In the context of the Building Engineering Services Association (BESA) is a guide to good practice for the Site Pressure Testing of Pipework
BESA TR6 provides comprehensive guidelines for the verification of cleanliness in ventilation systems. It outlines the standards required to ensure that air distribution systems do not become a source of contamination or a fire hazard. The document covers several critical areas: besa tr6 pdf
If you want, I can run a live web search for "besa tr6 pdf" and summarize available PDFs I find. In the context of the Building Engineering Services
Where such PDFs usually come from