4 mesh chimney cap & fireplace spark arrester screen has 4 openings per linear inch. Woven to NFPA 211 / IRC R1003.9 with a standard aperture of 5.35 mm (5350 µm), this page lists the controlling specification — wire diameter, aperture, micron rating, open area and cloth weight — together with the wire options available at this count and the duties it is normally specified for.
4 Mesh Specification Row (NFPA 211 / IRC R1003.9)
| Mesh count | Wire diameter (mm) | Aperture (mm) | Micron rating (u00b5m) | Open area (%) | Material |
|---|---|---|---|---|---|
| 4-Mesh | 0.800 | 5.550 | 5550 | 76.4 | SS304 / galvanized |
4 Mesh to Micron & Aperture
| Openings per inch | 4 |
|---|---|
| Aperture (opening width) | 5.35 mm |
| Micron rating | 5350 µm |
| Standard wire diameter | 1 mm |
| Open area | 71 % |
Aperture = (25.4 mm ÷ mesh count) − wire diameter. The micron rating equals the aperture in micrometres; actual retention also depends on particle shape and cake formation.
Wire Diameter Options at 4 Mesh
| Option | Wire dia | Aperture | Micron | Open area | Weight (SS) |
|---|---|---|---|---|---|
| Heavy wire | 1.300 mm | 5.050 mm | 5050 µm | 63.2 % | 3.48 kg/m² |
| Standard wire | 1.000 mm | 5.350 mm | 5350 µm | 71.0 % | 2.06 kg/m² |
| Fine wire | 0.750 mm | 5.600 mm | 5600 µm | 77.8 % | 1.16 kg/m² |
Heavier wire adds strength and abrasion life but closes the aperture; finer wire opens the aperture and raises throughput at the cost of durability. Specify mesh count AND wire diameter to fix the aperture unambiguously.
Open Area & Flow at 4 Mesh
The standard 4 mesh weave presents an open area of about 71%. At this count the mesh presents little flow resistance; selection is normally driven by particle retention and mechanical strength rather than pressure drop.
4 Mesh Cloth Weight
Standard 4 mesh stainless cloth weighs approximately 2.06 kg/m² (density 7.93 g/cm³ basis; brass and copper weave roughly 10% heavier, aluminum about one third). Use this figure for roll handling and freight estimation.
Typical Applications for 4 Mesh Chimney Cap & Fireplace Spark Arrester Screen
4 mesh chimney cap & fireplace spark arrester screen is commonly specified for coarse screening and grading, safety guarding, animal enclosures, plaster and render reinforcement, and support layers behind finer filter cloth.
When to Step Up or Down from 4 Mesh
Move to 8 mesh when particles are passing that must be retained; drop back to 2 mesh when the element blinds too quickly or the pressure drop is excessive. In a multi-layer pack, pair this count with a coarser support mesh downstream to carry the pressure load.
What Chimney Cap & Fireplace Spark Arrester Screen Does
Stopping burning embers from leaving the chimney and keeping birds and animals out, while letting flue gas draw freely.
Fitting & Care
- Inspect the screen at every sweep; creosote glaze can close openings and choke the draft.
- Fit the cap with stainless fasteners so it can be removed for sweeping.
