BS 2782-11 Method 1121H-1996 Methods of testing plastics - Thermoplastics pipes fittings and valves - Thermoplastics pipes for the transport of liquids under pressure - Calculation.pdf

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1、BRITISH STANDARD BS 2782-11: Method 1121H:1996 ISO/TR 10501:1993 Methods of testing Plastics Part 11: Thermoplastics pipes, fittings and valves Method 1121H: Thermoplastics pipes for the transport of liquids under pressure Calculation of head losses ICS 23.040.20BS 2782-11: Method 1121H:1996 This Br

2、itish Standard, having been prepared under the direction of the Sector Board for Materials and Chemicals, was published under the authority of the Standards Board and comes into effect on 15 August 1996 BSI 11-1998 The following BSI references relate to the work on this standard: Committee reference

3、 PRI/61 Draft for comment 90/39660 DC ISBN 0 580 26033 X Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee PRI/61, Plastics piping systems and components, upon which the following bodies were represented: British Gas plc Br

4、itish Plastics Federation British Plumbing Fittings Manufacturers Association British Valve and Actuator Manufacturers Association Chartered Institution of Water and Environmental Management Department of the Environment (British Board of Agrment) Department of the Environment (Building Research Est

5、ablishment) Department of the Environment (Property and Buildings Directorate) Department of Transport Electricity Association Federation of Civil Engineering Contractors Health and Safety Executive Institute of Building Control Institute of Materials Institution of Civil Engineers Institution of Ga

6、s Engineers National Association of Plumbing, Heating and Mechanical Services Contractors Pipeline Industries Guild Plastics Land Drainage Manufacturers Association Society of British Gas Industries Society of British Water Industries Water Companies Association Water Services Association of England

7、 and Wales Amendments issued since publication Amd. No. Date CommentsBS 2782-11: Method 1121H:1996 BSI 11-1998 i Contents Page Committees responsible Inside front cover National foreword ii Foreword ii 1 Scope 1 2 Definitions 1 3 Symbols and units 1 4 Method of calculation 1 Annex A Formulae used in

8、 calculations 3 Table 1 1 Table 2 2 Table 3 2BS 2782-11: Method 1121H:1996 ii BSI 11-1998 National foreword This British Standard has been prepared by Technical Committee PRI/61 and is identical with ISO/TR 10501:1993 Thermoplastics pipes for the transport of liquids under pressure Calculation of he

9、ad losses, published by the International Organization for Standardization (ISO). It is incorporated into BS 2782 Methods of testing plastics Part 11: Thermoplastics pipes, fittings and valves, as Method 1121H:1996, for association with related test methods for plastics materials and plastics piping

10、 components. No existing British Standard is superseded by this standard. NOTEThroughout the text the words “formula” and “formulae” are used where for correct English “equation(s)” would be more appropriate. A British Standard does not purport to include all the necessary provisions of a contract.

11、Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theISO title page, page ii, pages 1 t

12、o 4 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 theinside front cover.BS 2782-11: Method 1121H:1996 ii BSI 11-1998 Foreword ISO (the International Organization for Standardization) is

13、 a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represen

14、ted on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The main task of technical com

15、mittees is to prepare International Standards, but in exceptional circumstances a technical committee may propose the publication of a Technical Report of one of the following types: type 1, when the required support cannot be obtained for the publication of an International Standard, despite repeat

16、ed efforts; type 2, when the subject is still under technical development or where for any other reason there is the future but not immediate possibility of an agreement on an International Standard; type 3, when a technical committee has collected data of a different kind from that which is normall

17、y published as an International Standard (“state of the art”, for example). Technical Reports of types 1 and 2 are subject to review within three years of publication, to decide whether they can be transformed into International Standards. Technical Reports of type 3 do not necessarily have to be re

