1、BRITISH STANDARD BS EN ISO 3993:1996 Liquefied petroleum gas and light hydrocarbons Determination of density or relative density Pressurehydrometer method The European Standard EN ISO3993:1995 has the status of a British Standard ICS 75.200BSENISO3993:1996 This British Standard, having been prepared
2、 under the directionof the Sector Board for Materials and Chemicals, was published under the authority of the Standards Board and comes into effect on 15 February1996 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference PTI/12 Draft for comment 76/51650 D
3、C ISBN 0 580 23949 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee PTI/12, Petroleum measurement and sampling, upon which the following bodies were represented: Department of Energy (Gas and Oil Measurement Branch) Depa
4、rtment of Trade and Industry (National Engineering Laboratory) Institute of Petroleum Salvage Association The following was also represented in the drafting of the standard through subcommittees and panels: GAMBICA (BEAMA Ltd.) Amendments issued since publication Amd. No. Date CommentsBSENISO3993:19
5、96 BSI 11-1999 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 1 Scope and field of application 3 2 Definitions 3 3 Principle 3 4 Apparatus 3 5 Reference liquids 4 6 Sampling 4 7 Calibration of apparatus 6 8 Procedure 6 9 Precision 7 10 Test report 7 Annex U
6、se of thermohydrometers 8 Figure Pressure hydrometer cylinder 5 Table 1 Ranges and dimensional specification for pressure hydrometers 4 Table 2 Coefficients for conversion of hydrometer readings to density or relative density for butadiene 7BSENISO3993:1996 ii BSI 11-1999 National foreword This Brit
7、ish Standard has been prepared by Technical Committee PTI/12 and is the English language version of ENISO3993:1995 Liquefied petroleum gas and light hydrocarbons Determination of density or relative density Pressure hydrometer method, published by the European Committee for Standardization (CEN). It
8、 is identical with ISO3993:1984 published by the International Organization for Standardization (ISO). BSENISO3993 supersedes BS6665:1985 which is withdrawn. This edition takes account of the adoption of ISO3993:1984 as a European Standard, but does not reflect a full review or revision which may be
9、 undertaken in due course. CAUTION. This British Standard calls for the use of procedures that may be hazardous if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from legal obligations relating to health and safety at any stage. Particular a
10、ttention is drawn to the cautionary notes in4.3 and8.5. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from lega
11、l obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theEN ISO title page, pages2 to8 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
12、 on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM ENISO3993 August1995 ICS 75.200 Descriptors: Petroleum products, liquefied petroleum gases, hydrocarbons, tests, physical tests, determination, density (mass/volume), hydrometers, test equipment English version Liquefied pe
13、troleum gas and light hydrocarbons Determination of density or relative density Pressurehydrometer method (ISO3993:1984) Gaz de ptrole liqufis et hydrocarbures lgers Dtermination de la masse volumique ou de la densit relative Mthode de laromtre sous pression (ISO3993:1984) Flssiggas und leichte Kohl
14、enwasserstoffe Bestimmung der Dichte oder der relativen Dichte Verfahren mittels Druck-Arometer (ISO3993:1984) This European Standard was approved by CEN on1995-07-06. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European St
15、andard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, Frenc
16、h, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, Fr
17、ance, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1
18、995 All rights of reproduction and communication in any form and by any means reserved in all countries to CEN and its members. Ref. No. ENISO3993:1995 EENISO3993:1995 BSI 11-1999 2 Foreword The text of the International Standard from ISO/TC28 “Petroleum products and lubricants” of the International
19、 Organization for Standardization (ISO) has been taken over as a European Standard by the Technical Committee CEN/TC19 “Petroleum products, lubricants and related products”. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endo
20、rsement, at the latest by February1996, and conflicting national standards shall be withdrawn at the latest by February1996. According to CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Gree
