40 CFR § 420.21 - Specialized definitions.

---
identifier: "/us/cfr/t40/s420.21"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 420.21 - Specialized definitions."
title_number: 40
title_name: "Protection of Environment"
section_number: "420.21"
section_name: "Specialized definitions."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "N"
subchapter_name: "EFFLUENT GUIDELINES AND STANDARDS"
part_number: "420"
part_name: "IRON AND STEEL MANUFACTURING POINT SOURCE CATEGORY"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "33 U.S.C. 1311, 1314, 1316, 1317, 1318, 1342, and 1361."
regulatory_source: "47 FR 23284, May 27, 1982, unless otherwise noted."
cfr_part: "420"
---


# 420.21 Specialized definitions.

As used in this subpart:

(a) For the sintering subcategory, the term *product* means sinter agglomerated from iron-bearing materials.

(b) The term *dry air pollution control system* means an emission control system that utilizes filters to remove iron-bearing particles (fines) from blast furnace or sintering off-gases.

(c) The term *minimum level (ML)* means the level at which the analytical system gives recognizable signals and an acceptable calibration point. For 2,3,7,8-tetrachlorodibenzofuran, the minimum level is 10 pg/L per EPA Method 1613B for water and wastewater samples.

(d) The *term pg/L* means picograms per liter (ppt = 1.0 × 10-12 gm/L).

(e) The term *sintering* means a process for agglomerating iron-bearing materials into small pellets (sinter) that can be charged to a blast furnace.

(f) The term *wet air pollution control system* means an emission control system that utilizes water to clean process or furnace off-gases.

[67 FR 64264, Oct. 17, 2002]