Basic Principles

The fluid filled in the pipeline, when it flows through the throttling element inside the pipeline, will form a local contraction at the throttling element, resulting in an increase in flow velocity and a decrease in static pressure, thus creating a pressure difference before and after the throttling element. The larger the fluid flow rate, the greater the pressure difference generated, which can be used to measure the flow rate. This measurement method is based on the flow continuity equation (law of conservation of mass) and Bernoulli equation (law of conservation of energy). The magnitude of pressure difference is not only related to the flow rate but also to many other factors, such as when the form of throttling device or the physical properties of the fluid in the pipeline (density, viscosity) are different, the pressure difference generated at the same flow rate is also different.

structural classification

1. Standard orifice plate, also known as concentric right angled edge orifice plate, is a thin plate processed into a circular concentric shape with sharp right angled edges. The upstream edge of the orifice plate opening should be a sharp right angle. There are three pressure tapping methods for standard orifice plates: corner joint, flange, and D-D/2 pressure tapping. To measure flow from either direction, a symmetrical orifice plate can be used, with both edges of the orifice conforming to the characteristics of the upstream edge of a right angled orifice plate, and the entire thickness of the orifice plate not exceeding the thickness of the orifice plate.
Specification: DN20~3000mm

2. Standard nozzle
Features: It has high temperature and high pressure resistance, impact resistance, long service life, large measurement range, and high measurement accuracy.
Application: Suitable for measuring high temperature and high pressure steam flow, heat network pipelines, and fluid flow with high flow rates.
There are two structural forms: ISA1932 nozzle and long diameter nozzle.
a. The upstream surface of the ISA1932 nozzle consists of a contraction section determined by a plane perpendicular to the axis and two arcs with a circular profile, a cylindrical throat, and a groove. The pressure measurement method of ISA1932 nozzle is only corner connection pressure measurement.
b. The upstream surface of a long diameter nozzle consists of a plane perpendicular to the axis, a contracting section with a 1/4 elliptical shape, a cylindrical throat, and possibly grooves or oblique angles. The pressure measurement method for long diameter nozzles is only D-D/2 pressure measurement.
Specification: DN ＜ 1000mm

3. Classic Venturi tube Venturi nozzle
Features: It has the characteristics of low pressure loss, high measurement accuracy, short length of front and rear pipes, and long service life. Used as a flow device for water and gas.
Specification: 50 ＜ DN ＜ 3500mm

4. Double Venturi tube

Features: It has the characteristics of low pressure loss and stable measurement, suitable for measuring air volume in circular or rectangular pipelines.

Specification: DN200~4000mm

5. Circular orifice plate, circular orifice plate, eccentric orifice plate

Features: It has the characteristics of being difficult to block and having shorter straight pipes at the front and back. Suitable for measuring gases and liquids containing dust and impurities, such as blast furnace gas and coke oven gas.

Specification: DN-3500

6. Double orifice plate 1/4 round nozzle

Features: Suitable for various flow rates under low Reynolds number conditions, widely used for measuring liquids and gases with low flow rates.

Specification: DN25-600

7. Anuba flowmeter

Features: It has the characteristics of low pressure loss and easy installation. Suitable for flow measurement of circular and rectangular pipelines.

Specification: PN ＜ 10DN50~4000

8. Flow restriction orifice plate

Features: It has the characteristics of flow limitation and pressure reduction, suitable for limiting flow or reducing pressure.

Specification: DN10~1000

9. Single and double chamber balanced containers

Features: Suitable for height measurement of liquid and steam drum water levels.

Specification: PN<32