SELECTION GUIDE: ENVIRONMENTAL CORROSION PROTECTION

SELECTION GUIDE:

ENVIRONMENTAL CORROSION

PROTECTION

Condenser Coils and Cooling/Heating Coils

for Commercial Products

Carrier Corporation

Syracuse, New York

December 2012

TABLE OF CONTENTS

INTRODUCTION .............................................................. 2

CORROSION ................................................................. 2-4

Localized Corrosion .................................................... 2

General Corrosion........................................................ 4

CORROSIVE ENVIRONMENTS ................................. 4-6

Coastal/Marine ............................................................ 4

Industrial ...................................................................... 5

Combination Coastal/Marine and Industrial ................ 5

Urban ........................................................................... 5

Rural ............................................................................ 5

Localized Environment—Corrosivity of

the Surroundings ..................................................... 6

CORROSION PROTECTION ..................................... 7-11

Condenser Coils ........................................................... 7

Cooling/Heating Coils ................................................. 8

Carrier’s E-Coating Process ........................................ 9

E-Coated Material and Chemical Resistance ............... 9

Field-Applied Coatings .............................................. 11

SELECTION SUMMARY ........................................... 11-13

Selection Tables ......................................................... 11

Selection Example ..................................................... 11

JOB SITE COMMISSIONING AND PROPER

EQUIPMENT STORAGE ................................................. 14

COIL MAINTENANCE AND CLEANING

RECOMMENDATIONS ................................................... 14

APPENDIX ........................................................................ 15

E-Coating Chemical Resistance Guide ...................... 15

_________________________________________________________________________________________________________

INTRODUCTION

Corrosion is costly. By definition, corrosion is the

destruction or deterioration of a metal or alloy due to a

reaction with an environment.

In HVAC/R equipment, heat exchangers, including

condensers, evaporators, and hydronic coils, must be

protected from environments that may lead to

localized and/or generalized corrosion. Corrosion of

heat exchangers may lead to performance loss,

unsightly appearance, and possible equipment failure.

Fortunately, the harmful effects of coil corrosion can

be significantly delayed or avoided if the application

environment is correctly identified and the appropriate

corrosion protection option is selected.

This selection guide will provide information on

the causes of corrosion and identify corrosive

environments in order to aid in the selection of the

proper coil.

CORROSION

There are many types of corrosion. The two forms of

corrosion most common to HVAC/R equipment are

known as localized (galvanic, pitting, or formicary

corrosion) and general corrosion. Each of these

corrosion types can lead to equipment failure,

depending on conditions and the material systems

used.

Localized Corrosion

ROUND TUBE PLATE FIN COILS

One form of localized corrosion is galvanic corrosion.

The necessary conditions for galvanic corrosion occur

when dissimilar metals, in contact, are exposed to an

electrolyte, a substance that is electrically conductive

when dissolved in water. The environment creates the

electrolytes necessary for general and localized

corrosion of materials.

Standard round tube plate fin (RTPF) condenser coils

have copper tubes mechanically bonded to aluminum

fins with wavy enhancements. Figure 1 shows a cross-

section of a copper tube and several aluminum fins.

High thermal efficiency is achieved through direct

metallic contact between the tube and fin. As a result,

maximum thermal performance is achieved with this

high-efficiency coil design, provided there is no

corrosion.

Fig. 1. Standard Coil Construction

Figure 2 shows a typical RTPF coil prior to galvanic

corrosion.

During galvanic corrosion, the aluminum fin initially

corrodes at the copper/aluminum interface as this is

the point of electrical contact between the dissimilar

metals. As corrosion of the aluminum fin progresses,

the fin conductivity deteriorates which in turn reduces

the coil thermal performance. Aluminum oxide

deposits that are formed in the process (Fig. 3) can

further reduce performance by impeding air flow

through the coil.

One way of preventing galvanic corrosion of RTPF

coils is through the effective elimination of the bi-

metallic couple. An example of this approach is the

all-copper RTPF coil. The use of an all-copper

construction, i.e., copper tube/copper fin, virtually

eliminates the presence of dissimilar metals, one of the

necessary requirements for galvanic corrosion.

Another method commonly used to prevent galvanic

corrosion is to isolate the two dissimilar metals from

the electrolyte through use of a protective coating. The

protective coating in effect creates a barrier between

the dissimilar metallic couple and the electrolyte,

thereby eliminating the electrolyte from this interface.

A third way to prevent galvanic corrosion is to insulate

the electrical connection of the copper and the

aluminum through the use of a pre-coated aluminum

fin. The pre-coating insulation removes the electrical

contact of the dissimilar metals.

NOVATION

HEAT EXCHANGERS WITH

MICROCHANNEL COIL TECHNOLOGY

Novation

heat exchangers with microchannel coil

technology utilize several aluminum alloys in

combination with a metallic coating. The alloys are

carefully chosen to extend the life of the coil.

Furthermore, the coil has been designed so that any

galvanic couple within the coil has been carefully

chosen to provide the maximum life possible for the

coil.

