High pressure cleaning issues

10th of December 2012
High pressure cleaning issues

Ducts, solar panels, restaurant hoods, graffiti-covered walls - which tasks represent the biggest challenges for high pressure cleaning machine manufacturers? And how are the machines on the market adapted to cope with difficult applications?

High pressure cleaning is an extremely effective method of removing all types of substances from a wide range of surfaces. It can be used for removing paint, rubber, sealants, chewing gum and other soiling from walls, roofs, car parks, pavements, vehicles, ducts and vents.

Variables such as water pressure, water temperature and the type of nozzle used can adapt this cleaning method to suit many different applications. But what are the most difficult challenges for high pressure cleaning systems? And are there any surfaces that cannot be cleaned using this process?

Graffiti removal represents one of the biggest challenges according to Andrew Caddick, Nilfisk-Advance’s senior group product manager for professional high pressure washers.  “This is due to the very wide range of surfaces on which graffiti appears today,” he said. “While removing graffiti from basic concrete walls that have no inherent value is a fairly simple process, graffiti removal from soft stone, monuments or glass require very specific treatment to avoid damaging the surface.

“Hard cleaning methods such as sandblasting have been replaced by ‘soft blasting’ – the combination of low aggressive powders and water which has a much less abrasive effect.”

He says an example of such a product is Armex, which is based on bicarbonate of soda. “This is sufficiently abrasive to remove graffiti from glass, vehicle surfaces and soft stone, but it is also ecologically friendly, soluble and easier to dispose of than other materials,” claims Caddick. “But care must be taken even here to carefully flush the stone surface afterwards to prevent the penetration of salts.”

He says restaurant hoods also provide challenges for high pressure cleaners. “The difficulty here arises from access to the area to be cleaned and evacuation of the water afterwards,” he said. “Also since restaurant hoods are typically covered in grease and fats, this application should really be solved by hot water. However the use of diesel-fired heating systems is not permitted in the food industry which often means that restaurant cooker hoods have to be cleaned with cold water.”

This can be solved by using an electrically-heated pressure washer or by feeding several cold water machines with pre-heated water, says Caddick. “Failing this, the use of food industry standard detergents is required.”

Solar panels can also be difficult to clean, says Caddick. “Most suppliers of solar panels do not recommend high pressure washers for this application to avoid damaging sensitive surfaces,” he said. “When we are called upon for this task, however, we use a high pressure washer on the lowest pressure mode and utilise more water and softer brushes to clean dust and light dirt from the solar panel surfaces. We would also usually recommend the use of pure water to avoid leaving stains.”

When it comes to cleaning ducts and vents, says Caddick, the main problem lies in how to gain access to such hard-to-reach areas. “The task is not difficult in itself since it is simply a question of cleaning away greases and fats, and a good detergent and hot water will handle this,” he said. “The hard part is gaining access to the surface area.”

Biggest challenge

He adds that accessories such as pipe cleaning equipment, tank cleaners and long or curved lances will all aid the duct and vent-cleaning process. “Other items such as filters from restaurant hoods can often be removed and cleaned outside,” he said.

Marketing manager of Dibo Cleaning Systems Katrien Jacobs agrees that graffiti removal remains one of the biggest challenges for high pressure cleaning companies. “Today there is not only the cleaning task itself to consider, there is also the environment,” she said. Dibo offers a system with built-in vacuum for removing graffiti and collecting residual water.

“For one of our Dutch customers we built such a system into a truck along with two large 3,000 litre tanks,” said Jacobs. “This allowed the customer to clean for a whole day using the clear water in one tank and collecting the residual water in the other.”

She says pipework such as sewer systems can be difficult to clean due to access problems. “However there are special lances, hoses and nozzles available for this,” she said. “Depending on the specific task it is sometimes better to use less water at higher temperature whereas at other times you need more water at lower pressure.”

According to Jacobs the temperature, pressure and water throughput of Dibo high pressure washers can be easily adjusted. “This makes our systems suitable for a wide range of jobs – particularly since it is also possible to connect them to a variety of accessories and specialist equipment.”

Dibo’s research and development department often helps customers to come up with the right solution for their requirements, says Jacobs. “For example, we recently built a high pressure unit designed for cleaning the hold of a ship – the unit had to be placed in the engine room,” she said.

The water was fed from the engine room to the ship’s hold via a network of pipes, and four operators were then able to simultaneously clean the hold using a set of special hose reels.

According to environmental matters public relations officer for Karcher David Wickel, pressure washers are not always the best solution for removing graffiti. “The highest possible pressure is not a critical factor when removing graffiti from walls, and in fact on sensitive surfaces the best result is often achieved by low pressure particle blasting,” he said. “This involves blowing a blasting agent on to the surface at relatively low pressures to gently remove the soiling.”

Expand with accessories

He says that depending on the robustness of the surface the blasting agent used may be glass powder, basalt, lime powder or nutshell granules of different particle sizes. “In order to bind the dust that this method generates, water can be added to the airstream provided that the surface can tolerate it without suffering damage,” he adds.

Wickel claims that accessories can be used to almost infinitely expand a pressure washer’s area of use. “These accessories can be anything from patio and terrace cleaners to foam nozzles for cleaning casks, plus pipe-cleaning hoses and a wide range of different washing brushes and spray lances,” he said.

So if high pressure cleaning is so versatile, can it be used for any cleaning task? Dibo’s Katrien Jacobs says no. “Some surfaces are impossible to clean using high pressure,” she said. “If you have to clean a soft surface such as Styrofoam isolation, for example, this cannot be achieved using high pressure without damaging the surface.”

Nilfisk-Advance’s Andrew Caddick believes that most areas can be cleaned using high pressure in principle – provided that care is taken. “Textile surfaces are typically not cleaned using this type of system because the drying is the main problem,” he said.

“The question is more whether or not high pressure washers are the best solution. With a high pressure washer you could, for example, clean the floor of a supermarket but water recovery would be a problem. Therefore a scrubber dryer would be a better solution for this type of indoor application.”

And Karcher’s David Wickel concurs. “Any surface can be cleaned using a pressure washer in principle, but one needs to consider the particular cleaning problem,” he said. “Should I use high or reduced pressure? Water flow? Hot water or cold water? Asking these questions makes it possible to deduce the most economical solution – and this may be a different cleaning solution to that of pressure washing.”


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