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Environmental Code of Practice for Elimination of Fluorocarbon Emissions from Refrigeration and Air Conditioning Systems

Commercial /Industrial Systems

2.1 Design and General Practices
2.2 Compressors
2.3 Condensers and Evaporators
2.4 Piping Fittings and Practices
2.5 Air Purge and Pump-down Systems
2.6 Manufacturing Operations, Refrigerant, and Equipment

2.1 Design and General Practices

This section deals with the design of refrigeration and air conditioning systems and their components, and identifies possible sources of refrigerant emissions of CFC/ HCFC/HFCs to the atmosphere.

Application of established technology in both the design, construction, proper operation, and maintenance of refrigeration systems constitutes a good foundation for the prevention of refrigerant leakage to the atmosphere. Improved design of systems and use of new technologies and practices are essential for reduction and elimination of emissions.

2.1.1 General Design Principle

Commercial/Industrial refrigeration and air conditioning sectors are the major source of emissions. Environmentally sound design, therefore, is an important goal in pollution prevention. Equipment manufacturers, distributors, and associated service industries should incorporate product stewardship into their corporate policies, if not already present.

2.1.2 Building Owners, Operators, and Managers

Equipment owners and managers using ODS equipment should be informed of the environmental impact of ODS emissions and use of alternative refrigerants. The immediate need is to communicate that planned preventative maintenance is an essential component of preventing emissions. The second need is to improve maintenance techniques and procedures for maintaining the equipment to reduce or eliminate the potential for refrigerant release.

2.1.3 Relief Devices

Effective on the date of publication of this document, all new units containing over 10 kg (22 lb) of refrigerant should have a self-reseating relief valve vented to the outside atmosphere in accordance with the applicable B-52 code requirements. Also, units with over 50 kg (110 lb) should have a monitoring system in the compressor room, capable of detecting leakage greater than 30 ppm.

2.2 Compressors

To prevent fugitive emissions, compressors or associated equipment fitted to them, e.g., gauge and cut-out connections, oil return, oil drain, oil level sight glass, relief valve and connecting pipe work, need to be inspected regularly according to manufacturer's specifications, or at least twice a year if no specifications exist.

2.2.1 Mechanical Seals

Damaged mechanical seals on open type compressors are a frequent source of refrigerant leakage. Some manufacturers indicate that a small amount of oil leakage is required to keep dirt out of the seal and keep the seal surface lubricated. However, damage to the seals may be caused by oil contamination or lubrication breakdown.

A clean, dry system is essential for prolonged mechanical seal effectiveness to eliminate emissions. Compressor oils used for HCFCs and HFCs will absorb moisture readily and must be kept dry to prevent refrigerant decomposition.

Straining and filtration of refrigerant and compressor oil should be provided on new equipment to minimize mechanical seal wear and thereby reduce the possibility of having leaks. Existing equipment should be modified to include these features.

Gland housing should be designed to prevent oil draining away from the mechanical seal during shutdown, which may cause leakage due to seal face damage on startup.

2.2.2 Seal Lubrication

During shutdown the mechanical seals on large open compressor systems should be lubricated weekly before the compressor is started. A film of oil maintained on the shaft and seal surface, helps to prevent refrigerant from escaping.

2.2.3 Vibration

Compressors should be mounted on a solid foundation and/or with vibration eliminators to prevent leaks due to vibration and failures.

Gauges and Cutouts. Snubber valves should be used to protect gauges and cutouts. They are also required to permit removal of these devices for repair.

Isolating Valves and Access Valves. All commercial and industrial compressors should have isolating and access valves on both the suction and discharge sides. New units/systems immediately or from the date of publication of this document should have "refrigerant recovery access valves" sized to allow 0.64 cm (1/4") of free area for flow of refrigerant on units/systems having up to 4 kg (8.8 lb) of refrigerant charge and 0.95 cm (3/8") I.D. for systems containing over 4 kg (8.8 lb) of refrigerant to permit recovery of refrigerant before the system is opened.

