JIS-Z-8762-1988-ENG.pdf

J I S Z*87b2 88 W 4933b08 0079822 T - J7- I UDC 532.575.52:532.575.53 JIS JAPANESE INDUSTRIAL STANDARD Measurement of Fluid Flow by Means of Orifice Plates, Nozzles and Venturi lubes JIS Z 8 7 6 2 - 1 9 8 8 Translated and Published by Japanese Standards Association Printed in Japan 48 S 1 Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/11/2007 06:32:04 MDTNo reproduction or networking permitted without license from IHS -,-,- ' J I S Z*87b2 48 4933b08 0079823 I ! .- . . . . . . i . - . . - . .I In the event of any doubt arising, the original Standard in Japanese is to be final authority. . . . . _ ' . . . 2 -: . . . . . . . - . Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/11/2007 06:32:04 MDTNo reproduction or networking permitted without license from IHS -,-,- JIS Z*8762 88 i 4933608 0079824 3 0 C O N T E N T S Pages 1 . Scope 1 2 . Symbols and Definitions . 1 2.1 Symbols . 1 2.2 Definitions 3 3 . Principle of the Method of Measurement and Computation . 5 3.1 Principle of the Method of Measurement 5 3.2 Operation of Measurement 5 3.2.1 Introduction 5 3.2.2 Measurement of Differential Pressure 5 3.2.3 Determination of Density 5 3.2.4 Measurement of the Bore of the Contraction Device 6 3.3 Computation of Rate of Flow . 6 3.3.1 Computation of Rate of Flow 6 3.3.2 The Case Where the'Change of the Coefficient of Discharge c or the Flow Coefficient a Dependent on the Reynolds Number Cannot Be Ignored 7 3.4 Uncertainty in Measurement of Rate of Flow 7 3.4.1 Definition of Uncertainty 7 3.4.2 Indication of Uncertainty . 7 3.4.3 Computation of Uncertainty 7 4 . General Requirements for the Measurements 8 4.1 Fluid Contraction Device . 8 4.2 Fluid 8 4.3 Flow Conditions 9 5 . Installation Requirements . 9 5.1 General . 9 5.2 Straight Lengths Required . 9 Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/11/2007 06:32:04 MDTNo reproduction or networking permitted without license from IHS -,-,- Pages 5.3 Straightening Devices 13 5.4 Additional Specific Installation Requirements for Orifice Plates . Nozzles and Venturi Nozzles 13 5.4.1 Circularity of the Pipe 13 5.4.2 Drain Holes and Vent Holes . 14 5.4.3 Location of Contraction Device and Rings . 14 5.4.4 Fixing and Gaskets . 15 5.5 Additional Specific Installation Requirements for Classical Venturi Tubes 15 5.5.1 Circularity of the -Pipe 15 5.5.2 Alignment of the Classical Venturi Tube 16 5.5.3 Drain Holes and Vent Holes . 16 6 . Orifice Plates 16 6.1 General 16 6.2 Structure of Orifice Plate . 16 6.3 Methods of Taking Out Pressure 18 6.3.1 Installation of Pressure Tapping . 18 6.3.2 Construction of Pressure Tapping . 18 6.3.3 Spacing of Pressure Tappings . 21 6.4 Coefficients and Corresponding Uncertainties of Orifice Plates . 22 6.4.1 Limits of Use 22 6.4.2 Coefficients . 23 6.4.3 Uncertainty . 25 6.5 Pressure Loss 25 7 . Nozzle ; . 25 7.1 General . 25 7.2 ISA 1932 Nozzles 25 7.2.1 Profile of ISA 1932 Nozzles . 25 . f 7.22 Pressure Tapping . 28 (ii) Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/11/2007 06:32:04 MDTNo reproduction or networking permitted without license from IHS -,-,- 11 -. c Pages 7.2.3 Coefficients of ISA 1932 Nozzles and Their Uncertainties 28 7.2.4 Pressure Loss 29 7.3 Long Radius Nozzles 29 7.3.1 General . 29 7.3.2 Profile of High-Ratio Nozzle 30 7.3.3 Profile of Low-Ratio Nozzle 31 7.3.4 Pressure Tappings 31 7.3.5 Coefficients of Long-Radius nozzles and Their Uncertainties 31 7.3.6 Pressure Loss . 32 8. Venturi Tubes . 32 8.1 32 8.2 Classical Venturi Tubes 32 8.2.1 Profile of Classical Venturi Tubes 32 8.2.2 Pressure Tappings . , 36 8.2.3 Coefficients of Classical Venturi Tubes and Their Uncertainty. 37 8.2.4 Pressure Loss . 38 8.3 Venturi Nozzles . 38 . . . . . . . . . . . . . . . . . . . . . . . . . . . General . . . . , . . i., . . . . . . . . . . . 8.3.1 Structure of Venturi Nozzles 38 8.3.2 Pressure Tappings 40 8.3.3 Coefficients of Venturi Nozzles and Their uncertainty . 41 8.3.4 Pressure Loss .,e 41 Annex 1. Flow Coefficient (a) of Orifice Plate, Nozzle and Venturi Tube 58 Annex 2. Method for Taking Out the Pressure of Orifice Plate by Means of Flow Contraction Tappings . 