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Drawing essentials · Written guide · 1 min read

Airlock, baglock, NPU and route symbols explained

Consistent symbology helps site teams read enclosure plans quickly. This guide explains the common asset categories used in AsbestoPlan and typical enclosure documentation.

By AsbestoPlan · Published 2026-06-16 · Planning support only — not compliance advice

Airlocks and baglocks

Airlocks control personnel entry and exit through staged decontamination. Baglocks handle waste material transfer. Position them where the RAMS describes — not where they fit easiest on a copied drawing.

NPUs and DCUs

An NPU symbol indicates the planned location of a negative pressure unit; a DCU symbol indicates a decontamination unit. These are generic planning representations. The Extraction planning panel estimates requirements from enclosure volume and assigned NPUs, using the airflow figures entered. It does not measure site airflow or simulate pressure. Check the figures and equipment suitability against the site-specific design.

Routes

Decontamination routes, waste routes and equipment paths should be readable at a glance. Use colour and line style consistently across projects.

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