MCP15‐80
02
Septtember, 201
11
THE
T
TECH
T HNICA
AL TI
TIMESS Th
he Atherrion Advvantage
Qu
uality Cabine
et Construction Providess Long Life, Energy Savings, and Susstainability
Outer Coating
Electtrostatically Applied aand
Baked
d on Grey‐Green Thermal
Setting Polyester Resin Powder Paint
Fibergglass Insulation
Full 2" of 1 1//2# Density Fiberglasss
Between Panels
Outer Casing
18 G auge Corrosion Resisstant
Alum
minized Steel Sheet M
Metal
In
nner Liner
Minimum
m 20 Gauge G90
Galvanized
d Steel Sheet Metal
Outer Wall & Inner Wall Interfacess
e purpose of any product enclosure
e
is first
f
and
The
To reduce the potential for air leakage, aand/or moisture transmission between the inneer and fore
emost to prov
vide a safe, se
ecure, and prrotective
o
outer walls, all conneecting surfaces betweeen the envvironment fo
or the co
omponents of the
Overall Panel Thickness
in
nner and outer wall aare permanently sealed with 2.09" to Acco
ommodate Full 2" off
a highly durable clea
ar silicon based seala
ant. In mechanical equipment. Carreful selection
n of the
Fiberglass Insu
ulation Between Paneels
addition, all wall orr ceiling penetrationss (i.e. ention to deta
ail in the
encclosure materrials and atte
refrigerant lines,, power feeds, etc.) aare appropriately sealed
con
nstruction of the
t enclosure
e are prerequisites to
a ssuccessful de
esign. Equipment designed for
outtdoor use will be expose
ed to many varying
The combination of a corrosion resistant paint along
e
envvironmental issues such as extreme temperature
ate is often
with an aluminizzed coated steel substra
swings, wind, rain, sleet, snow, and atmospheric
c
rred
to
as
a
“
osion
resistan
nce
system”.
“duplex
corro
refer
An
nd yes, let’s
s not forget about the
e
corrrosion.
Whe
en
paint
and
aluminized
steel
are
use
ed
together,
aessthetics comp
ponent of the design. Appe
earance does
s
the ccorrosion pro
otection is sup
perior to eithe
er protection
cou
unt. The Atherion’s double wall, 2”+ th
hick insulated
d
syste
em
used
alon
ne.
cab
binet design meets
m
all of th
hese challenges and more..
All of the unit su
urfaces that are
a exposed to
o conditioned
d
ed air section
ns of the unit,
air, including retturn and mixe
e constructed of full 2”+ ins
sulated double
e wall panels.
are
This includes the roof, walls, floor, panels
s, and access
s
ors.
doo
UTER CASIN
NG – Durrable Duplex
x Corrosion
n
OU
Pro
otection System - Heavy
y Duty 18 Gauge
G
ASTM
M
A46
63 (Type 1) Aluminized Steel
S
with Ele
ectrostatically
y
App
plied and Ba
aked on Gre
ey-Green The
ermal Setting
g
Polyester Powde
er Paint.
d steel forr outer cassing parts?
Whyy aluminized
Alum
minized steel offers better ccorrosion-ressistance than
galva
anized steel because alum
minum coatin
ngs generate
a de
ense and sta
able oxide an
nd hydro-oxide film when
expo
osed to air and water. Application tests have
show
wn that alu
uminized ste
eel conforming to the
speccifications of A
ASTM A463 T
Type 1 provid
des excellent
weattherability.
However, unlike zin
nc coatings
(galvvanized coatings), aluminu
um does not provide the
galva
anic edge protection e
exhibited by galvanized
coat ings, but be
ecause Modin
ne pre-paintss all of the
arts prior to a
assembly, exp
posed edges
exterrior casing pa
are e
eliminated an
nd therefore not a concern..
MCP15‐802
M
Modinee Manufacturing Company ‐Septtember, 2011 Experience has shown that aluminized steel is easier
to clean and pre-treat in preparation for painting than
galvanized steel and it is a better substrate for
achieving an even and high quality paint adhesion
system during the painting process. In addition,
aluminized steel does not contain the heavy metal
“zinc” which can be an environmental concern. Zinc is
listed by the Environmental Protection Agency as one
of 129 priority pollutants. The application of paint onto
a hot dip galvanized surface requires careful surface
preparation and a good understanding of both the
preparation of the galvanized steel surface and the
compatibility of the paint being applied. The margin for
error is very small when dealing with newly galvanized
steel surface preparation. When galvanized steel is
pre-treated (which is a prerequisite for good paint
adhesion) some of the zinc coating is removed during
the pre-cleaning and abrading process and this
contaminant can enter into water and waste-water
systems. Elevated concentrations of zinc in water are
particularly toxic to many species of algae and
crustaceans. Elevated concentrations of zinc in water
have especially strong impacts on macroinvertebrates
such as mollusks and crustaceans.
