Section 20 of the Confined Spaces Regulation (O. Reg. 632/05) in Ontario, Canada, addresses safety measures related to atmospheric hazards in confined spaces. Here's a summary:

1. **Applicability (Subsection 1):**
- The section applies specifically to atmospheric hazards described in clause (b) or (c) of the definition of "atmospheric hazards" in section 1.

2. **Purging and Ventilation (Subsection 2):**
- If there are existing or potential atmospheric hazards in a confined space, it must be purged, ventilated, or both before any worker enters. The goal is to maintain acceptable atmospheric levels inside the confined space during work.

3. **Mechanical Ventilation, Warning System, and Exit Procedure (Subsection 3):**
- If mechanical ventilation is necessary, an adequate warning system and exit procedure must be in place. This ensures that workers are warned in case of ventilation failure and can safely exit the confined space.

4. **Exception for Technical Reasons (Subsection 4):**
- If compliance with purging and ventilation is impractical due to technical reasons:
- Compliance with warning and exit procedures is not required.
- Workers entering the confined space must use respiratory protective equipment and other necessary safety equipment. Adequate equipment for locating and rescuing the worker must also be provided.

5. **Equipment Inspection (Subsection 5):**
- The equipment mentioned in subsection 4 must be inspected by a person appointed by the employer, possessing adequate knowledge, training, and experience.
- The inspection ensures that the equipment is in good working order before a worker enters the confined space.

In summary, Section 20 focuses on addressing atmospheric hazards in confined spaces through purging, ventilation, and the provision of necessary safety equipment, with specific considerations for technical exceptions and equipment inspection.

The distinction between "purging" and "ventilating" lies in their approaches to managing contaminants in a confined space. "Purging" entails the removal of contaminants by displacing them with air, reducing concentrations to acceptable atmospheric levels. For instance, if a confined space initially contains toxic gas, air is introduced to diminish the toxic gas concentration to below the appropriate exposure level.

Once contaminants are eliminated through "purging," the confined space can undergo "ventilation." "Ventilation" involves the continuous introduction of fresh air through mechanical means to maintain acceptable atmospheric conditions. This process is crucial during work within the space to sustain adequate oxygen levels, guard against accidental chemical releases, remove work-generated contaminants, or cool the enclosure.

Ventilation achieves air displacement and dilution, either through forced-air introduction or continuous removal of contaminants via local exhaust ventilation for specific sources. Effective ventilation requires separating air supply and exhaust points as much as possible. Adequate openings are necessary for clean replacement air entry or air exhaust. Importantly, pure oxygen should not be used for ventilating confined spaces.

According to the Confined Spaces Regulation, an adequate warning system is essential for worker protection. "Adequate" is defined as sufficient for both intended and actual use, safeguarding workers from occupational illness or injury. The warning system, required by the Regulation, may indicate ventilation failure through audible or visual signals. The specific type of warning system must be detailed in the plan and could be as straightforward as constant visual monitoring by the attendant.

When employing electronic or electrical warning systems for ventilation failure, they should be activated by the loss of airflow and strategically located in the air stream. This ensures activation in cases of ventilation failure caused by motor failure, as well as cases without motor failure (e.g., fan belt failure or blocked airflow).

Supplynow's Air Systems Ventilators are equipped with warning systems and alarms for confined spaces.