1、BRITISH STANDARD BS 6866-1: 1990 ISO 7278-1: 1987 Proving systems for meters used in dynamic measurement of liquid hydrocarbons Part 1: IntroductionBS6866-1:1990 This British Standard, having been prepared under the directionof the Petroleum Standards Policy Committee, waspublished under the authori
2、tyof the Board ofBSIandcomes into effect on 31 July 1990 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference PTC/12 Draft for comment 84/51853 DC ISBN 0 580 18712 8 Committees responsible for this British Standard The preparation of this British Standard
3、 was entrusted by the Petroleum Standards Policy Committee (PTC/-) to Technical Committee PTC/12, upon which the following bodies were represented: Department of Energy (Gas and Oil Measurement Branch) Department of Trade and Industry (National Engineering Laboratory) Department of Transport (Marine
4、 Directorate) General Council of British Shipping Institute of Petroleum Royal Institution of Naval Architects Salvage Association The following bodies were also represented in the drafting of the standard, through subcommittees and panels: GAMBICA (BEAMA Ltd.) Institute of Measurement and Control U
5、nited Kingdom Offshore Operators Association Amendments issued since publication Amd. No. Date CommentsBS6866-1:1990 BSI 11-1999 i Contents Page Committees responsible Inside front cover National foreword ii 0 Introduction 1 1 Scope and field of application 1 2 Reference 1 3 Types of prover 1 4 Gene
6、ral considerations 1 5 Tank prover systems 3 6 On-line pipe prover systems 4 7 Centralized prover systems 4 8 Master meter systems 5 9 Bibliography 6 Publications referred to Inside back coverBS6866-1:1990 ii BSI 11-1999 National foreword This Part of BS 6866 has been prepared under the direction of
7、 the Petroleum Standards Policy Committee and is identical with ISO 7278-1:1987 “Liquid hydrocarbons Dynamic measurement Proving systems for volumetric meters Part 1: General principles”. ISO 7278-1 was prepared by Technical Committee 28, Petroleum products and lubricants, of the International Organ
8、ization for Standardization (ISO) as the result of discussions in which the United Kingdom participated. BS 6866-1 forms part of a series, each of which is identical with the corresponding Part of ISO 7278. The other Parts of BS 6866 are as follows: Part 2: Methods for design, installation and calib
9、ration of pipe provers (Identical with ISO 7278-2:1988); Part 3: Methods for pulse interpolation (Identical with ISO 7278-3:1986). ISO 4124 to which reference is made in clause 2 and elsewhere in this standard has not yet been published but it is likely to be approved by the responsible BSI Committe
10、e for implementation as a British Standard. With reference to the footnote to clause 9 both standards referred to have now been published. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct applicati
11、on. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard BS 6169 Methods for volumetric measurement of liquid hydrocarbons ISO 2714:1980 Part 1:1981 Displacement meter systems (other than
12、dispensing pumps) (Identical) ISO 2715:1981 Part 2:1984 Turbine meter systems (Identical) ISO 4267-2:1988 BS 7286 Method for calculation of petroleum and liquid petroleum products Part 2:1990 Dynamic measurement (Identical) BS 6866 Proving systems for meters used in dynamic measurement of liquid hyd
13、rocarbons ISO 7278-2:1988 Part 2:1990 Methods for design, installation and calibration of pipe provers (Identical) ISO 7278-3:1986 Part 3:1987 Methods for pulse interpolation (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 6, an in
14、side back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6866-1:1990 BSI 11-1999 1 0 Introduction This document is the first part of an International Stand
15、ard on proving systems for meters used in dynamic measurement of liquid hydrocarbons. Future parts of ISO 7278 will provide more detailed descriptions of pipe provers, tank provers and pulse interpolation techniques; these parts are in preparation. Parts covering other aspects or types of proving sy
16、stems may be added as the need arises. The purpose of proving a meter is to determine its relative error or its meter factor as a function of flow rate and other parameters such as temperature, pressure and viscosity. The purpose of determining the relative error is to find out whether the meter is
17、working within prescribed or specially accepted limits of error, whereas the meter factor is used to correct any error in the indication of a meter by calculation. 1 Scope and field of application This part of ISO 7278 provides general principles for proving systems for meters used in dynamic measur
18、ement of liquid hydrocarbons. 2 Reference ISO 4124, Liquid hydrocarbons Dynamic measurement Statistical control of volumetric metering systems 1) . 3 Types of prover 3.1 The following types of proving systems are in use: a) tank prover systems; b) pipe provers, bidirectional and unidirectional. Pipe