2.3 Condensers and Evaporators

Effective on the date of publication of this document, the refrigerant should not be used as a holding charge for storage or shipping; use dry nitrogen or dry air that meets ASHRAE standards.

2.3.1 Condenser and Evaporator Vibration

Excessive vibration from compressors or other equipment can cause evaporator and condenser tube failure. Antivibration mountings and vibration eliminators should be used where feasible. Piping should have flexible connectors and be solidly anchored. Equipment should be inspected periodically to identify and remediate any excessive vibrations.

2.3.2 Excessive Water Velocity

Excessive water velocity through the tubes of shell and tube units should be avoided. On larger units (e.g., greater than 50 tR), eddy current testing of tubes every three years and water flow measurements will help minimize refrigerant losses due to tube failure. Adequate protection against water hammer is also recommended to reduce failure.

2.3.3 Water Quality

Water treatment and filtration should be used where needed to avoid corrosion or erosion failure. Careful selection of tube materials can also help to minimize corrosion.

For non-ferrous tubes, sacrificial anodes should be used to reduce corrosion pitting.

Reduced or suspended water flow can lead to serious corrosion problems. Flushing and a regular inspections should be done.

Sacrificial anodes are ineffective unless there is water flowing through the tubes. Tube sheets should also have a tube sheet vent valve to avoid trapped gases. These should be purged at least once a month.

2.4 Piping Fittings and Practices

2.4.1 Piping and Fittings

Vibration eliminators should be included in the suction and discharge lines near the compressor to prevent and eliminate leaks and vibration transmission.

Adequate support of pipeline connections to the compressor should be provided to avoid unacceptable stresses that could lead to leakage.

All pipelines should be designed so that the number of joints is minimized. Swedged joints should be used by both manufacturing process and the service person in the field. Welding or brazing is the preferred method of attachment on all refrigerant lines. The use of back seating access valves for attaching control and safety devices or gauges is preferred. Capillary lines on these devices must be positioned to ensure they can absorb vibration without rubbing together or against another object.

Gasket Material Compatibility. Ensure that gaskets are compatible with the refrigerant/refrigerant oil mixture where flanged joints are used, especially when the system is converted to an alternative refrigerant or oil. Equipment manufacturers should always be consulted before any retrofitting to help avoid leakage.

Welded or Brazed Flanges. To eliminate potential leaks in new systems, welding or brazing should be used to join flanges to the pipeline, instead of threaded connections. Where threaded connections must be used, fluoropolymer film is the preferred pipe lubricant. On existing systems back-weld screwed flanges should be used where possible.

Back Seating Valves. Use valves designed for tightening or replacement of the gland packing/diaphragm under line pressure except when ball valves are involved. Be sure to check valves carefully before servicing. Leak test the gland-packing nut regularly.

Capped Valves. Capped valves which can retain any leakage from the spindle gland should be used for all service stop valves. Regular operating valves in the system should be leak tested regularly.

Welded, Brazed Valves. Valves with welded, brazed, or flanged connections should be used instead of a flared or screwed type, for sizes greater than 19 mm (3/4") outside diameter (O.D.). For small sizes use compression fittings instead of flared fittings.

Bolt-on Valves. Bolt-on valves should not be used on smaller applications. Saddle valves can be used as a tool but must be replaced by weld-in access valves or welded shut before the service person leaves the site. One exception is for recovery of refrigerant when a bolt-on valve can be used during decommissioning of smaller equipment.

Isolation and Access Valves. Valves allowing isolation of all vessels and equipment are required to minimize the risk of refrigerant loss during servicing. Access valves for recovery of residual refrigerant in isolated components are also required. Any piping or segment between two shut-off valves must be protected by a pressure-relief, in accordance with the B52-M1995 Mechanical Refrigeration Code (as amended from time to time).

Isolation valves should be added, if not present, when vessels or equipment have to be shut down and evacuated for service.

