Refrigeration Plants and Installations
26.4 (1) A refrigeration plant or installation that is comprised of only high pressure refrigeration units using Category 1 refrigerants may be operated unattended if, (a) all refrigeration units have non-positive displacement compressors; (b) no refrigeration unit rating is more than 1000 kW; (c) no refrigeration installation rating is more than 3000 kW; and (d) every refrigeration installation is equipped with the systems, devices and controls referred to in subsections (2), (3) and (4). (2) A refrigeration installation referred to in subsection (1) shall be equipped with, (a) an audible and visible alarm system that, if any potentially unsafe condition is indicated by a protective device, (i) gives a warning to the operating engineer or operator or any other person who is located in the plant and is in charge of the installation, and (ii) continues to give a visible warning until the potentially unsafe condition is rectified or the installation is safely shut down; (b) an automatic control system that controls the installation when the operating engineer, operator or any other person in charge of the installation leaves the controls of the installation; (c) protective devices and controls, including pressure relief devices, required by the Boilers and Pressure Vessels Act or the regulations under that Act; (d) fail-safe devices required by subsection (3) which shall, if a potentially unsafe condition occurs, interrupt the supply of energy to the refrigerant compressor prime movers and prevent the installation from restarting under automatic control or under remote control; and (e) such other devices as are necessary to allow the installation to be operated safely. (3) For the purposes of clause (2) (d), the following devices are required: 1. A refrigerant high pressure limiting device in the refrigerant discharge line from the compressor. 2. A refrigerant high liquid level limiting device in the evaporator or the refrigerant suction accumulator, unless the design inherently prevents the possibility of liquid refrigerant being drawn into the compressor. 3. A low flow limiting device in the condenser coolant circuit, if the refrigerant coolant is liquid cooled. 4. A low flow limiting device in the compressor coolant circuit, if the compressor is liquid cooled. 5. A low oil pressure limiting device, if a pressurized lubricating oil system is used. (4) A refrigeration installation referred to in subsection (1) and located in a machinery room shall be equipped with a gas detector system that will activate the alarm system required by clause (2) (a) and start a mechanical ventilation system if there is a leak of Category 1 refrigerant causing, (a) the oxygen level in the room to fall below 19.5 per cent by volume; or (b) the airborne concentration of refrigerant to rise above the “immediately dangerous to life or health” limit as defined by CAN/CSA-B52-92. (5) For the purpose of subsection (4), “machinery room” means a machinery room as defined by CAN/CSA-B52-92. (6) A refrigeration installation referred to in subsection (1) shall comply with CAN/CSA-B52-92 and shall be installed and operated so as to ensure public safety. O.Reg. 46/93, s. 1.