The refrigerant carrying tube is essentially flat, with its

interior sectioned into a series of multiple, parallel

flow microchannels that contain the refrigerant (Fig 4).

In between the flat tube microchannels are fins that

have been optimized to increase heat transfer.

The microchannel tubes in the heat exchanger have

excellent heat transfer characteristics on the refrigerant

side. On the air side, heat transfer is improved due to

the enhanced surface area contact and the

metallurgical bond between tube and fin. Fin design is

optimized to enhance the fin heat transfer

performance. The fin-to-tube bond reduces thermal

resistance between tube and fin, resulting in better heat

conduction.

The microchannel heat exchanger (MCHX) coil design

uses zinc-enriched surfaces that perform in a manner

similar to the zinc layer in galvanized steel. The zinc-

enriched surface allows the tube to weather laterally,

preventing corrosion pits from progressing deeply into

the tube. The zinc layer will not be consumed during

the effective service life of the MCHX coil when the

coil is applied properly.

Fig. 2. Standard Copper Tube/Aluminum Fin Coil

Fig. 3. Galvanic Corrosion Begins

Fig. 4. Microchannel/Fin Center

In corrosive environments an unprotected coil may

face a rapid direct pitting attack of the tube and/or

tube-to-manifold joint, which may lead to a

catastrophic refrigerant leak and system failure. These

conditions can be found in aggressive marine,

industrial, urban, or highly alkaline environments.

The latter condition can occur, for example, at new

construction sites if the unprotected MCHX coil is

exposed to excessive quantities of concrete dust and

moisture.

A protective coating may be applied to MCHX coils

for use in corrosive application environments.

General Corrosion

General corrosion is the degradation of metal caused

by a reaction with the surrounding environment. Since

general corrosion consumes metal and typically forms

metal oxides, unsightly surface conditions usually

result. Unprotected metal will continue to react with

the contaminant resulting in corrosion. Under severe,

prolonged conditions, the metal continues to corrode

until the integrity of the material and equipment is

jeopardized. Unprotected copper or aluminum tubes in

polluted industrial environments can lead to tube leaks

and failure of the refrigeration system. Sulfur and

nitrogen based electrolytes in combination with

chloride environments are often the cause of

accelerated corrosion of these metals.

The environment in which HVAC/R equipment is

applied varies throughout the globe and in some

instances, even within a local area. Corrosive

environments occur not only in coastal or marine

climates and industrial areas, but also are present in

urban or rural areas, localized microclimates, and

combinations of these conditions. Factors including

but not limited to the presence of flue gas, sewage

vents or open sewage systems and diesel exhaust can

all have a detrimental effect on HVAC/R coils.

These pollutants, in combination with other factors

such as wind direction, humidity, water, fog,

temperature, proximity to pollutant source, and dust or

particle contamination, may result in the premature

failure of equipment.

For both RTPF and MCHX coils it is therefore critical

that the application environment is properly identified,

and if needed, the appropriate corrosion protection is

used.

CORROSIVE ENVIRONMENTS

As previously discussed, potentially corrosive outdoor

environments include areas adjacent to the seacoast,

industrial sites, heavily populated urban areas, some

rural locations, or combinations of any of these

environments. These macro environments are often

characterized as rural, urban, coastal (marine),

industrial, or industrial marine. In addition, some air-

handling applications, indoor environments such as

swimming pool areas, water treatment facilities, and

industrial process areas can also produce corrosive

atmospheres.

Local environments called micro environments must

also be considered. Close proximity to laundry

facilities, diesel-burning devices/exhaust piping, sewer

vents, and traffic can lead to premature failure of

improperly protected equipment, in a similar manner

as the macro environmental conditions.

Contaminants in an environment typically result in the

creation of electrolytes that facilitate the corrosion

process. Electrolytes are substances that are

electrically conductive when dissolved in water.

Common electrolytes may contain chloride

contaminants from sources such as seawater, road

salts, cement dust, pool cleaners, laundry facilities, and

household cleaning agents, which are typically sodium

or calcium chloride-based compounds. Other relevant

contaminants that contribute to the formation of

electrolytes include sulfur and nitrogen bearing

compounds from the combustion of coal and fuel oils.

Chemical contamination from industrial processes,

e.g., ammonia, can also contribute to the formation of

an electrolyte.

In view of this it is necessary to identify each of these

environments so that appropriate corrosion protection

methods may be used.

Coastal/Marine

Many emerging HVAC/R

markets have a majority of

their populations located

in coastal regions, leading

to an increased number of

applications in corrosive

environments. Coastal or

marine environments are

characterized by the

abundance of sodium

chloride (salt) and sulfur

compounds that are

carried by sea spray, mist,

fog, or prevailing winds. Sea spray, mist, and fog

contain tiny droplets of salt water that can be

transported many miles by ocean breezes and result in

equipment contamination. The deposition of salt

water spray onto metallic substances is the most

corrosive aspect of the marine environment.

