C02 (R744) – FREQUENTLY ASKED QUESTIONS
WHAT IS R744
R744 is the chemical reference for carbon dioxide (CO2) used as refrigerant. It is a naturally occurring substance that can be applied as a working fluid in different heating and cooling applications, due to its excellent heat transfer properties and its high volumetric cooling capacity.
ARE R744 & C02 THE SAME THING
Yes. According to industry standards, each refrigerant receives a nomenclature starting with the letter R (for Refrigerant) and a number, which follows an order depending on the “family” the substance belongs to. R744 / R-744 is hence the standard nomenclature for CO2used as a refrigerant: “7” indicates the natural fluid while “44” refers to the fluid’s weight. The term R744 is applied when referred to the refrigerant itself, and CO2, and/ or CO2Technology is used when referring to an application or use.
WHAT ARE THE MAIN CHARACTERISTICS OF R744
· Environmentally friendly, with a Global Warming Potential = 1
WHY IS R744 ENVIRONMENTALLY FRIENDLY
Applying R744 in vapour compression applications reduces significantly the amount of greenhouse gas (GHG) emissions released into the atmosphere, which is at the origin of climate change. Besides, R744 systems, in many applications, have the potential to be more efficient than current systems in most climate conditions, and therefore indirect emissions of GHG resulting from energy consumption are also reduced.
DOES R744 HAVE AN IMPACT ON THE OZONE LAYER
No, R744 does not contribute in any way to the depletion of the ozone layer.
IS R744 FLAMABLE
No, R744 is not flammable and presents no risks in case of interaction with other substances or chemical blends. CO2 is applied in many fire extinguishers.
IS R744 TOXIC
R744 is not toxic at moderate concentrations. Given the small system charge used for heating and cooling applications, R744 thus presents minimal health risks. In the US, for example, this is reflected by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) with the common standard ASHRAE 34, which lists R744 as Safety Class A1 – a low toxic, non-flammable refrigerant.
When inhaled at high concentrations, however, carbon dioxide can lead to a risk of asphyxiation, since it displaces oxygen. In such case it would produce a sour taste in the mouth and a stinging sensation in the nose and throat combined with dizziness.
IS R744 A TOTALLY NEW REFRIGERANT
Not exactly. CO2 was already used as a refrigerant in the mid-nineteenth century and its use steadily increased, reaching a peak in the 1920s. After that, the natural refrigerant was displaced by chlorofluorocarbons (CFCs) that operated at much lower pressures. Due to the impact of CFCs, and later HFCs, on the environment, CO2 was re-evaluated as an alternative refrigerant in the late 1980s. A new way to contain the high pressure was discovered by a group of researchers in Norway, giving way to the application of transcritical R744 to be used in different heating and cooling systems.