Document Citation: 8 CCR 8437

Header:
CALIFORNIA CODE OF REGULATIONS
TITLE 8. INDUSTRIAL RELATIONS
DIVISION 1. DEPARTMENT OF INDUSTRIAL RELATIONS
CHAPTER 4. DIVISION OF INDUSTRIAL SAFETY
SUBCHAPTER 20. TUNNEL SAFETY ORDERS
ARTICLE 12. VENTILATION AND DUST CONTROL

Date:
08/31/2009

Document:
§ 8437. Ventilation

(a) Fresh air shall be delivered in adequate quantities to all underground work areas. The supply shall at least be sufficient t o prevent dangerous or harmful accumulations of dusts, fumes, vapors or gases, and shall not be less than 200 cubic feet per minute for each man underground. The lineal velocity of the air flow in the tunnel bore shall not be less than 60 feet per minute in those tunnels where blasting or rock drilling is conducted or where there are other conditions that are likely to produce dusts, fumes, vapors or gases in harmful quantities.

Exception: The lineal velocity of air flow in tunnels or chambers more than 30 feet in diameter may be reduced to 30 feet per minute provided that air quality is maintained.

(b) The main ventilation system shall be so arranged that the air flow can be reversed from the surface if a fire or some other emergency makes this advisable.

(c) Ventilation systems shall be arranged to exhaust smoke and fumes to the outside atmosphere before work is resumed in the heading.

(d) Men shall not be permitted, except in extreme emergencies to work in a place where the oxygen content of the air is less than 20 percent by volume (dry basis), unless they are wearing permissible self-contained oxygen breathing apparatus.

(e) Where flammable gas or air contaminants have been encountered, adequate ventilation shall be maintained to keep the gas or vapor concentrations within safe limits as provided by Safety Order 8424 and the Threshold Limit Values.

(f) Bulkheads and forced ventilation in one direction shall be provided after holing through to prevent harmful accumulations of dusts, fumes, vapors, gases, and concrete curing compounds from exceeding allowable concentrations.

(g) Auxiliary ventilation shall be provided to prevent dead air space between the face and the end of the vent line.

(h) See Safety Order 8470 for diesel engine ventilation requirements.