It’s a summer night. Your car’s clock shows it’s two in the morning. You feel relieved. A long weekend awaits, with nothing to think about except relaxing. Alongside you, the person you hold dearest in your life can hardly keep their eyes open. Outside it’s 24°C, the air slightly warm; your hand sways, almost as if cradled by the carefreeness of the moment. You can still perceive a saltiness in your nostrils despite the pungent smell of the asphalt. Your car’s headlights shine dimly onto road. You had promised to replace the bulbs the next day. That day you had just wanted to get away, to spend time with the person you love.
It’s a summer night. You’re out with friends. You’re travelling along a bumpy country road. That evening you celebrated a promotion at work, and you know you drank a little too much. You insist on driving, you’re certainly more sober than others. You feel as if you are completely wrapped in darkness, if not for the faint moonlight, a veiled reassurance.
It’s a summer night. A deafening noise wakes you up in the middle of the night and you jump out of bed, worried. In the distance, flames shooting up into the sky, almost illuminating the fields nearby. You rush out into the street. Those images will remain etched in your memory.
Three different experiences that converge into a single, indelible scene in the memory of time.
Such situations can be avoided by adopting the safety measures required for vehicles and by traffic laws. In this case, however, freedom of choice means that such measures can be adopted at the driver’s “discretion”, albeit punishable by law. There are no safety measures that, if not adopted, prevent a device from achieving the purpose it is used for. In the case of a motor car, its purpose is to be travel, to move quickly.
Every year, 1.35 million people die in fatal road accidents (source WHO), due to carelessness, negligence of rules and safety precautions. There are solutions, however these are not adopted because they are inconvenient; for example, seat belts are only worn by 62% of drivers and 15% of passengers, even though they have been mandatory for decades. It’s not only in the automotive sector, but in every other sector too there are solutions to ensure safety and prevent damage, however they are adopted at the discretion of the individual.
Safety should not be seen as an obligation but rather welcomed as a basic principle and ethical value, something needed to safeguard our lives and those of the people around us.
In the automotive industry, I regret to say, it is actually because there are now many more vehicles and drivers and therefore accidents that the rules of good, safe design have been defined. Here I’m referring to a set of regulations that must be complied with by manufacturers during the design phase, with the precise purpose of increasing safety for drivers and passengers.
So in the air-conditioning and refrigeration industry, what weight in terms of importance do you think is given to safety in the design stage? Does design incorporate safety, or is safety adapted to the design, certifying the basic minimum requirements?
In this specific market of products intended for a use similar to that of a motor vehicle, i.e. comfort, there are regulations to ensure that safe design is guaranteed. In recent years, important innovations have been introduced at a system level, reaching the highest levels in efficiency, sustainability and performance. After the advent of the electronic expansion valve, the product that has certainly had the biggest impact is the inverter, which, thanks to the concept of load modulation, has brought significant advances in the design of the final unit. Even though the refrigeration circuit is consolidated technology from a thermal-mechanical point of view, the introduction of power and control electronics has helped define a new starting point for the design of the entire system. So what part does safety play in all of this? Established refrigeration circuit technology has allowed the creation of a sort of “manual” for correct sizing, so as to prevent damage due to overpressure, overheating or refrigerant leakage. Just how much such damage may endanger the safety of people varies, and depends on several factors, however it is undeniable that good mechanical and thermal design has now reached a standard that minimises risks and limits damage.
Regarding HVAC/R systems then, is safety something that is duly taken into consideration? As previously mentioned, the introduction of new technologies has shaken up a market that was previously consolidated and that centred around the standard refrigeration circuit, with only slight variations. Just like with any new invention, a gap opened up in terms of regulations, which was only subsequently bridged by the introduction of specific standards. Design ethics however cannot be said to have adapted as quickly. Indeed, as mentioned in the “ECOdesign” post, design ethics take much longer to adapt compared to the introduction of regulations that establish requirements or limits, even when manufacturers take part in devising such regulations, giving themselves years to prepare in advance. From a safety point of view, the most critical component in operational terms should also be the one that requires more protection that the others. In HVAC/R systems, this component is the compressor, which creates the flow of fluid in the refrigerant circuit. Compressor failures are prevented not only by correctly sizing the component itself, but also by ensuring that the component never approaches conditions in which there is a high likelihood of damage. The main problem involves the locked rotor phenomenon, which could lead to sublimation of the insulation and voltage being distributed directly on the unit’s casing, endangering maintenance personnel or the end user. To avoid this, it is necessary to understand the phenomenon, define it, assimilate it and finally propose preventive solutions.
Hence there are specific standards, such as EN/UL 60335-1 Safety of Household and Similar Appliances, which establishes the procedures required to implement thermodynamic unit protection in the most delicate conditions for safety, i.e. the household environments. There are different methods to protect the unit in such a way as to reduce or almost totally eliminate the risk that a malfunction may cause damage: equip the system with pressure and temperature sensors, safety contactors and a circuit breaker, or integrate safety as part of the control logic, certified according to EN/UL 60730-1 Automatic Electrical Controls for Household and Similar Use. Beyond the multiple benefits that derive from adopting technology that implements safety internally, anyone who uses a refrigerating appliance in no way expects to be at any risk. For this reason, whatever method is chosen, the important thing is the awareness that the system purchased is reliable and certified in compliance with all applicable standards, proof that the principle of safety has been applied as a precautionary design measure for the user, and not as a precaution for the manufacturer.
Without forgetting that users are obliged to comply with the manufacturer’s installation and operating instructions, safe design does not mean providing a seat belt, but rather preparing the device so that it implements the action of fastening the seat belt autonomously and intrinsically.
[ECO]Design our future