Protection In Harsh Environments

March 3, 2004
/ Print / Reprints /
ShareMore
/ Text Size+
In the first step in the process, the coils and copper refrigerant are removed for cleaning. (Photos courtesy of Tim Rodwell — Blygold Houston.)
STEVENSVILLE, Md. - Even though an entire condenser and evaporator may be covered with an effective coating system, the coils must ultimately be soldered into the copper refrigerant circuit. This results in sections of the tubing being exposed to the atmosphere.

In a marine or coastal environment, this may be an acceptable condition. Bare copper is fairly resistant to the corrosive effects of salt air. This is why, for many years, copper fin/copper tube (Cu/Cu) coils have been a popular solution for corrosion in marine applications. The all-copper coil will hold up reasonably well against salt air exposure, without the galvanic corrosion inherent with dissimilar metals.

However, what works well in one environment does not necessarily work well in another. Ask anyone who has ever installed a Cu/Cu coil in a sulfur or methane environment. Cu/Cu coils are not a good solution for locations where the unit may be exposed to various aggressive acids and other chemicals. Several specific applications that come to mind include waste water treatment facilities, pulp and paper mills, refineries, chemical plants, meat and dairy processing facilities, and hog and mushroom farms.

These environments contain varying parts per million (ppm) concentrations of chemicals such as methane, ammonia, and sulfur compounds that cause exposed copper to start deteriorating.

Moreover, coating only the U-bends and headers of aluminum-copper (Al/Cu) coils will not prevent chemicals from eating away at the remaining copper tubing left uncoated inside the unit. Pitting on tubing walls may cause pinholes to develop, which in turn cause the coil to leak. Exposed solder joints are particularly vulnerable to attack.

Next, the end plates, U-bends, compressor, and complete copper circuit are primed.

Cover All Bases

The solution for these environments is to provide an effective protective coating for all of the exposed copper in the circuit, as well as the copper on the condenser and evaporator coils. Typically an aftermarket modification/coating service provider can perform these services for new equipment. This is best done before the equipment goes into the field.

Once corrosion starts, it is very difficult (and usually not cost-effective) to contain. A small investment at the beginning of a project can bring big savings in terms of possible downtime costs, leak repairs, coil replacements, and unit efficiency losses (increased energy consumption).

On smaller units, the entire refrigerant circuit can be removed for coating. In addition to making the job easier, the circuit is not cut and the refrigerant does not have to be recovered. Larger units may require some disassembly for accessibility. The coils may need to be removed for coating, depending on the extent of access and the coating system used.

Either way, the coils' galvanized end plates should be prepped in accordance with a coating system.

Then, the coils, compressor, and the complete copper circuit are topcoated with PoluAl and reinstalled in the cabinet.
The coils and all exposed tubing should be washed thoroughly with an effective detergent, rinsed, and allowed to dry. It is important to use a detergent that is effective but not harsh, and one that does not leave a residue.

A primer formulated for use on copper should be applied to all exposed tubing to provide an enhanced adhering surface for the topcoat.

Once the primer is dry, the topcoat can be applied to the tubing and the coils.

If the circuit has been cut when the coils were removed for coating, it must be resoldered, tested, and the refrigerant recharged. In this instance, the areas left uncoated for soldering will need to be washed, dried, and touched up with the primer and topcoat.

Griffin is the marketing manager of Blygold America Inc. For more information, call 410-643-6080 or visit www.blygoldamerica.com.

Publication date: 03/08/2004

Did you enjoy this article? Click here to subscribe to The NEWS Magazine

You must login or register in order to post a comment.

Multimedia

Videos

Image Galleries

2014 Energy Efficiency Forum

Highlights from the 25th annual Energy Efficiency Forum in Washington, D.C.

Podcasts

NEWSMakers: John Missell

John Missell, vice president and COO of Spectrum Design, joins the program to discuss how his company has utilized geothermal technologies, and we examine the future of renewable energy resources. Posted on Aug. 15.

More Podcasts

ACHRNEWS

NEWS 08-18-14 cover

2014 August 18

Check out the weekly edition of The NEWS today!

Table Of Contents Subscribe

Prohibiting HFCs

EPA is proposing a rule that would prohibit some HFCs in select refrigeration applications. Do you agree with this move?
View Results Poll Archive

HVACR INDUSTRY STORE

plumbing-hvac.gif
2014 National Plumbing & HVAC Estimator

Every plumbing and HVAC estimator can use the cost estimates in this practical manual!

More Products

Clear Seas Research

 

Clear Seas ResearchWith access to over one million professionals and more than 60 industry-specific publications, Clear Seas Research offers relevant insights from those who know your industry best. Let us customize a market research solution that exceeds your marketing goals.

DON'T MISS A THING

Magazine image
 
Register today for complete access to ACHRNews.com. Get full access to the latest features, Extra Edition, and more.

STAY CONNECTED

facebook icontwitter iconyoutube iconLinkedIn i con