Several factors should be considered when choosing

the best solution for a coastal or marine environment:

land formation (e.g., islands, depending on size, often

are influenced by coastal contaminations); distance

from the coast and the direction of the prevailing

winds (wind direction helps to determine the distance

that contaminants can be carried); corrosion on other

equipment or infrastructure in the area (an excellent

indicator of the corrosiveness of the environment);

common practices that have worked well in the area;

and other pollution sources, such as industrial

influences.

Industrial

Industrial environments

are very diverse, with the

potential to produce a

variety of corrosive

compounds. An industrial

environment can exist on a

macro or micro scale, each

with the same detrimental

effect. Sulfur and nitrogen

containing contaminants

are most often linked but

not limited to industrial

and high-density urban

environments. Combustion of coal and fuel oils release

sulfur oxides (SO

, SO

) and nitrogen oxides (NO

)

into the atmosphere. Other contributors such as

ammonia and its salts and hydrogen sulfide can have a

detrimental effect on materials. Many of these gases

accumulate in the atmosphere and return to the ground

in the form of acid rain or low pH (acidic) dew.

Not only are industrial emissions potentially corrosive,

but many industrial dust particles can be laden with

harmful metal oxides, chlorides, sulfates, sulfuric acid,

carbon and carbon compounds. These particles, in the

presence of oxygen, water, or high humidity can be

highly corrosive and may lead to many forms of

corrosion including general corrosion and localized

corrosion such as pitting and formicary corrosion.

Combination

Coastal/Marine and

Industrial

Salt-laden seawater mist,

combined with the harmful

emissions of an industrial

environment (either on a

macro or micro level), poses

a severe threat to the life of

HVAC/R equipment. The

combined effects of salt

contamination and industrial

emissions will accelerate

corrosion of any improperly protected coil. This harsh

environment requires superior corrosion resistant

properties for HVAC/R components to maintain

acceptable product quality. Complete encapsulation of

the coil surfaces (such as e-coating for MCHX coils) is

strongly recommended. When identifying this type of

environment it is essential that local influences not be

overlooked. Open sewage systems, vents, diesel

exhaust, emissions from dense traffic, landfills, aircraft

and ocean vessel exhaust, industrial manufacturing,

chemical treatment facilities (cooling tower

proximity), and fossil fuel burning power plants are

potential contributors to consider.

Urban

Highly populated areas

generally have high levels of

automobile emissions and

high rates of the byproducts

of the combustion of

building heating fuels. Both

conditions elevate sulfur

oxide (SO

) and nitrogen

oxide (NO

) concentrations.

Corrosion severity in this

environment is a function of

pollution levels, humidity,

average temperature, and equipment usage, which in

turn depend on several factors including population

density for the area, emission control, and local

pollution standards. In areas with rapid growth, such

as many areas in China and India, contamination levels

can change drastically; thus, the future direction of a

region should be considered when looking at the best

corrosion protection system.

Note that any HVAC/R equipment installed near diesel

exhaust, incinerator discharge stacks, fuel-burning

boiler stacks, areas exposed to fossil fuel combustion

emissions, or areas with high automobile emissions

should be considered industrial applications.

Rural

A rural environment typically is unpolluted by exhaust

and sulfur containing gases. Rural environments are

usually sufficiently inland so that contamination and

high humidity from coastal waters are not present. Coil

protection in these environments is typically not

required beyond the standard MCHX coil or aluminum

fin/copper tube offerings.

However, rural environments may contain high levels

of ammonia and nitrogen contamination from animal

excrement, fertilizers, and high concentrations of

diesel exhaust. In this case, these environments should

be considered industrial applications and would

require e-coated coil protection.

Localized Environment - Corrosivity of the

Surroundings

All of the above environments are subject to

microclimates that can significantly increase the

corrosivity of the environment. Care should be taken

to ensure that the localized environment surrounding

the HVAC/R equipment does not contain

contaminants that will be detrimental to the

equipment. An example would be equipment placed

near a diesel vehicle loading area or a diesel generator.

Although the general area in which the building is

located may meet the scope of a coastal or marine

environment, the localized elements that surround the

equipment may actually classify the application as

industrial or industrial marine, and protection of the

coil should be planned accordingly.

Localized environments can result from a variety of

contaminants, including but not limited to those

originating with:

 Traffic

 Airports

 Power plants

 Power generators

 Factories and chemical plants

 Breweries and food processing plants

 Wastewater treatment plants

 Dumps and incineration plants

 Cruise ships and shipping traffic

 Swampy areas (rotting vegetation)

 Farms and nurseries

 Fisheries

The contaminants in the preceding list must be

considered in combination with other contributing

factors, including but not limited to:

 Distance from contaminant source. The most

detrimental effect in a micro environment occurs

within 50 ft (15 meters); in a macro environment,

within 1 mile (1.6 km)

 Prevailing wind direction

 Acid rain (note that sources may be hundreds of

miles away)

 Condensation

 Temperature

 Humidity

The following are examples of contaminants that can

create a micro environment within 50 ft (15 meters).

