Pressure Nozzles: Applications, Advantages and Limits

Single-component pressure nozzles are also often referred to simply as pressure nozzles. They are among the most frequently used nozzle types. This type of nozzle is usually inexpensive and can also be operated reliably.

For certain applications, it is also advantageous that no additional energy sources have to be used for the atomisation process. In contrast to twin-flow nozzles or pneumatic atomizers, the use of compressed air is not necessary.

Typical applications of pressure nozzles

This nozzle design can be found in a variety of technical applications. It is obvious that the pressure nozzles have to provide very special spray properties depending on the intended application. This has to be taken into account when selecting the right product!

Here are some typical examples for the use of pressure nozzles.

  • Washing and cleaning operations.

  • Fire fighting.

  • Cooling and cleaning of gases.

  • Surface cooling.

  • Combustion of fuels.

  • Cutting of materials.

  • Agriculture and plant protection.

  • Special applications in medical technology.

  • Painting of surfaces with the airless method.

  • Fine atomization with high pressure differences.

Pressure nozzles in car wash systems
Agriculture and plant protection

The simplest design of the pressure nozzle is the so-called hole nozzle.

The simple hole nozzle is one of the jet-forming pressure nozzles.

Conceptually, this nozzle type is very simple. The liquid to be atomized is accelerated in the bore. If the flow velocity is sufficiently high, the jet disintegrates into droplets.

This nozzle has no additional elements like changes of cross-section or diversions for flow. This pressure nozzle usually produces only coarse drops. If the viscosity of the liquid is high, this nozzle will fail very quickly.

For this reason, it is rarely used in process engineering. With special mounting parts, this nozzle is used for spraying liquids when coarse droplets and a high momentum are desired.

Pressure nozzles producing lamellae are used to produce finer droplets.

The conical nozzle is one of the pressure nozzles forming lamellae.

It is a preliminary stage to the hollow cone pressure nozzle.

It delivers much finer droplets than simple hole nozzles. These nozzle types do not produce a compact liquid jet, but a liquid lamella.

In addition, the spray angle can be adjusted within certain limits. Thin liquid lamellae mean fine droplet diameters.

Therefore, lamellar nozzles are preferably used where a fine spray is desired. And at the same time pressure nozzles are needed.

When choosing a pressure nozzle, it is therefore necessary to clarify in a first step which requirements must be placed on the spray. This concerns not only the drop size distribution, but also spray angle and drop momentum. In addition, the required flow rate range must of course be taken into account!

This unfortunately is overlooked from time to time! The rheological properties of the liquid to be atomized must be known. Viscosity plays a particularly important role here. If pressure nozzles fail, this can almost always be traced back to a too high viscosity in connection with a too low volume flow rate.

The result: If the viscosity is higher than allowed, the desired volume flow rate is no longer achieved at a given pressure differential Δp. This also causes the spray to be very poor or, in extreme cases, the nozzle even fails completely.

There is a great danger with respect to pressure nozzles!

There is a special danger lurking here!

In the catalogues of most nozzle manufacturers, the volume flow rate at pressure nozzles is specified as a function of the pressure.

These values are almost always valid only for water as the liquid to be atomized.

If another fluid whose viscosity or density differs from water has to be atomized, these values are no longer correct!

Of course, this can have considerable consequences!

While spraying water or other low-viscosity liquids, the pressure nozzles work excellently, they may fail during your application. Simply because the viscosity of your liquid is higher. In addition, the density of the liquid also plays a role!

For this reason, we strongly recommend that you do not simply select and use a pressure nozzle from a manufacturer's catalogue. Especially not if you want to fog small volume flows and the viscosity of your liquid differs from water. If suspensions are to be atomized, detailed consultation is absolutely essential! In addition to the special flow behaviour of suspensions, additional aspects of nozzle clogging must also be taken into account!

Please let us advise you in detail. After clarification of all relevant questions, we procure the appropriate pressure nozzle for you or recommend alternative atomizers!

An important note on drop size distributions at these nozzles

At first glance, pressure nozzles appear quite simple and trivial. Nevertheless, not only the flow through the pressure nozzles is sometimes very complicated from a fluidic point of view. In addition, the disintegration of liquid jets and lamellas is turbulently overlaid and influenced by the surrounding atmosphere. Therefore, it is still impossible to reliably calculate characteristic drop diameters such as the mean diameter D50 or the Sauter diameter D32 reliably in advance. Complete drop size distributions anyway not!

For this reason, we offer the measurement of drop size distributions and drop velocities as part of joint projects or as a separate service. If you need this information about the spray characteristics, we are of course your partner as well.

Do you have any questions about pressure nozzles? Please contact us!

You want to use pressure nozzles? Do you need advice or would you like to have nozzles delivered?

Then please discuss your requirements with our engineers beforehand.

Please use our hotline

+49 (0)251 - 2 87 99 53 - 0

or simply use our enquiry form.