煤矿安全资料.pdf

OIML TC 8/SC 7 1WD OIML R 137-1 to be specified by the manufacturer Note 1 DC mains voltageNote 2 as specified by the manufacturer AC mains voltageNote 2 Unom –15 to Unom 10 Note 1 Supercritical refers to the situation where there is no distinction between the gaseous and liquefied state of the fluid. Note 2 Whatever is applicable. 4.2 VALUES OF QMAX, QT AND QMIN The flowrate characteristics of a gas meter shall be defined by the values of Qmax, Qt and Qmin as stated in Table 1. Table 1 Flowrate characteristics Qmax / Qmin Qmax / Qt 50 10 5 and 50 5 4.3 ACCURACY CLASSES AND MAXIMUM PERMISSIBLE ERRORS 4.3.1 General Gas meters shall be designed and manufactured such that their errors do not exceed the limits of the applicable maximum permissible error under rated operating conditions, listed in 4.3.3. 4.3.2 Correction for known errors Gas meters may be equipped with a correction device, which can be used to bring errors as close as possible to zero. A correction device can be used to improve the Accuracy Class specification. The correction device shall not be used for the correction of a pre-estimated drift. 4.3.3 Accuracy Classes and maximum permissible errors MPE Gas meters shall be classified into the Accuracy Classes given in Table 2. The errors shall be within the applicable values given in Table 2. OIML TC 8/SC 7 1WD OIML R 137-1 b an electromechanical or electronic indicating device as described in 5.4.5; c a combination of a and b. Indicating devices shall be non-resetable and shall be non-volatile i.e. they shall be able to show the last stored indication after the device has recovered from an intervening power failure. Where the indicating device shows decimal submultiples of the quantity measured, these submultiples shall be separated by a clear decimal sign from those showing units. It may be possible to use one display for other indications as well, as long as it is clear which quantity is being displayed. 5.4.2 Indicating range The indicating device shall be able to record and display the indicated quantity of gas corresponding to at least 1000 hours of operation at the maximum flowrate Qmax, without returning to the original reading. 5.4.3 Resolution The quantity corresponding to the least significant digit shall not exceed the quantity of gas passed during one hour at Qmin. If the least significant digit last drum shows a decimal multiple of the quantity measured, the faceplate or electronic display shall bear a either one or two, or three, etc. fixed zeros after the last drum or digit; or b the marking “ 10 “ or “ 100 “, or “ 1 000 “, etc., so that the reading is always in the units mentioned in 3.1. 5.4.4 Mechanical indicating device A mechanical indicating device shall consist of drums; the last element i.e. the one with the smallest scale interval may however be an exception to this rule. The minimum height of the numerals shall be 4.0 mm and their minimum width shall be 2.4 mm. The advance by one unit of a figure of any order shall take place completely while the figure of an order immediately below passes through the last tenth of its course. 5.4.5 Electromechanical or electronic indicating device The continuous display of the quantity of gas during the period of measurement is not mandatory. The electronic indicating device shall be provided with a display test. 5.4.6 Remote indicating device If an indicating device is used remotely, the associated gas meter shall be clearly identified. The integrity of the communication between the instrument and the indicating device shall be checked. Note The serial number of the associated gas meter can be used for a clear identification. 5.5 TEST ELEMENT 5.5.1 General OIML TC 8/SC 7 1WD OIML R 137-1 b a pointer moving over a fixed dial with a scale, or a disk with a scale moving past a fixed reference mark, where each subdivision on the dial or disk is regarded as an increment of the test element. On the numbered scale of a test element the value of one complete revolution of the pointer shall be indicated in the “1 rev . “. The beginning of the scale shall be indicated by the figure zero. The scale spacing shall not be less than 1 mm and shall be constant throughout the whole scale. The scale interval shall be in the 1 10n, 2 10n, or 5 10n n being a positive or negative whole number or zero. The scale marks shall be fine and unily drawn. With an electronic indicating device the last digit is used as integral test element. The number of digits may be increased via a specific test mode, which can be accessed through either physical or electronic buttons or switches. If applicable to the gas meter, the test element shall allow the experimental determination of the cyclic volume. The difference between the measured value of the cyclic volume and its nominal value shall not exceed 5 of the latter at reference conditions. 