Api - Rp 556 Pdf _hot_

Before any ignition attempt, the furnace or boiler must be purged with at least (or inert gas) at a flow rate sufficient to achieve 25% of upper explosive limit (UEL) dilution. The purge timer must be hardwired or programmed with safety-rated logic—not controlled by a standard PLC.

If you're diving into the latest 2nd Edition (2011, reaffirmed 2019), keep an eye on these critical updates: Burner Management System Standards - BMS - Profire Energy api rp 556 pdf

As of April 2026, the status of the document is transitioning: Before any ignition attempt, the furnace or boiler