The use of
aluminized steel for painted parts eliminates these
concerns.
Why Polyester Powder Paint (and Subsequent Paint
System Analysis Under ASTM D1654, ASTM B117
and ASTM 3359, Method B, ASTM D3363 ASTM
D552, ASTM, ASTM D4587, G151 and G154)?
Powder coating is a type of coating that is applied as a
free-flowing, dry powder. The coating is typically
applied electrostatically and is then cured under heat to
allow it to flow and form a "skin".
Powder paint
creates a hard finish that is tougher than conventional
paint and is used mainly for coating metals. Modine
powder paint also includes UV inhibitors to reduce
coating breakdown over time. Powder coatings emit
zero or near zero volatile organic compounds. This is
good for the environment. In addition, overspray can
be captured and recycled, and powder coating
production lines produce less hazardous waste than
conventional liquid coating lines. Polyester powder
paint is also less permeable to moisture and is ideal for
outdoor applications.
It is critical that the corrosion resistance and adhesion
quality of the painting process be included in any
analysis of the duplex corrosion resistance system.
This is why Modine has developed a painting system
specification that not only tests the durability of the
P a g e | 2 paint itself, but also tests the durability of the entire
duplex corrosion protection system, including the metal
cleaning, preparation, and application processes
involved. Painted test panels are prepared per ASTM
D1654 Standard Test Method for Evaluation of Painted
or Coated Specimens. Test panels are scribed
diagonally prior to testing. These specimens are then
tested in a salt spray/fog environment per ASTM B-117
which covers the apparatus, procedure, and conditions
required to create and maintain the salt spray (fog) test
environment. Breakdown of the paint film in excess of
10% constitutes a test failure. Film breakdown includes
corrosion spots and/or blisters and is judged by using a
6.4mm (1/4-in) transparent overlay and calculating the
percentage of squares that contain corrosion spots
and/or blisters. Film breakdown within 6.4 mm (1/4 in)
of the diagonal scribe is ignored. Average creepage
from the diagonal scribe in excess of 3.2 mm (1/8 in)
constitutes a failure. ASTM B-117 does not prescribe
the type of test specimen or exposure periods to be
used for a specific product, nor the interpretation to be
given to the results. Simply stating a painted panel has
survived under ASTM B117 salt spray/fog test
environment tells nothing about how the specimen was
prepared (i.e. did it include diagonal scribes, and/or
cross hatching for evaluation of the entire painting
system and processes?)
If a coating is to fulfill its function of protecting or
decorating a substrate, it must adhere to the substrate
for the expected service life of the equipment. Because
the substrate and its surface preparation (or lack of it)
have a drastic effect on the adhesion of coatings, a
method to evaluate adhesion of a coating to different
substrates is very important. Recognizing this Modine
subjects painted test panels to ASTM 3359, Method B
and requires the panel to have a rating of “5B” in the
1.6-mm (1/16-in) crosshatch tape adhesion test along
with the following physical characteristic tests.
Hardness - A painted test panel shall show a film
hardness of “2H” minimum in the gouge hardness test
(Ref ASTM D3363).
Flexibility - A painted test panel shall show no film
cracking during a 180°-flexibility test around a 3.2-mm
(1/8-in) mandrel (Ref ASTM D 522, Method B).
UV Resistance - A painted test panel shall withstand
1000 ± 5 hours exposure in a QUV Weatherability
Chamber utilizing UVA-340 lamps. Cabinet operation
MCP15‐802 Modine Manufacturing Company ‐September, 2011 to consist of continuous cycles with four hours UV
exposure at 60 °C (140 °F) followed by four hours
condensation at 50 °C (122 °F). The paint film shall not
blister, show more than 30% loss of gloss, or exhibit
total color difference. (Ref: ASTM D 4587, G 151, G
154).
Because of the wide range of available R value
designs, it is important to know which R-value designs
are being compared when energy savings claims are
being made. The savings between an R-2 enclosure
and an R-13 enclosure is going to be much different
than between an R-8 and R-13 enclosure.
Discoloration - A painted test panel shall withstand a
minimum of 80 hours at 191 °C (375 °F) without
discoloration.
Figures 3.1 and 3.2 graphically represent the added
cooling load and estimated added cooling costs
associated with heat gains and losses through a typical
cabinet of a 15-30 ton packaged rooftop cooling unit
located in Atlanta, Georgia. It is assumed that the unit
is configured for 100% return air. The graphs show the
average cooling temperatures and hours of duration at
each temperature for a typical Atlanta cooling season.