5.5.3 Pulse generator A pulse generator may be used as a test element if the value of one pulse, expressed in units of volume, mass or energy, is marked on the gas meter. The gas meter shall be constructed in such a way that the pulse value can be checked experimentally. The difference between the measured value of the pulse value and its value indicated on the gas meter, shall not exceed 0.05 of the latter. 5.5.4 Portable test unit An indicating device may include provisions for testing by inclusion of complementary elements e.g. star wheels or discs, which provide signals for a portable test unit. The portable test unit may be used as a test element if the value of one pulse, expressed in units of volume, mass or energy, is marked on the gas meter. 5.5.5 Increment of test element or pulse The increment of the test element or pulse shall occur at least every 60 seconds at Qmin. 5.6 ANCILLARY DEVICES 5.6.1 General The gas meter may include ancillary devices, which may be permanently incorporated or added temporarily. Examples of their use are OIML TC 8/SC 7 1WD OIML R 137-1 means for testing, verification and remote reading; prepayment. Ancillary devices shall not affect the correct operation of the instrument. If ancillary devices are not subject to legal metrology control this shall be clearly indicated. 5.6.2 Protection of drive shafts When not connected to an attachable ancillary device, the exposed ends of the drive shaft shall be suitably protected. 5.6.3 Torque overload The connection between the measuring transducer and the intermediate gearing shall not be broken or altered if a torque of three times the permissible torque as indicated in 6.1.3 s and 6.1.3 t is applied. 5.7 POWER SOURCES 5.7.1 Types of power sources This Recommendation gives requirements for instruments powered by mains power; non-replaceable battery; replaceable battery. These three types of power sources may be used alone or in combination. 5.7.2 Mains power An electronic gas meter shall be designed such that in the event of a mains power failure AC or DC, the meter indication of the quantity of gas just before failure is not lost, and remains accessible for reading after failure without any difficulty. Any other properties or parameters of the meter shall not be affected by an interruption of the electrical supply. Note Compliance with this requirement will not necessarily ensure that the gas meter will continue to register the quantity of gas that passed through the gas meter during a power failure. The connection to the mains power source shall be capable of being secured from tampering. 5.7.3 Non-replaceable battery The manufacturer shall ensure that the indicated lifetime of the battery guarantees that the meter functions correctly for at least as long as the operational lifetime of the meter. 5.7.4 Replaceable battery If the instrument is powered by a replaceable battery, the manufacturer shall give detailed specifications for the replacement thereof. The date by which the battery shall be replaced shall be indicated on the meter. Alternatively, the remaining battery life can be displayed or a warning can be given when 10 of the estimated life of the battery remains. OIML TC 8/SC 7 1WD OIML R 137-1 check the integrity of stored, transmitted and presented data; and check the pulse transmission if applicable. Note Pulse transmission checks focus on missing pulses, or additional pulses due to interference. Examples are double pulse systems, three-pulse systems or pulse timing systems. 5.8.2 Limits The gas meter may also be capable to detect and act upon overload flow conditions; measurement results that are outside the maximum and minimum values of the transducers; measured quantities that are outside certain pre-programmed limits; and reverse flow. If the gas meter is equipped with limit detection the correct functioning shall be tested during the type uation. 5.8.3 Alarms If malfunctions are registered while checking the items as indicated in 5.8.1 or if the conditions as indicated in 5.8.2 are detected, the following actions shall be pered a visible or audible alarm, which remains present until the alarm is acknowledged and the cause of the alarm is suppressed; continuation of the registration in specific alarm registers if applicable during the alarm, in which case default values may be used for the pressure, temperature, compressibility, density or superior calorific value; and registration in a log if applicable. OIML TC 8/SC 7 1WD OIML R 137-1 b Name or trade mark of the manufacturer; c Type designation; d Serial number of the gas meter and its year of manufacture; e Accuracy class; f Maximum flowrate Qmax ; g Minimum flowrate Qmin ; h Transition flowrate Qt ; i Gas temperature range and pressure range for which the errors of the gas meter shall be within the limits of the maximum