The Need for Refrigerant Monitoring
Refrigerant gas detection has been used in the marketplace for many years. The drivers for this have included safety, regulation, cost, energy efficiency, environmental protection and protection of the workplace and product inventory or produce. Currently the refrigeration market in Europe is seeing an increased awareness of all these factors driven by the F-Gas regulations and the associated impact these changes are having, and will have into the future.
As the refrigeration market shapes itself to adjust to tighter industry regulation, two distinct approaches are becoming apparent when looking at refrigerant gas detection – compliance, and refrigerant management.
F-Gas 517/2014 determines that refrigeration systems containing gas with a global warming potential (GWP) of 500 tCO2e or greater must have a permanent leak detection system installed. Those with more than 5 tCO2e must be inspected, with mandated intervals for inspection halved if a permanent leak detection system is installed.
F-Gas is, however, not the only relevant legislation regarding refrigerant detection. EN 378-3:2008+A1:2012 states that systems with a charge of greater than 25kg refrigerant shall be fitted with a refrigerant detection system in the machinery room, designed to trigger ventilation when concentrations reach 50% of the occupational exposure limit (OEL) or 25% of the lower flammability limit (LFL). In addition, an alarm must be activated if the potential concentration of leaking refrigerant may exceed the practical limit in accordance with EN 378-1:2008+A2:2012, Annex C.
These two regulations, in addition with safety codes related to the asphyxiation risk from CO2 in enclosed spaces (for example, cold rooms using CO2 as a refrigerant), are driving an increased need for compliance-focused refrigerant detection in the commercial environment. Most frequently this type of gas detection instrument will be employed in a machinery room housing compressor, chillers and other large refrigeration plant.
The devices used for this type of compliance refrigerant detection are generally fairly simple and very cost effective. Typically, these instruments consist of a fixed position point detector with a localized audio-visual alarm, and some form of external communications capability such as relays, analogue output signals or BUS communications. These are used to drive alerts to then instigate actions to mitigate the leak.
The technology used in these instruments is well suited for this type of gross leak detection, with alarms typically in the region of 500 ppm (parts per million) for HFC refrigerants, usually at 5,000 ppm or higher for CO2. What this technology delivers, is a solution that ticks the box for compliance with regulation, and for safe operation of systems. Increasingly, more users of refrigerant gas are seeing a need to monitor gas leakage at much lower levels to facilitate other benefits from the systems put in place. This approach is known as “refrigerant management”.
Technology exists which can monitor the presence of refrigerant at levels as low as 1 ppm. This type of high precision sensor is usually found at the heart of aspirated, sampling systems which use a pump to draw a gas from the monitored area back to the gas monitoring system for analysis. There are two reasons for this: the cost of the sensor elements is prohibitive to deployment in multiple locations on one site, and the size of the sensor does not allow for it to be housed as a small point detector. However, used appropriately to monitor from multiple zones, this type of system can be very cost effective to install. For example, in a supermarket a single system can be used for monitoring the store floor, machinery rooms, cold rooms and freezers.
The benefits to be gained from the refrigerant management approach go beyond compliance and safety monitoring, and the use of a system which can detect refrigerant gas at very low levels such as 1 ppm is essential to be able to deliver on this approach. Gas diffusion modelling shows that even a significant refrigerant leak will quickly disperse so the levels picked up by a gas detection instrument can be lower than 10 ppm. It follows that in order to detect these leaks early and before they become critical, a refrigerant gas detector would need a minimum detection limit sub-10 ppm. This is where the high precision sampling systems give their benefit as leaks can be detected and repaired early, before large volumes of gas are lost, before energy efficiency is compromised and before the loss through mandated disposal of refrigerated produce (which can have a value of £1,000 just for a small case) becomes a real risk.
The Carbon Trust’s Refrigeration Systems Technology Overview quoted a study that showed an annual leakage rate of 20% from a typical refrigeration system. This means a reduction in energy efficiency of 11%, and the equivalent increase in energy costs. Putting some costs on this, the study estimated an energy cost of £1,400 as the result of a small but continuous leak left unrepaired for 3 months on a typical 300kW refrigeration system, with additional costs to be covered to actually get the leak repaired. Given that many stores have 5 or more of these systems in place, the overall costs can be multiplied accordingly. It should also be noted that fines for uncontrolled refrigerant loss can be up to £5,000 in a Magistrates Court with summary conviction; unlimited if tried in a Crown Court. Bearing in mind all of these factors, the savings to be made through refrigerant management quickly become very significant.
The Future for Refrigerant Gas Detection
The gains in energy efficiency, reductions in the volume and cost of gas required to recharge the refrigeration system, and the delivery of environmental excellence through reduction of emissions of harmful gases into the atmosphere, are all powerful reasons behind the growing interest in refrigerant management.
Regulations continue to develop and are expected to demand ever lower levels of environmental impact from the industry through reduced emission and usage of greenhouse gases. Furthermore, market trends suggest that there will be an increasing variety of refrigerants on the market, many in the category of being mildly flammable, and an increasing push to natural refrigerants such as R-290 (propane), CO2 and NH3 (ammonia). The associated risks with newer gases may lead to a greater push for refrigerant management to be the approach taken to refrigerant gas detection.