(See Fig. 5.):

 Heavy/frequent fertilizer or insecticide usage

 Chemical/cleaner storage areas

 Bus or truck loading areas or heavy traffic

 Power generators

 Fan-powered exhaust vents

 Cooling towers due to drift of chemical treatments

Fig. 5. Sources of Contaminants in Micro Environments

Diesel Bus Loading Area

Diesel Tank/ Loadin

Area

Cooling Tower

Plumbin

Vent Stack

Laundr

Vent

Exhaust Vent

CORROSION PROTECTION

The choices available for Carrier’s commercial

products offer protection for most common aggressive

environments. Note that not all options are available

for all products. For information on coil options for

specific products, consult your Carrier sales office.

Condenser Coils

MCHX COILS

MCHX coils are constructed utilizing all-aluminum

alloys with brazed fin construction. Microchannel

heat exchangers provide high thermal performance per

unit volume. Unprotected MCHX coils should never

be applied in corrosive environments.

E-Coated MCHX Coils

E-coated coils provide superior protection against

many corrosive atmospheres. E-coated MCHX coils

have an extremely durable and flexible epoxy coating

uniformly applied over all coil surfaces for complete

isolation from the contaminated environment. A

consistent coating is achieved through a precisely

controlled electrocoating process that bonds a thin,

impermeable epoxy coating to the specially prepared

coil surfaces. A detailed description of the proprietary

Carrier e-coating process is provided on page 9.

RTPF COILS

The standard aluminum fin/copper tube coil generally

provides high performance for non-corrosive

environments (e.g., non-polluted rural environments).

Application of this coil in any environment containing

corrosive elements is not recommended because of the

likelihood of deterioration resulting from corrosion.

Pre-Coated Aluminum-Fin Coils

Pre-coated aluminum fin/copper tube coils have a

durable coating applied to the fin. This design offers

protection in mildly corrosive coastal environments,

but is not recommended in severe industrial or coastal

environments.

Aluminum fin stock is coated with a baked-on coating

prior to the fin stamping process (Fig. 6). Coating of

the fin material prior to the fin stamping process is

known as “pre-coating.” The pre-coated fin material is

then stamped to form the desired fin pattern for

optimum thermal performance.

A thin layer of a non-metallic pre-coating material

insulates the dissimilar metals of the coil (copper tube

and aluminum fin) from one another. As a result, the

electrical connection between the copper and

aluminum is disrupted, thus minimizing galvanic

corrosion. In mild coastal environments pre-coated

coils are an economical alternative to e-coated coils

and offer improved corrosion protection beyond the

standard uncoated copper tube/aluminum fin coil.

Copper-Fin Coils

Typically, a copper wavy fin pattern is mechanically

bonded to the standard copper tube. Protective

isolators are installed between the coil assembly and

sheet metal coil support pan to further protect the coil

assembly from galvanic corrosion. (See Fig. 7.)

Copper is generally resistant to unpolluted

coastal

environments due to a natural protective film that is

formed on the copper surfaces. Furthermore, galvanic

corrosion is not an issue in these mono-metal coils.

However, copper-fin coils are priced significantly

higher than other coil options since material costs for

copper are greater than those for aluminum. Other

alternatives (see summary guide) provide preferred

solutions for most applications.

Fig. 6. Pre-Coated Coil Assembly

Fig. 7. Copper-Fin Coil Assembly

Uncoated copper coils are not suitable

for dense urban,

polluted coastal applications, industrial applications, or

industrial marine applications since many pollutants

attack copper putting both the fin and the tube at risk.

The use of uncoated copper in these applications is not

recommended. E-coated aluminum fin/copper tube or

e-coated MCHX coils should be considered for such

applications.

E-Coated Aluminum-Fin Coils

E-coated coils provide superior protection against

many corrosive atmospheres with the exception of

formic acid and nitric acid environments.

The aluminum fin/copper tube coils are e-coated using

the same proprietary process described above. A very

flexible and durable epoxy coating is uniformly

applied over all coil surfaces for complete isolation

from the contaminated environment (Fig. 8). A

consistent coating is achieved through a precisely

controlled electrocoating process that bonds a thin,

impermeable epoxy coating to the specially prepared

coil surfaces.

The proprietary Carrier e-coating process is described

in further detail on page 9.

E-Coated Copper-Fin Coils (not available with all

products)

E-coated copper fin/copper tube coils have the same

durable and flexible epoxy coating uniformly applied

over all coil surfaces as the e-coated aluminum-fin

coils (Fig. 9). However, these coils combine the

natural resistance of all-copper construction with

complete encapsulation from the e-coat process. As

noted previously, e-coated copper fin/copper tube coils

may be specified for severe marine environments that

are void of industrial contaminants.

Cooling/Heating Coils

Standard Coil Construction

The standard cooling/heating coil (water, steam or

direct expansion) has copper tubes mechanically

bonded to aluminum fins. The fin pack is assembled

with galvanized steel tube sheets and coil case. This

assembly has classic galvanic corrosion components

with multi-metal bonds between the fin-and-tube and

tube-and-tube sheet.

In cooling applications, condensate accumulates on the

coil surfaces when dehumidification occurs. Wet coil

surfaces resulting from condensation in the presence of

a contaminated airstream will lead to galvanic

corrosion if not properly protected.

