumetric verification procedure The actions described below must be repeated for each test. 7.2.5.1. Check that the instantaneous totalizer reading is at zero on commencing each delivery. 7.2.5.2. Opening and closing the nozzle outlet valve of the selected measuring system, collect a volume preferably the same as the nominal volume of the test measure or an amount close to the nominal volume. Whilst filling, measure the time taken to collect one quarter of the nominal capacity of the volumetric test measure. This time must be measured after the first quarter and before the last quarter of the nominal capacity of the volumetric test measure. Take and record the reading on the volumetric test measure and then the reading on the built-in thermometer or take a reading of the temperature of the fuel contained in the measure using a separate thermometer, waiting 60 s in order to reach thermal equilibrium. 7.2.5.3. Drain the volumetric test measure, waiting until the main flow ceases. The drainage time should be that indicated in the calibration report. 7.2.5.4. The measuring instruments shall be verified by carrying out three tests for each flow rate provided by the volumetric flow rate selector on the nozzle outlet valve:

a) with the nozzle outlet valve volumetric flow rate selector set at the maximum flow rate;

b) with the nozzle outlet valve volumetric flow rate selector set at the medium

flow rate, and

c) with the nozzle outlet valve volumetric flow rate selector set at the minimum

flow rate. 7.2.5.4.1. Test at the maximum volumetric flow rate With the nozzle outlet valve volumetric flow rate selector set at the maximum flow rate, dispense the fuel directly into the volumetric test measure up to the nominal capacity. Next, record the reading on both the instantaneous indicator and on the volumetric test measure, taking the latter from the bottom of the meniscus. The difference between the two readings shall be determined to the nearest centilitre. 7.2.5.4.2. Test at the medium volumetric flow rate With the nozzle outlet valve volumetric flow rate selector set at the medium flow rate, dispense the fuel directly into the volumetric test measure up to the nominal capacity. Next, record the reading on both the instantaneous indicator and on the volumetric test measure, taking the latter from the bottom of the meniscus. The difference between the two readings shall be determined to the nearest centilitre. 7.2.5.4.3. Test at the minimum volumetric flow rate With the nozzle outlet valve volumetric flow rate selector set at the minimum flow rate, dispense the fuel directly into the volumetric test measure up to the nominal capacity. Next, record the reading on both the instantaneous indicator and on the volumetric test measure, taking the latter from the bottom of the meniscus. The difference between the two readings shall be determined to the nearest centilitre. 7.2.5.5. Number of tests Each of the tests shall be carried out three times, calculating the average for each flow rate. The latter must be entered in the table shown in Section 7.2.7(V). Check that the volumes delivered obtained from the totalizer readings are identical for each test. Check and enter in the table shown in Section 7.2.7(V) that the difference between the initial and final readings on the cumulative totalizer is the same as the reading in litres rounded off to the nearest whole number given by the instantaneous totalizer in each test. Note: In view of the fact that, when the volumetric test measure is being filled with fuel, a certain amount of foam is formed, where necessary it is acceptable to wait until the foam has disappeared, then continue dispensing the fuel as far as possible in accordance with the test procedure for the flow rate in question, until the volumetric test measure is filled to its nominal capacity.

7.2.6. Maximum permissible errors None of the errors in the average readings obtained for the maximum, medium and minimum flow rates for the measuring instrument selected must exceed either the maximum permissible error or the repeatability error specified in Sections 5.1.1. and 5.1.2. respectively of this Draft Mexican Official Standard.

7.2.7. Calculations and corrections I. Calculating the correction factor for thermal expansion, CTS

Where:

is the cubic thermal expansion coefficient of the material of which the volumetric test measure is made, in °C-1 (For stainless steel 304, = 0.000 047 7 °C-1 and for low-carbon steel

= 0.000 034 °C-1)

Tmv is the working temperature of the volumetric test measure

20 °C is the temperature at which the calibrated volume is specified in the measurement report for the volumetric test measure.

II. Calculating the volume of the volumetric test measure corrected for the working temperature, Vcmv

Where:

Vcmv is the volume of the volumetric test measure corrected for the working temperature, in mL

V20 is the volume of the volumetric test measure at 20 °C, in mL (This figure can be found in the calibration report for the volumetric

test measure) Lc is the reading from the meniscus on the scale at the neck of the

volumetric test measure, in mL (The reading is positive if it is above the nominal volume mark and

negative if it is below that mark) Kc is the correction factor for the graduated scale on the neck of the

volumetric test measure, which is a non-dimensional value (This figure can be found in the calibration report for the volumetric

test measure) CTS is the thermal expansion coefficient for the material of which the

volumetric test measure is made.

III. Calculating the indication error

Where:

I is the volume displayed on the indicating device of the measuring instrument selected, in mL

Vcmv is the volume of the volumetric test measure corrected for the working

temperature, in mL.

A negative indication error indicates that the measuring instrument is delivering more product than it is recording. A positive indication error indicates that the measuring instrument is delivering less product than it is recording. IV. Calculating the flow rate at which the test is conducted, qv

Where:

qv is the test flow rate, in L/min T is the length of the test, in min. Vcmv is the volume of the volumetric test measure corrected for the working

temperature, in mL. (The time recorded in Section 7.2.5.2. must be multiplied by 4 to

obtain time t representing the length of the test).