permissible error, expressed as tmin – tmax - ; pmin – pmax - gauge pressure. j The density range within which the errors shall comply with the limits of the maximum permissible error may be indicated, and shall be expressed as - This marking may replace the range of working pressures i unless the working pressure marking refers to a built-in conversion device; k Pulse values of HF and LF frequency outputs imp/, pul/, /imp; Note The pulse value is given to at least six significant figures, unless it is equal to an integer multiple or decimal fraction of the used unit. l Letter V or H, as applicable, if the meter can be operated only in the vertical or horizontal position; m Indication of the flow direction, e.g. an arrow if applicable, see 5.2.1 and 5.2.2; n Measurement point for the working pressure according to 5.3.4; and o Environmental temperatures, if they differ from the gas temperature as mentioned in i. OIML TC 8/SC 7 1WD OIML R 137-1 q Temperature tsp specified by the manufacturer according to 4.3.4. 6.1.3 Additional markings for gas meters with output drive shafts r Gas meters fitted with output drive shafts or other facilities for operating detachable additional devices shall have each drive shaft or other facility characterized by an indication of its constant C in the 1 rev ‖ and the direction of rotation. rev‖ is the abbreviation of the word revolution‖; s If there is only one drive shaft the maximum permissible torque shall be marked in the Mmax N.mm‖; t If there are several drive shafts, each shaft shall be characterized by the letter M with a subscript in the M1, M2, Mn‖; u The following ula shall appear on the gas meter k1M1 k2M2 knMn A N.mm, where A is the numerical value of the maximum permissible torque applied to the drive shaft with the highest constant, where the torque is applied only to this shaft; this shaft shall be characterised by the symbol M1, ki i 1, 2, n is a numerical value determined as follows ki C1 / Ci, Mi i 1, 2, n represents the torque applied to the drive shaft characterized by the symbol Mi, Ci i 1, 2, n represents the constant for the drive shaft characterized by the symbol Mi. 6.1.4 Additional markings for gas meters with electronic devices v For an external power supply the nominal voltage and nominal frequency; w For a non-replaceable or replaceable battery the latest date by which the battery is to be replaced, or the remaining battery capacity; x Software identification of the firmware. OIML TC 8/SC 7 1WD OIML R 137-1 b maximum and minimum storage temperatures; c rated operating conditions; d warm-up time after switching on the electrical power if applicable; e all other relevant mechanical and electromagnetic environmental conditions; f for instruments, powered by an external power converter specifications of this power converter; g any specific installation conditions like for instance a limitation of the length of signal, data, and control lines; h if applicable the specifications of the battery; i instructions for installation, maintenance, repairs, permissible adjustments this can be in a separate document, not meant for the user/owner; j conditions for compatibility with interfaces, sub-assemblies modules or other measuring instruments. 7.2 INSTALLATION CONDITIONS The manufacturer shall specify the installation conditions as applicable with respect to - the position to measure the working temperature of the gas; - filtering; - levelling and orientation; - flow disturbances; - pulsations or acoustic interference; - rapid pressure changes; - absence of mechanical stress due to torque and bending; - mutual influences between gas meters; - mounting instructions; - maximum allowable diameter differences between the gas meter and connecting pipework; and - other relevant installation conditions. OIML TC 8/SC 7 1WD OIML R 137-1 Note This requirement is only necessary if the nameplate can be detached from the meter. b On all parts of the case which cannot be otherwise protected against interference likely to affect the accuracy of the measurement. 8.1.4 Electronic sealing devices 8.1.4.1 When access to parameters that contribute to the determination of results of measurement needs to be protected, but is not protected by mechanical seals, the protection shall fulfil the following provisions a Access shall only be allowed to authorized people, for example by means of a code password or special device hard key, etc. and, after changing parameters, the instrument may be put into use in sealed condition‖ again without any restriction, or Unrestricted access is allowed but, after changing the parameters, the instrument shall be put back into use in sealed condition‖ only by authorized persons, e.g. by using a password‖ similar to classical sealing. b The code password shall be changeable. c The device shall either clearly indicate when it is