ECJ EUROPEAN Cleaning Journal

High pressure cleaners can be used for many cleaning tasks - among them is professional abrasive blasting. This brings with it new business opportunities, writes RM Suttner for ECJ.

The high pressure cleaning device is the universal platform for a wide variety of cleaning tasks. In order to open up new fields of application of the device and to recoup the investment in a high pressure cleaner as quickly as possible, a maximum utilization by the device should be aimed for. This succeeds in particular, if new services can be offered with the device in a simple way. One such service is professional abrasive blasting.

Abrasive blasting is known as a number of other different names such as wet blasting, media blasting, vapour blasting, slurry blasting and dustless blasting. These are all terms used to describe this form of surface preparation which is different to sandblasting.

Wet abrasive blasting works by abrasive added into a high pressure water jet with high velocity. This drastically increases the mass and impact energy, while reducing the amount of dust that regular sandblasting would produce.

Remove stubborn material

Wet abrasive blasting works on the same principal. By adjusting the ‘false air-intake’ at the suction pipe the amount of abrasive material and water in the mixture allows the operator to remove stubborn surface material or carefully remove surface material from delicate surfaces.

Main advantages of wet blasting are that it’s a much faster process. You can easily paint strip a vehicle in under two hours depending on the surface material. Water encapsulates the abrasive material and dirt, which minimises the amount of dust produced. You can use any kind of abrasive material for the best possible surface finish as long it is not sticking to itself at the multi-phase flow process in the suction pipe and hose.

Water prevents friction and unlike sandblasting, the wet blasting method will not warp metal through the production of heat from friction, however the pressure from the blast nozzle could warp metal that does not have sufficient support structures in place which is why care is need in blasting certain surface types.

By use of rust inhibitor in both the blasting procedure and the wash down at the end which decontaminates metal leaving a clean, chloride free paint ready surface for approximately 72 hours. Priming the surface area as soon as possible after the blasting process to further prevent flash rusting is highly recommended. The rust inhibitor might be injected by a high pressure stainless steel injector right at the outlet of the pressure washer.

Sandblasting and wet abrasive blasting are different because wet blasting uses water where as sandblasting doesn’t. Wet blasting requires water which is added to the blasting process.

Wet abrasive blasting, also known as dustless blasting, uses three elements being water, air and abrasive to remove contaminants from surface substrates. The type of finish you require on the substrate determines the type of blasting media that will need to be used for your specific project.

Wet abrasive blasting also significantly lowers dust emissions due to the element of water being added to the process. By suppressing the ambient dust we are able to cause minimal disruption to those around us.

Abrasive media is encapsulated in water which immediately falls to the ground. In fact wet blasting eliminates up to 92 per cent of the dust that is caused by the sandblasting process.

Sandblasting or dry blasting does not use water which significantly increases the amount of dust particles that remain suspended in the air. It is also more dangerous than the wet blasting process and usually requires a special license due to the small particles that are produced from the process. Dry blasting or sand blasting also produces a lot more friction on metal surfaces which can cause stretching and warping of metal surfaces.

Even though wet blasting is a better form of blasting, sandblasting does have its place in certain industries. Metal surfaces such as oil tankers require sandblasting, however wet blasting can be used on any type of surface substrate and by adding certain additives it is possible to control things such as flash rusting.

What Is dustless blasting?

Dustless blasting is wet abrasive blasting. They are exactly the same thing.However when we talk about dustless blaster you need to understand that there is no such thing as ‘dustless blasting‘ or dust free blasting.

There is research that has shown that the most effective vapour blasting system suppresses no more than 92 per cent of dust produced by dry blasting.

Dustless blasting is a term used to cleverly trick the customer into thinking that this process is dust free however any wet blasting process does leave some sort of a mess. Even though the wet blasting process may not create plumes of dust it leaves a mess on the ground because the water that encapsulates the abrasive media.

This wet blasting process causes the dust that would initially be suspended in the air if using the sandblasting process to fall to the ground. By laying out groundsheets we can easily clean up most of the mess that is left behind.

Gardens can be hosed down as the abrasive media used is completely eco friendly, however it’s the surface substrate profile that is the concern as that can contaminate waterways and land.

The accident prevention regulations of the Employer’s Liability Insurance Association regarding “the use of high pressure cleaner” (BGV D15) and “tasks with liquid jets” (BGV 26) prescribe that adequate eye and face protection have to be worn in case of an operating pressure of 25 bar and more.

Varied granules

Modern machines provide perfect abrasion and cleaning results in combination with the most varied sandblasting granules. Thanks to their stainless steel bodies, modern sandblasters feature utmost pressure resistance up to a continuous operating pressure of 500 bar.

Usually three symmetrical high pressure nozzles in the blasting head provide for a flow of the blasting agent without any deflections. This is how wear of the ceramic diffuser nozzle is reduced to a minimum and pulse energy of the blasting agent is used optimally.

Sandblasters are suitable for dust-free blasting of the following solids with a grain size ranging from 0.2 to 1.5 mm:
• Mineral blasting agent (sand) removal of rust from metals or of old coatings and paintings. Cleaning and grinding of concrete surfaces. Varnish removal
• Sodium carbonate (water-soluble) cleaning of sensitive surfaces such as aluminium, glass, plastics, stainless steel
• Slag (fine) for cleaning of sandstone or brick as well as removal of graffiti from dark surfaces
• Slag (coarse) removal of rust from metals or of old coatings and paintings. cleaning and grinding of concrete surfaces
• Glass beads for cleaning of copper and bronze as well as polishing of stainless steel
• Glass powder for cleaning of stainless steel and natural stone or for removal of graffiti from light surfaces.

Long hose

Supplied double suction pipes can be set continuously and thus enable perfect metering of the amount of blasting agent and thanks to the different nozzle sizes, the blasting head can be adjusted to the performance of the device and to the sensitiveness of the surface structure.

The blasting agent hose could be extended to 10 metres without suffering any considerable performance loss. In this case, the height difference to overcome should not exceed two metres.
The backflow of water into the blasting agent hose is prevented efficiently by the geometry inside the blasting head. Bonding of the blasting agent in the blasting head is thus almost excluded.

rm-suttner.com