18、viewed until the data they provide are considered to be no longer valid or useful. ISO/TR 10501, which is a Technical Report of type 3, was prepared by Technical Committee ISO/TC 138, Plastics pipes, fittings and valves for the transport of fluids, Sub-Committee SC 2, Plastics pipes and fittings for

19、 water supplies.BS 2782-11: Method 1121H:1996 BSI 11-1998 1 1 Scope This Technical Report gives a method of calculating head loss in the transport of liquids under pressure in hydraulically smooth thermoplastics pipes. The formulae given in the Technical Report apply to the transport of water under

20、pressure, or to all other liquids of the same dynamic viscosity, at temperatures of up to 45C. 2 Definitions For the purposes of this Technical Report, the following definitions apply. 2.1 flowrate, q v volume of water flowing through the pipe per unit time 2.2 steady flow flow in which the flowrate

21、 through a measuring section does not vary with time 2.3 average velocity, v flowrate through the pipe divided by the reference cross-section of the pipe. It is calculated by dividing the actual flowrate through the pipe by the cross-section of the pipe 2.4 reference cross-section of the pipe, A are

22、a of the circle with a diameter equal to the average internal diameter of the pipe. The free cross-sectional area of the pipe is calculated from the inside diameter of the pipe 2.5 head loss, Dh change in pressure head between two sections of a horizontal pipe due to liquid flow through the pipe 2.6

23、 head drop, J head loss per unit length of pipe 3 Symbols and units The symbols and units used in this Technical Report are given in Table 1. Table 1 4 Method of calculation 4.1 Formulae for calculating head drop 4.1.1 The head drop for water, J o , in metres per metre, at a temperature of 20C, is c

24、alculated using one of the following formulae: 4.1.1.1 Where the Reynolds number 1)lies within the range 4 10 3# Re 1,5 10 5 : J o= 5,37 10 -4 (d 1,24V 1,76 ) 4.1.1.2 Where the Reynolds number 1)lies within the range 1,5 10 5# Re # 10 6 : J o= 5,79 10 -4 (d 1,20 V 1,80 ) NOTE 1The various formulae g

25、enerally used in calculating head loss in pipes are given in annex A. 4.1.2 The head drop J xfor a liquid x which differs from that of water is calculated by the following formula: where J zis the head drop for a specific liquid; J ois the head drop for water at a temperature of 20C; v wis the kinem

26、atic viscosity of a specific liquid at the desired temperature; Sub- Clause Quantity Symbol Unit 2.1 Flowrate q v m 3 /h 2.3 Average velocity v m/s 2.4 Average internal diameter d m 2.5 Head loss Dh m 2.6 Head drop J m/m 4.1 Reynolds number Re dimension- less 4.1 Kinematic viscosity v m 2 /s 4.2 Pip

27、e length l m 4.3 Temperature of liquid t C 4.3 Temperature correction factor k t dimension- less 1) See formula for Reynolds number in annex A. J x J o V x V w - b =BS 2782-11: Method 1121H:1996 2 BSI 11-1998 v wis the kinematic viscosity of water at a temperature of 20C. Exponent b has the followin

28、g values: a) when the Reynolds number lies within the range 4 10 3# Re 1,5 10 5 : b = 0,24 b) when the Reynolds number lies within the range 1,5 10 5# Re # 10 6 : b = 0,20 4.2 Formula for calculating head loss The head loss Dh of a liquid column is calculated from the following formula: Dh = Jl 4.3

29、Formula for temperature correction The formulae for calculation of J given in 4.1 relate to the flow of water at a temperature of 20C. When the water temperature differs from 20C, the value of J is determined by applying the following temperature correction formula. J t= k t J o where J tis the head

30、 drop at temperature t. 4.3.1 When the Reynolds number lies within the range 4 10 3# Re 1,5 10 5 the k tvalues given in Table 2 should be taken. Table 2 4.3.2 When the Reynolds number lies within the range 5 10 5# Re # 10 6 , the k tvalues given in Table 3 should be taken. Table 3 NOTE 2For liquids

