What is EN378?
The European standard EN378 governs the safety and environmental standards of air conditioning, refrigeration, chillers, and heat pump systems. First introduced in 2008, the standard was revised in 2016 to include A2L refrigerants. It specifies the maximum refrigerant charge permissible in a system, taking into account both toxicity and flammability. The previous standard only considered flammable and non-flammable substances, making the updated EN378 more comprehensive.
The main reason for the detection of gas is to protect personnel, protect the environment and save costs.
The standard also allows for the provision of leak detection and ventilation, which brings into play the following terms:
- QMLV Quantity limit with minimal ventilation in kg/m³
- QLAV Quantity limit with additional ventilation in kg/m³
- RCL Refrigerant concentration limit in kg/m³
For example, the value 0.42kg/m³ is for R410a, 0.063kg/m³ (QLMV). Above this value, a sensor is required.
The standard assumes that the maximum leak into an occupied space is no greater than a pinhole; therefore, the maximum charge is based on this fact.
How Many Gas Sensors do I need?
In an application such as hotel rooms or small offices, one sensor mounted at a low level is sufficient to provide the correct level of protection. However, this depends on the room size and amount of AC units within the space.
Good practise states
- One sensor for every 36m² of floor area.
- One sensor for each air conditioning unit.
Where should a sensor be placed?
The sensor location should be around 200 to 300mm above the floor in an area where refrigerant vapours are most likely to accumulate. The sensor should be placed at a low level for occupant safety or near any potential leak source if refrigerant conservation is a high priority, such as ceiling voids.
EN378 states that a ceiling void is part of the occupied space unless it is airtight. Therefore, monitoring ceiling voids would not be acceptable.