S.O.P. No. MLD 020 - Cleaning 6-Liter Summa Polished Canisters
This document describes the method for cleaning 6-liter Summa polished canisters used for ambient sampling of aromatic and halogenated hydrocarbons, and non-methane organic compounds. This SOP also describes a method to evacuate and pressurize individual canister or groups of canisters that do not require cleaning. This method is developed based on the U.S. EPA Method TO-14.
SUMMARY OF METHOD
Eight 6-liter canisters are connected to manifolds in two ovens at 50oC and evacuated to less than 1.0 torr (1.0 mm Hg). The canisters are heated and purged four times with humidified zero air. A liquid nitrogen cold trap on the vacuum line prohibits back-diffusion of the vacuum pump oil vapor. Zero air is supplied by passing headspace liquid nitrogen through a local Aadco air purifier. Both manual and automated procedures are provided.
Cleaned canisters must meet the criteria levels listed in Table 1 for
volatile organic compounds (VOCs).