Requirements for lint arrestors generally call for an aperture size no greater than 4 mm, for both the removable basket and the fixed screen.
Alongside that, a compliant installation is generally expected to have:
- a fixed screen, or a fail-safe cut-off mechanism, robust enough to prevent removal, intentional damage or bypass;
- a removable basket supplied for use in conjunction with that fixed screen or cut-off mechanism;
- a handle or other grip on the removable basket to allow easy removal;
- materials that withstand high temperature and extreme ranges of pH.
Requirements vary between authorities and change over time. Confirm the current standard with your local water authority before submitting.