V. Table of results Time taken to

fill ¼ of the volumetric test measure (t)

Test flow rate (qv)

Volume displayed on the indicating device of the selected measuring instrument (l)

Volume of the volumetric test measure corrected for the working temperature (Vcmv)

Working temperature of the volumetric test measure (Tmv)

Indication error (E)

Maximum permissible error (specified in 5.1.1.)

Repeatability error (R) (ml) (specified in 5.1.2.)

Difference between the initial and final readings of the cumulative totalizer, compared with the instantaneous totalizer (specified in 7.2.5.5.)

Units Min L/min mL mL °C mL mL mL mL Minimum volumetric flow rate

Average Medium volumetric flow rate

Average Maximum volumetric flow rate

Average The average flow rate and the average error refer to the average of the three measurements made for each of the flow rates tested (minimum, medium and maximum). The average error for each flow rate must comply with Section 5.1.1. Maximum permissible errors. The repeatability error for each flow rate must comply with Section 5.1.2. Repeatability error

7.2.8. Volumetric flow rates during the tests The maximum and minimum flow rates during the operational tests must not exceed the measuring range of the measuring instrument declared by the manufacturer. 7.3. Test method for validating the electronic system and the computing programmes 7.3.1. Design The type- or prototype approval relating to the electronic part of the system for measuring and dispensing petrol and other liquid fuels must be based on the information supplied by the manufacturer, as stated in Section 7.1.1. of this Draft Mexican Official Standard and direct checks must be made that the electronic components comprising the electronic part of the system for measuring and dispensing petrol and other liquid fuels [sic]. Ancillary systems such as the remote control systems shall not be subject to type- or prototype approval and only need to be declared for the purpose of checking that they comply with the specifications and nomenclature used by the manufacturer. The verification shall focus on the following components: 7.3.1.1. Electronic cards, all parts of which must undergo visual and physical inspection, in order to check that each card displays the following identifying information in permanent, visible and indelible form:

• Make (Identifying name, letter, hologram or logo representing the make in question)

• Place of origin (Hecho en México [Made in Mexico], Made in USA, etc.)

• Card number (corresponding to the type and function of the device in

question)

• Upgrade or version number of the card

• Year of manufacture, modification or upgrade

• Where there has been any change, replacement or repair, this must be reported and explained by the manufacturer to the Directorate-General of Standardization

• Identification of the software applications by means of a visible, permanent

and indelible label, located on the card on which the applications are loaded, which must display the versions of applications operating the system for measuring and dispensing petrol and other liquid fuels

• Connection and design diagrams for the electronic system.

7.3.2.1. Tamper-proof characteristics 7.3.1.2.1. Encapsulated integrated circuit A visual check must be made to ascertain that the circuit is totally covered with a layer of transparent material, enabling the integrated circuit to be identified, such as epoxy resin, ceramic, glass or other material adhering permanently to the printed circuit card, so as to ensure that, if it is altered in any way or if it is the subject of any intervention, there is easily identifiable visual evidence of this. 7.3.1.2.2. Main electronic card with embedded system A visual check must be made to ensure that the majority of the components are permanently affixed to the base plate (main card) and that parts of them cannot be removed or replaced without leaving a trace. The integrated circuits containing the program controlling the operation of the system for measuring and dispensing petrol and other liquid fuels must be completely covered with a layer of transparent material, enabling the electronic circuit to be identified, such as epoxy resin, ceramic, glass, transparent lacquer, transparent varnish or other material adhering permanently to the printed circuit card, so as to ensure that, if it is altered in any way or if it is the subject of any intervention, there is easily identifiable visual evidence of this. 7.3.1.2.3. Software applications for the system for measuring and dispensing petrol and other liquid fuels The software application or applications must be controlled and managed solely and exclusively by the manufacturer of the system for measuring and dispensing petrol and other liquid fuels. These applications must be validated by verification of the checksum using the 128-bit MD5 cryptographic hash function. 7.3.1.2.3.1. The software applications must be available for reading exclusively via a serial port (RS232), for which the communication parameters must be supplied by the manufacturer of the system for measuring and dispensing petrol and other liquid fuels. 7.3.1.2.3.2. The embedded system must have a checkable and certifiable function ensuring that the software applications are read-only via the serial port (RS232), that is to say the system does not permit writing or overwriting of the programs. 7.3.1.2.3.3. The software applications may only be read via the serial port (RS232) once a password has been entered on the control panel of the system for measuring and dispensing petrol and other liquid fuels. This password must be supplied to the Federal Consumer Protection Office, so that periodic and extraordinary verifications may be carried out, and also to the Centro Nacional de Metrología [National Metrology Centre] for the purposes of initial verification. 7.3.1.2.4. Audit trails or event logger The system for measuring and dispensing petrol and other liquid fuels must include one of the two control devices or equivalent thereof. The audit trails or the event logger must record events consecutively over a period of 12 months of normal operation. The event logger must be downloaded via the serial port (RS232) once a password has been entered on the control panel of the system for measuring and dispensing petrol and other liquid fuels. This password must be supplied to the

Federal Consumer Protection Office and the National Metrology Centre to enable the relevant verifications to be carried out. 7.3.1.2.4.1. The events which must be recorded are as follows:

• Adjustments made to a system for measuring and dispensing petrol and other liquid fuel (adjustments to the volume dispensed)

• Price changes (alterations)

• Instances where the electronic system has been accessed, in particular the

opening of ports

• Instances where the programming mode has been accessed

• The conversion factor (ratio between number of pulses and the volume dispensed in litres).

