LG series flow measurement throttling device
- Commodity name： LG series flow measurement throttling device
- Product Description
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Overview
The LG series flow measurement throttling device is a primary device of the differential pressure flow meter, which works in conjunction with differential pressure gauges or differential pressure transmitters and display instruments to form a differential pressure flow meter. It has advantages such as simple structure, convenient installation and maintenance, stable performance, and high accuracy. The product complies with national standards GB/T2624.1～4-2006 and international standards ISO5167-1～4-2003 for standard throttling devices, including standard orifice plates, ISA1932 nozzles, long diameter nozzles, and Venturi tubes. It also includes special throttling devices such as 1/4 round orifice plates, double orifice plates, eccentric orifice plates, round hole orifice plates, conical inlet orifice plates, end orifice plates, and double Venturi tubes.
Throttling device model representation method
1. Type
L G □ □ —— □□ □□ □ Flow throttling device Throttling element Pressure tapping method Nominal diameter DN (mm) Nominal pressure PN (MPa) A. Without upstream and downstream straight pipe sections
B. With upstream and downstream straight pipe sections
C. With upstream and downstream straight pipe sections and connection flanges2. Throttling element representation method (see table below)
Code Description Code Description Code Description B Standard orifice plate N Eccentric orifice plate C Long diameter nozzle S Double orifice plate H 1/4 round nozzle L Venturi nozzle Q Round hole orifice plate P ISA1932 nozzle W Classic Venturi tube X Small orifice plate M Small nozzle 3. Pressure tapping method representation method (see table below)
Code Description Code Description H Annular chamber pressure tapping J Diameter distance pressure tapping Z Drilled pressure tapping T Special pressure tapping F Flange pressure tapping 4. Nominal diameter representation method (see table below)
Code 02 03 04 05 06 08 10 12 15 17 20 22 25 Nominal diameter (mm) 25 32 40 50 65 80 100 125 150 175 200 225 250 Code 27 30 32 35 37 40 45 50 60 70 80 90 99 Nominal diameter (mm) 275 300 325 350 375 400 450 500 600 700 800 900 1000 For pipe diameters greater than 1000mm, it is represented as 1/10 of the actual pipe diameter.
5. Nominal pressure representation method (see table below)
Code 00 01 02 03 04 06 10 16 20 25 28 32 40 Nominal Pressure (MPa) 0.6 1.0 1.6 2.5 4.0 6.4 10 16 20 25 28 32 40 6. Upstream and downstream straight pipe section representation method (see table below)
Code Description A Without upstream and downstream straight pipe sections B With upstream and downstream straight pipe sections C With upstream and downstream straight pipe sections and connection flange Technical specifications of throttling devices
Throttling element Model Pressure tapping method Applicable range Adopted standard Nominal diameter
(mm)Nominal Pressure (MPa) Standard orifice plate LGBH Annular chamber pressure tapping 50～400 ≤10 GB/T2624-2006 LGBZ Drilled pressure tapping 400～3000 ≤1.6 GB/T2624-2006 LGBF Flange pressure tapping 50～1000 ≤42 GB/T2624-2006 LGBJ Diameter distance pressure tapping 50～1000 ≤42 GB/T2624-2006 ISA1932 nozzle LGPH Annular chamber pressure tapping 50～400 ≤10 GB/T2624-2006 LGPZ Drilled pressure tapping 400～500 ≤42 GB/T2624-2006 Long diameter nozzle LGCJ Diameter distance pressure tapping 50～630 ≤42 GB/T2624-2006 Classic Venturi tube LGWT Special pressure measurement for 'coarse casting' shrinkage section 100～800 ≤1.6 GB/T2624-2006 LGWT Special pressure measurement for machined shrinkage section 50～250 ≤42 GB/T2624-2006 LGWT Special pressure measurement for coarse welded iron plate shrinkage section 200～1200 ≤42 GB/T2624-2006 Venturi nozzle LGLZ Angle connection pressure measurement 65～500 ≤16 GB/T2624-2006 1/4 round nozzle LGHH Annular chamber pressure tapping 40～400 ≤10 LGHZ Drilled pressure tapping 400～500 ≤10 LGHF Flange pressure tapping 40～500 ≤42 Conical inlet orifice plate LGRH Annular chamber