What must be done to appliances before they are placed into operation after a piping system is live?

The requirement to purge appliances before they are placed into operation after a piping system is live is crucial for ensuring safety and efficiency. Purging involves removing air or any potentially hazardous substances from the lines and the appliance itself before it starts to operate. This process helps eliminate the risk of explosions or dangerous situations that could arise from gas mixing with air, as gas appliances need a safe and pure gas supply for optimal functioning. Proper purging ensures that the pipes and appliances are filled with the correct gas, allowing them to operate safely and efficiently.

In contrast, while inspection by a third party might be relevant in some contexts, it is not a universally mandated step specifically tied to the immediate operation of appliances in relation to live piping. Testing for efficiency could be a part of routine maintenance but does not directly address the immediate safety concerns associated with starting up appliances after the piping system is live. Unboxing is a preliminary activity that does not relate to the operational safety of the appliance concerning the gas piping. Therefore, purging stands out as the essential procedure that ensures safe and effective appliance operation.