7.3.1.2.4.1.1. The event log must include the date and time of the event. Where the event description is abbreviated, the Federal Consumer Protection Office and the National Metrology Centre must be supplied with a table showing the events represented by the abbreviations. 7.3.1.2.4.1.2. Events must be logged in the following format: Description of the event in a minimum of 4 characters followed by the date in a 6-digit ‘yymmdd’ format, followed by the time in 24 hour format (hhmm). Example: CAMP1005221430. This means that there was a price change on 22 May 2010 at 14:30. 7.3.1.2.4.1.3. The characters forming the description must be presented in accordance with the following table:

Description Explanation CALI Adjustment CAMP Price change APPU Opening of port ACMO Access to programming mode LECS Reading of the software application operating

the system for measuring and dispensing petrol and other liquid fuels

LEMC Reading of the conversion factor for the pulse generator with which the system for measuring and dispensing petrol and other liquid fuels operates

7.3.2. Safe operation during tests and analyses 7.3.2.1. Apparatus and equipment

• Laptop with serial port (RS232) and connecting cables and, where appropriate, the communication interface for the system for measuring and

dispensing petrol and other liquid fuels, which must be supplied by the manufacturer to the National Metrology Centre and the Federal Consumer Protection Office.

• Multimeter

7.3.2.2. Characteristics of the system for measuring and dispensing petrol and other liquid fuels to be analysed It must have all the necessary accessories and the verification must be carried out at the relevant rated voltages. The equipment must have the internal and external safety features specified in NOM-001-SCFI-1993 (see Section 2 ‘References’ of this Draft Mexican Official Standard). 7.3.2.3. Preparation of the system for measuring and dispensing petrol and other liquid fuels The indicating devices must not display variations, whether or not these derive from movement of the primary measuring device selected, when the latter is not operating, in accordance with Section 7.2.4. and that movement must be recorded by the calculating device or the meter, as appropriate. 7.3.2.4. Identification of the item(s) of equipment installed at the establishment Where the system for measuring and dispensing petrol and other liquid fuels has some form of remote control system, the characteristics of the interconnection specified by the manufacturer must be examined, thereby ensuring that it is functioning properly, and specifically:

• The wiring loom to which the remote control system is connected

• The communication port

• The list of communication instructions and commands. 7.3.2.5. Determination of the test conditions The system for measuring and dispensing petrol and other liquid fuels must comply with the safety guidelines indicated and the manufacturer’s requirements for the safe operation of its measuring instruments. In addition, the measuring instrument must not be tested in places close to high voltage power transmission lines, which could alter the content of the electronic circuits or cause damage to them. 7.3.2.6. Procedure for electronic verification During this test, the measuring devices of the system for measuring and dispensing petrol and other liquid fuels must not deliver fuel. 7.3.2.6.1. The electronic and mechanical sections of the system for measuring and dispensing petrol and other liquid fuels must be free of obstructions when are they being tested.

7.3.2.6.2. The following data must be recorded for each system for measuring and dispensing petrol and other liquid fuels, in accordance with the procedure or configuration guide supplied by the manufacturer:

• Make • Model

• Serial number of the system for measuring and dispensing petrol and other

liquid fuels

• Measuring instrument or filling position

• Unit price for each type of fuel

• The totalizer indication of sales made, both in terms of volume and money, for each side of the system for measuring and dispensing petrol and other liquid fuels and for each type of fuel

• Make, model, serial number, range and type of primary measuring device and

a means of identifying the model and series

• Conversion factor (ratio between pulses and volume dispensed in litres). 7.3.2.6.3. Taking readings Readings must be taken from the cumulative totalizer of the system for measuring and dispensing petrol and other liquid fuels, in order to check its operation and recording compared with the instantaneous totalizer. The result of the product of the volume delivered multiplied by the unit price of the fuel must be checked manually against the amount displayed by the system for measuring and dispensing petrol and other liquid fuels. 7.3.2.6.4. Verification of the junction box The electrical wiring looms and the general cabling of the electrical, communications or data connections must be inspected in order to determine whether they comply with the prototype, that is to say with the technical specifications provided by the manufacturer. Checks must be made on the electrical wiring loom connecting the remote control system, the specific communication port and the list of communications commands and instructions between the system for measuring and dispensing petrol and other liquid fuels and the remote control system. 7.3.2.6.5. Inspection of the pulse generator This should be opened where possible, bearing in mind that in some cases it will have been sealed by the manufacturer. For this inspection, account must be taken of the following, based on the information supplied by the manufacturer:

• The pulse generator must have the marks or perforations specified by the manufacturer

• The physical condition of the optical sensor (an electronic device whereby the

mechanical movement of the disc is converted to electrical pulses). It must have the power supply, data and earth connections in the form indicated in the manuals provided by the manufacturer, with no alterations.

