Technical Aspects of Modernization of R-134a

• Toxicity, Flammability, corrosion. R-134a is considered one of the most friendly refrigerants still be implemented on the basis of current data on toxicity. In the chemical industry programme for Alternative fluorocarbon Toxicity Testing (PAFT) tested R-134a in full battery of laboratory animals Tox-icity research. The results show that R-134a not pose cancer or birth defects danger. In addition, R-134a is used in metered dose inhalers in Europe. Flammability and corro-sivity each potential of R-12 replace considered producers of chemicals and various institutions. For example, R-12, R-134a is not ignited at ambient temperature and atmospheric pressure. Some mixtures of air and R-134a has been shown to be combustible at high pressures. These mixtures can be potentially dangerous, causing injury or damage to property. R-134a is not corrosive for reference steel, aluminium, copper and samples.
• Processing. While working with R-134a as any other chemical, service personnel must be sure that working in a well ventilated area. It is never a good idea to inhale, to the extent that it replaces oxygen in the lungs.
• Charging of the system. Number of R-134a charged into the system should be, as a rule, 80-90% of the amount of R-12 in the system. Most system manufacturers provide guidance regarding the amount of R-134a to be used.
• Lubricants (T against esters). Mineral oils used with R-12, may not be enough transported throughout the system R-134a. Manufacturers of T tests and esters refrigerant/lubricant compatibility, lubricity, chemical stability, and materials compatibility. In the process of developing recommendations, they are also considered to be additives and modifiers present in oils. The majority has decided to use PAG lubricants in new systems equipped with R-134a, and recommended PAG lubricants for modernization. Some manufacturers of compressors delivery of new compressors with T, some with esters, and some are shipping them empty. T are hygroscopic, which means that they will draw water from the atmosphere when exposed. Many aftermarket experts prefer to use ester lubricants, because they believe that hygroscopic characteristics of the T may limit its lubricating ability may cause corrosion in the system. Esters also hygroscopic (although to a lesser extent than T), and you must still be careful to excess moisture gets into the system. Good practice is to use PVC-coated gloves (or, if this is impractical, protective creams) and goggles when handling these lubricants, since prolonged contact with the skin and/or even the brief eye contact may cause irritation, such as burning, stinging sensation. You should also avoid inhalation of vapours produced oils and make sure to use them in a well-ventilated areas, not taking Tons of esters in a tightly closed container, so that the humidity of not polluting oil and so that couples can not be avoided.
• Flushing. Amount of mineral oil that can safely remain in the system after the upgrade without affecting performance, is still controversial. Initially it was assumed that any mineral oil remaining in the system may cause the system to fail. While technical staff deleted a large part of the old mineral oil as possible, any residual R-12 left in the system should not have a significant impact on system performance. Extraction of the mineral oil may require some components drain. Hoses and seals. When R-134a was first introduced, it was thought that all nonbarrier/nitrile hoses will be replaced during retrofit. At the beginning of laboratory tests showed that small R-134a molecules leaked through walls nonbarrier hoses more readily, more than of R-12 molecules did. In the laboratory, it caused unacceptably high leakage rates. More recent tests, however, showed that the oil used in the automotive air conditioning system absorbed in the hose to create a natural barrier to R-134a penetration. In most cases, R-12 hose system will work fine, provided they are in good condition. Cracked or damaged hoses should always be replaced with barrier hoses. If the fitting was broken during the process modification, substitution will not be necessary. Most of the modernization of the call instruction for lubrication replace the o-rings with mineral oil to provide this protection.
• Compressors. Industry experts once thought that modernization will require replacement of the compressor. This belief has helped create some of the horror stories about the expense of modernization. Now it is usually accepted that the majority of compressors that work well in R-12 systems will continue to work once these systems have been modified. When you first start the compressor with R-12, a thin film of metal chloride forms on the surface of bearings and acts as an excellent anti-wear agent. This film continues to defend after the system has been converted to R-134a. This helps explain why the new R-12 compressor can be completed sooner, if installed R-134a systems excluding breaks during the R-12. A couple of old compressors use seals, which are not compatible with any R-134a or new lubricants. Compressor manufacturer may determine, compressors, which need special attention.
• Capacitors and pressure cutout switches. When modernization were first studied a few years ago it was considered that the condenser and perhaps the evaporator will be replaced to maintain an acceptable level of efficiency of cooling systems upgraded. Now it is generally accepted that if R-12 system operates within specification of the manufacturer, there is probably no need to replace any parts. However, it should be noted that the higher the vapour pressure associated with R-134a would cause the loss of the capacitors. Modernization should be considered as air flow and condenser is designed for a particular vehicle, will affect the success of the modernization. It should be noted that the bent, misshapen, or improperly positioned air dams and Directors may affect performance. In addition, in systems that do not have high pressure switch must be one installed to prevent damage to the system, and to prevent emissions of refrigerants. It is recommended that the installation of the high pressure cutout switch for compressor off at high pressures encountered, reducing the likelihood of discharge pressure refrigerant and engine overheating cooling system.
• Device management. Refrigerant management (whether they are orifice tube or expansion valves that refrigerant flow meter or pressure, pressure Cycling, switches and other controls for antifreeze) can be changed in the course of modernization.