What is the recommended method to purge a horizontal tank?

The recommended method to purge a horizontal tank is filling and draining. This method is effective because it ensures that the tank is completely filled with an inert gas or liquid that displaces any remaining hazardous vapors, followed by draining to remove any contaminants or residual fluids. By continuously filling and then draining the tank, the risk of any flammable vapors accumulating is minimized, allowing for a thorough cleansing of the tank's interior.

Other methods may not achieve the same level of safety or efficacy in vapor removal. For instance, using the siphon method may not completely purge the tank and can pose complications regarding maintaining the tank's integrity during the process. Blowing with air may not adequately remove heavier than air vapors and may even lead to the creation of flammable mixtures. Infusing steam, while effective in some contexts for cleaning, can potentially introduce moisture which may react with residual chemicals, leading to further complications. Hence, filling and draining remains the standard practice due to its effectiveness and safety profile.