High pressure cleaner, one of the most common cleaning machines of today, possesses flexible methods of cleaning and has the most varied applications. Flexible, as it can clean components, cars, machines, equipment and buildings from the inside or outside, vertically or horizontally.
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 the mechanical dirt removing action, there are three more factors that play important roles: temperature, cleaning agent and reaction time.
High Pressure (HP) water jet machines can be adapted as required and its special nozzles and accessories are available for each cleaning requirement. Besides being flexible, HPs have many features, including –
• An adjustable combination of pressure and water flow rate can remove even the most stubborn dirt
• The high-pressure jet reaches even into those places where access is difficult, and it also adapts to irregular surfaces
• As a result of the reduced cross sectional area of the nozzle, the water consumption is considerably lower compared to working with a normal water hose (up to 80%)
• A wide range of accessories is available from leading suppliers and only the right combination of the high pressure washer and the accessory guarantees the best performance
• The mechanical cleaning process is an environment-friendly alternative compared with using chemicals applied with manuals tools, and in many cases it achieves much better results within a shorter time
Buying HP 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. 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 HP cleaner.
If it is 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 estate car. Machines are offered with 230 V/50 Hz, 3-Phase 400 V/50 Hz and with combustion engines either petrol or diesel. 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 HP 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 hold 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 speeded 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 water-cooled motor, the water is preheated and this also helps save energy.
Hot-water units are effective
• Oil, grease and other types of soiling are removed much more easily and quickly. In some cases, there is no need for detergent at all
• In the steam mode (boiler temperatures from 80 to 155°C) sensitive surfaces can be cleaned at a reduced pressure. Pathogenic micro-organisms are effectively reduced before subsequent disinfection is carried out
• As the steam mode works with reduced water quantity, it is also suitable for sandstone, mineral plaster and other porous natural materials which are hygroscopic
• The surfaces cleaned heat up and dry faster
Compared with cold-water units, cleaning times can be reduced up to 40% in practice by using water heated to 80°C, and the results are better. It is obvious that, with time savings of this kind, a hot-water unit quickly pays for itself.
Burner technology
When buying a hot-water high-pressure cleaner it is important to make sure it is a low-emission unit. Upright burners with continuous ignition are particularly effective in achieving a high degree of efficiency, as no fuel residuals can settle at the bottom, and there is less condensation. Many units can be run on environment friendly biological diesel fuel, if required. There are electrically heated HP cleaners with no emissions for special applications in wash rooms/WCs and in the pharma, food and beverage industry.
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 butts. An integral fine-mesh filter retains dirt particles to protect the pump from damage.
The water temperature can normally be varied between 20 and 155°C to suit the application and save energy. Many stains can be easily removed at temperatures of about 60°C. In this case modern units can be permanently set to the so-called Eco mode in order to reduce fuel consumption by up to 20%.
Brass and stainless steel for a long service life
Low-speed four-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, if thermal problems, dry run or sub- and overvoltage occur. 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 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. If the high-pressure cleaner has an on-board hose reel, the hose can be easily wound up so it is stored perfectly and also protected from being accidentally run over or other damage.
Ergonomics
The trigger gun should be comfortable to hold and require minimum 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 area 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.
The heart of the matter – nozzles
Basically, the pressure impact breaks up and loosens the layer of dirt, thus producing the desired cleaning effect. The bigger, faster and more concentrated the impact of the water droplets on the surface, the better the cleaning result. The factors involved in this process are nozzle pressure, water flow rate, the geometry and spray angle of the jet. The factors depend essentially on the shape and size of the nozzle orifice. Narrowing the flow ports converts pressure into kinetic energy. The force of impact decreases as the distance between the nozzle and object being cleaned increases; at a distance of 30cm, it is only one hundredth of its initial value. Depending on type of surface and degree of soiling, the spraying distance should be no greater than 10 to 30cm.
There are three different jet patterns, i.e. fan, pencil and rotary jets. The fan jet achieves high area coverage: Water emerges from the nozzle at a spray angle of up to 45° to create a broad jet. This type of jet is also used for applying detergents and disinfectants.
The concentrated pencil jet, on the other hand, achieves a high impact pressure and very good mechanical dirt removal. Therefore heavily soiled areas are best cleaned with pencil-jet nozzles. The working width and area performance, however, are relatively small because of the narrow spray angle.
The so-called rotary nozzle combines the cleaning power of a pencil jet with the higher area coverage of a fan jet. The rotary nozzle’s pencil jet, which rotates at high speed and the linear movement of the spray lance, produces a wide spray pattern that uniformly covers the surface to be cleaned. The rotary nozzle achieves an area coverage which is ten times greater than that of conventional pencil-jet nozzles and is therefore ideally suited for heavily soiled surfaces which are insensitive to pressure.
A combination of several nozzle types is also possible. There are triple nozzles which allow the user to work alternatively with a fan or pencil jet without having to change the nozzle, and to add detergent in the low-pressure mode.
The power nozzle (right) with its special nozzle geometry achieves an impact pressure which is about 40% higher than that of a conventional nozzle.
Spray patterns of fan jet, pencil jet and rotary jet (right). The rotary nozzle combines the area coverage of a fan jet with the cleaning power of a solid pencil jet (centre).
On the whole, HP cleaning, like mechanical cleaning in general, is increasingly gaining significance in industrial operations in India. There are two reasons in particular for this. Firstly, the increasingly complicated and hence more sensitive machines need to be protected from dirt which is becoming more and more time consuming and costly and secondly, staff-intensive cleaning work needs to be streamlined. There is an array of cleaning problems that simply cannot be resolved economically without high-pressure cleaning. This applies in particular for operations where hygiene is the top priority, so in the pharmaceutical industry and the food industry, for example.
HP cleaners today are used in Indian industry for a very wide range of purposes but mainly for machine cleaning and production plant equipment cleaning as two typical fields of application.
But also in areas outside of production, for example kitchens, sanitary facilities and vehicle fleets, HP cleaners are being used for many different jobs time and again.
Hitesh Mathur
Marketing Manager
Kärcher Cleaning Systems Pvt Ltd