Technical aspects of air nozzles

What you should keep in mind when planning

Different compressed air nozzles are required depending on the application and ambient or operating conditions. With its wide range of air nozzles, Lechler offers the optimum nozzle solution for every task. The following criteria are helpful in selecting the right air nozzles.

Technische Aspekte von Druckluftdüsen

Criteria for the nozzle selection

Impact area and spray pattern
Impact area and spray pattern
Spray depth
Spray depth
Spray distance
Spray distance
Pressure
Pressure
Behavior with temperature
Behavior with temperature
Blowing force
Blowing force
Noise level
Noise level
Air consumption
Air consumption
Materials
Materials
Abrasion
Abrasion
Spray pattern of air nozzles

Spray pattern of air nozzles

Air is also discharged at a specific angle. However, this is not comparable with that of liquids.

Air expands when it is discharged from the nozzle orifice, which leads to the expansion of the jet. The spray angle is normally approx. 20°.

Innovatives Düsendesign der Lechler Mehrkanaldüse

Innovative nozzle design

Conventional air nozzles:

  • Air is blown through a narrow gap
  • Turbulence results
  • Loud hissing noises

Lechler multi-channel nozzle:

  • Several flow-optimized air channels
  • Reduced turbulence
  • Uniform, targeted and powerful air flow
  • Reduced noise development
  • Reduced air consumption

Relationship between standard and operating flow rate

  • Standard flow rate:
    Unit quantity of gas at 101,325 Pa and 273.15 K
  • Operating flow rate:
    Flow rate under actual operating conditions


Exact calculation:

p: Absolute pressure (atmosphere + system pressure = 1.013 bar + ps)
T: Absolute temperature (273.15 K + TMedium)

 

Figure to the left: Operating and standard flow rate at 298 K (+25° C).
Relationship between standard and operating flow rate at different pressures and constant temperatures.

Standard volume flow and operating volume flow

The term „standard volume flow“ refers to a unit quantity of a gas based on a standard reference. These standard conditions are used in nozzle technology, process engineering and other areas to compare gases on the basis of quantity information. If reference is made to standard volume flows in relation to nozzle technology, Lechler always bases its values on DIN EN ISO 1343.

In contrast, the term „operating volume flow“ describes the volume of the corresponding gas under the actual operating/application conditions. Since these normally diff“er from the standard conditions, pressure and temperature must always be clearly defined. If an operating volume is delivered in a certain time, this results in the operating volume flow.

Gases

The output of gases (e.g. air) is fundamentally di“fferent to the output of liquids. Gases are compressible fluids, whereas liquids are considered as incompressible fluids. Gases can be supplied with practically all nozzles that can also be used for atomizing liquids. However, due to the compressibility and lower density of gases, gas jets cannot be formed in the same way as with liquids.

Compressibility behaviour Compressibility behaviour: Water (left), air (right)

Gases tend to generate a significantly increased noise level under certain conditions (pressure and nozzle design). The development of multichannel nozzles with specially shaped nozzle orifices makes it possible to considerably reduce the turbulence in the nozzle that causes noise. In addition, this nozzle design increases blowing force while at the same time reducing air consumption. The speeds of gases can be very high under certain conditions. If a specific pressure diff“erence is applied to a nozzle, speeds of approx. 320 m/s can often occur in the smallest cross section. This speed can even increase shortly after the gas leaves the nozzle.

Representation of the speed curve of outflowing air Representation of the speed curve of outflowing air

Recognized safety – Approval requirements fulfilled

The regulation (EC) No. 1935/2004

The regulation (EC) No. 1935/2004: Regulation of the European Parliament for general safety requirements to all food and beverage contact materials.

OSHA

OSHA (Occupational Safety and Health Administration): The US federal authority of accidents at work.

Recognized safety – Approval requirements fulfilled

FDA anerkannt

FDA

The U.S. Food & Drug Administration. Many Lechler nozzles meet the requirements of the FDA.

EG 1935/2004 anerkannt

The regulation (EC) No. 1935/2004

The regulation (EC) No. 1935/ 2004 of the European Parliament regulates general safety requirements to all food and beverage contact materials. Various Lechler nozzles are designed for food contact.

OSHA anerkannt

OSHA

The Occupational Safety and Health Administration (OSHA) is a US federal authority for the prevention of accidents at work. Numerous Lechler compressed air nozzles contribute to safety and health protection at the workplace.

Air nozzles: Efficiency and range of products

Efficiency of air nozzles

Can you hear anything? No? That's how quiet productivity can be achieved – even with air nozzles. To avoid unpleasant hissing noises with air nozzles, Lechler has developed special air nozzles that are quiet and economical in air consumption. Air nozzles

Lechler product range of air nozzles

Lechler compressed air nozzles are available in two basic versions: flat fan nozzles and as solid stream nozzles – depending on whether a flat or a round, concentrated air spray is required. Air nozzles