---
kind: "section"
citation: "40 C.F.R. § 63.1653"
title: "40"
number: "63.1653"
heading: "Opacity standards."
url: "https://uscodex.org/cfr/40/63.1653"
---

# §63.1653. Opacity standards.


No owner or operator shall cause emissions exiting from a shop due solely to operations of any affected submerged arc furnace, to exceed 20 percent opacity for more than one 6-minute period during any performance test, with the following exceptions:

- (a) Visible particulate emissions from a shop due solely to operation of a semi-closed submerged arc furnace, may exceed 20 percent opacity, measured as a 6-minute average, one time during any performance test, so long as the emissions never exceed 60 percent opacity, measured as a 6-minute average.
- (b) Blowing taps, poling and oxygen lancing of the tap hole; burndowns associated with electrode measurements; and maintenance activities associated with submerged arc furnaces and casting operations are exempt from the opacity standards specified in this section.

## Notes

### Source

Source: 64 FR 27458, May 20, 1999, unless otherwise noted.

### Authority

Authority: 42 U.S.C. 7401 et seq.

### Source

Source: 57 FR 61992, Dec. 29, 1992, unless otherwise noted.