(1) Air requirements in buildings, where persons are habitually employed, must meet the requirements of the general occupational health standard, WAC 296-62-100 through 296-62-11013.

(2) Where the natural ventilation is not sufficient to remove dust, fumes or vapors that create or constitute a hazard, additional means of removal must be provided.

(3) All mills containing one or more machines whose operations create dust, shavings, chips or slivers during a period of time equal to or greater than one-fourth of the working day or shift, must be equipped with a collecting system either continuous or automatic in action and of sufficient strength and capacity to thoroughly remove such refuse from the points of operation of the machines and the work areas.

(4) Each woodworking machine that creates dust, shavings, chips, or slivers must be equipped with an exhaust or conveyor system located and adjusted to remove the maximum amount of refuse from the point of operation and immediate vicinity.

(5) Blower, collecting and exhaust systems must be designed, constructed and maintained in accordance with American National Standards Z33.1 - 1961 (for the installation of blower and exhaust systems for dust, stock and vapor removal or conveying) and Z12.20 - 1962 (R1969) (code for the prevention of dust explosions in woodworking and wood flour manufacturing plants).

(6) Fans used for ventilating must be of ample capacity, as evidenced by the performance schedules of the manufacturers, and must be guarded when exposed to contact. Hoods, dust conveyors, dust collectors and other accessary equipment must be large enough to insure free intake and discharge.

(7) The outlet or discharge of all ventilating equipment must be arranged so that at no time will the dust, vapors, gases or other air borne impurities discharged, create or constitute a hazard.

(8) Where a hood is used to form a part or all of the guard required on a given machine, it must be constructed of no less than ten U.S. gauge sheet metal, or if of cast iron it must not be less than three-sixteenths inches in thickness.

(9) All exhaust pipes must be of such construction and internal dimensions as to minimize the possibility of clogging. They must be readily accessible for cleaning.

(10) All exhaust pipes must empty into settling or dust chambers which must effectively prevent the dust or refuse from entering any work area. Such settling or dust chambers must be so designed and operated as to reduce to a minimum the danger of fire or dust explosions.

(11) In lieu of a general ventilating system, exhaust or blower units may be installed on the dust or fume producing machine, provided the required protection is secured thereby.

(12) When proper ventilation is not provided, and temporary hazardous conditions are therefore encountered, you must furnish approved respiratory and visual equipment: Provided, however, That the exposure to such hazard must not be for more than two hours duration. Protective measures and equipment must meet the requirements of chapter 296-842 WAC, Respirators.

(13) Provisions for the daily removal of refuse must be made in all operations not required to have an exhaust system, or having refuse too heavy, or bulky, or otherwise unsuitable to be handled by an exhaust system.

PDFWAC 296-78-71019

Exhaust systems.