Filtering classes

In the industrial filtration process usually what is important is that the particles dimension present in the coolant are above a requested value without any questions on: its quantity, the quantity and dimension of the particles smaller than the requested value.

In that way speaking of filter degree, like the size of the suspended solids present in the coolant, is unusefull if at the requested value are not added the maximum quantity of suspended solid for each dimensional class.

The performances of a filtering system should be identified by two values for example 20 µm with 250 p.p.m. of suspended solids.

W.M.T. has made a research, during years, to study and classify the filtering industrial process in order to define the filtering class regarding the operation type, the better type of filter for each operation, the maximum value admitted of suspended solids for each class to grant the maximum quality in working process.

W.M.T. has coded these result in the ST-1584 table

The filter flow rate shall be determined regarding:

  • the process liquid,
  • the filter media permeability.

To determine the data shown in the table the following test condition has to be considered:

  • the sample of the liquid process is be taken on the machine.
  • the table values are the medium one measured on samples taken before and after the filter index.
  • the suspended solids concentration is been determined filtering each sample with calibrated nylon mesh of 5, 10, 20, 40, 60 e 100 µm not sequentially.

The values shown are the medium of 345 filtering system tested for more than one year.

What W.M.T. after these results suggest is: