Micron guide
What a micron rating means, how felt and mesh differ, and how to choose between them.
A micron (µm) is a thousandth of a millimetre. The rating on a filter sock tells you the size of particle it is built to stop: a 100 micron sock targets particles of about a tenth of a millimetre and larger. The smaller the number, the finer the filter, and the sooner it fills up.
Pick a micron rating
In the shop Made to order Scale in microns (µm). 1,000 µm = 1 mm. Particle sizes are approximate.
Choosing a rating
| Rating | Catches | Typical use |
|---|---|---|
| 1 to 25 | Fine silt, haze, the particles that make liquid cloudy | Final polishing, where a coarser sock upstream takes the bulk first |
| 50 | Anything you can see, plus fines just below visible size | Clear water, coolant and cutting-fluid tanks, live-feed harvesting |
| 100 | Fine sand, fibres, most visible debris | The general-purpose choice for sumps and recirculating tanks |
| 150 to 200 | Sand, swarf, food and plant debris | High flow with light cleaning; longer between changes |
| 400 to 800 | Leaves, grit, coarse solids | Ponds, first-stage straining, protecting pumps |
If a fine sock blocks too quickly, stage it: run a coarse sock first and a fine one after it. Each lasts longer than a single fine sock doing all the work.
Felt or mesh
| Polyester felt | Nylon mesh | |
|---|---|---|
| How it filters | Through its depth. Particles lodge inside the thick needle felt. | At the surface. Woven monofilament with an exact square opening. |
| Rating | Nominal: it stops most particles at its rating, not every one. | Close to absolute: nothing larger than the opening passes. |
| Dirt capacity | High | Lower, but it rinses clean |
| Reuse | A consumable. It can be washed a few times but never fully clears. | Washable and reusable for a long time |
| Flow | Good | Very good |
| Choose it when | You want the cleanest result and treat socks as consumables | You want a precise cut-off, fast flow and a sock that goes back in |
Materials and what they tolerate
The shop stocks polyester felt and nylon mesh. Other materials are made to order. This is a general guide only: the liquid, its concentration and the temperature all affect the result.
| Material | Max temperature | Acids | Alkalis | Aromatic solvents |
|---|---|---|---|---|
| Polyester | 150 to 170 °C | Yes | No | Yes |
| Polypropylene | 90 to 100 °C | Yes | Yes | No |
| Nylon | 150 to 170 °C | No | Yes | Yes |
| Nomex | 200 to 220 °C | Yes | Yes | Yes |
| PTFE | 250 to 270 °C | Yes | Yes | Yes |
Still not sure? Tell us what you are filtering and we will recommend a material and rating with your quote.