31、other than water, it is not necessary to specify special methods for calculating J, since the formula given in 4.1.2 can also be used for variations in the temperature of the liquid. This is due to the fact that the temperature in the formula is expressed in the kinematic viscosity of the specific l

32、iquid at the desired temperature. Temperature of water (t) (C) Temperature correction factor (K t ) 0 1,148 5 1,105 10 1,067 15 1,033 20 1,000 25 0,972 30 0,947 35 0,925 40 0,904 45 0,885 Temperature of water (t) (C) Temperature correction factor (K t ) 0 1,122 5 1,087 10 1,055 15 1,027 20 1,000 25

33、0,977 30 0,956 35 0,937 40 0,919 45 0,903BS 2782-11: Method 1121H:1996 BSI 11-1998 3 Annex A Formulae used in calculations This annex gives a number of formulae generally used for calculating head losses in pipes, caused by the flow of liquid. The formulae given in A.1.1 to A.1.10 are generalized fo

34、rmulae applicable to all types of pipe. The formulae given in A.1.11 and A.1.12 were developed especially for plastics pipes. A.1 Head loss formulae A.1.1 Chezy formula where A.1.2 Hagen and Poiseuille formula (in the metric system) where A.1.3 Reynolds number A.1.4 Von Karman formula where l is a f

35、unction of the Reynolds number and of the relative roughness k/d where k is the roughness of the pipe wall. A.1.5 Colebrook formula where k is generally taken between 0,001 and 0,007 for plastics pipes. A.1.6 Hazen-Williams formula (in the metric system) J = 2,16 10 7(v 1,852C 1,852d 1,167 ) where C

36、 is the the Hazen-Williams coefficient, which depends on the roughness of the pipe. A.1.7 Strickler formula (also known as the Manning-Strickler formula) A.1.8 Scimeml formula (in the metric system) v = 61,5 d 0,68J 0,56 A.1.9 Blasius formula l = 0,3164 Re 0,25 A.1.10 Tison formula (in the metric sy

37、stem) J = 0,000545 v 1,75d 1,25 or v = 73,3 d 0,714J 0,571 A.1.11 Formulae proposed by SII (Israel) for flow of water in plastics pipes (in the metric system) (1) J o= 0,518 10 3 (v 1,76d 1,24 ) or v = 73,6 d 0,705J 0,568 for Reynolds number range 4 10 3# Re 1,5 10 5 (2) J o= 0,590 10 3(V 1,81d 1,11

38、9 ) or v = 60,8 d 0,618J 0,552 or Reynolds number range ,5 10 5# Re # 10 6 A.1.12 Formula proposed by SNV Switzerland) for flow of water in plastics pipes (in the metric system) or v = k9 d 0,714J 0,571 A.2 Formulae for plastics pipes proposed in this Technical Report The formulae given in 4.1 propo

39、sed by France are almost identical to formulae A.1.10, A.1.11 andA.1.12 cited above. v is the velocity; r h is the hydraulic radius; J is the head drop; A is the coefficient. d i is the internal diameter of the pipe; v is the dynamic viscosity; g is the gravitational acceleration. vAr h J = J 32 vv

40、gd 1 2 - = Re vd i v - = 1 l -2 251 , Rel - log = 1 l - 2 k 37d , - 251 , Rel - + log = vkrh 23 J 12 = J p 4 -kv 175 , d 125 , () =BS 2782-11: Method 1121H:1996 4 BSI 11-1998 The values for head losses for water flow in plastics pipes published in the technical literature are generally similar to th

41、ose obtained from the formulae given in 4.1. In addition, it should be noted that laboratory test measurements of head losses in plastics pipes, such as PVC and polyethylene, have given results which are very close to those obtained by the theoretical calculcation when using the formulae proposed in

42、 4.1.5 blankBSI 389 Chiswick High Road London W4 4AL | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |

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