Questioning whether stringent safety standards restrict the wider benefits of propane refrigeration.

I have spent my whole career designing, constructing and enabling the operation of safe industrial refrigeration systems. When I started, most of the plants we built used R-22 (having recently transitioned from R-502), but relatively early in my employment we switched back to ammonia as the refrigerant of choice. I then had the opportunity to get in on the very early stages of the rediscovery of carbon dioxide’s unique contribution to the industrial refrigeration world.Throughout that time it has been easy to follow the goal of making systems as safe as they possibly could be. More recently, however, I have come to realize that this is not necessarily in society’s best interest. My confusion in this regard is encapsulated by the visual dissonance of the elephant and the hamster in last month’s column. Put simply, if our safety standards require a level of security that is far more stringent than the level that is generally accepted by society, are we best serving its needs?The parallel that came to mind was the introduction of the Red Flag Act in the United Kingdom in 1865. The act required that, when a powered vehicle was moving on the public highway, a person was required to walk at least 60 yards (180 feet or 55 meters) in front of the vehicle, waving a red flag to warn other road users of the approach of the vehicle. If the speed of walking is taken as 3 mph (4.8 km/h) it seems obvious that, as the number of powered vehicles on the roads increased, this well-intentioned law was no longer in the public’s best interest. The act was repealed in 1896 and in the 130 years since then the average speed of motor vehicles in Central London has increased from 3 mph (4.8 km/h) to a massive 7.5 mph (12 km/h).When we ensure that refrigerating systems are safe by limiting the amount of refrigerant that they can hold to such an extent that an unsafe condition cannot possibly arise, we are applying the same logic that required a person with a flag to walk in front of a car in Victorian London. This acts in opposition to the interests of society in several ways. Since the use of R-12 started to be restricted in the 1980s due to concerns about its effect on the ozone layer, we have been subjected to a sequence of compromises where each succeeding development addresses another environmental concern and in the process sacrifices a bit more of the mixture of characteristics that made R-12 such a good choice in the first place. Throughout that process there has been a refrigerant offering similar or even better performance than R-12 in a wide range of applications with the sole disadvantage that it is in the “higher flammability” classification according to ASHRAE Standard 32. The public is prevented from enjoying the full benefits of that alternative, known as R-290, C₃H₈, or simply propane because the safety standards such as ASHRAE Standard 15, UL 60335-2-40 or ISO 5149 apply such stringent limits on the amount that can be used in many applications.Is it time to rewrite the rules, or is that a red flag for you?