High pressure cleaners can be used for the most varied applications because their water jet can be adapted as required.  No other method of cleaning is so flexible: Items and equipment can be cleaned on the inside or outside, horizontally or vertically, be it buildings, vehicles or machinery. But flexibility is not the only advantage of this cleaning method:

• By a suitable combination of pressure and water flow rate, even stubborn dirt can be removed.
• The high pressure jet reaches even into those places where access is difficult, and also adapts to irregular surfaces.
• Dirt and germs are not spread because the soiled surfaces are not actually touched by hand.
• As a result of the reduced cross sectional area of the nozzle, water consumption is considerably lower compared to working with a normal water hose. Cleaning with a high pressure cleaner can save up to 3000 litres of water per hour compared to a regular hose pipe.
• The mechanical cleaning process is an environmentally friendly alternative to using chemicals, and in many cases it achieves much better results within a shorter time.

What is the basis of the high pressure water jet's cleaning action?
The water applied at high velocity to a dirty surface generates a high impact pressure, which loosens the adhesion between the dirt particles and the surface.  Apart from this mechanical dirt removing action, there are three more factors that play important roles: Temperature, cleaning agent, reaction time.

What criteria have to be considered when buying a high pressure cleaner?

Anyone wanting to buy a high pressure washer has a vast number of units to choose from.  Leading manufacturers offer up to 60 models, in three different performance classes, for the most varied cleaning tasks.  The following general rule applies: Heavy duty units are suitable for cleaning large objects and construction machinery as well as for agricultural applications.  Those who have to clean machinery, vehicles or factory premises in a fixed location on a daily basis, usually select a versatile medium duty high pressure cleaner.

If its necessary to work at different locations or the machine is to be used only occasionally for light cleaning work, the best choice would be a comparatively low priced entry level model.  Mobile high pressure cleaners should preferably be lightweight and compact enough to fit into an light delivery vehicle.  Many machines require a 230V supply and can be plugged in practically anywhere.  Upright units with large wheels and an adjustable push handle can easily be moved over all types of terrain, including uneven ground and steps, like a cart.

The performance of a high pressure cleaner depends primarily on the pressure and water delivery rate of the pump.  When comparing models, many users focus on the maximum achievable pressure, and thus the dirt removing effect.  In many cases, however, the water volume and its flushing action has a much greater influence on the cleaning result.  This factor is particularly important in those cases where large quantities of dirt have to be shifted from machinery or floors, e.g. in the construction industry and in agriculture.

Entry level models in the cold water high pressure cleaner line operate at a defined pressure.  With most units, however, the pressure can be adjusted within a predefined range.  The adjustment can be made either on the unit or – more conveniently – directly on the trigger gun.  The latter method allows the operator to react flexibly to changing surfaces, which are not all of the same consistency.

In many cases, dirt can be reliably removed with a cold water high pressure cleaner.  If necessary, the cleaning process may be sped up or improved by using detergents.  The detergent quantity can be set to the required minimum and added via a metering valve far more accurately than by hand.  Contrary to manual dosing, the risk of over-dosing with a metering valve is minimized.  This avoids unnecessary consumption of detergent and reduces costs.  Units with built in detergent tank have a convenient level indicator.  Most cold water units can be used with feed water at a temperature of 60°C, which enhances the cleaning effect. On models with a watercooled motor, the water is preheated and this helps save energy. 

Another important aspect is the required power supply.  Compact units can usually be connected to standard AC power outlets.  Heavy duty units, however, normally require a 400V, three-phase power supply.  A diesel or petrol powered unit with a water tank is the answer for total independence from water and power supplies.  Most high pressure cleaners can pick up water from external reservoirs such as ponds and water reservoirs. An integral fine mesh filter retains dirt particles to protect the pump from damage.

An important criterion when choosing a new machine is its useful service life.  In high quality pumps, the cylinder head and components through which water flows are made of corrosion proof brass.  Stainless steel valves are another quality mark.  High quality pistons are also made of stainless steel or ceramic material or protected by ceramic sleeves.

Low speed 4-pole motors have a particularly long service life.  Compared to air-cooled motors, those cooled with feed-water do not overheat even in high ambient temperatures.  An electronic motor monitoring system comprising automatic shutdown, low fuel cut out and scale inhibitor also contributes to a longer service life.  In the case of overload, for example, or if the trigger gun is not activated for a certain time, the automatic shutdown protects the motor and pump unit, because water is otherwise pumped in a closed circuit which eventually leads to signs of wear.

Reinforced and abrasion resistant high pressure hoses are particularly durable and can be subjected to heavy loads.  They are mounted in an anti twist rotary coupling in the trigger gun for easy handling.

Ergonomics is a further important factor when using a high pressure cleaner: The trigger gun should be comfortable to hold and require a minimum of effort to operate.  On very user friendly trigger guns, pressure and water flow can be adjusted directly on the handle.  A pivot-mounted spray lance, which is angled at its front end allows the user to get into corners and other areas that are difficult to reach.  The bend counteracts the kickback forces to a certain extent and makes the lance easy to hold during high pressure cleaning.  It is convenient and saves time if the spray lance and nozzle can be changed without the need for tools.