Potentially corrosive airstreams may not be suitable

for building occupants. If a contaminated airstream

can lead to corrosion, special consideration with

respect to indoor air quality and potentially harmful

side effects to building occupants is recommended.

Copper Fin/Copper Tube Coils

Much like the all-copper condenser coil, all-copper

cooling/heating coils eliminate the bi-metallic bond

found on standard coils. A copper fin with wavy

pattern is mechanically bonded to the standard copper

tube to ensure a single-metal assembly. Most air-

handling equipment is available with copper or

stainless steel tube sheets and coil cases to improve the

corrosion durability of the entire coil assembly. As a

result of the reduction of the bi-metallic couples, the

potential for corrosion within the coil assembly is

reduced.

Fig. 8. Magnification of E-Coated

Aluminum Fin/Copper Tube Coil

Fig. 9. E-Coated Copper Coil

E-Coated Coils

E-coated cooling/heating coils have the same e-coating

as the condenser coils. All e-coated coils have a

durable and flexible epoxy coating uniformly applied

over all coil surfaces, including tubesheets and coil

cases. The coating provides a barrier between the coil

surfaces and the corrosive effects of the atmosphere.

In considering e-coated coils, it is important to also

consider the effects of moisture carryover. Moisture

carryover occurs when accumulated condensation is

blown from the coil surface during cooling coil

applications. The extent of carryover is a function of

airstream velocity across the coil, fin spacing, fin

geometry and material of construction. When e-

coating is applied to a cooling coil, carryover will

occur at lower coil face velocities. Recommendations

shown in Table A should be considered when selecting

chilled water or DX (direct expansion) coils to ensure

moisture carryover will be prevented.

Table A

Maximum Recommended Face Velocity (FPM)*

Fin Spacing

(FPI)

Aluminum-

Fin Coil

Copper-Fin

Coil

E-Coated

Coil

8 650 500 500

11 650 425 425

14 575 375 375

FPI - Fins per Inch

FPM - Feet per Minute

*External fouling on cooling coils will adversely affect the

maximum recommended face velocities. Data based on

clean coils with proper filtration and periodic cleaning of coil

surfaces

Carrier’s E-Coating Process

Electrocoating is a multi-step process that ensures ultra

clean coils are properly coated, cured, and protected

from environmental attack (Fig. 10). This process

includes complete immersion cleaning to remove

contamination and ensure all surfaces are ultra clean.

The water bath rinses residual dust and contamination

away in preparation for the e-coating process. The

fundamental principle of electrocoating is that the

materials with opposite electrical charges attract each

other. An electrocoating system applies a DC charge to

the coil immersed in a bath of oppositely charged

epoxy molecules. The molecules are drawn to the

metal, forming an even, continuous film over the

entire surface. At a certain point, the coating film

insulates the metal, stopping the attraction, and

preventing further coating deposition (self-limiting

nature of the coating process).

The final rinse bath removes and recovers residual

coating material to ensure a smooth coating and

minimize process waste. A precisely controlled oven

bake cures the coating uniformly to ensure consistent

adhesion on all coil surfaces. This electrocoating

process creates a smooth, consistent, and flexible

coating that penetrates deep into all coil cavities and

covers the entire coil assembly including the fin edges.

The process in conjunction with the coating material

results in a less brittle, more resilient, and more

durable coating without bridging between adjacent

fins. E-coated coils provide superior protection in the

most severe environments.

Finally, a UV protective topcoat is applied to shield

the finish from ultraviolet degradation and to ensure

coating durability and long life.

E-Coated Material and Chemical Resistance

Chemical resistance of the e-coating material is

described in the appendix, “E-Coating Chemical

Resistance Guide.” Application of an e-coated coil

should only be considered when the contaminant is

listed in the Appendix guide. If the e-coating is NOT

resistant to the contaminant listed or if the contaminant

is not listed in the appendix, application in this

environment is not recommended. Contact your

Carrier representative for further guidance.

Some common industrial processes and their related

contaminants that are resisted by the e-coated coils are

shown in Table B.

