{"data":{"id":"us/30-cfr-33.21","jurisdiction":"us","citation":"30 CFR 33.21","heading":"Modification of test equipment.","body":"For test purposes the unit or system may be modified, such as by attaching instruments or measuring devices, at MSHA's discretion; but such modification shall not alter its performance.","path":["Title 30—Mineral Resources","CHAPTER I—MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR","SUBCHAPTER B—TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS","PART 33—DUST COLLECTORS FOR USE IN CONNECTION WITH ROCK DRILLING IN COAL MINES","Subpart B—Dust-Collector Requirements"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-30.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:25:24Z","sha256":"334ad20d7d0918e5f8fb2050783b36100d093604f938556001d5193603962098","source_id":"us-cfr","stale":true,"prev":"us/30-cfr-33.20","next":"us/30-cfr-33.22"},"notice":"GroundRules: Original legal text. Not legal advice."}