ECJ EUROPEAN Cleaning Journal

The high-pressure cleaner is the central drive element for many different accessories being used for various applications. For example, it can be a sandblaster to remove graffiti, with telescopic lances for façade or roof cleaning or with injectors and foam lances for foam disinfection. Dirk Niesen, director sales and innovation at R+M de Wit, takes a look at the possibilities.

Water under high pressure is still the optimal and most universal solution for removing dirt from surfaces quickly, gently and efficiently.

The cleaning effect is significantly influenced by the five parameters of pressure or water speed, water quantity, water temperature, added cleaning agents and the nozzles or accessories used.
The parameters water volume and water speed bring the dynamic component into the overall cleaning result. Depending on the cleaning application, typical professional high-pressure cleaning devices work with working pressures from 120 bar.

Higher pressures also increase the ability to loosen dirt and debris or increase cleaning speed. Depending on the application, the amount of water used varies between 10 and over 40 litres per minute. Larger amounts of water produce greater cleaning effects due to ideally larger individual droplets. In addition, a larger amount of water also has a significantly improved rinsing effect, so that dirt is quickly transported away from the surface to be cleaned. Both flow rate and pressure are therefore important parameters for effective cleaning.

Cold water high-pressure cleaners can be used very successfully in many different applications. Generally, cold water is used in applications such as heavy construction equipment cleaning, marine life removal, general maintenance and commercial cleaning, and other areas where grease and oil are not a concern.

When it comes to cleaning applications where you need to disinfect or degrease an area, hot-water pressure washers are ideal. They clean there much faster and more thoroughly than their cold-water counterparts. The reason for this is that the hot water can dissolve the fat instead of just shifting it like cold water does. This results in a much cleaner surface. The hot water is also ideal for areas that require hot water or steam for disinfection - for example food processing plants, pharmaceutical plants and other government-controlled areas.

Counteract bacterial growth

With their integrated heaters, hot water high-pressure cleaners can heat the water from approximately. 12°C to up to 150°C. This enables a reduction in the working pressure, the time required and the amount of cleaning agent to be used. Cleaning with hot water offers a wide range of options for optimising the cleaning process and convincing advantages. With hot-water high-pressure cleaners, the required impulse energy can be significantly reduced for the same cleaning time, which protects the surface to be cleaned.

Surfaces cleaned with hot water dry out faster due to the heat and are therefore available more quickly for further processing or further use. New bacterial growth is only effectively counteracted when all surfaces are completely dry after cleaning. After cleaning with hot water, a significant reduction in germs is detectable. This germ reduction achieved without disinfectants is completely sufficient for many hygiene requirements.

In order to get by with as little energy as possible in the form of water, pressure and temperature, cleaning agents are often used to loosen the dirt. The general rule here is that the longer a cleaning agent in the optimal dosage is in contact with the dirt without drying up, the greater the benefit of the cleaning agent.

As a result, in the last three to five years, foam cleaning applications have almost completely replaced the classic pre-spraying of cleaning agents. Foam is a substance formed by trapping air in liquids forming a sphere. The outer area is a thin film of liquid substance (water/detergent/chemical) that expands to the point where it ruptures. The bubble film carries the cleaning agent and holds it in place for a period of time to act on the contact surface.

The advantages of the foam are obvious. The visibility on the surface to be cleaned prevents repeated application of chemicals by the user. This saves costs, time and reduces the consumption of cleaning agents to the bare minimum. Due to its larger volume, foam can also be applied more easily to the surface uniformly and, especially in the case of large areas, much more quickly than pure liquid. Gels are also usually not very visible.

The biggest advantage of foam is the long contact time on the surface. The foam keeps the active cleaning chemicals on the surface. Slow gliding on vertical surfaces and the successive collapse of the foam bubbles support optimal distribution of the cleaning agent. In addition, detergents bound in foam pollute the ambient air less.

As a result, particularly aggressive cleaning chemicals can be applied much more safely.

New business opportunities

The possible applications are wise-ranging. In addition to applications in vehicle washing or the food industry that have been established for decades, the development of environmentally friendly cleaning agents is also creating more and more new application options that open up new business areas for service providers.

