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Long March Instrument (Jinhu) Co., Ltd
venturi flowmeter
NegotiableUpdate on 11/19
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Overview
Introduction: Classic Venturi tube, also known as classical Venturi tube. Commonly referred to as standard Venturi tubes. Compliant with lS05167 or GSfT2624 standards. Used to measure the flow rate of single-phase stable fluids in closed pipelines, commonly used to measure the flow rate of fluids such as air, natural gas, coal gas, water, etc. classic
Product Details
Classic Venturi tube, also known as classical Venturi tube. Commonly referred to as standard Venturi tubes. Compliant with lS05167 or GSfT2624 standards. Used to measure the flow rate of a single-phase stable fluid in a closed pipeline, commonly used for measuring
Measure the flow rate of fluids such as air, natural gas, coal gas, water, etc.
Classic characteristics of the Venturi tube:
Simple structure, durable, and stable performance.
Low pressure loss, saving energy required for fluid transportation.
Within the diameter range of 50-1200, no real flow calibration is required. Beyond this range, reference design and manufacturing can be used. When a higher degree is required, real flow calibration can be performed.
The installation size of the body is relatively long, which is not convenient for transportation and installation of large caliber instruments.
Main technical parameters of the classic Venturi tube:
Nominal diameter (mm): DN50 to DN1200 (~2600)
Nominal pressure (MPa): 0.25 to 4.0 (to 6.3)
Degree of uncertainty: ± 1% to ± 15%
Classic Venturi structure
The axial cross-section of the classic Venturi tube is shown in the above figure. It consists of an inlet cylindrical section A, a conical contraction section B, a cylindrical throat section C, and a conical diffusion section E. The diameter of cylindrical segment A is D, and its length is equal to D;
The contraction segment B is conical and has an angle of 21 °± 1 °; The throat C is a circular cylindrical segment with a diameter of d, and its length is equal to d. The diffusion segment E is conical with a diffusion angle of 7 °~15 °.
① The curvature radius of the elbow is greater than or equal to the pipe diameter.
Note:
1. The length of the small straight pipe section refers to the length between various flow barriers upstream of the classic Venturi tube and the classic Venturi tube. The length of the straight pipe section is from the downstream end of the curved surface near (or only) the elbow or gradually increasing
Measure from the downstream end of the converging and diverging pipes until it reaches the plane of the pressure tapping port upstream of the classical Venturi tube.
2. Column A of each blocking component represents the length value of "zero additional uncertainty".
3. The length value of "0.5% additional uncertainty" in column B of each blocking component.
If the thermometer sleeve or socket is installed upstream of the classic Venturi tube, it must not exceed 0.13D and be set at least 4D upstream of the pressure tap of the Venturi tube.
5. Various flow blocking components or other interfering components (as shown in the table) or density meter sleeves should be placed at least 4 times the throat diameter downstream of the pressure tapping port plane, and should not affect the accuracy of the measurement.
| type | nominal diameter | Throttle aperture ratio β | Reynolds number range | material |
| Rough casting shrinkage section | 100mm≤DN≤800mm | 0.3≤β≤0.75 | 2×105≤Re ≤2×106 | Cast iron or copper |
| Mechanical processing shrinkage section | 50mm≤DN≤250mm | 0.4≤β≤0.75 | 2×105≤Re ≤2×106 | Carbon steel or stainless steel |
| Shrinkage section of rough welded iron plate | 200mm≤DN≤1200mm | 0.4 ≤β ≤0.7 | 2×105≤Re ≤2×106 | Carbon steel or stainless steel |
Classic Venturi structure
The axial cross-section of the classic Venturi tube is shown in the above figure. It consists of an inlet cylindrical section A, a conical contraction section B, a cylindrical throat section C, and a conical diffusion section E. The diameter of cylindrical segment A is D, and its length is equal to D;
The contraction segment B is conical and has an angle of 21 °± 1 °; The throat C is a circular cylindrical segment with a diameter of d, and its length is equal to d. The diffusion segment E is conical with a diffusion angle of 7 °~15 °.
The length of the straight pipe section required by the classic Venturi tube (without flow regulator) (value expressed as a multiple of the pipe diameter D)
| Diameter ratio β | Single 90oelbow① | Two or more 90 on the same plane or different planesoelbow① | The tapered tube changes from 1.33D to D within a length of 2.3D | Gradual expansion tube changes from 0.67D to D within a length of 2.5D | Fully open full bore ball valve or gate valve | |||||
| A | B | A | B | A | B | A | B | A | B | |
| 0.30 | 8 | 3 | 8 | 3 | 4 | 4 | 4 | 4 | 2.5 | 2.5 |
| 0.40 | 8 | 3 | 8 | 3 | 4 | 4 | 4 | 4 | 2.5 | 2.5 |
| 0.50 | 9 | 3 | 10 | 3 | 4 | 4 | 5 | 4 | 3.5 | 2.5 |
| 0.60 | 10 | 3 | 10 | 3 | 4 | 4 | 6 | 4 | 4.5 | 2.5 |
| 0.70 | 14 | 3 | 19 | 3 | 4 | 4 | 7 | 5 | 5.5 | 3.5 |
| 0.75 | 16 | 8 | 22 | 8 | 4 | 4 | 7 | 6 | 5.5 | 3.5 |
① The curvature radius of the elbow is greater than or equal to the pipe diameter.
Note:
1. The length of the small straight pipe section refers to the length between various flow barriers upstream of the classic Venturi tube and the classic Venturi tube. The length of the straight pipe section is from the downstream end of the curved surface near (or only) the elbow or gradually increasing
Measure from the downstream end of the converging and diverging pipes until it reaches the plane of the pressure tapping port upstream of the classical Venturi tube.
2. Column A of each blocking component represents the length value of "zero additional uncertainty".
3. The length value of "0.5% additional uncertainty" in column B of each blocking component.
If the thermometer sleeve or socket is installed upstream of the classic Venturi tube, it must not exceed 0.13D and be set at least 4D upstream of the pressure tap of the Venturi tube.
5. Various flow blocking components or other interfering components (as shown in the table) or density meter sleeves should be placed at least 4 times the throat diameter downstream of the pressure tapping port plane, and should not affect the accuracy of the measurement.