2.4.2 Piping Practices

Pipelines should always be supported against vibration stresses, which cause leaks, by being adequately clamped to solid fixtures. Use insulated hangers for non-ferrous pipe. Vibration eliminators and expansion bends should be used. Use trombone bends or sprung hangers for lines too large for vibration eliminators. Gauges, high pressure and low pressure shut-off, and oil safety switches should be connected to the main system via flexible connections so that vibrations are absorbed.

Filter Driers. To prevent leakage, filter driers in the range of 5 to 20 µm should be used to reduce particulate matter and avoid damage to the mechanical seal faces and other working parts of compressors. Similar damage can also be caused to motor windings and compressor parts of hermetic and semi-hermetic compressors. A moisture indicating sight glass is strongly recommended. New systems should have a liquid line filter drier of sufficient size welded into place at the time of manufacture, to protect the equipment. Replaceable filter drier cores are available for larger systems to avoid emissions.

The drier should have isolation and refrigerant recovery connections. A new filter/drier should be installed, complete with required valves in the case of a system that is opened to replace a component that has no filter/drier.

Welding Blanket. Refrigerant should not be used as welding blanket. Dry nitrogen should be used during welding or brazing.

Relief Devices. A nonfragmenting rupture disc in conjunction with a self-reseating type relief valve is recommended for low pressure refrigerant systems. All relief devices must be vented to the outdoors.

Three-way Refrigerant Valves. A three-way refrigerant valve is required to accommodate dual-relief valves on all high pressure refrigerant machines with a charge of over 50 kg (110 lb), to facilitate repair or replacement. To eliminate emissions the relief valve setting shall be in accordance with the B52-M1995 Mechanical Refrigeration Code. (As amended from time to time).

2.5 Air Purge and Pump-down Systems

2.5.1 Air Purgers

Air purge systems should vent outdoors. When purge systems operate, some refrigerant is emitted with air and frequent purging indicates a system leak. High-efficiency purgers will help to significantly reduce refrigerant purge emissions. In conjunction with adsorption technology, a 100% capture rate of normal purge emissions is possible. To correct the problem, trained qualified service persons must inspect and repair all leaks in the system. Regular leak testing is essential.

High-efficiency Purgers. Effective on the date of publication of this document, all new low pressure centrifugal units using refrigerants such as CFC-11, CFC-113, or HCFC-123 should be fitted with high-efficiency air purgers or other devices designed to emit less than 0.1 parts of refrigerant per part of air during usual operation, according to manufacturer's specifications.

It is recommended that by January 1, 1999, existing chillers be retrofitted with a new high-efficiency purge or other device that is designed to reduce emissions below 0.1 kg of refrigerant/kg of air.

After January 1, 2000, all purge systems should have zero refrigerant emissions.

Pre-vacuum systems are available to prevent low pressure systems from going into a vacuum during idle periods. Potential refrigerant loss or leakage will be reduced; however, leaks should still be eliminated through proper leak testing and maintenance.

Residual refrigerant should also be recovered from the purge exhaust port using the best available technology. Systems to be shut down more than four months should have the refrigerant removed and transferred to approved storage vessels or containers.

2.5.2 Pump-down Equipment

Effective on the date of publication of this document, all new high pressure refrigeration and air conditioning units with a refrigeration capacity of 35.2 kW (10 tR) or greater, should incorporate a fully protected and isolatable liquid receiver to facilitate pump down during servicing, repairs, or winter lay ups. A condenser and receiver combination of sufficient capacity to hold the complete refrigerant charge is also acceptable.

Auxiliary Receivers. If manufactured before the date of publication of this document, units containing a refrigerant charge of over 10 kg (22 lb) should be installed with auxiliary receivers, if required, to hold the complete refrigerant charge during winter and summer. Units using capillary expansion control, however, need not necessarily be fitted with an isolatable liquid receiver. For smaller systems approved containers can be used.

