author
Bobby Brown
Post 2016-12-14
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Overview

  • About Flow: Measured in LPM, flow is influenced by pressure in a nonlinear relationship.
  • Flow Distribution: Can appear as mound-shaped, plateau, or donut-shaped, affected by pressure and angle.
  • Key Considerations: Flow distribution changes with pressure, theoretical models may not fully align with reality, and both angle and flow impact distribution.

Contents

Flow and its distribution play critical roles in industries and applications involving fluids. This article aims to succinctly explain the characteristics of flow and its distribution, providing key insights and visual aids to ensure a rapid and thorough understanding of the subject, laying the groundwork for further exploration.


1. About Flow

( 1 ) Unit

We often hear about LPM, which stands for liters per minute. Below are some commonly used flow rate units and their applications:

1. Liter/Minute (L/min): Also known as LPM, frequently used to measure liquid flow rates, such as in water treatment equipment and the delivery rate of liquids in medical devices.
2. Liter/Hour (L/h): Used for measuring longer-term liquid flow, like in the chemical industry.
3. Cubic Meter/Minute (m³/min): Used for large-scale liquid or gas flow in industrial systems.
4. Cubic Meter/Hour (m³/h): Describes large flows over time, like in municipal water supply.
5. Cubic Foot/Minute (ft³/min): Measures gas flow in HVAC and industrial piping.
6. Cubic Foot/Hour (ft³/h): Long-term gas flow measurement in distribution systems.
7. Gallon (US)/Minute (gal (US)/min): Common in US water systems.
8. Gallon (UK)/Minute (gal (UK)/min): Used in the UK for liquid flow measurements.
9. Gallon (US)/Hour (gal (US)/h): Measures long-term water flow in agriculture.
10. Gallon (UK)/Hour (gal (UK)/h): Used in the UK for long-term liquid flow measurements.

For flow rate unit calculation, visit Mathematical Formulas for Flow
For quick flow unit conversions, visit online flow converter.

( 2 ) Characteristics

  • Higher pressure increases flow.
  • The relationship between flow and pressure is not linear.
  • For instance, the flow from a nozzle at 8kg/cm^2 is not double that at 4kg/cm^2.

2. Flow Distribution

( 1 ) Mound-shaped: More in the middle, less on the sides.

Mound-shaped: More in the middle, less on the sides.
The spray volume is greatest in the middle of the spray pattern and gradually decreases towards the edges, forming a mountain-shaped distribution curve. 
This "mountain" flow distribution nozzle provides the highest impact force, making it ideal for applications requiring concentrated impact, such as cleaning surface dirt. However, due to insufficient coverage at the edges, it is not suitable for applications requiring even coating. 
To improve edge coverage, the nozzle spacing can be reduced, allowing the spray patterns of adjacent nozzles to overlap, thus improving overall coverage.

( 2 ) Plateau: Similar to mound-shaped with a flat top.

Plateau: Similar to mound-shaped with a flat top.
The spray maintains an even and higher flow in the middle, with relatively lower flow at the edges, forming a plateau-like distribution. This pattern is suitable for applications requiring uniform coverage over a large area, such as coating and chemical treatments, providing consistent coverage. However, edge flow may still be insufficient.

( 3 ) Donut-shaped: Less in the middle, more on the sides.

Donut-shaped: Less in the middle, more on the sides.
The spray volume is greatest at the edges of the spray pattern, with relatively less in the center, forming a ring or donut-shaped distribution. 
This pattern is ideal for applications where avoiding excessive wetting of the central area is crucial, such as in precision spraying or specific chemical reactions. 
It is important to adjust the spray angle and distance to ensure that the edge areas do not become overly concentrated.

3. Three Things to Know About Flow

  • Flow distribution often changes with pressure.
  • There is a discrepancy between perfect and real-world scenarios.
  • The angle and flow rate affect the achievable distribution.
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