7.3.2.6.6. Inspection of the electronic system A visual inspection must be made of the connections and also the electronic and communications cards, which must comply with the specifications laid down by the manufacturer of the system for measuring and dispensing petrol and other liquid fuels in question. A check must also be made to ensure that there are no cables, connections or electronic devices which did not form part of the prototype (see Section 7.1.1. of this Draft Mexican Official Standard). If it is found that no alterations have been made to the electronic part, the configuration of the system for measuring and dispensing petrol and other liquid fuels must then be inspected, in accordance with Section 7.3.2.6.7. 7.3.2.6.7. Check on configuration via the programming of the system for measuring and dispensing petrol and other liquid fuels. Depending on the make, model and calculating device contained within the system for measuring and dispensing petrol and other liquid fuels, enter that system’s programming mode (see Section 7.1.1. of this Draft Mexican Official Standard).

• Check the details of how the calculating device is programmed and check them against those supplied by the manufacturer

• Check the programming functions of the calculating device in accordance with

the information supplied by the manufacturer relating to:

a) Deliveries, both in volume and amounts programmed

b) Price changes

c) Downloading of the event logger

d) Electronic adjustments

e) The version of the software application operating the system for measuring and dispensing petrol and other liquid fuels

f) The connection with the remote control system, if such a system is

built in or linked to the system for measuring and dispensing petrol and other liquid fuels

g) The back-up battery

h) The conversion factor.

7.3.2.6.8. Testing the information storage device Consult the manual for the make of system for measuring and dispensing petrol and other liquid fuels and switch off its power supply. The test shall be deemed satisfactory if the following two conditions are fulfilled:

• The indicating devices continue to display the details of the last delivery (volume, amount and price to pay) visibly and with no change for at least seven minutes

• When the power supply is restored, the system for measuring and dispensing

petrol and other liquid fuels maintains its configuration. 7.3.2.6.9. Verification test on the version(s) of the software applications controlling the operation of the system for measuring and dispensing petrol and other liquid fuels, contained in the control card(s). Consult the manual for the make of system for measuring and dispensing petrol and other liquid fuels. Depending on the make or model, it may be equipped with one or more applications controlling its operation. 7.3.2.7. Procedure for verification of the software applications controlling the operation of the system for measuring and dispensing petrol and other liquid fuels 7.3.2.7.1. In order to verify the software applications, it is necessary to:

• Determine whether the system(s) for measuring and dispensing petrol or other liquid fuels is/are connected to a remote control system, depending on the make and type of system for measuring and dispensing petrol or other liquid fuels

• Where necessary, switch off the power supply to the system for measuring

and dispensing petrol and other liquid fuels from the electrical switchboard or from its independent power source, following the manufacturer’s instructions

• Depending on the make and model and on the calculating device contained in

the system for measuring and dispensing petrol and other liquid fuels, connect the serial port (RS232) to the laptop and run the relevant communication program. This program should initiate and use the communication protocol specified by the manufacturer of the system for measuring and dispensing petrol and other liquid fuels

• Follow the procedure for downloading the software application controlling the

operation of the system for measuring and dispensing petrol and other liquid fuels, which must be done via the serial port (RS232) referred to in Section 7.3.1.2.3.1. in such a way that the application is obtained in an electronic file, so that it can be validated in accordance with Section 7.3.1.2.3.

• If for the model of the system for measuring and dispensing petrol and other

liquid fuels being tested it proves necessary to interconnect an interface between the electronic section and the laptop in order to access the application, account should be taken of the recommendations made by the manufacturer, thereby ensuring that it will function properly

• In order to download the application via the serial port (RS232), commercial software must be used to effect the communication with the laptop. Where the manufacturer uses proprietary software to download the application, that proprietary software must be validated following the procedure described in Section 7.3.1.2.3.

• In order to obtain the checksum, the software used to apply the 128-bit MD5

cryptographic hash function must be commercial software. 7.3.2.7.2. Verification of the checksum Once the version of the software application(s) operating the system for measuring and dispensing petrol and other liquid fuels is known, which can be found from the identification labels in accordance with Section 7.3.1.1., the checksum obtained on the laptop shall be compared with the checksum provided by the manufacturer, which should be the same. The algorithm used to calculate the checksum shall be that known as a 128-bit MD5 function. 7.3.2.7.3. Validation, verification and approval of the software application(s) Note the data from the identification label of the software applications and the result of the reading of the checksum obtained pursuant to Section 7.3.2.7.2. 7.3.2.7.4. Audit trails or event logger The event logger must be downloaded via the serial port (RS232) in accordance with the manufacturer’s instructions once a password has been entered on the control panel of the system for measuring and dispensing petrol and other liquid fuels. This password must be supplied to the Federal Consumer Protection Office and the National Metrology Centre to enable the relevant verifications to be carried out. The event log must include the date and time of the event. Where the event description is abbreviated, the Federal Consumer Protection Office and the National Metrology Centre must be supplied with a table showing the events represented by the abbreviations.

• The events to be verified shall be as set out in the following table:

Description Verify CALI Record of the adjustment made in accordance with Section 5.3.3. CAMP Record of price change and the new price, carried out in

accordance with the manufacturer’s programming manual, which must tally with the periods and amounts established by the competent authorities.