Shell and Tube Condenser. The previous paragraph on auxiliary receivers does not necessarily apply to systems containing a shell and tube condenser if the condenser shell is on the refrigerant side; is large enough to contain the entire refrigerant charge; is fully isolatable and is protected by a pressure-relief device.

Evaporator and Accumulator. The paragraph on auxiliary receivers does not necessarily apply when the evaporator and/or liquid accumulator separator can contain the entire refrigerant charge and is fully isolatable and protected by a pressure-relief device.

Pump-down Attachments. Large systems may incorporate a separate pump-down condensing unit and receiver. Compressors and major equipment should be fitted with suitable refrigerant access valves to allow connection of a recovery unit for the removal of refrigerant before service or repair operations or any section of the system.

2.5.3 Oil Draining

Since refrigerants are soluble or miscible in compressor lubricating oils, compressor crankcases should be designed for pumped-down to below atmospheric pressure, before the oil is removed. High pressure systems should have discharge oil separators.

2.5.4 Leak Detection and Alarms

Refrigerant analyzers and warning alarms should be incorporated into the mechanical room design in accordance with the B52-(latest edition) Mechanical Refrigeration Code, to detect refrigerant emission.

Refrigerant alarms are not a substitute for actual leak testing on the system itself. Alarms should always give warnings before the TLV level for a particular refrigerant is reached.

A regular leak testing program (minimum twice a year) for all systems is essential. Use industry recognized leak detection equipment and methods. High refrigerant levels, i.e., greater than 10 ppm in the compressor room is an indication that one or more systems are leaking. All compressor rooms should have refrigerant detectors and alarms.

2.6 Manufacturing Operations, Refrigerant, and Equipment

2.6.1 Product Stewardship

Refrigerant manufacturers and suppliers should incorporate product stewardship ("Responsible Care®") as a part of the corporate ethic, to ensure that their product is used safely and in an environmentally sound manner.

The Canadian Chemical Producers' Association (CCPA) "Responsible Care®" program states that: "A Total Commitment" signifies commitment to the responsible management of the total life cycle of our products; from the very beginning in the laboratory to the very end at ultimate disposal or destruction". This should be adopted throughout the refrigeration and air conditioning industry.

There are many stakeholders that have a role and responsibility for the disposal or transformation of surplus stock of ODS. Leadership from the chemical industry (i.e., the refrigerant manufacturers) that is consistent with Responsible Care® should be forthcoming to prevent future problems. It should be the same type of leadership that industry initiated for development of new alternatives.

A responsible corporate environmental ethic should not tolerate leaks of ODS and should incorporate and implement the best available design, maintenance, and operational practices to eliminate and prevent leaks.

Components of this program should also include:

  • the phaseout of use of CFCs;
  • maintaining on-going records of sources and quantities of emissions;
  • a preventive leak detection and maintenance repair program;
  • routine (such as annual) progress and performance reporting that is readily available to the public; and
  • management systems to audit progress and ensure that programs are in place and working.

2.6.2 Refrigerant Manufacturers

Sources of emissions during the refrigerant manufacturing process should be eliminated.

The main sources include:

- chemical processing and fugitive emissions;

- bulk loading;

- storage and cylinder filling; and

- laboratory analysis.

The best available technology should be applied in monitoring and processing refrigerant to prevent emissions.

Emissions of chemicals at the plant level are monitored by Federal or Provincial Environment Officers with the goal of pollution prevention.

Chemical Processing. Emissions from chemical processing can be eliminated or minimized by using technologies or

techniques that include, but are not limited to:

  • vapour recovery;
  • minimum volume fittings;
  • systems using welded piping and fittings, or if not possible, a minimum number of screwed mechanical joints;
  • gaskets specifically designed for the process materials to prevent leaks;
  • transfer hoses/tubing of high integrity and chemical resistance which are regularly inspected and/or replaced;
  • routine inspections and testing for leaks in systems
  • online monitors and/or analyzers strategically located in the operations areas and compressor rooms to detect leaks and sound alarms should a leak occur;
  • maintenance and repair program to respond rapidly to a detected leak; and
  • records maintained and analyzed on leaks and emissions to determine where improvements can be made.