72 Annex 3. Discharge Coefficient and Its uncertainty of Classical Venturi Tubes Used Outside the Scope Covered by 8.2.3 (1) of the Body of This Standard 86 (iii) Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/11/2007 06:32:04 MDTNo reproduction or networking permitted without license from IHS -,-,- J I S Z8K8762 88 9 4733608 0079827 7 = U DC 532.57 5.52: 532.57 5.53 JAPANESE INDUSTRIAL STANDARD J I S Measurement of Fluid Flow by Means of Orifice Plates, Nozzles and Venturi Tubes Z 8762-1988 1. Scope the rate of the fluid flow running full in a circular conduit whose. cross section diameter is 50 to 1200 mm by means of the fluid contraction devices. This Japanese Industrial Standard ' specifies the method of measurement of Contraction devices dealt with in this standard are as follows: (1) Orifice plates; (a) Corner tapping orif ice, (b) (c) Flange tapping orifice, D and D/2 tapping orifice, (2) Nozzles; (a) ISA(') 1932 nozzle, Note ( l ) ISA is the abbreviation for “International Federation of the Natio- nal Standardizing Associations“, the body which was successed by ISO. (b) Long radius nozzle, (3) Venturi tubes; (a) Classical venturi tube, (b) Venturi nozzle. 2. Symbols and Definitions 2.1 Symbols The symbols used in this standard are given in Table 1 below. Corresponding International Standard: IS0 5167-Measurement of fluid flow by means of orifice plates, nozzles and Venturi tubes inserted in circular cross-section conduits running f u11 Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/11/2007 06:32:04 MDTNo reproduction or networking permitted without license from IHS -,-,- ' J I S 2*8762 88 m 4733b08 0077828 O m I i 2 Z 8762-1988 Table 1. Symbols C d D e E k 1 L m U X Name of symbols Symbols Xmensions M : mass 2 : length r : time i : temper- ature Coefficient of discharge, C = E Diameter of orifice or throat of primary device at operating conditions . Upstream internal pipediameter (or upstream diameter of a classical venturi tube) at operating conditions Relative uncertainty (relative value) Velocity of approach factor, E= (i-p4)+ Uniform equivalent roughness Pressure tapping spacing Relative pressure tapping spacing, L = Area ratio m=p2 Static pressure of the fluid (absolute pres- sure) Mass rate of flow Volume rate of flow Radius Arithmetical mean deviation from the mean line of the profile Reynolds number Reynolds number referred to D Reynolds number referred to d Temperature of the fluid Mean axial velocity of the fluid in the pipe Acoustic ratio, x = p / p L L L L VL-' T-= M í - ' L3 l - ' L L 6 L T-1 SI Unit m m m m Pa kg/s m8/s m m “C m/s Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/11/2007 06:32:04 MDTNo reproduction or networking permitted without license from IHS -,-,- Symbols a a A P AG e x V 2 P I 9 J I S Z*8762 88 4933608 0079829 2 Table 1. (Continued) Name of symbols Flow coefficient Diameter ratio, ß=d/D Differential pressure Pressure loss Expansibility (expansion) factor Isentropic exponent( ) Dynamic viscosity of the fluid Kinematic viscosity of the fluid, v=dp Relative pressure loss Mass density of the fluid Pressure ratio, I=PJ$ Total angle of the divergent Dimensions M : mass L : length T : ime e : temper- ature ML-1 T -2 ML-1 T -2 ML- T-1 L2 T-1 ML-3 3 Z 8762-1988 SI Unit Pa Pa Pa-s m2/s kg/m3 rad Note ( 2 ) For ideal gases, the ratio of the specific heat capacities and the isentropic exponent have the same values. Remark: Subscript 1 refers to the cross-section at the plane of the upstream pressure tapping. Subscript 2 refers to the cross-section at the plane of the downstream pressure tapping. 2.2 below: Definitions The principal terms used in this standard are defined as given (1) contraction devices The devices which are placed in a pipeline for reducing the cross-sectional area of the conduit (general term of orifice, nozzle and venturi tube). (2) diameter ratio of contraction device divided by the diameter of the pipeline upstream of the contraction device. The bore of the contraction device Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/11/2007 06:32:04 MDTNo reproduction or networking permitted without license from IHS -,-,- ; J I S Z*8762 88 m 4933608 0079830 9 = I I- 4 Z 8762-1988 (3) area ratio of primary device divided by the cross-sectional area of the pipe. The sectional area of the contraction device (4) differential pressure Difference between the static pressure measured by pipe-wall taps, one of which is on the upstream side and the other on the downstream side of contraction device, when there is no variation in gravitational energy between the upstream and downstream taps. (5) pressure ratio The static pressure on the downstream pressure tapping divided by the static pressure on the upstream pressure tapping (absolute - - - pressure), which is given by the following formda: ( 1 ) Pl (6) pressure pipe The pipe for transmitting