When a spare filter element that has been in the store for months or longer is finally fitted, some people fit it as it is and others scrap the whole element. The first approach may produce a leak or an abnormal pressure drop a few days later; the second pays for a problem that has not been confirmed. This article explains which parts of an element storage affects and what should be checked before the element goes into the machine.
Storage changes two parts of the element
The first part is the sealing element. The sealing ring between the end cap of the element and the filter housing is an elastomer, and a dry storage environment, large temperature swings or a long time under compression will all change its recovery and its surface condition. The typical symptoms are oil seeping from the mating face even though the end cap has been tightened, or a pressure drop reading that takes a long time to settle after fitting.
The second part is the medium itself. A medium kept compressed for a long time in the dry state may show a collapse of the fibre structure or local sticking; if the element was stored with oily residue, the oil oxidises and gums up in the cold and seals a share of the pores. An element left open in a damp store takes up moisture, and when oil is fed back in afterwards new problems appear at the oil and water interface.
Which cases can go straight into the machine
Neither the storage condition nor the way it is handled is a simple yes or no, and working through the classification below is more reliable. It also makes it easier to explain to the shift team why one element can be used and another has to be replaced. The judgement is based on the state that can actually be observed, not on the purchase date or the number of days in store, which are not easy to verify.
| Storage condition | Judgement | How to handle it |
|---|---|---|
| Original packaging intact, unopened, stored in a dry place | Can go into the machine | Put into service through the normal wetting routine |
| Packaging opened but the element looks clean and there is no gum | Usable with checks | Check the sealing ring and the surface of the medium item by item, then wet and put into service |
| Oxidised oil residue or gum on the element surface | Not recommended to fit as it is | Clean it and inspect the medium first, and replace it if it cannot be restored |
| Stored in a damp place, packaging already damaged | Replacement recommended | After long contact with moisture the performance of the medium is hard to assess |
| Stored for an unusually long time or beyond the warranty period | Decided on the result of the checks and the tests | The actual inspection result governs, storage time alone does not decide it |
The checklist before fitting
- Take the element out and smell the medium; if there is a clear sour or burnt smell, do not use it.
- Run your eye round the sealing ring at the end face of the medium and look for cracks, indentation, distortion and permanent compression marks.
- Bend the edge of the medium gently and watch for embrittlement, powdering or pieces breaking off.
- Check the model and the specification of the element and confirm they match the position it came from: coarse 150-250-50 and 110-250-50, second stage 110-400-20, fine 110-600-5 and 150-500-5.
- Check that the inside of the housing is clean, with no residual liquid, rust or fragments of the old sealing ring; the dirt inside the housing damages the new element as well.
- After fitting, feed the oil in at low speed following the wetting sequence, record the initial pressure drop and compare it with the reading from before the change.
The storage conditions are part of the management
Storing an element is not finished once it is put in the store. The humidity, the temperature and the way the elements are stacked all affect the condition of the sealing ring and the medium, and keeping first in first out properly in use is far less trouble than deciding afterwards whether an element is still good, and it cuts the waste caused by inconsistent judgements.
Putting the storage time, the inspection result and the issue record of the spare elements into one ledger answers the questions that purchasing, the store and the site each have: how many are left, which ones are near the end of their life and who checked this one. When all three look at the same sheet, the responsibility has somewhere to land.
Storing an element is not finished once it is in the store; the life of the sealing ring and the medium starts counting on the day it goes in.