APPU Record of port opening, carried out in accordance with the manufacturer’s specifications

ACMO Access to the programming mode in accordance with the specifications and parameters (actions, commands and routines) permitted by the manufacturer

LECS Reading of the software application operating the system for measuring and dispensing petrol and other liquid fuels, the version of which must tally with that declared by the manufacturer according to the identification label pursuant to Section 7.3.1.1.

LEMC Reading of the conversion factor for the pulse generator, which must tally with that declared by the manufacturer pursuant to Section 7.1.1.3.3.

7.3.2.7.5. Restoration of the system for measuring and dispensing petrol and other liquid fuels

• Exit the communication program of the system for measuring and dispensing

petrol and other liquid fuels following the manufacturer’s recommendations

• Disconnect the interface with the electronic section or the communication port RS232 serial connection between the system for measuring and dispensing petrol and other liquid fuels and the laptop

• Where it was necessary to switch off the power supply in order to carry out

the verification, restore the system for measuring and dispensing petrol and other liquid fuels via the electrical control switchboard or via its independent power source

• Test it by dispensing a volume of fuel from the system for measuring and

dispensing petrol and other liquid fuels in order to check that it is operating properly

• Close the system for measuring and dispensing petrol and other liquid fuels

which has been tested, noting all the data obtained during the verification. 8. Commercial information 8.1. On the system for measuring and dispensing petrol and other liquid fuels The systems for measuring and dispensing petrol and other liquid fuels must as a minimum be marked with the following information in a permanent and visible manner on their external housing:

• Make or manufacturer’s name

• Manufacturing serial number

• Type and model

• Measuring range of the system for measuring and dispensing petrol and other liquid fuels in terms of the volumetric flow rate for which it is designed

• Year of manufacture (except for systems for measuring and dispensing petrol

and other liquid fuels with a scale interval of between 350 L/min and 2 650 L/min)

• Type- or prototype-approval number

• User instructions (in a prominent position)*

• Identification of the product it dispenses

• The words ‘HECHO EN MEXICO’ [Made in Mexico] for domestically

produced products or the country of origin for imported products

(*) The user instructions or warnings shall consist of signs bearing the following or equivalent wording:

• Important user instructions

• Make sure that the indicator is set to zero before commencing sale

• Check that the price per litre is correct

• Peso sign on the indicating device. Once they have been installed at service stations, systems for measuring and dispensing petrol and other liquid fuels must provide a clear and accurate indication of the type of fuel they dispense. 8.2. On the body, housing or casing The body, housing or casing of systems for measuring and dispensing petrol and other liquid fuels must as a minimum display the following information:

• Make or manufacturer’s name • Model

• Serial number

• The words ‘HECHO EN MEXICO’ [Made in Mexico] for domestically produced

products or the country of origin for imported products

• Name and address of the Mexican manufacturer or the importer. 9. Initial, periodic and extraordinary verification 9.1. Initial, periodic and extraordinary verification of systems for measuring and dispensing petrol and other liquid fuels must be carried out in accordance with the provisions laid down in the ‘List of measuring instruments for which initial, periodic and extraordinary verification is compulsory and also the rules for conducting such verifications’, using the following procedure. 9.2. Visual verification A check that the system for measuring and dispensing petrol and other liquid fuels meets the following requirements: In order to be used and considered fit for the conduct of commercial transactions, the system for measuring and dispensing petrol and other liquid fuels must not contain defects in its operating systems which could lead to errors, that is to say, it should have no loose parts or other obvious defects. A check should also be made to ascertain whether it bears the following or similar wording:

• Important user instructions

• Make sure that the indicator is set to zero before commencing sale

• Check that the price per litre is correct.

Once they have been installed at service stations, systems for measuring and dispensing petrol and other liquid fuels must provide a clear and accurate indication of the type of fuel they dispense. 9.2.1. Metering or calculating devices The instantaneous totalizer of the metering or calculating devices must display zeros and must as a minimum display the volume of liquid fuel dispensed, the price per litre and the price to pay. In the case of systems for measuring and dispensing petrol and other liquid fuels classed as metering systems, they must display the volume of liquid fuel dispensed. 9.2.2. Indicating device It must comply with the requirements of Section 5.3.2.3. of this Draft Mexican Official Standard. 9.2.3. Adjusting mechanism In addition to complying with Section 5.3.3., this mechanism must have the special fittings enabling the official tamper-proof seals to be affixed. These must remain in the appropriate place. At the time of periodic or extraordinary verification, the system for measuring and dispensing petrol and other liquid fuels must bear the verification mark specified in Section 9.3.4. from the initial verification or from the previous periodic or extraordinary verification and checks must be made to ensure that they have not been tampered with or altered in any way through the application of heat or the application of force. 9.2.4. Delivery devices 9.2.4.1. Delivery hose The delivery hoses and the non-return and nozzle outlet valves must be checked to ensure that there is no damage to their external walls or cracks allowing constant dripping or adaptations which could affect their operation in accordance with the specifications of the manufacturer of the system for measuring and dispensing petrol and other liquid fuels. This shall be checked by visual inspection (see Section 5.4. of this Draft Mexican Official Standard). 9.3. Verification of metrological characteristics This verification must be carried out during all verifications, both initial, periodic and extraordinary. 9.3.1. Procedure For the purposes of this verification, the provisions of all parts of Section 7.2. of this Draft Mexican Official Standard must be applied.

