Overview
Flow nozzles are a type of differential pressure flow element used for measuring the flow rate of liquids, gases, or steam. The long-diameter flow nozzle is especially suitable for high-pressure or high-temperature conditions such as main steam lines, feedwater systems, and desuperheating water circuits in power plants.
It is known for its excellent mechanical strength, wide measurement range, high accuracy, shock resistance, and low pressure loss, making it ideal for demanding industrial environments.
Key Features
🔧 Nominal Diameter (DN): 50 mm to 630 mm
🧪 Nominal Pressure (PN): ≤ 32 MPa
🔢 Orifice Ratio (β): 0.2 to 0.8
🔁 Reynolds Number Range: 10,000 to 10,000,000
🎯 Measurement Accuracy: Class 0.5 or Class 1
🌀 Low Permanent Pressure Loss compared to orifice plates
🛠️ Long Service Life with stable structural integrity under high stress
Structure
The flow nozzle consists of three main sections:
Inlet Converging Section (A) – Smoothly accelerates the flow
Cylindrical Throat (B) – Maintains a constant cross-section to create differential pressure
Downstream End Plane (C) – Guides flow downstream and helps pressure recovery
Pressure Tapping Method: D–D/2 (corner tapping and half diameter)
Types of Long-Diameter Nozzles
| Type | β Range | Application |
|---|---|---|
| High-Ratio Nozzle | 0.25 ≤ β ≤ 0.8 | Wide flow range and higher flow capacity |
| Low-Ratio Nozzle | 0.25 ≤ β ≤ 0.5 | Better suited for lower velocity flow measurement |
📌 When β is between 0.25 and 0.5, both types are applicable depending on installation preferences and system dynamics.
Applications
🚢 Thermal and Nuclear Power Plants
💧 Boiler Feedwater and Main Steam Systems
🏭 High-Temperature and High-Pressure Process Lines
🔬 Scientific Flow Testing Platforms
Advantages Over Orifice Plates
Higher strength, suitable for harsh conditions
Better long-term stability with less wear
Lower pressure loss for energy-efficient operation