40 CFR Table 6
Examples of Techniques for Equipment Problem Identification, Leak Detection and Mercury Vapor
June 9, 2020
As stated in Tables 1 and 2 of Subpart IIIII, examples of techniques for equipment problem identification, leak detection and mercury vapor measurements can be found in the following table:
Open Table
| To detect . . . | You could use . . . | Principle of detection . . . |
|---|---|---|
| 1. Leaking vent hoses; liquid mercury that is not covered by an aqueous liquid in open-top containers or end boxes; end box covers or stoppers, amalgam seal pot stoppers, or caustic basket covers not securely in place; cracks or spalling in cell room floors, pillars, or beams; caustic leaks; liquid mercury accumulations or spills; and equipment that is leaking liquid mercury | Visual inspections | |
| 2. Equipment that is leaking hydrogen and/or mercury vapor during inspections required by Table 2 to this subpart | a. Auditory and visual inspections | |
| b. Portable mercury vapor analyzer—ultraviolet light absorption detector | A sample of gas is drawn through a detection cell where ultraviolet light at 253.7 nanometers (nm) is directed perpendicularly through the sample toward a photodetector. Elemental mercury absorbs the incident light in proportion to its concentration in the air stream. | |
| c. Portable mercury vapor analyzer—gold film amalgamation detector | A sample of gas is drawn through a detection cell containing a gold film detector. Elemental mercury amalgamates with the gold film, changing the resistance of the detector in proportion to the mercury concentration in the air sample. | |
| d. Portable short-wave ultraviolet light, fluorescent background—visual indication | Ultraviolet light is directed toward a fluorescent background positioned behind a suspected source of mercury emissions. Elemental mercury vapor absorbs the ultraviolet light, projecting a dark shadow image on the fluorescent background. | |
| e. Portable combustible gas meter | ||
| 3. Level of mercury vapor in the cell room and other areas | a. Portable mercury vapor analyzer—ultraviolet light absorption detector | See Item 2.b. |
| b. Portable mercury vapor analyzer—gold film amalgamation detector | See Item 2.c. | |
| c. Permanganate impingement | A known volume of gas sample is absorbed in potassium permanganate solution. Elemental mercury in the solution is determined using a cold vapor adsorption analyzer, and the concentration of mercury in the gas sample is calculated. |
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