Figure 3.1 shows the added cooing load in BTU’s, and
Figure 3.2 shows the estimated added cooling cost at
each temperature and hours of operation data point
(assuming an energy cost of $0.08/kW). It is clearly
evident that the much lower R2 value unit construction
has relatively high thermal losses when compared to
cabinets with R8 through R13 construction. However
the differences between R8 and R13 construction are
almost negligible.
Conclusion - The use of a highly corrosion-resistant
and environmentally friendly aluminized steel substrate
along with a technically advanced baked-on thermal
setting polyester resin power paint system provides an
attractive and long lasting, durable, duplex corrosion
resistant outer casing system for the Modine Atherion
unit.
INSULATION – 2” R8 Fiberglass insulation between
outer and inner casing wall, floor and roof panels
provides energy savings over lower R-value insulating
systems. Just as adding insulation to a home or
building can offer substantial energy savings compared
to a lesser insulated building, the same is true for
mechanical HVAC equipment.
The Atherion ventilation system conditions outside air
in both the heating and cooling modes, and once
conditioned it is important not to lose the energy in the
conditioned air back to the environment via thermal
losses through the unit’s cabinet. The Atherion’s 2”
double-wall fiberglass insulated cabinet design offers a
thermal resistance value of approximately R-8. This is
a very good R-value for outdoor mechanical
equipment. Some older unit cabinet construction
methods provided R-values as low as R-2, which left a
lot of room for improvement. Current day, higher
quality HVAC equipment is usually designed with Rvalues in the range of R4 to R13. To economically
achieve an insulation value of R13 in a 2” thickness
configuration it almost always requires the use of
petroleum based polyurethane foam insulations.
Fiberglass insulation can offer values of around R8 or
slightly higher.
P a g e | 3 Be alert to savings claims that only provide information
relative to older lower R-2 construction methods but do
not provide comparative information relative to current
day improved double-wall cabinet construction
methods. The cooling savings for R-8 through R13
rated cabinets are substantial when compared to R-2
cabinet systems, but the savings between R8 through
R13 are relatively small.
Figure 3.1
MCP15‐802 Added Cooling Load (BTU's) from Cabinet Thermal Gains/Losses
Based on 15‐30 Ton Unit Casing ‐ Atlanta, GA
R2
R8
R9
R13
1,200,000
1,000,000
BTU's
Modine’s baked-on polyester powder paint test panels
have to pass all of the aforementioned test criteria
before the paint material and application methods are
acceptable.
800,000
600,000
400,000
200,000
0
‐200,000
Outdoor Fo 97
92
87
82
77
72
67
Hrs per Yr 9 32 220 758 768 1037 1162
Modine Manufacturing Company ‐September, 2011 made from recyclable plastic materials. Polystyrene
foams require the use of hydrochloro-fluorocarbons,
which are less dangerous to the Earth's ozone layer
than the old chlorofluorocarbons but still cause some
damage.
Figure 3.2
Added Cooling Cost from Cabinet Thermal Gains/Losses
Based on 15‐30 Ton Unit Casing ‐ Atlanta, GA
R2
R8
R9
R13
$26.00
$21.00
A review of a typical “Material Safety Data Sheet” for
polyurethane under “Regulatory Information” states:
Dollars
$16.00
$11.00
$6.00
$1.00
‐$4.00
92
87
82
77
72
67
Outdoor Fo 97
Hrs per Yr 9 32 220 758 768 1037 1162
Why Fiberglass Insulation? As seen earlier, fiberglass
can provide relatively high R-values for HVAC
cabinetry. Polyurethane, if properly protected against
thermal drift has a higher R-value per inch of thickness
than fiberglass, but polyurethane does have some
downsides. Fiberglass is an environmentally friendly
and sustainable insulating material. The basic raw
materials for fiberglass products are a variety of natural
minerals and some manufactured chemicals. The
major ingredients are silica sand, limestone, and soda
ash. Silica sand is used as the glass former, and soda
ash and limestone help primarily to lower the melting
temperature. Other ingredients are used to improve
certain properties, such as borax for chemical
resistance. Waste glass, called cullet, is also used as a
raw material. Fiberglass is not petroleum based,
therefore it offers greater sustainability and is
environmentally friendlier than expanded foam options.
A review of the “Material Safety Data Sheet” for
fiberglass, under “Regulatory Information” states;
Regulatory Information - US Federal Regulations: A: General
Product Information - SARA 311/31
This product is not classified as hazardous under SARA
311/312.
