At Applied Thermal Control, we understand that the use of A3L refrigerants such as R290 naturally raises questions around safety, compliance, and room limits. This article is designed to reassure users of modern A3L refrigerant chillers and explain how room size, refrigerant charge, and applicable standards work together.

Modern laboratory and process chillers using R290 are designed with very small refrigerant charges, typically well below 150g per circuit. Each chiller operates as a hermetically sealed, independent refrigeration system, meaning that compliance is assessed per individual circuit rather than simply summing the total refrigerant charge across all equipment in a room.

This approach is fundamental to EN 378, IEC 60335-2-89, ASHRAE 15, and UL 60335-2-89, and is why multiple low-charge A3L systems are widely accepted in laboratory and industrial environments across Europe, the UK, and the US.

To illustrate how current safety standards apply in practice, consider a 20 square metre laboratory or technical room fitted with ATC G02 2.15kW recirculating chillers, each containing 95g of R290 (propane).

Each ATC G02 is a hermetically sealed, self-contained refrigeration system with an independent refrigerant circuit. With a refrigerant charge well below the widely recognised 150g per-circuit threshold, each unit falls into the low-charge category addressed by EN 378, IEC 60335-2-89, ASHRAE Standard 15, and UL 60335-2-89.

Under these standards, safety is assessed on the basis of a single worst-case-leak from one circuit, not the combined refrigerant charge of all equipment in the room. In a 20m² space, the full release of 95g of R290 from one G02 would not result in a refrigerant concentration exceeding the allowable fraction of the Lower Flammability Limit, provided the room has normal laboratory or plant-room ventilation.

Because each G02 is independently compliant, multiple units may be installed in the same room without triggering additional safety measures such as permanent leak detection or forced ventilation. In practical terms, a 20m² room can typically accommodate five or more G02 chillers, assuming that:

– Each unit remains below 150g or refrigerant
– The room is not fully sealed
– The space is classified as non-public (e.g. laboratory or technical area)

Even as the number of units increases, compliance is maintained because no single refrigerant circuit can release enough gas to exceed concentration limits defined by international safety standards.

This design-based approach is the reason that low-charge A3 refrigerant chillers such as the G02 are widely used in laboratories and industrial environments worldwide.

Safety standards distinguish between public and non-public spaces. Laboratories, plant rooms, and technical areas are typically classified as non-public and allow greater flexibility than publicly accessible areas. Most Applied Thermal Control installations fall into this non-public category under both European and US frameworks.

The information provided in this article is intended as general guidance based on typical laboratory and technical room conditions and the application of recognised safety standards. Final suitability for any installation will depends on site-specific factors such as room geometry, ceiling height, ventilation rate, occupancy classification, local regulatory requirements, and the exact equipment configuration. While modern low-charge A3 refrigerant chillers are designed to operate safely without active leak detection, individual projects may require a formal risk assessment or approval by a responsible safety officer, facilities team, or local authority.

We recommend that all installations are reviewed in line with applicable national and local regulations and that equipment is installed, operated, and maintained in accordance with manufacturer instructions and recognised good engineering practices.