Wash. Admin. Code § 296-24-71505 - Local exhaust hoods and booths

Mechanical local exhaust ventilation may be by means of either of the following:

(1) Hoods. Freely movable hoods intended to be placed by the welder as near as practicable to the work being welded and provided with a rate of airflow sufficient to maintain a velocity in the direction of the hood of 100 linear feet per minute in the zone of welding when the hood is at its most remote distance from the point of welding. The rates of ventilation required to accomplish this control velocity using a 3-inch wide flanged suction opening are shown in the following table:

Welding zone	Minimum air flow1 cubic feet/minutes	Duct diameter inches2
4 to 6 inches from arc or torch	150	3
6 to 8 inches from arc or torch	275	3 1/2
8 to 10 inches from arc or torch	425	4 1/2
10 to 12 inches from arc or torch	600	5 1/2

¹ When brazing with cadmium bearing materials or when cutting on such materials increased rates of ventilation may be required.

² Nearest 1/2-inch duct diameter based on 4,000 feet per minute velocity in pipe.

(2) Fixed enclosure. A fixed enclosure with a top and not less than two sides which surround the welding or cutting operations and with a rate of airflow sufficient to maintain a velocity away from the welder of not less than 100 linear feet per minute.

Notes

Wash. Admin. Code § 296-24-71505

Amended by WSR 15-24-100, Filed 12/1/2015, effective 1/5/2016

Order 73-5, § 296-24-71505, filed 5/9/73 and Order 73-4, § 296-24-71505, filed 5/7/73.