Fig. 10. E-Coating Process

Cleaning

Table B

Industrial Contaminants

Type of Industry/Application Source of Contaminant Contaminant

Pulp, Paper and Lumber Plants Process Emissions Nitrogen Oxides

Sulfur Oxides

Pulp Bleaching Dichloromethane

Chloroform

Methyl Ethyl Ketone

Carbon Disulphide

Chlormethane

Trichloroethane

Sulphite Mill Operations Sulfur Oxides

Kraft Pulping and Recovery Processes Volatile Organic Compounds

Chip Digester and Liquid Evaporator Terpenes

Alcohols

Phenols

Methanol

Acetone

Methyl Ethyl Ketone

Products of Combustion Nitrogen Oxides

Sulfur Oxides

Carbon Monoxide

Particulate Matter

Fly Ash

Incineration Facilities

Fuel Burning Power Generation

Diesel/Gasoline Engine Operation

Products of Combustion Sulfur Oxides

Nitrogen Oxides

Sulfur Trioxide

Sulfuric Acid

Ammonium Sulfate

Ammonium Bisulfate

Carbon Dioxide

Sulphate

Nitrate

Hydrochloric Acid

Hydrogen Fluoride

Particulate Matter

Ozone

Volatile Organic Compounds

Cleaning Agent Processing Process Emissions

Chlorine

Chlorides

Salt Mining/Processing

Swimming Pool Agents

Process By-Products Bromine

Chlorine

Sulfate

Sodium Bisulfate

Phosphate

Chlorides

Fertilizer Manufacturers Process By-Products Hydrogen Fluoride

Sulfites

Sulfuric Acid

Hydrofluoric Acid

Phosphoric Acid

Fluorosiliac Acid

Ammonia

Ammonia Salts

Waste Water Treatment Facilities Waste Digestion Methane

Sulfur Dioxide

Nitrogen Oxides

Volatile Organic Compounds

Chlorine

Chlorine Dioxide

Ammonia

Ammonia Salts

Sludge Processing Hydrogen Sulfide

Agriculture Animal Waste and Fertilizers Sulfu

Nitrous Oxide

Nitrogen Oxides

Methane

Hydrogen Sulfide

Ammonia

Ammonia Salts

Field-Applied Coatings

Field-applied sprayed-on coatings will not provide

sufficient protection in corrosive environments and

should not be used on Carrier coils. The use of field-

applied coatings on Novation

heat exchangers may

negatively affect the Carrier warranty. Possible

reasons for inadequate protection include:

 Coil cleanliness is crucial for proper adhesion.

Adequate field cleaning techniques are often

overlooked. In addition, the coil must be void

of any corrosion. Encapsulation of existing

corrosion makes the coating ineffective by

leading to continued deterioration and

eventual coating delamination.

 Field application cannot ensure continuous

coating of coil surfaces on multiple row coils.

It is difficult to ensure uniform coating quality

throughout the depth of the fin pack.

 Interior coil surfaces remain untreated when

sprayed-on from unit exterior; often, spray

applicators cannot reach deep into the coil

assemblies, leaving inconsistent thickness or

areas of no coverage.

 Inconsistent coating thickness can minimize

or negate coating protection. Recommended

coating thickness cannot be ensured with field

application on multiple row coils. Film

thickness measurements are often overlooked.

___________________________________________________________________________________________

SELECTION SUMMARY

Selection Tables

Tables C through F provide guidelines for coil

selection. To use the tables, first clearly identify the

operating environment for the intended installation.

Then determine the severity of each environmental

factor associated with the installation site. Choose the

protection option based on the most severe

environmental factor anticipated for the given site.

NOTE: In these tables, acceptability of a coil option is

based solely on corrosion performance. Other factors,

including cost, should be considered in making the final

coil selections.

For MCHX coils, the Carrier Electronic Catalog

(E-CAT) can be used to obtain confirmation on

whether or not corrosion protection is recommended

for particular applications in coastal/marine

environments.

Selection Example

Following is an example of the selection process as

applied to a coastal environment.

Step 1 – Identify the operating environment

according to the factors described in Table C.

For this example:

a. Site is on the coastline (distance from the coast is

<0.01 miles).

b. Condenser coil is facing the ocean, with the

direction of the prevailing wind from the coast to

the unit.

c. No noticeable corrosion on other equipment.

Step 2 – Determine the severity of each

environmental factor; always choose the option for

the most severe environmental factor present.

There is no noticeable corrosion on the unit, which

means low severity for this factor; however, the

distance from the coast and the prevailing wind are

both in the severe category, so coil selection should be

guided by recommendations in the last column on the

right, at the severe end of the range.

Step 3 – Identify coil options.

The acceptable coil options are as follows: copper

fin/copper tube, e-coated aluminum fin/copper tube, e-

coated microchannel heat exchanger coil, or e-coated

copper fin/copper tube coil.

Table C

Coastal Environment Protection Option

Global Coil and Coating Options*

Severity of Environmental Factors

Low

Severe

Distance from Coast**

Inland

> 5 mi 5 to 2 mi

Coastline

< 2mi to <0.01 mi

Direction of Prevailing Winds

From Unit to Coast From Coast to Unit

Corrosion Present on Other Equipment

None Present Noticeable Corrosion

Standard: Aluminum Fin / Copper Tube ACC ACC NR

Microchannel Heat Exchanger† ACC ACC NR

Pre-Coated Aluminum Fin / Copper Tube ACC ACC NR

Copper Fin / Copper Tube ACC ACC ACC

E-Coated Aluminum Fin / Copper Tube ACC ACC ACC

E-Coated Microchannel Heat Exchanger† ACC ACC ACC

E-Coated Copper Fin / Copper Tube ACC ACC ACC

ACC - Indicates that the option is acceptable for the application

and conditions shown; in some cases, the level of

corrosion protection provided by this option may be higher

than required. Acceptability is based solely on corrosion

performance. Other factors, including cost, should be

considered in making the final selections.

NR - Not recommended

*Other coating options may be available within a given region.