19、 provers with precision tubes as described in6.7 are available for special applications; c) master meters. Indirect procedure of volume comparison which causes additional uncertainties can be used for all liquids and flow rates, provided that the master meter is proved against acceptable proving sys
20、tems under conditions which simulate those under which it will operate. Sometimes, a meter is used as a means of standardization of transfer; this equipment is generally known as a “master meter”. 3.2 Provers can be used either connected (fixed or mobile) to the metering station or in a central prov
21、ing station to which the meters or the measures can be taken to be proved. 3.3 In order to limit the maximum uncertainty to 0,01 % when using a pulse generator for proving, at least10000 pulses shall be obtained from the meter per proving run. This number of pulses can be reduced by pulse-interpolat
22、ion techniques which allow either the use of meters with fewer pulses per unit volume or reduction of the prover volume. 4 General considerations 4.1 A meter should be proved at the expected operating or prescribed or agreed rates of flow, under the pressure and temperature at which it will operate
23、and on the liquid which it will measure. In situations where it is not feasible to prove the meter on the liquid to be metered, the meter should be proved on a liquid having a density, viscosity and, if possible, temperature as close as possible to those of the liquid to be measured. A meter that is
24、 used to measure several different liquids shall be proved on each such liquid. Similar liquids may be used if a simple, known relationship exists between the relative error, flow rate and viscosity, provided that the uncertainty of measurement remains within acceptable limits. In any event, calibra
25、tion should take place at a flow rate equivalent to that at which the meter will be used. A meter shall be proved in different circumstances as follows: a) Initial proving. This shall be carried out on the permanent location or in a central station where the expected conditions of operation can be r
26、eproduced. The initial proving makes it possible to determine the relationship between the relative error (or meter factor) and different parameters such as viscosity or temperature. b) Occasional or periodical proving. If a simple relationship between the relative error (or meter factor) and influe
27、ncing parameters can be determined, the meters shall be reproved periodically using a prover either on the site or in a centralised station. Otherwise, the meter shall be reproved on the site whenever significant changes in the influencing parameters, such as viscosity or temperature, occur. Regular
28、 provings are also needed to follow effects of mechanical changes. 4.2 Many petroleum liquids of high vapour pressures are measured by meter. If liquid evaporation during normal operation or proving could occur and affect measurement, the proving system should provide means to avoid evaporation. 1)
29、At present at the stage of draft.BS6866-1:1990 2 BSI 11-1999 4.3 The proving of a meter is like a laboratory test:when properly done, it provides a high degree of repeatability, which is necessary for measurement accuracy. There are as many details of the meter, its piping and the proving systems, w
30、hich can contribute to measurement uncertainty, as there are in determining physical properties of the measured liquid. Furthermore, the proving system shall be maintained in good operating condition. Thorough inspection of provers and their ancillary equipment should be made with sufficient frequen
31、cy to ensure reproducibility of proving results. It is essential that meter performance data be observed, recorded and studied and that calculations be correct (see ISO 4124). The accuracy and repeatability of the proving can be affected by observation errors in determining the opening meter reading
32、 or the closing meter reading, the test volume passing through or delivered to the prover and in reading temperature and pressure, and by implicit errors in computation in the process of correcting a measurement to standard conditions. 4.4 Meter proving can be classified according to procedure, as d
33、escribed below. a) The standing start-and-stop procedure uses registers (counters) from which the opening and closing readings are obtained at no-flow conditions. Opening and closing of valves shall be performed rapidly. b) The running start-and-stop procedure involves obtaining the opening and clos
34、ing meter readings of the proof while the meter is in operation. This is accomplished by the use of auxiliary or secondary registers of high discrimination which can be started and stopped while the meter and primary register continue to operate. 4.5 Every meter proof shall be made with the same reg
