In addition to the physical parameters of the water washing systems monitored daily in order to ensure the maximum final cleaning result, it is important for a company to carefully choose the type of detergent by evaluating the concentration levels.
The choice of detergent and its concentration are the key to process stability and the constancy of high-quality cleaning results.
During the washing phases of the metal parts, the detergent interacts with the parts contamination, it is slowly consumed and the concentration drops with a gradually deterioration effect on the quality of the entire cleaning process.
The dirt residues removed from the metal parts will accumulate in the cleaning solution and will continue to consume detergent.
It is therefore essential that the washing machine has means to:
- Measure detergent concentration in order to prevent excessive fluctuation of the values;
- Remove accumulating contamination from the aqueous detergent.
Along with the issue of cleaning quality there is the issue of life time economy of the entire cleaning cycle in terms of equipment, energy, consumables and labor.
How to measure detergent concentration?
Based on the chemical characteristics of the contamination and of the base material, different types of detergents can be selected.
The measurement of the detergent concentration should be carried out taking into account the following values:
- CONDUCTIVITY: as a correlation between a set concentration and the actual concentration..It is an indirect measure subject to fluctuation not only in relation to the concentration of remaining detergent but also on the basis of the type and degree of contamination accumulated in the detergent solution;
- PH, as a measure of alkalinity of the solution;
- SURFACE TENSION: as a measure of the surfactants present in the solution. These represent the “key ingredient” for the choice of detergents since they facilitate the penetration of the aqueous detergent between the contamination and the base material;
- CUSTOMIZED TITRATION: as a measure of the presence of other essential ingredients.
Of these methods the measuring of surface tension is to be considered as the best when it is necessary to measure the level of effectiveness of the detergent.
How to extract contaminants from the aqueous cleaning solution ?
The residues of dirt and contaminants extracted from the detergent in a water washing system can be:
- Large-size solids, floating, sinking or suspended;
- Small-size contaminants suspended or dissolved in water;
- Fats and oils, emulsified or floating.
The residues of dirt and floating solid contaminants can be eliminated through a skim conveyor that acts on the surface, discharging the waste into a special container.
The dirt residues that have ended up on the bottom of the tank containing the detergent solution can be extracted by means of an automatic sludge removal system of drag conveyor scraping the bottom of the tank; the collected waste is then thrown into special containers.
As to suspended solids, the choice of the detergent cleaning process is made on the basis of gravity and the size of the particles to be separated: usually companies in our sector propose the centrifuge method or the installation of a dedicated filtering system that filters the detergent solution.
Dissolved contaminants, slightly contaminated alkaline aqueous solutions and rinse waters can be treated by means of: Evaporation
Floating oils and greases can be separataed by means of skimmers or the continuous pouring into fluid separators that operate based on the difference in density of the two fluids.
Finally, in the case of emulsified oils, ultra filtering systems are effective.
Life time economy of your parts cleaning systems & operations
In addition to the quality and economic issues raised above, there are two other elements that have a great impact on the life-time economy of the water based machine:
- WATER CONSUMPTION: Recirculating water-based cleaning systems are always more economical than non-recirculating ones. The low temperatures during the washing cycle reduce evaporation losses and therefore the consumption of water in addition to the energy needed to heat it up.
- WASTE WATER DISPOSAL: All the above features will help to extend the tank life. Each tank change involves a production stop, maintenance labor for tank clean-out and disposal cost of waste water.
- ENERGY CONSUMPTION: All the issues rose in water consumption have an equal impact on energy consumption.
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