9.3.2. Primary measuring device A check must be made against the table contained in Section 7.2.7(V) that the range of the primary measuring device is within the range declared by the manufacturer pursuant to Section 7.1.1.2. 9.3.3. Adjustments During any initial or periodic verification, the measuring instrument must be adjusted using the procedure indicated by the manufacturer, applying the tests described above, in such a way that the error is adjusted as close to zero as possible, in accordance with the provisions of Section 5.1.1. c) of this Draft Mexican Official Standard. If it is not possible to adjust the measuring instrument to within the specified limits, the body conducting the verification must affix a sticker to the relevant delivery hose to indicate that the measuring instrument is not fit for use in commercial transactions. The measuring instrument must not be used until the appropriate extraordinary verification has been carried out. 9.3.4. Verification mark Once the verification has been carried out and it has been determined that the measuring instrument has satisfactorily fulfilled the requirements laid down for this procedure, the official verification stamps shall be affixed to the adjusting disc and/or the electronic adjusting device and the appropriate hologram shall be affixed to the calculating or metering device without obscuring the signage or the readings of the system for measuring and dispensing petrol and other liquid fuels, denoting that that system has been verified. The appropriate verification report shall be issued containing the identification details of the system for measuring and dispensing petrol and other liquid fuels and the service station at which it is installed. 9.4. Verification of the electronic system and software applications Using the information referred to in Section 7.3.1., a verification shall be carried out in order to validate the electronic system and software applications, the accessories and other components, equipment or systems linked with or connected to the system for measuring and dispensing petrol and other liquid fuels, including the remote control and monitoring systems, which must tally with the details contained in the type- or prototype-approval. 9.4.1. Procedure Verification of the electronic part of the system for measuring and dispensing petrol and other liquid fuels shall be based on the information supplied by the manufacturer, as set out in Section 7.3.1. of this Draft Mexican Official Standard. Direct checks shall be carried out to ensure that the electronic components comprising the electronic part of the system for measuring and dispensing petrol and other liquid fuels and also those comprising the remote control system(s) comply with the specifications and nomenclature used by the manufacturer. An exception may be made for original electronic components where the replacements have been approved by the Ministry of the Economy, provided that the software applications are the original applications installed by the manufacturer and the verification of the checksum complies with the requirements of Section 9.4.2.5.12. of this Draft Mexican Official Standard.

9.4.2. Safe operation during tests and analyses 9.4.2.1. Apparatus and equipment

• Laptop with serial port (RS232) and connecting cables and, where appropriate, the communication interface for the system for measuring and dispensing petrol and other liquid fuels, which must be supplied by the manufacturer to the National Metrology Centre and the Federal Consumer Protection Office.

Multimeter 9.4.2.2. Characteristics of the system for measuring and dispensing petrol and other liquid fuels It must have all the necessary accessories and the verification must be carried out at the relevant rated voltages. The equipment must have the internal and external safety features specified in NOM-SCFI-1993 (see Section 2 ‘References’ of this Draft Mexican Official Standard). 9.4.2.3. Preparation of the system for measuring and dispensing petrol and other liquid fuels The indicating devices must not display variations, whether or not these derive from movement of the primary measuring device selected, when the latter is not operating, in accordance with Section 7.2.4., and that movement must be recorded by the calculating device or the meter, as appropriate. 9.4.2.4. Identification of the item(s) of equipment installed at the establishment Where the system for measuring and dispensing petrol and other liquid fuels has some form of remote control system, the characteristics of the interconnection specified by the manufacturer must be examined, thereby ensuring that it is functioning properly, and specifically:

• The wiring loom to which the remote control system is connected

• The communication port

• The list of communication instructions and commands. 9.4.2.5. Procedure for electronic verification During this test, the measuring devices of the system for measuring and dispensing petrol and other liquid fuels must not deliver fuel and the verification must be conducted in the presence of the person responsible for the establishment being inspected. 9.4.2.5.1. The electronic and mechanical sections of the system for measuring and dispensing petrol and other liquid fuels must be free of obstructions when are they being tested.

9.4.2.5.2. The following data must be recorded for each system for measuring and dispensing petrol and other liquid fuels, in accordance with the procedure or configuration guide supplied by the manufacturer:

• Make • Model

• Serial number of the system for measuring and dispensing petrol and other

liquid fuels

• Measuring instrument or filling position

• Unit price for each type of fuel

• The totalizer indication of sales made, both in terms of volume and money, for each side of the system for measuring and dispensing petrol and other liquid fuels and for each type of fuel

• Make, model, serial number, range and type of primary measuring device and

a means of identifying the model and the series

• Conversion factor (ratio between pulses and volume dispensed in litres). 9.4.2.5.3. Taking readings Readings must be taken from the cumulative totalizer of the system for measuring and dispensing petrol and other liquid fuels, in order to check its operation and recording compared with the instantaneous totalizer. The result of the product of the volume delivered multiplied by the unit price of the fuel must be checked manually against the amount displayed by the system for measuring and dispensing petrol and other liquid fuels. 9.4.2.5.4. Verification of the junction box The electrical wiring looms and the general cabling of the electrical, communications or data connections must be inspected in order to determine whether they comply with the prototype, that is to say with the technical specifications provided by the manufacturer for the approved type. Checks must be made to ascertain whether the electrical wiring loom connecting the remote control system, the specific communication port and the list of communications commands and instructions between the system for measuring and dispensing petrol and other liquid fuels and the remote control system, comply with the approved model. 9.4.2.5.5. Inspection of the pulse generator This should be opened where possible, bearing in mind that in some cases it will have been sealed by the manufacturer. For this inspection, account must be taken of the following, based on the information specified by the manufacturer and approved by the Ministry of the Economy:

