2.2.8 Water- jetting cleaning and hydro-jetting
Two systems have already proven to be very good, which differ from the power required to generate kinetic energy.
Water-jetting cleaning
In these devices, water is taken via a pump to the ejection nozzle, and, if desired, it is also heated there. The following values are common:
- Operating pressures 25 – 170 b adjustable
- Temperatures 30 – 155° C adjustable
- Water quantities up to 2,000 l/h
In general, cleaning and inhibitor admixtures (admixtures to achieve a certain reaction) are fed.
It can be advantageous to spray on the cleaner at higher concentrations at first and to use the high-pressure jet only after sufficient exposure time.
These devices are used for cleaning surfaces and degreasing, but not much for derusting and roughening.
The main application concentrates on removing oily, fatty and wet impurities as well as of water-soluble contaminations at numerous objects, in particular of machine and steel construction, in the field of car mechanics and railway engineering; it is also used for preparing hot-galvanized surfaces. If coating shall be maintained wholly or partially temperature and cleaning agent have to be taken into account accordingly.
Hydro-jetting
The following values are common:
- Operating pressures 250 – 2,000 b
- Flow volumes 1,000 – 6,000 b
These systems can be used both for cutting, parting as well as for cleaning and roughening surfaces.
The high mass fraction is particularly advantageous resulting in a hard jet so that soft or elastic contaminations can be blasted considerably quicker than with other techniques. The difficult manual handling of the nozzles lances due to the high reactive power is a big disadvantage.
The high water quantities avoid, of course, the generation of dust. The disposal at building sites is disadvantageous because toxic substances can be transported through the water into the environment or the sewerage system.
At both methods, small amounts of abrasive can be added by injection to increase performance.