Sealers: Friend or Foe

October 5, 2009
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HVACR contractors wanting to use sealants to fix small leaks are being encouraged to use products specifically designed for the stationary sector; rather than those targeted for automotive.

With more than 1 million sealant applications now sealing and preventing leaks in air conditioning/refrigeration systems worldwide, the odds are high most service techs will be confronted, if not already, with recovering refrigerants that have sealants in them.

Regardless whether or not a service technician believes in or uses them, high-technology sealants are here to stay and a bona fide tool today of many HVACR service techs.

Therefore, a common question among service techs inexperienced with sealants is whether recovered refrigerant/sealant combinations will clog their manifold gauges, recovery machines, driers, and/or be rejected by their refrigerant reclamation vendor.

Many of the myths about sealants are derived mostly from the automotive a/c industry, which unlike the HVACR industry, has over a dozen sealant brands/types that work in various degrees of success. Another dissimilarity with the HVACR industry is the fact that automotive sealants are many times applied by unqualified do-it-yourselfers. Consequently, there are many overdoses, which can lead to some of the aforementioned problems until a qualified automotive mechanic is called in.

Since HVACR systems are comparably larger than their automotive counterparts, overdosing is rare. And, unlike automotive a/c, HVACR sealants (such as Cliplight Manufacturing’s Super Seal product line) are applied in 1-3-ounce doses, depending on the size of the system. Since a manufacturer gives specific guidelines, overdosing should not be an issue when qualified service techs work on the system.

Another dissimilarity is a chemical that swells gaskets in automotive a/c system sealants, which if included in sealants specifically designed for the HVACR industry, would cause a corrosive effect on HVACR systems compressor motor windings. This chemical is not present or needed in HVACR sealants. For this reason, it isn’t advisable to use automotive-based sealants in HVACR systems.

WHAT HVAC SEALANTS WON'T DO

Therefore, properly applied vacuum-packed HVACR sealants that meet Air-Conditioning, Heating and Refrigeration Institute (AHRI) purity standards do not clog manifold gauges, recovery machine gauges, thermostatic expansion valves, compressors, or driers. This applies to both driers that come standard with some recovery machines as well as additional driers some service techs like adding inline for protection against excess moisture and/or fine particulates. Additionally, recovered refrigerants with sealants that originated from vacuum-sealed packaging versus those that use hydrocarbons for propellants are not rejected by commercial reclamation companies.

One lesser-known fact about HVACR sealants is that they work best when a responsible approach is used, namely on systems with holes 300 microns and smaller, which is about the diameter of the human hair. No sealants have the ability to form a permanent seal in larger orifices or in the comparably larger openings of gauges.

Also, when gauges are used on systems containing sealants, the sealant has already reached system equalization, is less concentrated, and therefore does not adversely affect the manifold gauges or hoses.

However, it’s always good to know whether a system ready for recovery has sealant in it or not, especially if the refrigerant is later reapplied. Service techs that use sealants typically mark the system with a tag that’s originally supplied with the sealant application packaging.

A useful tool developed to solve the aforementioned automotive problems and now marketed to the HVACR trade is the Quick Detect by Neutronics Inc., which senses sealants in HVACR systems.

Quick Detect requires a system under pressure with refrigerant and oil to operate properly when its cartridge is connected to the high-pressure side port. It also requires a small amount of water injected into the cartridge by the service tech. Once connected, the cartridge simulates a leak as refrigerant flows through 1,500 microscopic orifices, which is considered “de minimis” release and allowable within the Environmental Protection Agency’s guidelines. If a system has sealant, one or more holes will be bonded and the flow of refrigerant through the flow meter will be greatly reduced. It works with all refrigerants.

Peter Coll, Neutronics’ refrigerant analysis product manager, said Quick Detect is now making the same inroads into the HVACR market, as it has the last five years in the automotive market as sealants become increasingly popular.

As previously mentioned, overdosing is not a problem in HVACR systems. However it’s important to know if sealant is already present in the system in order to properly diagnose, if needed.

Another precaution that has recently come to light involves sealants that use hydrocarbon refrigerants to propel the sealant versus the HVACR industry’s original sealants in vacuum-packed sealants. Vacuum-packed sealants use system pressure differences to draw the system’s own refrigerant into the can to mix with it then propels the sealant into the system while maintaining AHRI refrigerant purity standards.

For example, an HCFC-22 system that becomes contaminated with a hydrocarbon of the sealant is no longer AHRI certified. Plus there’s a good chance it will carry a reclamation surcharge or not be accepted at all from a reclamation company, according to Coll.

“Mixing in hydrocarbons with refrigerants within a system, we (Neutronics) feel is an unacceptable combination and practice,” said Coll. “If sealants with hydrocarbons as propellants become popular, we feel this will potentially contaminate and lessen the dwindling supply of R-22 around the world.”

REFRIGERANT RECLAMATION

Refrigerant reclamation companies can separate sealants and any other liquids out from the refrigerant, unless it has been contaminated with another refrigerant, in nearly any state to ISO-12810 or AHRI-740 specifications.

For example, the reclaimer RMS of Georgia has never had a failure in its company history in removing sealants and/or return the refrigerant to AHRI-700 standards, according to President Ken Ponder.

To recycle refrigerants, refrigerant reclamation companies perform four main tasks: filter out particulates, separate liquids (oils, sealants, etc.), boil off water, and dilute or reform (if needed) the refrigerant.

Since a sealant formula remains a liquid throughout its lifespan within the refrigerant, it can be separated from the refrigerant along with other liquids such as oil, moisture, etc.

Whether or not a service tech approves of using vacuum-packed sealants as an inexpensive alternative to conventional repairs when leaks are indiscoverable or inaccessible, sealants will continue to be more present in refrigerants during the recovery process.

Publication date: 10/05/2009

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