pressure tapping 25～400 ≤10 LGRZ Drilled pressure tapping 400～500 ≤10 Round hole orifice plate LGQH Annular chamber pressure tapping 100～400 ≤10 LGQZ Drilled pressure tapping 400～1000 ≤10 Double orifice plate LGSH Annular chamber pressure tapping 40～100 ≤10 End orifice plate LGDH(Z) Angle connection pressure measurement 25～3000 ≤6.4 Eccentric orifice plate LGNH(Z) Angle connection pressure measurement 100～1000 ≤6.4 Small orifice plate LGXH Annular chamber pressure tapping 12～50 ≤10 GB/T2624-2006 LGXF Flange pressure tapping 12～50 ≤42 GB/T2624-2006 Pitot Venturi LGST Special pressure tapping 200～2000 ≤2.5 Usage conditions of throttling devices
1. Usage conditions of standard throttling elements
Throttling element Usage conditions Features Application scenarios Standard orifice plate Angle connection pressure measurement
d≥12.5mm
50mm≤D≤3000mm
0.20≤β≤0.75
For 0.20≤β≤0.45
ReD≥5000
For β＞0.45 ReD≥10000Simple structure, can ensure certain usage accuracy, easy installation and replacement, wide range of pipeline sizes, can use various materials, low cost, but large permanent pressure loss and easy to clog. Measure clean, non-corrosive gases, liquids, and steam without solid particles. Flange pressure measurement
d≥12.5mm
50mm≤D≤1000mm
0.2≤β≤0.75
ReD≥1260β2DDiameter pressure measurement
d≥12.5mm
50mm≤D≤1000mm
0.2≤β≤0.75
ReD≥1260β2DNozzle ISA
1932
NozzleAngle connection pressure measurement
50mm≤D≤500
0.3≤β≤0.8
For 0.3≤β<0.44
70000≤ReD≤107
For 0.44≤β≤0.8
20000≤ReD≤107Erosion resistance is better than that of orifice plates, its permanent pressure loss is lower than that of orifice plates, but higher than that of Venturi tubes. It is complex to process and expensive. Used for measuring high-pressure superheated steam and other high-speed gas flow, suitable for fluids containing solids. Long
Diameter
Spray
NozzleDiameter pressure measurement
50mm≤D≤630mm
0.20≤β≤0.80
104≤ReD≤107Wen
Qiu
Li
Spray
NozzleAngle connection pressure measurement
65mm≤D≤500mm
d≤50mm
0.316≤β≤0.775
1.5×105≤ReD≤2×106Permanent pressure loss is small, can be used for large flow, and has higher accuracy than orifice plates and nozzles over a wide flow range, but it is large, heavy, difficult to install, and expensive. Suitable for low pressure loss, accurate measurement of clean fluids. Through
Typical Venturi TubeSpecial Pressure Tapping
1. Cast Shrinkage Section
100mm≤D≤800mm 0.3≤β≤0.75
2×105≤ReD≤2×106
2. Machined Shrinkage Section
50mm≤D≤250mm 0.4≤β≤0.75
2×105≤ReD≤1×106
3. Rough Welded Iron Plate Shrinkage Section
200mm≤D≤1200mm 0.4≤β≤0.7
2×105≤ReD≤2×106Note: D in the table is the inner diameter of the pipeline where the throttling device is installed; d is the inner diameter of the throttling component; β is the diameter ratio of the throttling component under working conditions, β=d/D; ReD is the Reynolds number relative to the pipeline.
2. Conditions for Using Non-standard Throttling Devices
Name Usage Conditions Characteristics Application Occasions Eccentric orifice plate 100mm≤D≤1000mm When installed in horizontal pipes, eccentric orifice plates are superior to round orifice plates for fluids containing solid particles, oily water, or gases or steam containing condensate. Suitable for measuring where accuracy requirements are not high, and the medium contains sediment, suspended matter, and bubbles. Round hole orifice plate 100mm≤D≤1000mm
0.32≤β≤0.7
5×103≤ReD≤2×1061/4 round nozzle 40mm≤D≤500mm
0.2≤β≤0.6
2×102≤ReD≤105More complicated to process compared to orifice plates. Suitable for fluids with large particle size and low flow rate, and small Reynolds number. Double orifice plate 50mm≤D≤400mm
0.32≤β≤0.77
3×103≤ReD≤3×105Permanent pressure loss is between that of standard orifice plates and ISA1932 nozzles. Suitable for flow measurement of fluids with small Reynolds numbers or high viscosity. Note: D - Inner diameter of the pipeline where the throttling device is installed;
d - Diameter of the throttling component opening;
β - Diameter ratio of the throttling component under working conditions, β=d/D;
ReD - Reynolds number relative to the pipeline.
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