In the documents that ship with the machine we have added a filter element reference card. It is a single sheet that brings onto one table the filter element numbers this machine uses, how many of each are fitted, and which housing each one goes into, and it is kept with the manual. The card solves a very specific problem: when the elements are changed, the operator does not have to dig through the manual or try to remember which one was fitted last time.
Where element changes go wrong on site
The element numbers themselves are not long: coarse filter elements 150-250-50 and 110-250-50, the secondary filter element 110-400-20, and fine filter elements 110-600-5 and 150-500-5. Copy one digit wrong or read one line wrong and the error does not necessarily show itself after fitting. Fitted the wrong way round, fitted as the wrong type, or with the labels on two housings read the wrong way round, the machine still runs and the pressure gauge may not alarm, yet the filtration accuracy and the element life have both been affected.
Such mistakes are hidden and their cost arrives late. With the wrong element fitted the machine still delivers oil and the oil really is clean; what has changed is how the burden is shared between the elements, and the problem only shows up at the next change or when the pressure drop is out of line.
A second use of the card is often underrated: it lets the element change be handed to someone who does not know the machine. The operator may have changed between two maintenance periods, and the element numbers explain nothing on their own. Without a reference card, everyone has to ask again what is fitted, how many and where. Information that could have been fixed once is most likely to go wrong when it is passed on verbally.
Which fields the card carries
| Field | What it records |
|---|---|
| Element number | Coarse filter elements 150-250-50 and 110-250-50; secondary filter element 110-400-20; fine filter elements 110-600-5 and 150-500-5 |
| Quantity | How many of that type are fitted on this machine |
| Position | Which housing it goes into, and where that housing stands on the frame |
| Flow direction and fitting | Inlet and outlet orientation, and whether it is fitted in parallel |
| Pressure drop reference | The pressure alarm value for a fine filter element, 0.35 MPa |
The field most easily left out is the position. The standard configuration of the ZYD-100 is five 150-500-5 fine filter elements in parallel, and the five housings stand in a row on the frame with the same number plate on the two that are next to each other, so a small change in where the operator stands is enough to read them the wrong way round. Marking the position on the card does more than writing the number alone.
The card also carries the pressure drop reference. The pressure alarm value for a fine filter element is 0.35 MPa, and with that figure on the card there is something to judge against after a change: the newly fitted elements should show a pressure drop close to the level before the change at the same flow, and a figure that is clearly higher points at something going wrong during fitting rather than at the elements themselves.
How to check the work afterwards
- Check the number and the position of each element against the card, and confirm that nothing is fitted as the wrong type or the wrong way round.
- Record the total pressure drop once the elements are fitted, and compare it with the reading from before the change.
- For parallel fine filter elements, measure each element on its own once, to establish a baseline for each of them.
- Write the time of the change, the numbers and the pressure drop into the log, so that the next change can be compared directly.
- Keep one of the removed elements on site as a reference, and dispose of the rest under the site procedure.
The card itself settles no technical question. It only gathers information that was spread across different chapters of the manual and across site experience onto one sheet that can be followed. It is also used in the handover training, which is more practical than asking the operator to learn the specification table.
Put everything that has to be checked on one sheet, and changing the elements becomes following a list rather than relying on memory.