• The pulse generator must have the marks or perforations specified by the manufacturer

• The physical condition of the optical sensor (an electronic device whereby the

mechanical movement of the disc is converted to electrical pulses). It must have the power supply, data and earth connections in the form indicated in the manuals provided by the manufacturer, with no alterations.

9.4.2.5.6. Inspection of the electronic system A visual inspection must be made of the connections and also the electronic and communications cards, which must comply with the specifications laid down by the manufacturer of the system for measuring and dispensing petrol and other liquid fuels in question and be approved by the Ministry of the Economy. A check must also be made to ensure that there are no cables, connections or electronic devices which did not form part of the prototype (see Section 7.1.1. of this Draft Mexican Official Standard). If it is found that no alterations have been made to the electronic part, the configuration of the system for measuring and dispensing petrol and other liquid fuels must then be inspected, in accordance with Section 9.4.2.5.7. 9.4.2.5.7. Check on configuration via the programming of the system for measuring and dispensing petrol and other liquid fuels. Depending on the make and model and on the calculating device contained within the system for measuring and dispensing petrol and other liquid fuels, enter that system’s programming mode (see Section 7.1.1. of this Draft Mexican Official Standard).

• Check the details of how the calculating device is programmed and check them against those supplied by the manufacturer

• Check the programming functions of the calculating device in accordance with

the information supplied by the manufacturer relating to:

a) Deliveries, both in volume and amounts programmed

b) Price changes

c) Downloading of the event logger

d) Electronic adjustments

e) The version of the software application operating the system for measuring and dispensing petrol and other liquid fuels

f) The connection with the remote control system, if such a system is

built in or linked to the system for measuring and dispensing petrol and other liquid fuels

g) The back-up battery

h) The conversion factor

9.4.2.5.8. Testing the information storage device Consult the manual for the make of the system for measuring and dispensing petrol and other liquid fuels and switch off its power supply. The test shall be deemed satisfactory if the following two conditions are fulfilled:

• The indicating devices continue to display the details of the last delivery (volume, amount and price to pay) visibly and with no change for at least seven minutes

• When the power supply is restored, the system for measuring and dispensing

petrol and other liquid fuels maintains its configuration. 9.4.2.5.9. Verification test on the version(s) of the software applications controlling the operation of the system for measuring and dispensing petrol and other liquid fuels, contained in the control card(s). Consult the manual for the make of system for measuring and dispensing petrol and other liquid fuels. Depending on the make or model, it may be equipped with one or more applications controlling its operation. 9.4.2.5.10. Procedure for verification of the software applications controlling the operation of the system for measuring and dispensing petrol and other liquid fuels 9.4.2.5.11. In order to verify the software applications, it is necessary to:

• Determine whether the system(s) for measuring and dispensing petrol or other liquid fuels is/are connected to a remote control system, depending on the make and type of the system for measuring and dispensing petrol or other liquid fuels

• Where necessary, switch off the power supply to the system for measuring

and dispensing petrol and other liquid fuels from the electrical switchboard or from its independent power source, following the manufacturer’s instructions

• Depending on the make and model and on the calculating device contained in

the system for measuring and dispensing petrol and other liquid fuels, connect the serial port (RS232) to the laptop and run the relevant communication program. This program should initiate and use the communication protocol specified by the manufacturer of the system for measuring and dispensing petrol and other liquid fuels

• Follow the procedure for downloading the software application controlling the

operation of the system for measuring and dispensing petrol and other liquid fuels, which must be done via the serial port (RS232) referred to in Section 7.3.1.2.3.1. in such a way that the application is obtained in an electronic file, so that it can be validated in accordance with Section 7.3.1.2.3.

• If for the model of the system for measuring and dispensing petrol and other

liquid fuels it proves necessary to interconnect an interface between the electronic section and the laptop in order to access the application, account

should be taken of the recommendations made by the manufacturer, thereby ensuring that it will function properly

• In order to download the application via the serial port (RS232), commercial

software must be used to effect the communication with the laptop. Where the manufacturer uses proprietary software to download the application, that proprietary software must be validated following the procedure described in Section 7.3.1.2.3.

• In order to obtain the checksum, the software used to apply the 128-bit MD5

cryptographic hash function must be commercial software. 9.4.2.5.12. Verification of the checksum Once the version of the software application(s) operating the system for measuring and dispensing petrol and other liquid fuels is known, which can be found from the identification labels in accordance with Section 7.3.1.1., the checksum obtained on the laptop shall be compared with the checksum provided by the manufacturer, which should be the same. The algorithm used to calculate the checksum shall be that known as a 128-bit MD5 function. 9.4.2.5.13. Validation, verification and approval of the software application(s) Note the data from the identification label of the software applications, affixed in accordance with Section 7.3.1.1., and the result of the reading of the checksum obtained pursuant to Section 9.4.2.5.12. 9.4.2.5.14. Audit trails or event logger The event logger must be downloaded via the serial port (RS232) in accordance with the manufacturer’s instructions once a password has been entered on the control panel of the system for measuring and dispensing petrol and other liquid fuels. This password must be supplied to the Federal Consumer Protection Office and the National Metrology Centre to enable the relevant verifications to be carried out.