21、ce, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the UnitedKingdom.ENISO3993:1995 BSI 11-1999 3 1 Scope and field of application 1.1 This International Standard specifies a method for the determination of density or relative density of liquefied
22、petroleum gases and other light hydrocarbons. The prescribed apparatus shall not be used for materials having gauge vapour pressures higher than1,4MPa 1) (14bar) (absolute vapour pressure1,5MPa) at the test temperature. CAUTION Attention is drawn to the hazards encountered when working with liquefie
23、d petroleum gas or light hydrocarbons. The requirements of any national, local or domestic safety code should always be strictly observed. 1.2 Alternative calibration procedures are described, but only the one using a certified hydrometer is suitable for the determination of density to be used in ca
24、lculations of quantities for custody transfer or fiscal purposes. NOTEAn alternative method for calculating the density of liquefied petroleum gases from gas chromatographic analysis is described in ISO6578 2) . 1.3 Provision is made in the Annex for the use of thermohydrometers. 2 Definitions For t
25、he purpose of this International Standard, the following definitions shall apply. 2.1 density the mass of the liquid divided by its volume when reporting the density, the unit of density used, together with the temperature, shall be explicitly stated, for example kilogram per metre cubed or gram per
26、 millilitre at t C (see the note). The standard reference temperature for international trade in petroleum and its products is15 C (seeISO5024), but other reference temperatures may be required for legal metrology or other special purposes NOTEIn this International Standard, the preferred unit is th
27、e kilogram per metre cubed, but provision is also made for the use of the gram per millilitre. 2.2 relative density (this term now replaces the former term specific gravity) the ratio of the mass of a volume of the liquid at a temperature t 1to the mass of an equal volume of pure water at a temperat
28、ure t 2 , i.e.the ratio of the density of the liquid at a temperature t 1to the density of pure water at a temperature t 2 when reporting the relative density, the temperatures t 1and t 2shall be explicitly stated, for example relative density60/60 F. The standard reference temperature is15 C, but20
29、 C and60 F are also in general use for t 1and t 2and other temperatures may be employed for t 1 3 Principle The apparatus is purged with a portion of the sample before filling with the portion to be used for testing. The pressure cylinder is filled to a level at which the enclosed hydrometer floats
30、freely. The hydrometer reading and the temperature of the sample are noted. 4 Apparatus 4.1 Hydrometers, made of glass, graduated in density or relative density, with the appropriate range and conforming to the dimensions given in Table 1. NOTEFor the use of thermohydrometers see the Annex. Use a ce
31、rtified hydrometer, or calibrate the hydrometers in accordance with clause7. Calibration corrections should be applied if the scale errors are in excess of0,5 of a subdivision of the scale. 4.2 Thermometer, having a sensitivity of at least2,7mm/1C(1,5mm/1 F) calibrated for total immersion and of sui
32、table dimensions to fit inside the hydrometer cylinder (4.3). A thermometer conforming to ISO/R653, STL/0.2/ 15/+45 is recommended. The thermometer shall be held firmly inside the hydrometer cylinder by means of a suitable clip in such a position as not to interfere with the free motion of the hydro
33、meter. 4.3 Hydrometer cylinder, constructed of glass or transparent plastics, for example polymethylmethacrylate or equivalent material, conforming to the design and dimensions given in the Figure. The ends shall be tightly sealed by means of chloroprene gaskets and metal end-plates as shown. CAUTIO
34、N As a precautionary measure a protective shield shall be placed around the plastics or glass cylinder. Replace any cylinders that show any fogging, crazing, cracking, or etching. 1) The SI unit of pressure is the pascal:1Pa =1N/m 2 ;10 5 Pa =1bar =1,01972kgf/cm 2 . 2) At present at the stage of dra
35、ft.ENISO3993:1995 4 BSI 11-1999 NOTECertain compounds attack plastics and cloud the inner surface of the cylinder, making it difficult or impossible to read the hydrometer. Tests have shown no attack by ethane, ethylene, propane, propylene, butane, isobutane, normal butylenes, isobutyiene, pentane a
