How A2L sensors make sure refrigerants don't blow(up)
60335 2-89 standards. For instance, they will need to integrate sensors and control boards that can detect and appropriately respond to a refrigerant leak. Specifically, they will need to add sensors that can sniff out A2L gas and message HVAC control boards so the system can: 1. Shut off the circulation of the refrigerant to stop it from pooling. 2. Shut off all potential ignition sources around the leak. 3. Blow air into where the leak is detected to reduce the chance of ignition. Engineers and technicians working around A2L refrigerants will also need to pay better attention to the tools they use. For instance, any power supply, drill or light source must be labeled A2L compatible if they are to be used in proximity to these refrigerants. Again, all these precautions have remained best practices within the HVAC industry. For instance, any refrigerant leak should be avoided, or quickly detected, to: ■ Maintain maximum efficiency of the HVAC system. ■ Meet OSHA exposure limit regulations. ■ Maintain proper charge, performance, and operations.
467. And though the risks of these refrigerants igniting are minor, engineers must maximize safety by ensuring HVAC systems are equipped with the tools to detect and react to refrigeration leaks. How flammable are we talking? And how engineers must respond. For a refrigerant to be classified as A2L or B2L, it must have a burning velocity lower than 10 cm/s (3.9 in/s). Though these materials will ignite, many tests have shown they tend to self-extinguish. Additionally, the gases must be highly concentrated to ignite as they have a lower flammability level of 300g/ m3 (10.8 lb/in3). Though it’s best to avoid sparks and flames, many A2L refrigerants have been assessed to be safe around some — but not all — common ignition sources. So, A2L refrigerants can and will ignite under various conditions. As a result, many of the ‘best practices’ used around A1 or B1 refrigerants — like purging and evacuating lines — become mandatory when working with A2L or B2L refrigerants. HVAC Engineers working with A2L refrigerants will also need to implement safety equipment into their systems designs as per UL
So, many engineers and technicians will hardly notice a change to their workflows, whereas anyone who took advantage of the ‘timesavers’ available when working with A1 refrigerants must change those habits.
A2L gas sensors and control systems
Engineers need sensors that are capable of detecting A2L refrigerant leaks to ensure the safe transition of the HVAC industry towards these more environmental materials. Fortunately, the HVAC industry is not the first to make this transition; most automotive vehicles already utilize A2L refrigerants. Therefore, HVAC engineers have access to tested equipment and procedures to ensure their future success. For instance, consider Sensirion thermal conductivity CMOSens MEMS chip series ¬— which contains the SGD43S-M3-S5 and SGD43S- M3-S7. They have already been used around the world for automotive and medical sensor applications. The sensor detects A2L gases using thermal conductivity. As a result, it is protected from common sensor issues like contamination, poisoning, drift, and the degradation of mechanical
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