†Information in this table is provided as a guide; contact a Carrier

Sales Engineer for an E-CAT selection.

**Refer to the E-CAT program for exact distance requirements

for MCHX coils.

Note: The distances stated relate to land distances to ocean.

Additional coating may be required for Marine Applications on-

board a ship.

Environments immediately adjacent to diesel exhaust,

incinerator discharge stacks, fuel burning boiler stacks, or areas

exposed to fossil fuel combustion emissions should be

considered a Combined Coastal/Industrial application.

Recommendations presented for Industrial and Combined

Coastal/Industrial Environments should be followed.

Table D

Industrial Environment Protection Option

Global Coil and Coating Options*

Severity of Environmental Factors

Low

Severe

Contaminant Concentration††

0 to 50 ppm 51 to 100 ppm >100 ppm

Corrosion Present on Other Equipment

None Present Noticeable Corrosion

Standard: Aluminum Fin / Copper Tube ACC NR NR

Microchannel Heat Exchanger† ACC NR NR

Copper Fin / Copper Tube NR NR NR

Pre-Coated Aluminum Fin / Copper Tube ACC ACC NR

E-Coated Aluminum Fin / Copper Tube ACC ACC ACC

E-Coated Microchannel Heat Exchanger† ACC ACC ACC

E-Coated Copper Fin / Copper Tube NR NR NR

ACC - Indicates that the option is acceptable for the

application and conditions shown; in some cases, the

level of corrosion protection provided by this option

may be higher than required. Acceptability is based

solely on corrosion performance. Other factors,

including cost, should be considered in making the final

selections.

NR - Not recommended

*Other coating options may be available within a given region.

†Information in this table is provided as a guide; contact a

Carrier Sales Engineer for an E-CAT selection.

††See “E-Coating Chemical Resistance Guide” in Appendix.

Testing for contaminants may be performed by Draeger tube

procedure.

Table E

Combined Coastal/Industrial Environment Protection Option

Global Coil and Coating Options*

Severity of Environmental Factors

Low

Severe

Distance from Coast**

Inland Coastline

> 5 mi 5 to 2 mi < 2 mi to <0.01 mi

Contaminant Concentration††

0 to 50 ppm 51 to 100 ppm >100 ppm

Direction of Prevailing Winds

From Unit to Coast From Coast to Unit

Corrosion Present on Other Equipment

None Present Noticeable Corrosion

Standard: Aluminum Fin / Copper Tube ACC NR NR

Microchannel Heat Exchanger† ACC NR NR

Copper Fin / Copper Tube NR NR NR

Pre-Coated Aluminum Fin / Copper Tube ACC ACC NR

E-Coated Aluminum Fin / Copper Tube ACC ACC ACC

E-Coated Microchannel Heat Exchanger† ACC ACC ACC

E-Coated Copper Fin / Copper Tube NR NR NR

ACC - Indicates that the option is acceptable for the application

and conditions shown; in some cases, the level of

corrosion protection provided by this option may be

higher than required. Acceptability is based solely on

corrosion performance. Other factors, including cost,

should be considered in making the final selections.

NR - Not recommended

*Other coating options may be available within a given region.

†Information in this table is provided as a guide; contact a

Carrier Sales Engineer for an E-CAT selection.

**Refer to the E-CAT program for exact distance requirements

for MCHX coils.

††See “E-Coating Chemical Resistance Guide” in Appendix.

Testing for contaminants may be performed by Draeger tube

procedure.

Note: The distances stated relate to land distances to ocean.

Additional coating may be required for Marine Applications on-

board a ship.

Environments immediately adjacent to diesel exhaust,

incinerator discharge stacks, fuel burning boiler stacks, or areas

exposed to fossil fuel combustion emissions should be

considered a Combined Coastal/Industrial application.

Recommendations presented for Industrial and Combined

Coastal/Industrial Environments should be followed.

Table F

Urban Environment Protection Option

Global Coil and Coating Options*

Severity of Environmental Factors

Low

Severe

Pollution Levels

(SO

levels in Cities with >50K Inhabitants)***

Low

<20 to 50 µg/m

51 to 125 µg/m

High

>125 µg/m

Corrosion Present on Other Equipment

None Present Noticeable Corrosion

Standard: Aluminum Fin / Copper Tube ACC ACC NR

Microchannel Heat Exchanger† ACC ACC NR

Copper Fin / Copper Tube NR NR NR

Pre-Coated Aluminum Fin / Copper Tube ACC ACC NR

E-Coated Aluminum Fin / Copper Tube ACC ACC ACC

E-Coated Microchannel Heat Exchanger† ACC ACC ACC

E-Coated Copper Fin / Copper Tube NR NR NR

ACC - Indicates that the option is acceptable for the application

and conditions shown; in some cases, the level of

corrosion protection provided by this option may be

higher than required. Acceptability is based solely on

corrosion performance. Other factors, including cost,

should be considered in making the final selections.

NR - Not recommended

*Other coating options may be available within a given region.

†Information in this table is provided as a guide; contact a

Carrier Sales Engineer for an E-CAT selection.

