262.061(1)The atmosphere of a confined space is within acceptable limits if
(a)
the percentage of oxygen is not less than 19.5% by volume and not more than 23% by volume,
(b)
the concentration of an air contaminant does not exceed 50% of the lower explosive limit or lower flammability limit of the air contaminant when the confined space work is cleaning or inspecting and does not create a source of ignition,
(c)
the concentration of an air contaminant does not exceed 10% of the lower explosive limit or lower flammability limit of the air contaminant when the confined space work is cold work using non-sparking equipment,
(d)
the concentration of an air contaminant does not exceed 5% of the lower explosive limit or lower flammability limit of the air contaminant when the confined space work is riveting, welding, flame cutting or other fire or spark-producing work,
(e)
the concentration of air contaminants and physical agents meet the requirements of this Regulation,
(f)
the concentration or percentage referred to in paragraphs (a) to (e) can be maintained during the period of proposed occupancy in the confined space,
(g)
any liquid in which an employee may drown or any free flowing solid in which an employee may become entrapped has been removed from the confined space,
(h)
the entry of any liquid, free flowing solid or hazardous substance into the confined space in a quantity that could endanger the health or safety of the employee has been prevented by a secure means of disconnecting the pipes adjacent to the confined space or fitting blank flanges or blind flanges to the pipes adjacent to the confined space, and
(i)
all electrical or other equipment and machines that present a hazard to an entrant while entering, exiting or occupying the confined space have been put in a zero-energy state and locked out in accordance with this Regulation.
262.061(2)In order to bring the atmosphere of a confined space within acceptable limits, an employer shall
(a)
ventilate the confined space,
(b)
remove air contaminants from the confined space by the displacement of air, or
(c)
intentionally flood the atmosphere inside the confined space with an inert gas such as nitrogen in order to eliminate the hazard of ignition of flammable vapours inside the confined space and create an oxygen deficient atmosphere.