And further under OSHA;
OSHA/HCS Status
Fiberglass is treated as a nuisance dust and is regulated by
OSHA as a particulate not otherwise regulated (total dust)
shown in CFR 1910.1000
In contrast to fiberglass, the production of rigid foam
insulation requires the use of petroleum based
products, which if not properly handled can produce
significant environmental issues. Most foam insulation
products are also difficult to recycle, though some are
P a g e | 4 Regulatory Information - US Federal Regulations: A: General
Product Information - SARA 311/31
SARA 311/312 MSDS distribution - chemical inventory hazard identification: Butane, 2- methyl-: fire hazard flammable, combustible liquid, pyrophoric Cyclopentane: fire
hazard - flammable, combustible liquid, pyrophoric Pentane:
acu, fire hazard - flammable, combustible liquid, pyrophoric
Aluminum: fire hazard - flammable, combustible liquid,
pyrophoric, rea.
SARA 311/312 Product Classification: Immediate (acute)
health hazard. Delayed (chronic) health hazard.
And further under OSHA
OSHA/HCS Status
This material is considered hazardous by the OSHA Hazard
Communication Standard (29 CFR 1910.1200).
Conclusion – The use of fiberglass insulation provides
high R-value cabinetry construction without the
necessity of using petroleum based insulating material.
Fiberglass manufacturing involves far less chemicals
than the manufacture of polyurethane foam and
therefore is overall more environmentally friendly.
Fiberglass is not regulated as a hazardous waste, it is
recyclable, and it is made from sustainable materials.
INNER LINERS – Minimum 20 Gauge G90 Galvanized
Sheet Steel (Base steel per ASTM Standard
Specification A924 and A653, Galvanized coating
thickness when tested per ASTM Standard Test
Method A 90 shall be a minimum of Z275(G90).
Why galvanized steel for inner liners? As discussed
earlier, galvanized coated steel provides better
galvanic corrosion edge protection.
During the
fabrication process the steel is sheared, punched, and
formed and can be scratched. Galvanized steel tends
to be self-healing and the coating tends to wipe over
the processed edges during fabrication. Because the
inner liners are not painted, this characteristic is
important for maintaining the overall corrosion
resistance of the inner liners, and because these parts
are not painted the better paint adhesion qualities of
aluminized steel is not needed.
MCP15‐802 Modine Manufacturing Company ‐September, 2011 Conclusion – The use of galvanized steel for the inner
liners is the best choice when the material is not
intended to be painted, but must still provide good
corrosion protection and cleanability.
OUTER WALL AND INNER WALL INTERFACES - To
reduce the potential for air leakage, and or moisture
transmission between the inner and outer walls, all
connecting surfaces between the inner and outer wall
are permanently sealed with a highly durable clear
silicon based sealant. In addition, all wall or ceiling
penetrations (i.e. refrigerant lines, power runs, etc.) are
appropriately sealed.
Inner Liners – All conditioned air wall, ceiling, and floor
surfaces are lined with robust minimum 20 gauge G90
galvanized steel. All interfaces between the inner liner
and outer casing parts, and all joints between casing
parts are sealed with durable, long lasting silicon
based sealant to minimize moisture and/or air
infiltration and/or exfiltration.
Power and Control Wiring Interfaces – All main power
and control wiring runs are made between the roof and
inner roof liners to keep the interior of the unit free from
electrical runs thus providing unobstructed access to
the unit’s interior during maintenance and cleaning.
POWER AND CONTROL WIRING INTERFACES – All
main power and control wiring runs are made within
the area between the roof outer casing and the roof
inner liners to keep the interior of the unit free from
electrical runs thus providing unobstructed access to
the unit’s interior during maintenance and cleaning.
Individual component power and control runs are fed
down from the inner roof with drop downs at the point
of usage of each of the components.
SUMMARY – Modine’s Atherion products are provided
with a highly durable, aesthetically pleasing, and
thermally efficient cabinet that maximizes the thermal
efficiency of the units, uses sustainable and
environmentally friendly materials wherever possible,
provides maximum protection for the unit components,
has excellent weatherability, and is designed to be
service and maintenance friendly.
Paint – Electrostatically applied and baked on greygreen thermal setting polyester resin powder paint.
Outer Casing – All casing parts are painted prior to
assembly. This assures full paint coverage on both the
interior and exterior surfaces of the sheet metal parts
and all edges and all fastener holes. The casing is
made from heavy duty 18 Gauge Aluminized Steel and
which is cleaned of all surface oil and debris prior to
painting. After parts are powder coated, they are
baked cured for a long lasting durable finish.
Insulation – All conditioned air wall, ceiling, and floor
surfaces are insulated with a full 2 inches of 1 ½#
density fiberglass insulation providing an insulation
value of at least R-8 for the double wall and insulated
cabinet.
P a g e | 5 MCP15‐802 Modine Manufacturing Company ‐September, 2011