36、nd isopentane and no attack is expected from butadiene. Users are cautioned, however, always to clean the cylinder thoroughly after each determination. Ketones and alcohols must not be used for cleaning as they attack and weaken plastics whilst aromatics also tend to attack the surface of plastics a
37、nd should similarly not be used. The liquid inlet valve and the liquid outlet valve shall be tightly connected to a base plate which shall be so bored as to give both valves a common inlet to the cylinder. The vapour vent valve shall be similarly connected to the top plate. All valves shall be6mm or
38、 equivalent needle valves. The cylinder shall not be operated at a gauge pressure greater than1,4MPa(14bar). 4.4 Water bath, fitted with a thermostat or other means of maintaining the bath at a constant temperature of15 0,2 C or20 0,2 C or60 0,5 F, and of such dimensions that the hydrometer cylinder
39、(4.3) can be completely immersed. 5 Reference liquids The following reference liquids are required for calibration of the hydrometer if a certified hydrometer is not available. 5.1 Pure propane, having a certified density or relative density. NOTEPropane of density507,6kg/m 3 (0,5076g/ml) at15 C or5
40、00,0kg/m 3 (0,5000g/ml) at20 C or a relative density60/60 F of0,5073 is suitable. 5.2 Pure butane, having a certified density or relative density. NOTEButane of density584,5kg/m 3 (0,5845g/ml) at15 C or578,8kg/m 3 (0,5788g/ml) at20 C or a relative density60/60 F of0,584 4 is suitable. 6 Sampling The
41、 procedure for sampling for calibration of the apparatus and for subsequent testing is described below. 6.1 Carefully clean and dry the hydrometer (4.1), the thermometer (4.2) and the inside wall of the pressure cylinder (4.3). Insert the hydrometer in the pressure cylinder and attach the thermomete
42、r and cover plate. 6.2 Connect the source of supply of the liquid to be tested to the inlet valve by suitable fittings so that a representative sample can be introduced into the cylinder (4.3); ascertain that these connections are free from leaks. Open the outlet valve and purge the sampling connect
43、ions by opening the inlet valve slightly, permitting the product to flow through the outlet valve at the bottom of the cylinder. 6.3 When the connections have been purged, close the outlet and vent valves and open the inlet valve, permitting the liquid to enter the cylinder until it is full. If nece
44、ssary, the vent valve may be opened slightly to permit complete filling of the cylinder, after which it shall be closed. At no time shall the pressure in the cylinder be allowed to rise above a gauge pressure of1,4MPa(14bar). 6.4 When the cylinder has been filled, close the inlet valve and open the
45、outlet valve, permitting the contents of the cylinder to be withdrawn completely and the pressure inside the cylinder to be reduced to that of the atmosphere. Table 1 Ranges and dimensional specification for pressure hydrometers Alternative ranges 500 to 580kg/m 3 570 to 650kg/m 3 0,500 to 0,580g/ml
46、 0,570 to 0,650g/ml 0,500 to 0,580 0,570 to 0,650 Subdivisions 1kg/m 3 0,001g/ml 0,001 Figured every 5 or 10kg/m 3 0,005 or 0,010g/ml 0,005 or 0,010 Overall length 330mm max. Bulb diameter 18 to 20mm Bulb wall thickness 0,4 to 0,6mm Stem diameter 8 to 9mm Stem wall thickness 0,3 to 0,35mm Scale leng
47、th 110 to 130mmENISO3993:1995 BSI 11-1999 5 Figure Pressure hydrometer cylinderENISO3993:1995 6 BSI 11-1999 6.5 Close the outlet valve and open the inlet valve, filling the cylinder to a level at which the enclosed hydrometer floats freely. If it is necessary to accomplish this filling by venting va
48、pour through the vent valve, repeat the purging to cool the cylinder sufficiently to permit its being filled without the necessity of venting. 6.6 With all valves closed, examine the apparatus for leaks; if leaks are detected, discard the sample, reduce the pressure to atmospheric and repair the lea
49、ks. Repeat the sampling procedure. 7 Calibration of apparatus 7.1 If a hydrometer having a calibration certificate issued by an approved laboratory is not used, the hydrometer shall be calibrated using one of the alternative procedures specified in7.2 or7.3 before densities are determined. 7.2 Take three or more samples having different densities in the range of the hydrometer to be tested. Using the procedure specified in clause8 determine in duplicate for each sample the hydrometer reading on a certifi