35、ister equipment as is used in regular operation or with additional synchronised auxiliary registers for the running start-and-stop procedure 4.4 b). Inclusion of special auxiliary equipment such as the following is permitted: density selector, temperature compensator, and quantity-predetermining reg
36、ister. If employed, the auxiliary equipment shall be set and operative when making the proof runs. Time between proving runs shall be kept to a minimum. 4.6 There are two general objectives to meter proving which usually depend on the type of service. In the first, a meter can be proved to establish
37、 its performance by adjustment of its registration, if necessary, to give a meter factor of 1,000 0 so that itsindicated volume will be the volume of liquid actually delivered (gross volume within desired tolerances). This is the normal practice for a meter operating on intermittent deliveries, such
38、 as a tank truck meter or a loading rack meter at a terminal or bulk plant. In the second, a meter can be proved to determine its meter factor or, if possible, a simple relationship between its meter factor and influencing parameters such as viscosity or temperature so that this factor or this relat
39、ionship can be applied to the indicated volume to compute the gross volume delivered through the meter. This is the normal practice in the case of continuous or long-duration measurement. 4.7 When a meter is being proved for adjustment, a preliminary unrecorded run shall be made, as necessary, to eq
40、ualise temperatures, displace vapours or gases and wet the interior of the prover. Subsequent recorded proving test runs shall be made in the required range of flow rates and the registration adjusted as necessary. Each calibration point for the same flow should be repeated at least twice and prefer
41、ably three times. Further repeats may be necessary, if specified. SeeISO 4124. 4.8 When a meter is being proved to determine the meter factor at one or several flow rates, the procedure shall be essentially as specified in 4.7, except that no changes shall be made to the meter registration adjusting
42、 device between runs. Proof runs shall be made and recorded until the specified number of consecutive runs at the same flow rate agree within an acceptable repeatability, at which point the average of these two runs shall be accepted as the established meter correction factor for this flow rate. 4.9
43、 If the registration of a meter, during proving, is not changing in accordance with adjustments made to the register adjusting device, or if four individual unadjusted proving runs are made without any two successive runs checking within an acceptable repeatability, all phases of the proving operati
44、on shall be examined for the cause of the discrepancy. If the cause is not found, the meter and its register mechanisms shall be inspected for electronic or mechanical defects, repaired and proved before being returned to service.BS6866-1:1990 BSI 11-1999 3 4.10 The practical limit of accuracy in an
45、y observed value such as the volume in the reference vessel during a meter proof is one part in10000. For this reason, meter factors shall be rounded to four decimal places, not more and not less, for example1,001 6. 4.11 The results of calculation can be adversely affected by the use of abbreviated
46、 tables, the unstandardized rounding of factors and/or intermediate calculations. The observed and computed data for all test runs made in obtaining a meter factor or other expression of meter performance shall be reported on a suitable meter proving report form. The completed form, when signed by t
47、he interested parties or by the legal authority, shall constitute approval, understanding and acceptance of the meter proof, unless otherwise limited to witnessing only by a notation on the report. 4.12 Most of the procedures specified above have been for the proving of a single meter. If the meter
48、to be proved is part of a battery of meters handling a common stream, it is necessary either to divert the stream from the selected meter to be proved through the prover or remove the meter to a central proving station. 5 Tank prover systems 5.1 As far as possible, the use of all united supplementar
49、y bodies/matters inside the standard gauge shall be avoided, and in no case shall the gauge be adjusted to a given value by this means. The prover should be recalibrated after any changes to components within the calibrated volume section such as gauge glasses, thermometer well or spray lines. The tank prover should be designed in order to avoid any variation in its metrological characteristics and also to reduce clingage of liquid to the walls. The prover tank shall be inspected frequently for internal corrosion and for accumulation of sediment, rust, valve lubr
