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We have seen how important it is to size the filter plates and the machine according to the type of process, after carrying out the appropriate laboratory tests to determine the fundamental parameters.
At this point, I would like to emphasize a parameter that is often (deliberately or not) overlooked or not adequately addressed, but which can cause serious problems in the practical field, namely the chemical compatibility of the filter plates and the thermal shock in the plates!
I have a temperature filtration process (i.e., with a high temperature, which can even be from 60 to 90°C), I have done laboratory tests for the choice of cloths, I have chosen the correct plates with the increased thickness of the core, I took the first quality Italian ones in virgin Polypropylene, I performed the insulation of the pipes and I also installed the high-pressure washing trolley to keep the performance of the filter cloths high.
So, on paper everything is ok, it seems that all the checks have been done.
Nevertheless, the filter plates break, crack and the machine does not go under pressure.
How is that?
Suggestion:
Have you checked the temperature of the water used to wash the cloth at high pressure?
What is most problematic for plates, and for plastics in general, is thermal shock.
A temperature variation of about 20°C is recommended to avoid crystallization of the plastic materials.
If the process is at high temperature, the high-pressure washing must also be carried out at high temperature (considering a maximum variation of 20°C).
It is clear that if I wash after 8 hours and the temperature of the plates has decreased and stabilized around 25°C, I can also wash with water at room temperature.
But are you really in control of the temperature?
Are you sure that users of the machine wait for this time and let the plates cool down gradually?
Or do you think instead that the frenetic way of working characteristic of the plants has the better of the real time necessary?
Asking yourself these questions during the design phase can save the life of the plates which could otherwise be irreversibly damaged.
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Similar problems exist for the chemical compatibility of the plates with respect to the material being filtered.
It is very important to make sure that there is compatibility between the material of the plates and that to be filtered, in fact a joint action of high temperature and chemical aggressiveness can be fatal for the pack of plates.
This is the reason why you should always check this data and find out what other materials you can use for the plate pack (nylon, PVDF, etc…)