Some specific examples are:

  • ensuring that sample valves do not leak (leak test regularly);
  • do not vent equipment and piping to atmosphere - recover to low vacuum levels;
  • evacuate hoses before disconnecting temporary equipment; e.g. service equipment or temporary replacement equipment
  • check relief valves to ensure they are not leaking;
  • ensure process refrigeration systems are leak tight; systems should not require regular topping up;
  • practice recovery and recycling when recharging dryers and filters; and
  • repair the leak before top up.

Storage and Filling Operations. Emissions from storage and filling operations should be eliminated or minimized by:

  • checking storage tank relief valves to ensure they are not leaking;
  • checking pump seals for leaks regularly;
  • not venting overfilled cylinders to the atmosphere;
  • ensuring that charging hoses for cylinders are self-sealing when disconnected; and
  • totally evacuating cylinders before opening for inspection.

Bulk Loading. Emissions from bulk loading operations should be eliminated or minimized by:

  • not venting loading hoses from trailers and railcars to the atmosphere at the plant or customer site; and by using recovery and recycling equipment;
  • customers should have recovery equipment available at the loading station;
  • when switching trailers from one product to another, all residual refrigerant should be recovered;
  • leak checking trailer valves and pumps regularly; and
  • all customer bulk installations should be leak tested once a year minimum.

Laboratory Analysis. Emissions due to laboratory and analysis should be eliminated or minimized by:

  • ensuring sample hoses are self-sealing;
  • recovering all unused portions of samples in the laboratory;
  • venting Goetz bulb analysis for volatile compounds to a chilled vacuum container;
  • passing vapour from boiling point analysis through resin adsorption;
  • sealing and keeping samples of liquid refrigerants sealed; and
  • evacuating sample containers and recovering refrigerant after use.

2.6.3 Manufacturers of Equipment

Deep vacuum evacuation, as per the manufacturers' specifications should be the only method used to evacuate and dehydrate refrigerating and air conditioning systems during the manufacturing process. Systems should be evacuated to 75 µm of Hg or less.

2.6.4 Holding Charges

Dry nitrogen or dry air (-40 °C dew point) meeting ASHRAE guidelines should be used as a holding charge, when shipping equipment.

2.6.5 Cleanliness of Systems

Irrespective of the type of compressor being used, the system should be absolutely clean to reduce the risk of contamination of refrigerant and the need for subsequent recharging. All key personnel involved should be conversant with refrigerant technology and familiar with the need for zero emission.

2.6.6 Leak Testing

Ozone-depleting substances should not be used as a trace gases and class one substances (CFCs) cannot be used for leak testing without recovering all of the leak test refrigerant using the best available technology. If a leak is found, the system should be evacuated and repaired before top-up.

Leak Testing Methods. Consideration should also be given to bubble testing with soap for larger leaks, or by water immersion. An electronic leak detection device, which will detect very small leaks, can also be used. Some of the major methods of leak detection include:

  • bubble testing with soap for larger leaks;
  • water immersion;
  • electronic leak detection; and
  • fluorescent dye.

Various electronic leak detectors are available, most new leak detectors can detect less than 14 g (0.5 oz) per year. Ensure that the detector is sensitive to the refrigerant to be detected.

If the fluorescent dye method is used, make sure there is no equipment warranty problem. Sulphur hexafluoride should not be used for leak testing as it has a high global-warming potential.

2.6.7 Access Valves

Discharge and evacuation valves should be fitted to compressors to assist in servicing and maintaining the installation, with removal of refrigerants to approved recovery containers.

Control Devices. When a low pressure control is used as a cycling control, it should be hooked up to a separate low side access port and not to the normal access suction service port where practicable.