New York Codes, Rules and Regulations
Title 12 - DEPARTMENT OF LABOR
Chapter I - Industrial Board Of Appeals
Subchapter A - The Industrial Code
Part 12 - Control Of Air Contaminants
Subpart 12-2 - Specific Operations And Specific Control Requirements
Section 12-2.3 - Melting apparatus

Vessels operated at or in excess of the temperature of volatilization of toxic metals, alloys or compounds which generate dangerous air contaminants shall be provided with local exhaust ventilation. Vessels used for melting or cleaning such metals, alloys or compounds shall be provided with exhaust ventilation when operated in such a manner as to generate dangerous air contaminants. The combustion chamber, when operated in such a manner as to release dangerous air contaminants, shall be provided with local exhaust ventilation.

Exception:

Portable receptacles or apparatus which have no fixed location and are used intermittently and which produce no dangerous air contaminants.