A five-layer sintered wire mesh element is often ordered by micron rating alone, then fails for a reason the rating never described: the element was backwashed at a differential pressure it was not built for, or cleaned with a method that moved the filtration layer out of alignment. This guide covers what the five layers actually do, what the laminate withstands, and how to clean it without losing the rating.
What each of the five layers does
The laminate is not five identical screens stacked together. Each layer has a job, and the sequence is what gives the element both a precise rating and a high collapse strength.
| Layer | Typical mesh | Function |
|---|---|---|
| 1 – protective | 100 mesh | Shields the filtration layer from coarse debris arriving on the face |
| 2 – filtration | Varies with the rating | Sets the micron rating and the bubble point. The only layer that changes between grades |
| 3 – dispersion | 100 mesh | Spreads flow across the filtration layer so the whole face is used |
| 4 – support | 12 x 64 Dutch weave | Carries the pressure load |
| 5 – reinforcement | 12 x 64 Dutch weave, crossed | Added at 90 degrees to layer 4 to stop the laminate warping under differential pressure |
Layers 1 and 3 protect the fine layer from both sides, layer 2 sets the rating, and layers 4 and 5 make the element rigid. Because the filtration layer sits inside the structure rather than on the surface, the element tolerates handling, installation and pressure cycling that a plain woven cloth of the same rating would not survive.
Structure codes and what they hold
The filtration layer decides the rating; the two Dutch-weave layers decide the pressure capability. The table below is the standard production range, published with the bubble point that verifies each grade.
| Structure code | Filtration layer (mesh) | Nominal rating (um) | Thickness (mm) | Air permeability (L/min.cm2) | Bubble point (mm H2O) |
|---|---|---|---|---|---|
| A5-1 | 400 x 2800 | 1 | 1.7 | 1.81 | 360 – 600 |
| A5-2 | 325 x 2300 | 2 | 1.7 | 2.35 | 300 – 590 |
| A5-5 | 200 x 1400 | 5 | 1.7 | 2.42 | 260 – 550 |
| A5-10 | 165 x 1400 | 10 | 1.7 | 3.00 | 220 – 500 |
| A5-20 | 165 x 800 | 20 | 1.7 | 4.50 | 170 – 450 |
| A5-25 | 165 x 600 | 25 | 1.7 | 6.12 | 150 – 410 |
| A5-40 | 325 | 40 | 1.7 | 6.86 | 100 – 350 |
| A5-50 | 250 | 50 | 1.7 | 8.41 | 90 – 300 |
| A5-100 | 150 | 100 | 1.7 | 9.10 | 70 – 190 |
Bubble point roughly halves each time the rating doubles, which makes it a fast check on grade in either direction: too low a bubble point and the element is coarser than ordered, too high and it is finer, with the matching increase in pressure drop. Porosity is about 37% for the 5-layer laminate, rising to about 14.4 kg/m2 for a 6-layer version of the same panel.
Pressure and temperature limits
| Parameter | Value | Note |
|---|---|---|
| Maximum differential pressure | Up to 3.0 MPa (about 435 psi) sustained; higher short-term collapse ratings available | The limit is set by layers 4 and 5, not by the filtration layer |
| Backwash differential | Must be included in the collapse rating, not treated separately | Most element failures occur on the reverse stroke |
| Operating temperature | -50 C to 500 C continuous (316L); -200 C to 600 C for suitable alloys | Hold time above 500 C shortens service life |
| Materials | 304, 304L, 316, 316L, 321, 904L, Hastelloy, Inconel, Monel | Alloy choice follows the medium, not the pressure |
| Standard panel sizes | 500 x 1000, 1000 x 1000, 1200 x 1200 mm | Panels, discs, tubes and pleated cartridges are formed from the same laminate |
The useful design rule is that the reverse differential is usually the binding constraint. A housing that backwashes with stored gas can apply a higher reversed differential in one second than the forward pressure ever reaches, and it is the reinforcement layer that has to absorb it.
Cleaning without losing the rating
The bonded structure means the element can be cleaned and returned to service, and the same bonded structure means certain cleaning methods are off-limits.
| Method | Effective against | Risk |
|---|---|---|
| Reverse-flow backwash | Surface cake and loosely held solids | Keep the reverse differential inside the collapse rating – this is where elements are damaged |
| Ultrasonic cleaning | Fine particles held in the pore channels | Most effective for fine grades; confirm the bath chemistry suits the alloy |
| High-temperature burn-off | Carbonised polymer and organic residue | Stay below the alloy limit; repeated cycles at the top of the range embrittle the wire |
| Chemical soak | Scale and inorganic deposits | The reagent must be compatible with the alloy, not only with the contaminant |
| Brushing or abrasive cleaning | Heavy soft cake | Avoid on fine grades, since it distorts the filtration layer and raises the bubble point |
After cleaning, two checks tell you whether the element is still good. Retest the bubble point against the band for its structure code; and compare the clean differential pressure with the value recorded when the element was new. A bubble point inside the band with a clean differential pressure close to the original means the element has returned to service, and the pressure recovery point on the next cycle is the number to trend.
Choosing between 5-layer mesh, fiber felt and powder
| Media | Structure | Choose when |
|---|---|---|
| 5-layer sintered mesh | Surface filtration, rigid laminate | Reusable element, high collapse or backwash differential, precise rating that must not drift |
| Sintered metal fiber felt | Depth filtration, 75-85% porosity | High-viscosity or high-temperature duty, large dirt load, low pressure drop at a fine rating |
| Sintered metal powder | Isotropic porous solid | Corrosive media, smaller pore sizes, gas distribution and sparging |
The three are not ranked by quality. A melt line wants fiber felt for the dirt-holding capacity; a hydraulic loop with stored-gas backwash wants the laminate for the collapse strength; a caustic or chloride duty wants powder or a suitable alloy. The specification follows the duty.
How to specify a 5-layer element
- Rating. Nominal or absolute, and the bubble point band you will accept.
- Form. Panel, disc, tube or pleated cartridge, with dimensions, or a drawing.
- Pressure. Forward differential and, if backwashed, the reverse differential and its rate of application.
- Medium and temperature. Including concentration and whether the atmosphere is oxidising or reducing.
- Cleaning plan. How often, and by which method – this decides the alloy and the layer count.
Related pages
- 5-layer sintered wire mesh filters – full specification table and ordering
- Wire mesh filter elements, multi-layer elements for hydraulic, oil and slurry duty
- Sintered stainless steel powder filters – isotropic porous elements
- How to choose a micron rating