TREATMENTS AND FLUIDS
the leak is intermittent. This solution, though, will not help if the leak is buried in the fabric of the building, or the leak site is inaccessible. Leak sealants are additives which are increasingly being used for repairing leaks. These products are introduced into a system, and mix with the refrigerant and oil. When a leak occurs, the escaping cold refrigerant gas lowers the ambient air’s dew point near the hole and causes moisture to condense. These water droplets react with the sealant c omposition to form a solid chemical weld over the leak point.
This is a very convenient way of repairing leaks as it requires no pump down or recovery. Some sealants are compatible with all oils and refrigerants and suitable for all types of systems including microchannel, heat pump and geothermal. Some sealants can remain in the system, and will stop leaks quickly and prevent future ones. In addition, they will not plug up or damage system componen ts such as capillaries and TEVs, and are compressor friendly. Do be sure to check with the sealant manufacturer before using. There are even some leak sealants on the market which also contain a moisture eliminator.
Moisture eliminators
With the emergence of HFC/POE systems and the moisture problems they presented, came the development of many products to reduce and eliminate moisture. Moisture eliminators generally operate on one of two principles – thawing with alcohol (methanol, ethanol) or changing the H2O’s molecular structure with hydrolytic action.
The alcohol-based moisture eliminators are compatible with today’s refrigerants and are ideal for unblocking TXVs or capillary tubes blocked with frozen water by thawing the ice build-up. The disadvantage is that moisture still remains in the system. If enough alcohol is present, the moisture won’t freeze, but the effects of moisture, such as acid transformation or waxing, are still potential threats. Some alcohol-based moisture eliminators, which are applied by pouring into an oil injector, have the potential of accidentally being exposed to the atmosphere and causing unwanted moisture absorption in the process. Other alcohol-based moisture eliminators are injected by connecting the can directly to the refrigerant access port. They are propelled into the system using butane or
propane, which adds another refrigerant to the refrigerant-oil mix of the system.
Hydrolytic moisture eliminators do not mask the moisture with alcohols, but instead chemically change the molecular structure of water so it is no longer H2O.
They break down the hydrogen and oxygen molecules into ethanol and hemiacetals that are compatible and harmless to the refrigeration process. Hydrolytic moisture eliminators are typically applied with a vacuum-packed can .
Therefore, they are not exposed to
atmospheric moisture. Refrigerant enters the vacuum-packed can via the pressure differential between it and the system. The refrigerant mixes with the moisture eliminator and then distributes it throughout the
system without the need to introduce foreign propellants that are potentially contaminating or incompatible with the system refrigerant. There is always a concern that additives will affect the warranty of a system. This is no doubt the case, so it is wise to check with the system manufacturer before using these types of products, if the system is still under warranty.
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