• The event log must include the date and time of the event. Where the event description is abbreviated, the Federal Consumer Protection Office and the National Metrology Centre must be supplied with a table showing the events represented by the abbreviations.

• The events to be verified shall be as set out in the following table:

Description Verify CALI Records of adjustments must be documented by

verification reports issued by an accredited and approved verification body or the Federal Consumer Protection Office.

CAMP Records of price changes and the resulting prices must tally with the periods and amounts established by the competent authorities.

APPU Records of port opening must tally with the information contained in the record sheets kept for this purpose

ACMO Records of access to the programming mode and the actions carried out (actions, commands and routines) must tally with the information contained in the record sheets kept for this purpose

LECS The version of the software application read during verification must tally with the version declared by the manufacturer according to the identification label pursuant to Section 7.3.1.1.

LEMC The reading for the conversion factor for the pulse generator must tally with that declared by the manufacturer pursuant to Section 7.1.1.3.3.

9.4.2.5.15. Restoration of the system for measuring and dispensing petrol and other liquid fuels

• Exit the communication program of the system for measuring and dispensing petrol and other liquid fuels following the manufacturer’s recommendations

• Disconnect the interface with the electronic section or the communication port

RS232 serial connection between the system for measuring and dispensing petrol and other liquid fuels and the laptop

• Where it was necessary to switch off the power supply in order to carry out

the verification, restore the system for measuring and dispensing petrol and other liquid fuels via the electrical control switchboard or via its independent power source

• Test it by dispensing a volume of fuel from the system for measuring and

dispensing petrol and other liquid fuels in order to check that it is operating properly

Close the system for measuring and dispensing petrol and other liquid fuels, noting all the data obtained during the verification.

10. High flow rate measuring devices 10.1. Fuels Liquid fuels (petrol, diesel, jet fuel, aviation spirit, kerosene or others, apart from liquefied petroleum gas).

10.2. Apparatus and equipment For verifying systems for measuring and dispensing petrol and other liquid fuels which operate at high volumes over short periods (350 L/min to 2 650 L/min), the inspector must use a container with capacity of 1 ½ times to twice the volume delivered in one minute by the system for measuring and dispensing petrol and other liquid fuels or a standard flow meter, which may be of the mass or positive displacement type or a three- or more path ultrasonic flow meter (suitable for HDPE pipes), the operating principles of which are not affected by the installation, and for which the measuring uncertainty does not exceed one-third of the maximum permissible error specified in Section 10.3. of this Draft Mexican Official Standard. These measuring instruments must have a current calibration report issued by an accredited and, where appropriate, approved calibration laboratory. 10.3. Maximum permissible errors The maximum permissible error and the repeatability error must not exceed the values specified in Sections 5.1.1. and 5.1.2. of this Draft Mexican Official Standard. 11. Conformity assessment The conformity assessment of the systems for measuring and dispensing petrol and other liquid fuels covered by this Draft Mexican Standard shall be carried out by the Federal Consumer Protection Office and persons accredited and approved pursuant to the Federal Law on Metrology and Standardization and its implementing Regulation. 12. Monitoring of compliance Monitoring of compliance with this Draft Official Mexican Standard shall be the responsibility of the Ministry of the Economy, via the Directorate-General for Standardization, and of the Federal Consumer Protection Office, each in their respective sphere of competence. 13. Bibliography

- International Recommendation. Dynamic measuring systems for liquids other than water. Part 1: Metrological and technical requirements, OIML-R-117-1 (2007)

- NIST HANDBOOK 44-2003. Specifications, Tolerances and Other Technical

Requirements for Weighing and Measuring Devices

- UL 330 Standard for gasoline hose, Fourth edition. June 29, 1973. Underwriters’ Laboratories Inc.

- SAE J285 Gasoline dispenser nozzle spouts. Jul. 81, 1985 SAE HANDBOOK

- BIPM 2008 International Vocabulary of Terms in Legal Metrology – Basic and

general concepts and associated terms (VIM).

14. Concordance with international standards This Draft Mexican Official Standard partially concords with the International Standard for Dynamic measuring systems for liquids other than water, Part 1: Metrological and technical requirements, OIML-R-117-1 (2007).

TRANSITIONAL PROVISIONS FIRST – This Draft Mexican Official Standard shall enter into force 60 days after its publication as a definitive standard in the Mexican Official Gazette. SECOND – Once it has been published as a definitive standard, this Draft Mexican Official Standard shall rescind Official Mexican Standard NOM-005-SCFI-2005 published in the Mexican Official Gazette of 27 September 2005. Mexico, D.F., 14 September 2011 – The Director-General of Standardization and the Chairman of the National Advisory Committee on Standardization for User Safety, Commercial Information and Trade Practices, Christian Turégano Roldán – Initials. .