As the car industry learns that the “mildly flammable” refrigerant (per ASHARE 34) HFO-1234yf is actually a Category 1 Extremely Flammable Gas (per the manufacturer’s SDS and 1910.1200) and those facilities who have over 10,000 pounds of HFO-1234yf fall under PSM (1910.119), it is becoming a less and less attractive global warming (GW) alternative. And those who have been following this concern in the vehicle manufacturing industry know that it was Daimler who bucked the European Union (EU) and said they would not use HFO-1234yf in their vehicles because of safety concerns they uncovered in their own testing, even so much that Daimler said they would pay the EU fines before using the new refrigerant. Heck, they even recalled some cars that had HFO-1234yf already in them. Well, Daimler just announced that in their 2017 Mercedes E-Class they will introduce an air conditioning unit that uses Carbon Dioxide (CO2). And if we can believe the media Audi, BMW, Porsche and Volkswagen are not far behind.
This refrigerant change all came about when the EU banned any refrigerant in a vehicle that has a GW potential over 150 way back in 2011. The current refrigerant, R-134a, has a GW potential of around 1,300 so it would have to be replaced by January 2017 (EU deadline). Along comes HFO-1234yf with a GW potential of 5. But some manufacturer’s, namely Daimler, had serious concerns about the safety of HFO (please see my previous articles) as it is indeed a Category 1 Flammable Gas. So there has been a battle as to what refrigerant could replace R-134a, which is NOT flammable.
Through all of this, it appears all eyes were on the Global Warming concerns and NOT on worker safety (drives me crazy!). But Daimler refused to use HFO-1234yf and began to develop a CO2 air conditioning system and in the interim, they developed a “special crash structure” to keep the HFO-1234yf refrigerant separate from the engine compartment and is engineering a system that will release argon gas to help prevent an HFO-1234yf fire during a crash. So to the argument that Daimler was being cheap and did not want to use the largely more expensive HFO-1234yf solely because of costs seems to be a mute argument seeing how they have spent a lot of $ to go with CO2 and to implement interim measures that appear to cost a lot of $. But I digress…
CO2 has a GW potential of ZERO vs. HFO-1234yf’s of 5, so the improvement from the global warming perspective is not that great, but for worker safety and OSHA compliance it could mean HUGE benefits! So why didn’t the car industry just go with CO2 to begin with?
Bottom line… COSTS! The transition from R-134a to HFO-1234yf required no major alterations to vehicle AC units and offered a much lower GW potential. CO2, on the other hand, will require the vehicle’s AC unit to operate at pressures greater than 1,450 psi; this is nearly 10X’s the pressure seen in units using R-134a and HFO-1234yf. This means the AC unit(s) using CO2 will have to be COMPLETELY redesigned with MUCH MORE substantial construction for EVERYTHING in the unit. This means MORE WEIGHT added to the car at a time manufacturers are trying to REDUCE weight for better fuel economy. CO2 also presents NEW hazards to workers and will require manufacturing plants and repair shops to obtain ALL NEW equipment to handle CO2 and require training for the industry on CO2 hazards (e.g. CO2 is a now officially considered to be cryogenic).
But as many car manufacturers’s are dealing with HFO-1234yf and all its safety compliance baggage which appears to have caught the industry by surprise, it seems that this battle may be short lived if CO2 takes hold. CO2 poses its own significant challenges, but OSHA’s Process Safety Management will not be one of those challenges. CO2 comes with some significant risks to workers, but flammability is NOT one of those hazards. So with its GW potential of ZERO and not being a Category 1 Flammable Gas, this refrigerant, officially known as R-744, may begin to look more and more attractive as the alternative refrigerant.
Sources:
http://blog.caranddriver.com/global-cooling-mercedes-to-debut-air-conditioning-with-co2-refrigerant/