The filter element is the consumable that is most easily reduced to a bare number: site purchasing usually writes down that a certain number of fine filter elements are required, and only when the goods arrive is it found that the connection does not match or the accuracy grade is wrong, so they will not fit and have to be returned and replaced. A filter element has no model to look up like a complete machine does; it states its specification in a string of numbers, and one digit missing from that string changes what it means.
The five element specifications most commonly used in the range
There are two coarse filter element grades, 150-250-50 and 110-250-50; the secondary filter element is 110-400-20; and there are two fine filter element grades, 110-600-5 and 150-500-5. Reading the last figure against the accuracy grade, the five are clear: the last figure 50 corresponds to coarse filtration, 20 to the secondary stage and 5 to fine filtration. The figures in front carry dimensions such as the outer diameter and the length, and different combinations within the same grade mean different connection sizes, so they cannot replace each other.
All three grades appear in the standard configuration of the TYA-50: one 110-250-50 coarse filter element, one 110-400-20 secondary filter element and one 110-600-5 fine filter element, chained into one filtration chain. The fine filter element of the ZYD-100 is 150-500-5, with 5 in parallel as the standard configuration. Both are fine filter elements, but 110-600-5 and 150-500-5 have different connection sizes, so one does not fit the other machine; this has to be stated clearly when the order is placed.
That difference has practical consequences. If the two machines are each fitted with one kind of fine filter element, the old elements removed from them are not interchangeable and the spare stock has to be maintained separately for each machine; had the same specification been ordered from the start, one element could be rotated between the two machines and both the number of stock lines and the working capital tied up in them would come down. Standardising the specification is therefore worth settling at the first purchase rather than each machine buying its own.
Writing the specification on the order also has a detail that is easily overlooked: whether it names the element itself or the position it is to be fitted in. On the same machine the elements in different positions do not work under the same pressure conditions, and the element on the oil inlet side carries a contaminant load that is not in the same order of magnitude as the one on the oil outlet side. If the position is stated together with the model, spare parts management will not end up mixing up two elements that are meant for opposite purposes.
There are two supply forms, do not state the quantity only
The 150-500-5 fine filter element can be supplied as a set of 5 or as single pieces. The standard configuration of the ZYD-100 is 5 in parallel, and the purpose of putting several in parallel is to extend the element replacement interval, not to change the accuracy; that matches the machine data. When ordering stock, if only the number of elements is written down and not the supply form, the form that arrives will often not match the installation position, and whether it has to be opened and repacked or can go straight in ends up being settled on site.
The three items that must be written out in full on the order
| Must be stated | Example of how to write it | The consequence of leaving it out |
|---|---|---|
| Complete specification | 150-500-5 | Only "fine filter element" is written and the connection size does not match |
| Accuracy grade | 5 μm fine filtration | It does not match the filtration accuracy required of the machine |
| Supply form | Set of 5 or single pieces | The form that arrives does not match the position |
The specification of the 150-500-5 fine filter element carries two further parameters that can be written down at the same time: the filter medium is imported HPM deep-layer filter material with an outer stainless steel mesh, and the differential pressure alarm value of 0.35 MPa is the electrical alarm setting matched to the machine. If this data is not written down at the selection stage it has to be looked up again at the point where the element condition is judged.
How to check on arrival
- Check the complete specification on the packaging against the order, word for word
- Confirm whether the supply form is a set of 5 or single pieces
- Measure the length and the end face connection size on one or two elements taken at random
- Register the specification received in the equipment records and copy it straight for the next element order
The model of a filter element is its parameters written into its name; stated in full it is an ordinary item of purchasing, stated short it is a return and replacement of something that will not fit; that string of numbers is worth reading out over the phone.