Owners and operators of industrial and commercial refrigeration systems could face stringent new requirements if a current proposal from the Environmental Protection Agency (EPA) becomes effective. Owners and operators in California already must satisfy new mandates thanks to new regulations already implemented by the California Air Resources Board (CARB).
The California Refrigerant Management Program decrees that for any appliance with more than 50 lb of ozone-depleting substances (ODS) or hydrofluorocarbon (HFC) refrigerants, owners or operators must:
- Repair leaks.
- Conduct leak inspections.
- Install automatic leak-detection equipment.
- Report their refrigerant usage and repairs.
Any facility with a refrigeration appliance containing more than 50 lb of refrigerant must report all service records annually to California.
Following the CARB dictates, on November 9, 2015, the EPA proposed an update to its refrigerant management requirements under the Clean Air Act, Section 608. Unlike CARB’s rules, the EPA proposal does not require periodic leak inspections if owners or operators install and operate an automatic leak-detection system that continuously monitors the appliance for leaks. However, the automatic leak-detection system must meet the CARB’s requirements: It should be capable of detecting 10 ppm of refrigerant and alarm at 100 ppm. The owner or operator must calibrate the system annually and keep records documenting the calibration.
Even for plants that already have some refrigerant leak detection equipment in place, this EPA rule, if passed, could trigger refrigeration leak-detection equipment changes.
The proposed EPA requirement could virtually eliminate the widely used semiconductor sensing technology. Those sensors are not capable of accurately detecting and measuring 10 ppm of refrigerant. In addition, an alarm setpoint of 100 ppm would be a challenge for semiconductor sensors if ambient conditions such as temperature and humidity are not constant.
Only infrared or photoacoustic sensing technologies will be able to meet these requirements. In effect, this regulation would change the focus from leak detection to refrigerant management.
Both infrared and photoacoustic technologies utilize physical principles rather than a change of conductivity. Infrared sensors use the principle of the absorption of light by the refrigerant. A photoacoustic sensor also uses infrared light; however, the infrared light is used to increase the temperature of the gas molecules. The resulting increase in pressure inside the measurement chamber creates an audible pulse that can be detected by an extremely sensitive microphone. Both principles are immune to interferences from the ambient environment because they use infrared light of a specific wavelength unique to the refrigerant. This enables the sensing technologies to be specific and ultra-sensitive, capable of detecting refrigerants in the low ppm level. Infrared detectors are available as centralized sampling systems or distributed point detectors. Photoacoustic systems require delivering the gas to the measurement chamber.
New Proposed Classifications and Requirements for Refrigerant Leak Detection
Along with the definition for the leak detector’s capabilities, the proposed rule also would specify new classifications and requirements for refrigeration appliances.
The RMP’s leak inspection would only apply to refrigeration appliances with a full charge of more than 50 lb. Depending on the size of the charge, proposed mandates for leak detection will require:
- An automatic leak-detection system to be installed that continuously monitors appliances normally containing 2,000 lb or more of refrigerant.
- Quarterly leak inspections for all appliances with more than 200 lb of refrigerant unless an automatic eak-detection system is installed.
- Annual leak inspections for all appliances with 50 to 199 lb unless an automatic leak-detection system is installed.
- Mandatory leak inspections before adding refrigerant to an appliance and after a leak is repaired.
The EPA also proposes changes to the record keeping and reporting requirements in 40 CFR 82.166, including leak inspection, full charge and service records.
Leak Inspection. Owners or operators of appliances normally containing more than 50 lb of refrigerant must maintain documentation from quarterly or annual leak inspections. The documentation must include the date of inspection and the component(s) where leaks were discovered. Alternatively, owners or operators may install an automatic leak-detection system and maintain records showing that the system is calibrated annually.
Full Charge. Owners or operators of appliances normally containing more than 50 lb of refrigerant must maintain records documenting the level of the full charge amount. The records for the current full charge must be maintained until three years after the appliance is retired.
Service Records Provided by Technicians. Persons adding or removing refrigerant from an appliance normally containing more than 50 lb of refrigerant must provide the owner or operator with documentation containing the identity and location of the appliance. This also must include the date and type of maintenance, service, repair or disposal performed; the name of the person performing the maintenance, service, repair or disposal; the amount and type of refrigerant added to or removed from the appliance; the full charge of the appliance; and the leak rate and the method used to determine the leak rate (unless disposing of the appliance).
Service Records Maintained by Owners and Operators. The appliance owner or operator must maintain service records provided by technicians and the identification of the owner or operator of the appliance. These also must include the full charge of the appliance and the method for how full charge was determined; the original range for the full charge of the appliance, its midpoint, and how the range was determined (if using method 4, as described in § 82.152, for determining full charge); any revisions of the full charge and how they were determined; and the dates such revisions occurred.
Key Considerations for Positioning Refrigerant Leak Detectors in Industrial Facilities
To ensure overall system performance and effectiveness, the selection of an installation site for the monitor or sampling point is one of the most important factors. Strict compliance where possible and considerable thought must be given to every detail of installation, particularly:
- Local, state and national codes and regulations that govern the installation of gas-monitoring equipment.
- Electrical codes that govern the routing and connection of electrical power and signal cables to gas-monitoring equipment.
- The full range of environmental conditions to which the monitor will be exposed.
- The physical properties of the gas to be detected. The molecular weight of most HFC, HFO, CFC and HFCF refrigerants is significantly higher than the molecular weight of ambient air (which consists of about 99 percent nitrogen and oxygen). Therefore, these refrigerants tend to accumulate at the lowest point of the installation.
- The specifics of the application, e.g. possible leaks, air movement/draft, etc. Detection-point installations are recommended below potential leak sources. In some installations where a strong airflow directs the gas from a possible leak to a ventilation system, it might be opportune to install a sampling point in the airstream.
- The degree of accessibility required for maintenance purposes.
- The need of a remote display in another location.
- The types of optional and accessory equipment that will be used with the system.
- Any other limiting factors or regulations that would affect system performance or installations.
Pinpointing a leak can be a challenge. Typical methods include the use of soap bubbles, ultrasonic leak detectors, pressure or vacuum tests, fluorescent dye and black light, infrared or semiconductor gas-detection devices. Besides the chiller in the machine room, possible sources for leaks such as valves, gauges, flanges, joints (brazed or mechanical) and filling or draining connections are not easily accessible. Hence, the more sensitive a leak detector is, the faster a leak can be located.
For ultrasonic devices, it is necessary that the instrument is pointing at the source of the leak (line of sight). Most portable gas detectors using a semiconductor sensor are in the detection range of 10s of ppm, have an auto-zero feature and respond to influences of ambient conditions. The most accurate portable leak detector utilizes infrared technology. This technology allows detecting single-digit ppm levels of refrigerants and significantly reduces the time of finding leaks. PC
Editor’s Note: As of February 10, EPA reports: “The public comment period for this proposed rule ended on January 25, 2016. We received many comments from our stakeholders, and are carefully reviewing them to consider our response, including what changes may be needed as we work to develop a final rule. We are working to publish a final rule as soon as possible.”