Opportunities to Improve Testing of Positive Air Shutoff Systems

Testing must be performed regularly on this safety critical device to ensure the shutoff valve functions as designed and avoid the potential for serious incidents or engine damage.

• Testing requirements and frequency vary depending on specific regulations or standards.
  • AER’s Site Directive 37 states that positive air shutoff systems should be tested weekly as part of the regular functional testing of diesel engines.
  • The Canadian Energy Regulator advises conducting “inspections, testing and maintenance pursuant to the schedule outlined in procedures or according to manufacturer’s specifications.”
• Operational reviews of positive air shutoff systems, including administrative actions, should be conducted frequently to ensure workers understand hazards when operating a diesel engine in locations with potential hydrocarbon vapours.

• Refer to the original equipment manufacturers (OEM) recommendations for instructions on installation, testing and inspection. If these conflict with regulations, consult the OEM and regulatory authorities.
• Ensure positive air shutoff systems comply with applicable regulations and standards.
• Install a redundant positive air shutoff system where necessary.
• Perform regular maintenance, including sensor checks and cleaning, and verifying wire connections.
• Conduct regular testing. Only perform testing in open, well-ventilated areas when the engine is functioning properly, and when the OEM testing recommendations can be followed.
• Ensure operators and maintenance personnel understand how positive air shutoff systems function and identifying and responding to system alerts.