H-type insertable Venturi flow meter

H-type insertable Venturi flow meter

The classic Venturi flow meter is also known as the classical Venturi tube. It is commonly referred to as the standard Venturi tube. It conforms to the ISO 5167 or GS/T 2624 standards. It is used to measure the flow rate of single-phase, steady fluids in closed pipelines, and is often used to measure the flow rate of fluids such as air, natural gas, coal gas, and water.

Classic Venturi flow meter

Overview of Classic Venturi Flowmeters
The classic Venturi tube is designed and manufactured according to the national standard GB/T2624-93 and calibrated according to the verification procedure JJG640-94. Among standard throttling devices, it requires the shortest upstream and downstream straight pipe sections, has the lowest pressure loss, stable performance, and is easy to maintain. Due to its accurate calculation and low energy consumption, it has been widely used in the petroleum, chemical, power, and metallurgical industries.

Applicable Range of Classic Venturi Flowmeters

1. Nominal Diameter: 50mm ≤ DN ≤ 1200mm (Calibration required for diameters outside this range)
Rough-cast contraction section: 100mm ≤ DN ≤ 800mm
Machined contraction section: 50mm ≤ DN ≤ 250mm
Rough-welded steel plate contraction section: 200mm ≤ DN ≤ 1200mm

2. Throttling Orifice Ratio β: 0.3 ≤ β ≤ 0.75
Rough-cast contraction section: 0.3 ≤ β ≤ 0.75
Machined contraction section: 0.4 ≤ β ≤ 0.75
Rough-welded steel plate contraction section: 0.4 ≤ β ≤ 0.7

3. Reynolds Number Range: 2 × 10⁵ ≤ ReD ≤ 2 × 10⁶
Rough-cast contraction section: 2 × 10⁵ ≤ ReD ≤ 2 × 10⁶
Machined contraction section: 2 × 10⁵ ≤ ReD ≤ 2 × 10⁶
Rough-welded steel plate contraction section: 2 × 10⁵ ≤ ReD ≤ 2 × 10⁶

4. Accuracy Class: Class 1

Features of Classic Venturi Flowmeters:

The classic Venturi tube has a simple structure, is durable, and has stable performance.
The classic Venturi tube has low pressure loss, saving energy required for fluid transportation.
The classic Venturi tube does not require actual flow calibration within the diameter range of 50-1200mm. For diameters outside this range, it can be designed and manufactured accordingly. Actual flow calibration can be performed when higher accuracy is required.

The body has a relatively long installation dimension, which may be inconvenient for transportation and installation of large-diameter instruments. Classic Venturi Flow Meter Technical

Specifications:

Nominal Diameter (mm): DN50 - DN1200 (~2600)
Nominal Pressure (MPa): 0.25 - 4.0 (~6.3)
Accuracy (Uncertainty): ±0.1% - ±1.5%

Classic Venturi flow meter structural design

The axial cross-section of a classic Venturi tube is shown in the figure above. It consists of an inlet cylindrical section A, a conical converging section B, a cylindrical throat C, and a conical diverging section E. The diameter of the cylindrical section A is D, and its length is equal to D; the converging section B is conical with an angle of 21°±1°; the throat C is cylindrical with a diameter d, and its length is equal to d; the diverging section E is conical with a diffusion angle of 7°–15°.
The converging section of the classic Venturi tube comes in three forms: rough-cast converging section, machined converging section, and roughly welded sheet metal converging section.
The upstream pressure tap and throat pressure tap of the classic Venturi tube are made into several (no less than 4) individual wall pressure taps, connected by a pressure averaging ring. When d ≥ 33.3 mm, the diameter of the throat pressure tap is 4–10 mm, and the diameter of the upstream pressure tap should not be greater than 0.1D; when d ≤ 33.3 mm, the diameter of the throat pressure tap is 0.1d–0.13d, and the diameter of the upstream pressure tap is 0.1d–0.1D.

Venturi tube flow meter selection:

Venturi tube installation schematic diagram

Certificate  Approved