Pressure cleaning is used for cleaning floors, walls, vessels, containers, open equipment and conveyors, and as a rinsing stage following cleaning and the application of chemicals. In high-pressure cleaning, water is sprayed at the surface to be cleaned at pressures ranging from 15 bars, which is considered to be low pressure, up to 150 bars, which is considered to be high pressure. A pressure of about 40 to 65 bars is also considered relatively high.

Cleaning agents are injected into the water, at moderate temperatures of up to 60° C. An important part of the cleaning action is due to mechanical effects. Pressure cleaning reduces water and chemical consumption compared with mains hoses. It is important to maintain pressure that is both safe and efficient. There is a concern in the food industry about the hygiene implications of over-splash and aerosols associated with the use of high-pressure hoses.

When using high-pressure cleaning, it is important that the correct balance is achieved between the pressure; water volume where the water is sprayed; the water temperature and chemical dosing for each particular application. Inadequate pressure may result in poor cleaning and excessive pressure can increase the risk of damage to surfaces and equipment, and even injury to people.

Effective high-pressure cleaning is helped by having a centralised water ring main available for use. Mobile pressure-cleaning machines require longer downtimes than those supplied from a ring main. Pressure washers installed on the company ring main are costlier, but have relatively short payback period. 

High- and medium-pressure cleaners have the following advantages compared with low-pressure cleaners:

• Water use is lower due to the mechanical cleaning action of the water jet
• Chemical use is lower because heavy soiling is removed by the water jet, and the reduced water volume means there is less of a breeding ground for bacteria