Applications such as cleaning the coated inner walls of road tunnels mean double safety, for example. On the one hand when carrying out the cleaning work, which can be done from inside the vehicle with the help of specially equipped road service vehicles during operation, and also during subsequent operation, where the walls, which are now brightly reflecting again and freed from dust and traffic film, ensure greater safety through brightness.

Another example is the professional cleaning of house façades and roofs. There are a variety of cleaning options for cleaning roof panels, tiles, stones, shingles or other covering materials, both from the floor and from the roof or scaffolding. The cleaning of thatched roofs is particularly special in this area of application.

Environmentally responsible

A thatched roof has an average lifespan of around 30 years. But the thatched roofs are susceptible to fungi, such as the white rot fungus, moss, algae and other substances. Over time, a layer of algae and moss develops on the thatched roofs, which first makes the reed roof unsightly and ultimately destroys it.

To remove moss and clean thatched roofs, work without pressure washing the roof and with a fully biological, environmentally friendly agent. The foaming agent is applied to the roof from the garden surrounding the house using an injector on the high-pressure cleaner and a long-cast foam lance on the high-pressure gun.

The agent is both a cleaner and a green film remover and is harmless to humans and animals. It acts on the thatched roof in connection with solar radiation.

After the agent has been applied to the thatched roof, it starts to work immediately. Mosses, fungi and algae die, the reed roof brightens and the more sun, the faster it goes. The process is completed after between one and three weeks.

It is not necessary to rinse off the cleaning agent, as this gradually rains down.

The last and probably most important parameter for efficient and effective cleaning is the optimal nozzle technology and the accessories suitable for the cleaning task. Here it is crucial to find the nozzle size that is precisely matched to the performance of the high-pressure cleaner, as well as the spray angle that is suitable for the application. It should be noted that, in general, smaller spray angles transmit greater impact energy to the surface to be cleaned due to better efficiency and larger droplets than wide spray angles, which can wet a larger surface with the same spray distance.

In daily practice, many high-pressure cleaning devices often have nozzles that are not properly designed and, above all, have been washed out as a result of intensive use. As a result, up to 50 per cent of the possible cleaning performance is often wasted. This means that with an optimally designed, high-quality and not worn-out nozzle, you could theoretically work with a device that is only half as powerful to achieve the same cleaning effect.

Impact energy benefits

Rotor nozzles combine the impact energy benefits of a small spray angle with the area coverage of a flat fan nozzle. With a rotor nozzle, a rotating point jet runs at around 4,000 to 6,000 revolutions per minute. The spinning water jet hits the surface area from multiple angles, quickly breaking down caked-on dirt and grime. As a result, rotary nozzles can cut cleaning time by half or more. A few larger droplets create much higher impact in a certain distance than many smaller droplets.

This is mainly due to air resistance of the droplets and the breakup of the jet. Due to the shape of the jet former in the rotor, the inner shape of the nozzle and the spinning speed and spray angle, the breakup of the jet occurs comparably later than on usual nozzles. This means, that drops can “hide” in the slipstream of droplets flying ahead and thus lose less speed and impact.

Central drive unit

However, the use of flat jet or rotary nozzles is only the initial possible use of the high-pressure cleaner. Due to the large number of available and constantly evolving accessories, the actual high-pressure cleaner will remain a central, universal drive unit in professional cleaning technology.
The high-pressure cleaner can be used as a drive for:
• Wet sandblasters to remove graffiti or paint
• Telescopic lances for façade or roof cleaning
• Tank cleaning heads for cleaning the inside of IBCs, food containers, garbage cans, tank trucks or cisterns
• Rotating floor cleaners for cleaning large areas like car parks, pedestrian areas or chewing-gum removal
• Injectors and foam lances for professional foam cleaning and disinfection
• Hot water jet device for removing weeds without the use of biocides
• Sewer hoses and jets for cleaning pipes and drains
• Vehicle wash setups for cars, trucks, trains or air planes
• Sludge pumps to empty ponds, pools or cellars
• Cutting nozzles for tree debarking or digging in hydro excavating applications
• Large scale fogging devices for disinfection, cooling or dust suppression.

In all these applications, the focus is on economy, environmental compatibility, energy efficiency and ergonomics. This is achieved through the use of professional accessories.

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