pressure. (7) differential-pressure gauge The instrument that directly or indirectly indicates the differential pressure transmitted through “the pressure pipe. (8) Reynolds number A value that is determined by the upstream condition of the fluid and the bore diameter of the pipe D or the bore of con- traction device d. (a) Reynolds number referred to D is given as follows: (b) Reynolds number referred to d is given as follows: ( 10) flow coefficient The value defined by the following formula referring to the results from the experiment of flowing incompressible fluid through a pipeline in which a contraction device is installed, . (4) 9m a= Tdzm (il) coefficient of discharge The ratio of the flow coefficient to the veloc- ity of approach factor which is given by the following formula. ( 5 ) c=s . ; (12) expansibility factor The value defined by the following formula, refer- ring to the results of experiment of flowing compressible fluid in a pipe- line in which a contraction device is installed. ( 6 ) m E = %d2J= 4 Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/11/2007 06:32:04 MDTNo reproduction or networking permitted without license from IHS -,-,- ' J I S Z*87b2 88 4933608 0079833 O 5 Z 8762-1988 (13) pressure loss Difference in static pressure between the pressure measured on the upstream side of the. contraction device, at a point free from the influence of approach impact pressure, and that measured on the down- stream side of the contraction device, at a point where static pressure recovery by expansion of the jet is completed. (14) uncertainty The range within which the true value exists in probability of 95 %. (15) arithmetic mean deviation from the mean line solute values of the deviation from the mean line of roughness curve Mean value of the ab- - which is given by the following formula: ( 7 ) R,=+lL I f(X)-h I Such conditions may be expected to exist if the installation conforms to requirements given in clause 5. 2. Even in the case where the installation requirements given in Table 2 and Table 3 or sub-clause 5.3 are not satisfied, this standard is applicable if the flow conditions immediately upstream of the contraction device conform to the following conditions. The ratio of the velocity in axial direction at each point on the cross-section of pipe to the maximum velocity in axial direction at the same section coincides within a range of 2 5 % with the value obtained from the flow free from swirl at the same radius position on the cross-section, located very long straight length of pipe (100 D or more) afterword, of the similar pipe. (a) (b) The swirling angle of the flow at each point on the cross- section in the pipe is limited to 2“ or smaller. (2) The contraction device, flanges and straight parts of pipe shall be lagged over the whole length. the temperature of the fluid, between the inlet of the straight length of the upstream side and the outlet of the straight length of the down- stream, does not exceed the permissible deviation determined as being sufficient for the accuracy of flow measurement. It is, however, unnecessary to lag the pipe when 5.2 Straight Lengths Required The straight lengths given in Table 2 and Table 3 is required to be installed in the upstream side and the downstream side of the contraction divice. shown below: . The straight lengths shall comply with the requirements Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/11/2007 06:32:04 MDTNo reproduction or networking permitted without license from IHS -,-,- 10 Z 8762-1988 To be cylinderical pipe, To be straight by visual inspection. There is no branch connection or valve and the internal surface is clean ranging at least over the length of 10 D at the upstream side of the contraction device and 4 D at the downstream side, and is free from the pitting and deposit. When the straight lengths are longer than the values given for “O % additional uncertainty“ shown in Table 2 and Table 3 (bracketed values in Table 2 and Table 3), there is no need to add any additional uncertain- ty to the uncertainty on the coefficient of discharge. When the upstream or downstream straight lengths are shorter than the “0 % additional uncertainty“ values shown in Table 2 and Table 3 (unbracketed values in Table 2 and Table 3), and longer than the “i 0.5 % additional uncertainty“ values (bracketed values in Table 2 and Table 3), an additional uncertainty of +_ 0.5 % shall be added to the uncertainty on the coefficient of discharge. If the straight lengths are shorter tha