REFRIGERANTS
section shall be of the manual reset type with the reset located inside the refrigerating machinery room.”
Refrigerant leak detection systems typically fit into one of two categories: ■ Aspirated systems with low minimum detectable levels (MDL) which are designed to catch leaks early and minimize refrigerant loss.
■ Diffusion-based instruments that offer 24/7 monitoring for safety compliance purposes.
The diffusion-based instruments commonly use semiconductor sensors. While this technology does not provide low MDLs, the detection capacity delivers alarms well below the thresholds stated in ASHRAE 34.
This type of instrument is typically less expensive and offers less complex features when compared to refrigerant monitors designed to reduce refrigerant loss. However, the reality is that due to the pressure on price in this sector of the market, most of the refrigerant leak detectors available for this type of application are older and are in need of modernisation. These leak detectors remain very unintuitive to install, configure and maintain. This paradigm is starting to shift as manufacturers find ways to improve the interface with these instruments using modern technology.
Older instruments are usually set up manually. Typically, a combination of potentiometers, jumpers on main printed circuit boards (PCBs) and DIP switches have been used for performing vital tasks when configuring and maintaining refrigerant leak detectors, including: ■ calibration ■ setting alarm levels ■ configuring alarm behaviour – failsafe, latching acknowledgement, reset
■ output scaling ■ alarm delay programming ■ modbus node addressing.
This results in a reliance on often complex instruction manuals, reviewing PCB drawings to determine where to connect voltmeters to in order to perform the assigned task, calculations to determine what the voltages mean in the real world. Such practices can create a lengthy process and require training in order to effectively maintain instruments.
Some instruments do offer a route alternative to this via using small LCD screens. While being a step forward, the number of functions that the user needs to perform can lead to complex menu structures. These lead toward continued reliance on product manuals and/or training to decipher the meaning of function codes and data assigned
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to items that cannot be textualised on the small screen.
New innovations eliminate the difficulties, confusion and complexity of configuring and maintaining refrigerant leak detectors. The industry is seeing new instrumentation that makes use of the ubiquitous and intuitive capabilities of the smartphone via dedicated apps and Bluetooth connectivity.
The use of an app allows for clear, organised and intuitive configuration. Where before a potentiometer would have been adjusted to a specific calculated voltage via intrusive connection to an instrument, an end user can now simply select the button in the app which says ‘Alarm Level’ and type in, for example, ‘500’ to set the parts per million alarm level to 500 ppm. Modbus node addressing and alarm configuration can be done in a similar manner. Maintenance is also becoming more straightforward and traceable. By initiating and performing instrument calibration via a dedicated app (with, of course, the required calibration gas), calibration certificates maybe generated and sent from in the field, capturing the data on the gas used and results to provide a maintenance audit trail. Furthermore, calibration itself can be eliminated as a requirement via the use of pre- calibrated smart sensors. These smart sensors
are used in a ‘plug-and-play’ manner, requiring minimal training, taking seconds to exchange, and removing the need for maintaining, carrying and using expensive calibration gas cylinders.
Time Is money
Refrigerant leak detectors must be configured and maintained appropriately for the application and site, as per any gas detector in any application. This is a stipulation of most regulations, in addition to a recommendation from manufacturers. Doing so requires time, which costs money. Whereas older instruments usually required training to configure and maintain, and used painstaking methods, newer instruments are changing this picture. By employing technology to create non-invasive methods of checking and maintaining instruments and by taking away the time required for calibration by using pre- calibrated sensors instead and in exchange for the old sensors, time is saved. This can be in the magnitude of up to 30 minutes per leak detector, reducing to five minutes per leak detector. Taken across a site with, for example, 20 detectors, a 10-hour workday becomes a job that takes under two hours, freeing resources and saving money. Refrigerant safety standards require refrigerant leak detection systems. Installing, configuring and maintaining them is becoming a lot easier.
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