***SO

levels shall be determined in accordance with ASTM

D2914, ISO/FDIS 10498.

Note: Environments immediately adjacent to diesel exhaust,

incinerator discharge stacks, fuel burning boiler stacks, or

areas exposed to fossil fuel combustion emissions should be

considered an Industrial application. Recommendations

presented for Industrial Environments should be followed.

JOB SITE COMMISSIONING AND PROPER

EQUIPMENT STORAGE

An important factor that is often overlooked is the

proper storage of HVAC/R equipment, including

equipment with coated or uncoated coils, prior to start-

up at new installations. It is not unusual for equipment

to arrive on site several months prior to the actual

installation and start-up, resulting in a potential for

premature corrosion to occur if the equipment is not

stored in a proper manner. Equipment should be stored

so that it is not exposed to excessive construction

debris and concrete dust, industrial contaminants,

coastal contaminants, or high levels of humidity and

moisture.

Improper storage can lead to premature corrosion prior

to start-up and can reduce the overall life of the

equipment.

Extra care should be taken to ensure that equipment

located on the ground level remains free from debris

prior to start-up.

COIL MAINTENANCE AND CLEANING

RECOMMENDATIONS

Routine cleaning of coil surfaces is essential to

maintain proper operation of the unit. Elimination of

contamination and removal of harmful residues will

greatly increase the life of the coil, optimize

equipment performance, and extend the life of the unit.

Maintenance requirements and correct cleaning

procedures for MCHX and RTPF coils may be found

in the Service instructions provided with each unit and

should be followed carefully.

APPENDIX

E-Coating Chemical Resistance Guide

The coating material used for e-coat is resistant to

fumes from the chemicals listed below. However,

Carrier does not recommend direct coil immersion

service for any of these chemicals. The chemical

resistance guidelines were determined by a 24-hour

spot test exposure of the chemical listed. Resistance

was determined for these chemicals at the

concentrations identified.

E-coat is resistant to the following fumes:

NOTE: All data, statements, and recommendations are based on research

conducted by the e-coat manufacturer and are believed to be accurate. It is

the responsibility of the user to evaluate the accuracy, completeness or

usefulness of any content in this paper. Neither Carrier nor its affiliates

make any representations or warranties regarding the content contained in

this paper. Neither Carrier nor its affiliates will be liable to any user or

anyone else for any inaccuracy, error or omission, regardless of cause, or

for any damages resulting from any use, reliance or reference to the content

in this paper.

Acetates (ALL)

Cresol

Lauryl Alcohol Propylene Glycol

Acetic Acid 99%

Dichloromethane

Magnesium Chloride Salicylic Acid

Acetone

Diesel Fuel

Magnesium Sulfate Salt Water

Alcohols Diethanolamine Maleic Acid Sodium Bisulfate

Amines (ALL) Ethyl Acetate

Menthanol

Sodium Bisulfite

Amino Acids Ethyl Alcohol

Menthol

Sodium Chloride

Ammonia Ethyl Ether

Methane

Sodium Hypochlorite 5%

Ammonia Salts Fatty Acid Methyl Ethyl Ketone Sodium Hydroxide 10%

Ammonium Bisulfate Fluoride Methyl Isobutyl Ketone Sodium Hydroxide 25%

Ammonium Sulfate Fluorine Gas Methylene Chloride Sodium Sulfate

Ammonium Hydroxide

Fluorosiliac Acid

Mustard Gas Sorbitol

Benzene

Formaldehyde 27%

Naphthol Stearic Acid

Borax Fructose

Nitrate Sucrose

Boric Acid Gasoline Nitric Acid 25%

Sulfates (ALL)

Bromine Glucose Nitrogen Oxides Sulfides (ALL)

Butric Acid Glycol Nitrous Oxide Sulfites (ALL)

Butyl Alcohol Glycol Lither Olale Acid Sulfur Dioxide

Butyl Cellosolve Hydrazine

Oxalic Acid

Sulfur Oxides

Calcium Chloride Hydrochloric Acid 37% Ozone Sulfur Trioxide

Calcium Ilypochloric Hydrofluoric Acid 30% Perchloric Acid Sulfuric Acid 25-85%

Carbon Dioxide Hydrogen Fluoride Phenol 85% Starch

Carbon Disulphide Hydrogen Peroxide 5% Phosgene Terpenes

Carbon Monoxide Hydrogen Sulfide Phosphate Toluene

Chlorides Hydroxylamine Phosphoric Acid Trichloroethane

Chlorine Iodine Phenolphthalein Triethanolamine

Chlorine Dioxide Isobutyl Alcohol Phosphoric Acid Urea

Chlorine Gas Isopropyl Alcohol Potassium Chloride

Vinegar

Chloroform Kerosene Potassium Hydroxide

Volatile Organic Compounds

Chromic Acid 25% Lactic Acid Propionic Acid Xylene

Citric Acid

Lactose Propyl Alcohol

This paper is provided for informational and marketing purposes only and shall not be deemed to create any implied or express warranties

or covenants with respect to the products of Carrier Corporation or those of any third party.

04-581043-01